What's hot today: Current papers in developmental biology and gene function

What's hot today:
Current papers in developmental biology and gene function

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Friday, December 5th - Genes and Proteins

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Roy, M. V., Neal, S. J., Pignoni, F. (2025). The third intracellular loop of Drosophila Lilipod is required for protein function in vivo and can mediate protein-protein interactions in vitro. PLoS One, 20(6):e0325326 PubMed ID: 40465773
Summary:
zzThe evolutionarily conserved Lipocalin-Interacting Membrane Receptor (LIMR) family (InterPro: IPR006876) consists of transmembrane (TM) proteins characterized by 9 TM domains (TMDs). Their reported biological functions are diverse and remain poorly understood. Previous work showed that the fly family member Lilipod (Lili) impacts biological processes regulated by the fly BMP/TGF-β ligand Decapentaplegic (Dpp), including germline stem cell self-renewal in the Drosophila ovary, dorsal closure during embryonic development and wing vein formation at the pupal stage. Based on this genetic evidence, Lili directly or indirectly enhances bone morphogenetic protein (BMP) signaling. In the ovary, Lili functions between the activated type I BMP receptor and the SMAD intracellular transducer. To gain insight into Lili function at the cellular and molecular levels, the functional significance of its largest intracellular loop, Intracellular Loop 3 (ICL3) was probed. Through mutational analysis, sequences critical for Lili function in vivo were mapped to the evolutionarily conserved regions of ICL3. Additionally, fly-human chimeric proteins in which Lili ICL3 is replaced with the ICL3 of its human homologs, LMBR1 and LMBR1L, can rescue lili null-mutant phenotypes. Using ICL3 as bait in an unbiased Yeast 2-Hybrid (Y2H) screen, putative interactors, including the BMP signaling cascade components Mad, Sara, Nup93 and Nup358 were identified, and further Y2H analyses identified distinct regions on ICL3 as potentially important for protein binding. Taken together, this work has identified ICL3 as a region that is critical for Lili protein function, most likely via its mediation of protein-protein interactions (PPIs).

Chen, W., Laremore, T. N., Yennawar, N. H., Showalter, S. A. (2025). Phosphorylation modulates secondary structure of intrinsically disorder regions in RNA polymerase II. J Biol Chem, 301(6):108533 PubMed ID: 40273986
Summary:
The intrinsically disordered C-terminal domain (CTD) of RNA polymerase II contains tandem repeats with the consensus sequence YSPTSPS and coordinates transcription and cotranscriptional events through dynamic phosphorylation patterns. While it has been long hypothesized that phosphorylation induces structural changes in the CTD, a direct comparison of how different phosphorylation patterns modulate the CTD conformation has been limited. Two distinct phosphorylation patterns were created in an essential Drosophila CTD region with the kinase Dyrk1a: one where Ser2 residues are primarily phosphorylated, mimicking the state near transcription termination, and a hyperphosphorylation state where most Ser2, Ser5, and Thr residues are phosphorylated, expanding on previous work on Ser5 phosphorylation, which mimics early transcription elongation. Using (13)C Direct-Detect NMR, the CTD was shown to tend to form transient beta strands and beta turns, which are altered differently by Ser2 and Ser5 phosphorylation. Small-angle X-ray scattering revealed no significant changes in the CTD global dimensions even at high phosphorylation levels, contradicting the common assumption of phosphorylation-induced chain expansion. These findings support a transient beta model in which unphosphorylated CTD adopts transient beta strands at Ser2 during transcription preinitiation. These transient structures are disrupted by Ser5 phosphorylation in early elongation, and later restored by Ser2 phosphorylation near termination for recruiting beta turn-recognizing termination factors.

Sullivan, K. G., Bashaw, G. J. (2025). Commissureless acts as a substrate adapter in a conserved Nedd4 E3 ubiquitin ligase pathway to promote axon growth across the midline. Elife, 13 PubMed ID: 40407164
Summary:
In both vertebrates and invertebrates, commissural neurons prevent premature responsiveness to the midline repellant Slit by downregulating surface levels of its receptor Roundabout1 (Robo1). In Drosophila, Commissureless (Comm) plays a critical role in this process; however, there is conflicting data on the underlying molecular mechanism. This study demonstrates that the conserved PY motifs in the cytoplasmic domain of Comm are required allow the ubiquitination and lysosomal degradation of Robo1. Disruption of these motifs prevents Comm from localizing to Lamp1 positive late endosomes and to promote axon growth across the midline in vivo. In addition, this study conclusively demonstrates a role for Nedd4 in midline crossing. Genetic analysis shows that nedd4 mutations result in midline crossing defects in the Drosophila embryonic nerve cord, which can be rescued by introduction of exogenous Nedd4. Biochemical evidence shows that Nedd4 incorporates into a three-member complex with Comm and Robo1 in a PY motif-dependent manner. Finally, genetic evidence is presented that Nedd4 acts with Comm in the embryonic nerve cord to downregulate Robo1 levels. Taken together, these findings demonstrate that Comm promotes midline crossing in the nerve cord by facilitating Robo1 ubiquitination by Nedd4, ultimately leading to its degradation.

Rickle, A., Sudhakar, K., Booms, A., Stirtz, E., Lempradl, A. (2025). More than meets the eye: mutation of the white gene in Drosophila has broad phenotypic and transcriptomic effects. Genetics, 230(3) PubMed ID: 40380877
Summary:
The white gene, one of the most widely used genetic markers in Drosophila research, serves as a standard background mutation for transgene insertions and genetic manipulations. While its primary function involves eye pigmentation, mutations in white have been associated with diverse phenotypic effects, including those related to metabolism, behavior, and stress responses. However, many of the published studies do not account for differences in genetic background, raising concerns about the interpretation of experimental results. To address this, fly lines were generated through 10 generations of backcrossing that are highly genetically similar except at the white locus, minimizing background variation. Given the likely metabolic consequences of white gene deletion and its role in neurotransmitter production, this study focused on behavioral, metabolic, and fitness-related traits and performed transcriptomic analysis on adult fly heads. Our findings both confirm and refine previous observations, revealing that some reported effects of white mutation are robust while others likely reflect underlying genetic background differences. These results emphasize the necessity of genetic background control in Drosophila research and warrant caution when using white mutants as a baseline for comparative studies.

Blanch, J. R., Woodward, N., Krishnamurthy, M., McVey, M. (2025). A non-tethering role for the Drosophila Pol theta linker domain in promoting damage resolution. Nucleic Acids Res, 53(8) PubMed ID: 40275613
Summary:
DNA polymerase theta (Pol Θ) is an error-prone translesion polymerase that becomes crucial for DNA double-strand break repair when cells are deficient in homologous recombination or non-homologous end joining. In some organisms, Pol Θ also promotes tolerance of DNA interstrand crosslinks. Due to its importance in DNA damage tolerance, Pol Θ is an emerging target for treatment of cancer and disease. Prior work has characterized the functions of the Pol Θ helicase-like and polymerase domains, but the roles of the linker domain are largely unknown. This study shows that the Drosophila melanogaster Pol Θ linker domain promotes proper egg development and is required for repair of DNA double-strand breaks and interstrand crosslink tolerance. While a linker domain with scrambled amino acid residues is sufficient for DNA repair, replacement of the linker with part of the Homo sapiens Pol @Theta; linker or a disordered region from the FUS RNA-binding protein does not restore function. These results demonstrate that the linker domain is not simply a random tether between the catalytic domains and suggest that intrinsic amino acid residue properties, rather than protein interaction motifs, are more critical for Pol Θ linker functions in DNA repair.

Pachinger, C., Dobbelaere, J., Rumpf-Kienzl, C., Raina, S., Garcia-Baucells, J., Sarantseva, M., Brauneis, A., Dammermann, A. (2025). A conserved role for centriolar satellites in translation of centrosomal and ciliary proteins. J Cell Biol, 224(8) PubMed ID: 40396915
Summary:
Centriolar satellites are cytoplasmic particles found in the vicinity of centrosomes and cilia whose specific functional contribution has long been unclear. This study identified Combover as the Drosophila ortholog of the main scaffolding component of satellites, PCM1 [Pericentrin-like protein (PLP)]. Like PCM1, Combover localizes to cytoplasmic foci containing centrosomal proteins and its depletion or mutation results in centrosomal and ciliary phenotypes. Strikingly, however, the concentration of satellites near centrosomes and cilia is not a conserved feature, nor do Combover foci display directed movement. Proximity interaction analysis revealed not only centrosomal and ciliary proteins, but also RNA-binding proteins and proteins involved in quality control. Further work in Drosophila and vertebrate cells found satellites to be associated with centrosomal and ciliary mRNAs, as well as evidence for protein synthesis occurring directly at satellites. Given that PCM1 depletion does not affect overall protein levels, it is proposed that satellites instead promote the coordinate synthesis of centrosomal and ciliary proteins, thereby facilitating the formation of protein complexes. `

Thursday, December 4th - Immune response

Toubarro, D., Kenney, E., Heryanto, C., Mallick, S., Simoes, N., Eleftherianos, I. (2025). Heterorhabditis bacteriophora Extracellular Vesicles Alter the Innate Immune Signaling in Drosophila melanogaster. Genes (Basel), 16(6) PubMed ID: 40565505
Summary:
Heterorhabditis bacteriophora entomopathogenic nematodes are commonly used in agricultural practices for the biological control of insect pests. These parasites are also used in basic research for unveiling the molecular basis of nematode parasitism in relation to the insect anti-nematode response. H. bacteriophora excreted-secreted products have been shown to reduce the expression of the antimicrobial peptide gene Diptericin in Drosophila melanogaster, which increases fly mortality due to enhanced propagation of the mutualistic bacteria Photorhabdus luminescens. However, the effect of entomopathogenic nematode extracellular vesicles (EVs) on the insect host defense remains unknown. This study injected adult flies with H. bacteriophora EVs and used quantitative RT-PCR together with gene-specific primers to analyze the activity of immune-related signaling pathways. H. bacteriophora EVs were found to be lethal to Drosophila melanogaster, and they downregulate the expression of Attacin, Cecropin, and Prophenoloxidase 3 in adult flies. These findings build on previous knowledge and strengthen the notion that H. bacteriophora entomopathogenic nematodes release a variety of effector molecules to modify the insect's innate immune signaling. This information is important because it contributes toward clarifying the molecular interplay between entomopathogenic nematode components and the host's innate immune system.

Bi, H., Guo, W., Lu, S., Zhang, H., Liu, Y., Lu, Q., Dong, M., Li, S., Feng, C. (2025). Eiger pleiotropically regulates the immunity of Ostrinia furnacalis larvae. Insect Sci, PubMed ID: 40601501
Summary:
The tumor necrosis factor (TNF) receptor superfamily is a set of essential inflammatory cytokines. In Drosophila, as a homolog of TNF, Eiger was first identified, which is involved in innate immunity signaling pathways. However, in Lepidoptera, the functions of Eiger and its molecular regulatory mechanisms on immune responses are unknown. In this study, Eiger was cloned from Ostrinia furnacalis. OfEiger has a conserved structural domain of the TNF family. The expression of OfEiger increased with the age of O. furnacalis larvae, and was the highest in the hemocytes. After O. furnacalis larvae were injected with Pseudomonas aeruginosa or Micrococcus luteus, the expression of OfEiger was significantly upregulated. The expression levels of several genes in the immune pathways of O. furnacalis larvae were downregulated at 60 h post-injection of double-stranded Eiger (dsEiger), including IMD, Toll, nitric oxide (NO), and mitogen-activated protein kinase (MAPK) signaling pathways. Moreover, the expression levels of the 4 antimicrobial peptides (AMPs), OfLebocin, OfAttacin, OfGloverin, and OfMoricin, were downregulated. In addition, the phagocytosis of Escherichia coli by hemocytes was reduced in O. furnacalis larvae after dsEiger injection. Injections of P. aeruginosa or M. luteus into O. furnacalis larvae following OfEiger RNA interference reduced the larvae's survival rate and increased the expression levels of OfMyD88 and OfJNK. Still, they suppressed the expression of OfNOS1 and AMP genes and inhibited phenoloxidase (PO) activity in O. furnacalis larvae. In conclusion, OfEiger is a vital insect immune regulator, which synergistically regulates IMD, Toll, NO, and MAPK signaling pathways and adjusts PO activity, cellular immunity, AMPs, and other effectors.

Arora, S., Critchley, G., Dekmak, A. S., Miesenbock, G., Kempf, A., Ligoxygakis, P. (2025). Loss of the NF-kappaB negative regulator Pirk in Drosophila links brain and gut immunity to neurodegeneration. Brain Commun, 7(2):fcaf144 PubMed ID: 40599166
Summary:
A gut-brain axis influenced by host innate immunity and resident microbiota has been implicated in neurological conditions including Alzheimer's disease. However, the precise connection of innate immunity to Alzheimer's disease remains unclear. Using Pirk, a negative regulator of the IMD/NF-kappaB pathway in Drosophila, the neurological phenotypes induced when genetically predisposing flies to chronically over-active immunity were studied. Pirk mutants exhibited age-dependent neurological phenotypes such as reduced locomotion and altered sleep patterns coupled to an increased number of brain lesions. Gut-specific pirk-RNA interference led to earlier onset of the neurological phenotypes which, alongside changes in intestinal bacteria in pirk mutants, highlighted a potential early role for the intestinal ecosystem in the onset of neurodegeneration. In contrast, glia-specific RNA interference of pirk resulted in late onset of the relevant phenotypes suggesting a later contribution of the nervous system to the underlying neuropathology. Knockout of the antimicrobial peptide (AMP) gene AttacinD or rearing flies in axenic conditions recovered some of the neurological phenotypes, suggesting both chronic AMP gene expression as well as gut bacteria changes as mediators. These results indicate an evolutionarily conserved path to neurodegeneration linked to dysregulated immunity. They also reveal that in this context, age-dependent neurodegeneration can happen in less complex non-vertebrate brains in the absence of beta-amyloid or tau aggregation.

Li, H., Zhao, Q., Xu, J., Li, X., Chen, X., Zhang, Y., Li, H., Zhu, Y., Liu, M., Zhao, L., Hua, D., Zhang, X., Chen, K. (2025). From Biomphalaria glabrata to Drosophila melanogaster and Anopheles gambiae: the diversity and role of FREPs and Dscams in immune response. Front Immunol, 16:1579905 PubMed ID: 40370466
Summary:
Fibrinogen-related proteins (FREPs) and Down syndrome cell adhesion molecules (Dscams; see Drosophila Dscam) are important immune-related molecules in invertebrates. Although they are found in different taxonomic groups and possess unique functions, both exhibit high diversity and adaptability. FREPs are characterized by their fibrinogen-related domains and have been primarily studied in mollusks, such as Biomphalaria glabrata. Through mechanisms of diversity generation, such as gene conversion and point mutations, BgFREP plays a critical role in the host's defense against parasites. Dscams are immunoglobulin-like transmembrane proteins, mainly studied in arthropods, such as Drosophila melanogaster and Anopheles gambiae. Through alternative splicing, Dscams generate multiple isoforms that participate in pathogen recognition and the precise wiring of neural circuits. In D. melanogaster, DmDscam plays a role not only in neuronal self-recognition but also in pathogen recognition. In A. gambiae, AgDscam defends against parasite infections, by binding to pathogens and mediating phagocytosis. This paper highlights the key roles of FREPs and Dscams in the immunity of two major invertebrate groups-mollusks and arthropods-and summarizes the main advancements in current research. These studies not only deepen the understanding of invertebrate immune mechanisms but also lay a solid foundation for future exploration of their potential applications in the biomedical field.

Wei, Y., Jia, W., Sun, Y., Zhang, T., Miao, H., Wu, Z., Dong, R., Ning, F., Kim, W. J. (2025). Investigating the immunomodulatory effects of honeybee venom peptide apamin in Drosophila platforms. Infect Immun, 93(7):e0013125 PubMed ID: 40470946
Summary:
Apamin, an 18-amino-acid honeybee venom peptide, although traditionally recognized for its neurotoxic effects, demonstrates potent antimicrobial properties when genetically expressed in Drosophila. This antimicrobial efficacy is independent of its disulfide bonds and is enhanced when the peptide is membrane-tethered. Apamin selectively inhibits pathogenic bacteria, such as Pseudomonas aeruginosa, Enterococcus faecalis, and Escherichia coli, while promoting beneficial bacteria like Lactobacillus plantarum, thereby improving the gut microbiome. This gut-localized antimicrobial activity is associated with increased intestinal stem cell proliferation, midgut acidification, and enteroendocrine cell calcium signaling. Furthermore, apamin's antimicrobial function relies on specific peptidoglycan recognition proteins, particularly PGRP-LA and PGRP-SCs. Apamin expression alone is sufficient to restore the integrity of the gut barrier compromised by stressful conditions. Ultimately, apamin supplementation enhances honeybee gut health in the presence of ingested bacteria. The expression of other honeybee antimicrobial peptides also significantly reduces bacterial infection in flies. Overall, this study provides a comprehensive understanding of honeybee venom peptides and antimicrobial peptides functions, utilizing the Drosophila model system to unravel their mechanisms of action and therapeutic potential.

Chauhan, M., Martinak, P. E., Hollenberg, B. M., Goodman, A. G. (2025). Drosophila melanogaster Toll-9 elicits antiviral immunity against Drosophila C virus. J Virol, 99(6):e0221424 PubMed ID: 40366172
Summary:
The Toll pathway plays a pivotal role in innate immune responses against pathogens. The evolutionarily conserved pattern recognition receptors (PRRs), including Toll-like receptors (TLRs), play a crucial role in recognition of pathogen-associated molecular patterns (PAMPs). The Drosophila genome encodes nine Toll receptors that are orthologous to mammalian TLRs. While mammalian TLRs directly recognize PAMPs, most Drosophila Tolls recognize the proteolytically cleaved ligand Spatzle to activate downstream signaling cascades. This study demonstrates that Toll-9 is crucial for antiviral immunity against Drosophila C virus (DCV), a natural pathogen of Drosophila. A transposable element insertion in the Toll-9 gene renders the flies more susceptible to DCV. The stable expression of Toll-9 in Drosophila S2 cells results in increased Dicer2 induction and reduced AKT phosphorylation, collectively establishing an antiviral state that inhibits DCV replication. Toll-9 localizes to endosomes, where it binds viral double-stranded RNA (dsRNA), highlighting its role in detecting viral replication intermediates. Together, these findings identify Toll-9 as a key player in antiviral immunity against DCV infection, acting through its ability to recognize dsRNA and drive Dicer2 expression, along with other AKT-mediated antiviral responses.

Wednesday, December 3rd - Evolution

Yamashita, H., Matsumoto, T., Kawashima, K., Abdulla Daanaa, H. S., Yang, Z., Akashi, H. (2025). Dinucleotide preferences underlie apparent codon preference reversals in the Drosophila melanogaster lineage. Proc Natl Acad Sci U S A, 122(21):e2419696122 PubMed ID: 40402244
Summary:
Fine-scale population genetic analyses was used to reveal dynamics among interacting forces that act at synonymous sites and introns among closely related Drosophila species. Synonymous codon usage bias has proven to be well suited for population genetic inference. Under major codon preference (MCP), translationally superior "major" codons confer fitness benefits relative to their less efficiently and/or accurately decoded synonymous counterparts. Codon family and lineage-specific analyses expand on previous findings in the Drosophila simulans lineage; patterns in naturally occurring polymorphism demonstrate fixation biases toward GC-ending codons that are consistent in direction, but heterogeneous in magnitude, among synonymous families. These forces are generally stronger than fixation biases in intron sequences. In contrast, population genetic analyses reveal unexpected evidence of codon preference reversals in the Drosophila melanogaster lineage. Codon family-specific polymorphism patterns support reduced efficacy of natural selection in most synonymous families but indicate reversals of favored states in the four codon families encoded by NAY [The four-codon families (known as 4-fold degenerate families or quartets] encoded by the general mRNA codon sequence NAY (where N is any nucleotide, A is adenine, and Y is a pyrimidine, C or U) are primarily those for the amino acids: alanine, proline, threonine and valine. Accelerated synonymous fixations in favor of NAT (The "NAT" in this context refers to codons ending in A or T) and greater differences for both allele frequencies and fixation rates among X-linked, relative to autosomal, loci bolster support for fitness effect reversals. The specificity of preference reversals to codons whose cognate tRNAs undergo wobble position queuosine modification is intriguing. However, this analyses revealed prevalent dinucleotide preferences for ApT over ApC that act in opposition to GC-favoring forces in both coding and intron regions. Evidence is presented that changes in the relative efficacy of translational selection and dinucleotide preference underlie apparent codon preference reversals.

Antunes, M. A., Grandela, A., Matos, M., Simoes, P. (2025). Long-term evolution experiments fully reveal the potential for thermal adaptation. J Therm Biol, 129:104118 PubMed ID: 40305922
Summary:
Evolutionary responses may be crucial in allowing organisms to cope with prolonged effects of climate change. However, a clear understanding of the dynamics of adaptation to warming environments is still lacking. Addressing how reproductive success evolves in such deteriorating environments is extremely relevant, as this trait is constrained at temperatures below critical thermal limits. Experimental evolution under a warming environment can elucidate the potential of populations to respond to rapid environmental changes. The few studies following such framework lack analysis of long-term response. This study focused on the long-term thermal evolution of two Drosophila subobscura populations, from different European latitudes, under warming temperatures.Reproductive success of these populations was tested in the ancestral (control) and warming environment after ~50 generations of thermal evolution. A general adaptive response was found to warming temperatures in the long term, since populations evolving in the warming environment showed increased performance in that environment relative to the respective control populations. On the other hand, no clear response was observed in the ancestral environment. Coupled with data from previous generations, this study highlighted a slow pace of adaptive response and differences in that response between populations of distinct histories. These findings demonstrate the need of long-term evolution experiments to fully reveal the potential for thermal adaptation. It also highlights that the scrutiny of different populations is needed as a measure of variation in evolutionary responses within a species. Accounting for these sources of variation - both temporal and spatial - will allow for more robust assessments of climate change evolutionary responses.

Mullinax, S. R., Darby, A. M., Gupta, A., Chan, P., Smith, B. R., Unckless, R. L. (2025). A suite of selective pressures supports the maintenance of alleles of a Drosophila immune peptide. Elife, 12 PubMed ID: 40445192
Summary:
The innate immune system provides hosts with a crucial first line of defense against pathogens. While immune genes are often among the fastest evolving genes in the genome, in Drosophila, antimicrobial peptides (AMPs) are notable exceptions. Instead, AMPs may be under balancing selection, such that over evolutionary timescales, multiple alleles are maintained in populations. This study, focused on the Drosophila AMP Diptericin A, which has a segregating amino acid polymorphism associated with differential survival after infection with the Gram-negative bacteria Providencia rettgeri. Diptericin A also helps control opportunistic gut infections by common Drosophila gut microbes, especially those of Lactobacillus plantarum. In addition to genotypic effects on gut immunity, we also see strong sex-specific effects that are most prominent in flies without functional diptericin A. To further characterize differences in microbiomes between different diptericin genotypes, 16S metagenomics was used to look at the microbiome composition. Both lab-reared and wild-caught flies were used for sequencing and overall composition as well as the differential abundance of individual bacterial families were looked at. Overall, flies were found that are homozygous for one allele of diptericin A are better equipped to survive a systemic infection from P. rettgeri, but in general have a shorter lifespans after being fed common gut commensals. These results suggest a possible mechanism for the maintenance of genetic variation of diptericin A through the complex interactions of sex, systemic immunity, and the maintenance of the gut microbiome.

Thorholludottir, D. A. V., Hsu, S. K., Barghi, N., Mallard, F., Nolte, V., Schlotterer, C. (2025). Reduced Parallel Gene Expression Evolution With Increasing Genetic Divergence-A Hallmark of Polygenic Adaptation. Mol Ecol, 34(12):e17803 PubMed ID: 40377062
Summary:
Parallel evolution, the repeated evolution of similar traits in independent lineages, is a topic of considerable interest in evolutionary biology. Although previous studies have focused on the parallelism of phenotypic traits and their underlying genetic basis, the extent of parallelism at the level of gene expression across different levels of genetic divergence is not yet fully understood. This study investigates the evolution of gene expression in replicate Drosophila populations exposed to the same novel environment at three divergence levels: within a population, between populations and between species. Adaptive gene expression changes are more heterogeneous with increasing genetic divergence between the compared groups. This finding suggests that the adaptive architecture-comprising factors such as allele frequencies and the effect size of contributing loci-becomes more distinct with increasing divergence. As a result, this leads to a reduction in parallel gene expression evolution. This result implies that redundancy is a crucial factor in both genetic selection responses and gene expression evolution. Hence, these findings are consistent with the omnigenic model, which posits that selection acts on higher-order phenotypes. This work contributes to understanding of phenotypic evolution and the complex interplay between genomic and molecular responses.

Bullo, E., Chen, P., Fiala, I., Smykal, V., Dolezel, D. (2025). Coevolution of Drosophila-type timeless with partner clock proteins. iScience, 28(5):112338 PubMed ID: 40322083
Summary:
Drosophila-type timeless (dTIM) is a key clock protein in fruit flies, regulating rhythmicity and light-mediated entrainment. However, functional experiments indicate that its contribution to the clock differs in various insects. Therefore, we conducted a comprehensive phylogenetic analysis was conducted of dTIM across animals and dated its origin, gene duplications, and losses. We identified variable and conserved protein domains and pinpointed animal lineages that underwent the biggest changes in dTIM. While dTIM modifications are only mildly affected by changes in the PER protein, even the complete loss of PER in echinoderms had no impact on dTIM. However, changes in dTIM always co-occur with the loss of CRYPTOCHROMES or JETLAG. This is exemplified by the remarkably accelerated evolution of dTIM in phylloxera and aphids. Finally, alternative d-tim splicing, characteristic of Drosophila melanogaster temperature-dependent function, is conserved to some extent in Diptera, albeit with unique alterations. Altogether, this study pinpoints major changes that shaped dTIM evolution.

Thompson, A., May, M. R., Hopkins, B. R., Riedl, N., Barmina, O., Liebeskind, B. J., Zhao, L., Begun, D., Kopp, A. (2025). Quantifying Transcriptome Turnover on Phylogenies by Modeling Gene Expression as a Binary Trait. Mol Biol Evol, 42(5) PubMed ID: 40423579
Summary:
Changes in gene expression are a key driver of phenotypic evolution, leading to a persistent interest in the evolution of transcriptomes. Traditionally, gene expression is modeled as a continuous trait, leaving qualitative transitions largely unexplored. This paper details the development of new Bayesian inference techniques to study the evolutionary turnover of organ-specific transcriptomes, which we define as instances where orthologous genes gain or lose expression in a particular organ. To test these techniques, the transcriptomes of 2 male reproductive organs, testes and accessory glands, across 11 species of the Drosophila melanogaster species group. We first discretize gene expression states by estimating the probability that each gene is expressed in each organ and species. We then define a phylogenetic model of correlated transcriptome evolution in 2 or more organs and fit it to the expression state data. Inferences under this model imply that many genes have gained and lost expression in each organ, and that the 2 organs experienced accelerated transcriptome turnover on different branches of the Drosophila phylogeny.

Tuesday, December 2nd - Tumors, Cancer, and Growth

Mim, M. S., Cini, S., Frank, C., Wang, Z., Dowling, A., Zartman, J. J. (2025). Forward Engineering Organ Development and Cancer Therapeutics with Optogenetics. bioRxiv, PubMed ID: 40475478
Summary:
Robust growth control is an essential requirement for the survival of living organisms, while its dysregulation results in diseases such as cancer. However, a significant knowledge gap exists in understanding how precise organ growth control is achieved. The growing arsenal of optogenetic toolkits allows precise, noninvasive control of cellular signaling in vivo, enabling research into how bioelectrical and chemical cues regulate organ growth. The red-light-activated channelrhodopsin, CsChrimson, was used to stimulate intracellular calcium signaling dynamics in the wing epithelium of Drosophila melanogaster , an established model system for investigating organ size control. By varying light intensity and activation dynamics systematically, a biphasic regulation of final organ size was identified. Illumination of CsChrimson depolarizes cells and stimulates spikes of cytosolic calcium concentrations, a phenomenon explained by a computational model that incorporates the inclusion of both gap junction closure and voltage-gated calcium channel activation. This calcium regulation tunes downstream effectors involved in growth regulation and apoptosis. In particular, prolonged bright red light exposure (100 lux/12 hours) increased cell death in wing imaginal discs and caused severe morphological abnormalities in adult wings, with phenotypic severity dependent on stimulation parameters defined by illumination intensity and period of activation. Strikingly, an optimum level of dim, pulsatile light (5 lux, 1 minute on/off pulse train) resulted in overgrown organs and significantly upregulated cell proliferation. An oncogene, Ras (V12), was overexppressed with CsChrimson; experimental optical simulation parameters can be exploited to control the morphology of tumorous tissues and initiate targeted remission of tumorous growth. These findings and approach provide a powerful framework to dissect the role of dynamic physiological signaling events in organogenesis and offer translational insights into new therapeutic strategies with applications in cancer and regenerative medicine.

Rai, M., Okah, P., Shefali, S. A., Fitt, A. J., Shen, M. Z., Molomjamts, M., Pepin, R., Nemkov, T., D'Alessandro, A., Tennessen, J. M. (2025). New alleles of D-2-hydroxyglutarate dehydrogenase enable studies of oncometabolite function in Drosophila melanogaster. G3 (Bethesda), PubMed ID: 40489577
Summary:
D-2-hydroxyglutarate (D-2HG) is a potent oncometabolite capable of disrupting chromatin architecture, altering metabolism, and promoting cellular dedifferentiation. As a result, ectopic D-2HG accumulation induces neurometabolic disorders and promotes progression of multiple cancers. However, the disease-associated effects of ectopic D-2HG accumulation are dependent on genetic context. Specifically, neomorphic mutations in the mammalian genes Isocitrate dehydrogenase 1 (IDH1) and IDH2 result in the production of enzymes that inappropriately generate D-2HG from α-ketoglutarate (αKG). Within this genetic background, D-2HG acts as an oncometabolite and is associated with multiple cancers, including several diffuse gliomas. In contrast, loss-of-function mutations in the gene D-2-hydroxyglutarate dehydrogenase (D2hgdh) render cells unable to degrade D-2HG, resulting in excessive buildup of this molecule. D2hgdh mutations, however, are not generally associated with elevated cancer risk. This discrepancy raises the question as to why ectopic D-2HG accumulation in humans induces context-dependent disease outcomes. To enable such genetic studies in vivo, two novel loss-of-function mutations were generated in the Drosophila melanogaster gene D2hgdh and these alleles result in ectopic D-2HG. Moreover, it was observed that D2hgdh mutations induce developmental and metabolomic phenotypes indicative of elevated D-2HG accumulation. Overall, these efforts provide the Drosophila community with new mutant strains that can be used to study D-2HG function in human disease models as well as in the context of normal growth, metabolism, and physiology.

Brutscher, F., Germani, F., Hausmann, G., Jutz, L., Basler, K. (2025). Activation of the Drosophila innate immune system accelerates growth in cooperation with oncogenic Ras. PLoS Biol, 23(4):e3003068 PubMed ID: 40294154
Summary:
Innate immunity in Drosophila acts as an organismal surveillance system for external stimuli or cellular fitness and triggers context-specific responses to fight infections and maintain tissue homeostasis. However, uncontrolled activation of innate immune pathways can be detrimental. In mammals, innate immune signaling is often overactivated in malignant cells and contributes to tumor progression. Drosophila tumor models have been instrumental in the discovery of interactions between pathways that promote tumorigenesis, but little is known about whether and how the Toll innate immune pathway interacts with oncogenes. This study used a Drosophila epithelial in vivo model to investigate the interplay between Toll signaling and oncogenic Ras. In the absence of oncogenic Ras (RasV12), Toll signaling suppresses differentiation and induces apoptosis. In contrast, in the context of RasV12, cells are protected from cell death and Dorsal promotes cell survival and proliferation to drive hyperplasia. Taken together, we show that the tissue-protective functions of innate immune activity can be hijacked by pre-malignant cells to induce tumorous overgrowth.

Singh, J., Srikrishna, S. (2025). Scribble knockdown induced metastasis, identification of its associated novel molecular candidates through proteome studies. Biochem Biophys Res Commun, 769:151999 PubMed ID: 40367906
Summary:
Loss of function of Scribble, a cell polarity regulator and tumor suppressor gene, is associated with many forms of human cancers but its role in cell proliferation and metastasis remains unknown. This study generated metastatic cancer condition in Drosophila using UAS(RNAi)-GAL4 system by knockdown of Scribble in the wing imaginal discs and tracked metastasis events from early to late pupae (0hr-84 h s) using fluorescence microscopy. The knockdown of Scribble alone leads to the development of primary tumor in the wing imaginal discs, which is capable of establishing metastasis. MMP1, a metastasis biomarker, levels were assessed during pre-and post-metastatic phases in pupae using qRT-PCR and Western blot analysis. Further, the proteome of Scribble knockdown induced tumor-bearing pupae was analyzed by 2-D gel electrophoresis followed by MALDI-TOF MS to identify some novel proteins possibly involved in the progression of tumorigenesis and metastasis events. Six differentially expressed proteins, Obp 99b, Fer2LCH,CG13492, Hsp23, Ubiquitin and Colt, were identified in Scrib knockdown pupae and validated their expression using qRT-PCR. These results suggested that loss of Scrib alone capable of causing metastasis, without the need for cooperative interaction with oncogenic Ras. The newly identified proteins could be important candidates for biomarker/therapeutic target against Scrib associated metastatic cancers.

Panagi, M., Galaras, A., Hatzis, P., Apidianakis, Y. (2025). A feed-forward loop between Toll/NF-kappaB and Rac1 promotes epithelial to mesenchymal transition of Ras-oncogenic hindgut enterocytes in Drosophila.. Biol Open, 14(6) PubMed ID: 40476337
Summary:
Cancer cell invasion and subsequent metastasis account for most cancer related deaths. However, despite recent progress, there is a need to understand how the main pathways involved in oncogenic cell invasion and metastasis amalgamate into multifunctional networks. Using functional transcriptomic analysis of Drosophila Ras oncogenic hindgut enterocytes, a feed-forward loop was identified between the archetypical Toll/NF-kappaB pathway and Rac1 signalling driving actin cytoskeleton rearrangements, basement membrane degradation, and loss of intercellular adhesion. These data support a signalling network in which Rac1, Toll and JNK signalling transmit the RasV12 signal that primes the hindgut enterocytes towards delamination and dissemination. Rac1 induces actin cytoskeleton signalling genes, Rok, sqh, Apr2, and Apr3, while JNK induces matrix metalloprotease-mediated basement membrane degradation and Toll induces snail-depended E-cadherin repression. Moreover, the Toll pathway positively regulates itself and the Rac1 pathway cytoskeletal genes downstream of the Ras oncogene, but JNK signalling alone does not suffice to induce cell dissemination. Notably, there is a tight crosstalk between Toll and Rac1 signalling that suffices to induce hindgut enterocyte invasiveness and has the key role in transmitting the RasV12 signal.

Paglia, S., Morciano, P., de Biase, D., Giorgi, F. M., Pession, A., Grifoni, D. (2025). Transcriptome-Wide Analysis of Brain Cancer Initiated by Polarity Disruption in Drosophila Type II Neuroblasts. Int J Mol Sci, 26(11) PubMed ID: 40507925
Summary:
Brain tumors, in particular gliomas and glioblastoma multiforme (GBM), are thought to originate from different cells facing specific founding insults, a feature that partly justifies the complexity and heterogeneity of these severe forms of cancer. However, gliomas and GBM are usually reproduced in animal models by inducing molecular alterations in mature glial cells, which, though being part of the puzzle, do not represent the whole picture. To fill this conceptual gap, a neurogenic model of brain cancer in Drosophila was developed, demonstrating that the loss of cell polarity in neural stem cells (called neuroblasts in the fruit fly) is sufficient to promote the formation of malignant masses that continue to grow in the adult, displaying several phenotypic traits typical of human GBM. This study expanded on previous work by restricting polarity disruption to Drosophila type II neuroblasts, whose self-renewal is comparable to that of mammalian neural progenitors, with the aim to capture the molecular signature of the resulting cancers in a specific and reproducible context. A comparison of the most deregulated transcripts with those found in human primary GBMs confirmed that this model can be proficiently used to delve into the roots of human brain tumorigenesis.

Monday, December 1st - Disease Models

Kassel, S., Yuan, K., Bunnag, N., Neitzel, L. R., Lu, W., Schwarzkopf, A., Maines, B., ..., Kettenbach, A. N., Robbins, D. J., Ahmed, Y., Lee, E. (2025). The TRIP12 E3 ligase induces SWI/SNF component BRG1-β-catenin interaction to promote Wnt signaling. Nat Commun, 16(1):5248 PubMed ID: 40473626
Summary:
SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes displace nucleosomes to promote the access of transcription factors to enhancers and promoters. Despite the critical roles of SWI/SNF in animal development and tumorigenesis, how signaling pathways recruit SWI/SNF complexes to their target genes is unclear. Here, we demonstrate that target gene activation mediated by β-catenin, the essential transcriptional coactivator in the Wnt signal transduction pathway, requires ubiquitylation of the SWI/SNF component Brahma-related gene-1 (BRG1) by the E3 ubiquitin ligase Thyroid Hormone Receptor Interactor 12 (TRIP12). TRIP12 depletion in Drosophila, zebrafish, mouse organoids, and human cells attenuates Wnt signaling. Genetic epistasis experiments place TRIP12 activity downstream of the β-catenin destruction complex. TRIP12 interacts with and ubiquitylates BRG1, and BRG1 depletion blocks TRIP12-mediated Wnt pathway activation. TRIP12 promotes BRG1 binding to β-catenin in the presence of Wnt. Our findings support a model in which TRIP12 ubiquitylates BRG1 in the presence of Wnt and promotes its interaction with β-catenin in the nucleus, in order to recruit SWI/SNF to Wnt target genes. Our studies suggest a general mechanism by which cell signaling induces the interaction between BRG1 and pathway-specific transcription factors to recruit SWI/SNF complexes to their appropriate target genes.

Dong, P., Li, Y., Wang, Y., Zhao, Q., Lu, T., Chen, J., Guo, T., Ma, J., Yang, B., Wu, H., Huang, H. (2025). Fat body-derived cytokine Upd2 controls disciplined migration of tracheal stem cells in Drosophila. Elife, 13 PubMed ID: 40485562
Summary:
Coordinated activation and directional migration of adult stem cells are essential for maintaining tissue homeostasis. Drosophila tracheal progenitors are adult stem cells that migrate posteriorly along the dorsal trunk to replenish degenerating branches that disperse the fibroblast growth factor mitogen. However, it is currently unknown how the overall anterior-to-posterior directionality of such migration is controlled. This study shows that individual progenitor cells migrate together in a concerted, disciplined manner, a behavior that is dependent on the neighboring fat body. The fat body-derived cytokine, Upd2, was identifed in targeting and inducing JAK/STAT signaling in tracheal progenitors to maintain their directional migration. Perturbation of either Upd2 production in fat body or JAK/STAT signaling in trachea causes aberrant bidirectional migration of tracheal progenitors. JAK/STAT signaling promotes the expression of genes involved in planar cell polarity leading to asymmetric localization of Fat in progenitor cells. Evidence is provided that Upd2 transport requires Rab5- and Rab7-mediated endocytic sorting and Lbm-dependent vesicle trafficking. This study thus uncovers an inter-organ communication in the control of disciplined migration of tracheal progenitor cells, a process that requires vesicular trafficking of fat body-derived cytokine Upd2 and JAK/STAT signaling-mediated activation of PCP genes.

Shodja, D. N., Glassford, W. J., Rice, G., Smith, S. J., Rebeiz, M. (2025). A Notch signal required for a morphological novelty in Drosophila has antecedent functions in genital disc eversion. bioRxiv, PubMed ID: 40463012
Summary:
The origin of morphological novelties has long fascinated biologists. Signaling pathways play important roles in the formation of novelties, however, the history of how they become integrated into new developmental programs remains unclear. This study investigated the evolution of the posterior lobe, a novel structure in the male genitalia of Drosophila melanogaster. A Notch signaling center is shown to be required for the formation of this novelty, and ienhancers of the ligand Delta, were identified which allowed tracking the evolutionary history of this signaling center. Surprisingly, it was found that the posterior lobe signaling center emerged from a pre-existing role in genital disc eversion. A likely mechanism is provided by which Delta contributes to genital eversion through a network of apical extracellular matrix, which also became integrated into the posterior lobe program. This work demonstrates that novelties may be formed in the context of already complex developmental processes, by appending new roles to pre-existing signals.

Julick, C. R., Thanintorn, N., Zhang, H., Tsatskis, Y., Glaeser, M., Qu, Y., Rusch, J., McNeill, H. (2025). Regulation of Hippo signaling and planar cell polarity via distinct regions of the Fat intracellular domain. Development, 152(11) PubMed ID: 40377178
Summary:
The large Drosophila protocadherin Fat (Ft) is a receptor for signal transduction pathways that control growth (Hippo signaling), planar cell polarity (PCP), metabolism and the proximodistal patterning of appendages. The intracellular domain (ICD) of Ft is crucial in implementing its biological functions. Six regions of high conservation (named A-F) within the ICD have been identified, as well as distinct regions mediating Hippo pathway activity that have been functionally characterized via transgenic expression rescue assays. This study made targeted deletions of these highly conserved residues and the putative Hippo- and PCP-regulating domains of endogenous Ft using CRISPR/Cas9. Through transcriptomic, developmental and phenotypic analyses, this study showed that different regions of Ft contribute uniquely to chromatin dynamics, tissue morphogenesis, PCP and metabolic regulation. This study also demonstrated that different regions of Ft regulate growth in opposite directions, with regions B and F promoting growth and region D inhibiting growth. Strikingly, conserved regions D and F are key regulators of the function of Ft in Hippo activity - exhibiting opposing effects on Hippo pathway modulation - and of the conserved regions, and D is the main regulator of PCP.

Liu, X., Montemurro, M., Vanzo, N., Crozatier, M. (2025). Serotonergic neurons regulate the Drosophila vascular niche to control immune stress hematopoiesis. Nat Commun, 16(1):5152 PubMed ID: 40461546
Summary:
In adult mammals, hematopoietic stem/progenitor cells reside in the bone marrow, in a specialized microenvironment called a "niche", which is composed of different cell types, including nerves. Although it is established that sympathetic nerves regulate hematopoiesis, little is known about the role of neural serotonin in bone marrow. The Drosophila hematopoietic organ, the lymph gland, is aligned along the aorta, which corresponds to the vascular niche. Serotonin signaling in the vascular niche regulates the hematopoietic response to an immune challenge. The serotonin receptor 1B expressed in vascular niche cells, together with serotonin produced by neurons regulate the degradation of the extracellular matrix of the lymph gland and prevent its premature dispersal after an immune challenge. Serotonin signaling in aorta cells acts via JAK/STAT pathway activation. These results provide novel insights into how vascular niche cells integrate neural information to regulate lymph gland immune stress hematopoiesis.

Wolfstetter, G., Masudi, T., Uçkun, E., Zhu, J. Y., Yi, M., Anthonydhason, V., Guan, J., Sonnenberg, H., Han, Z., Palmer, R. H. (2025). Alk(Tango) reveals a role for Jeb/Alk signaling in the Drosophila heart. Cell Commun Signal, 23(1):229 PubMed ID: 40382638
Summary:
Anaplastic lymphoma kinase (Alk) signaling is important in a variety of biological contexts such as cell type specification, regulation of metabolic and endocrine programs, behavior, and cancer. In this work, a Tango GPCR assay-based, dimerization-sensitive Alk activity reporter (Alk(Tango)) was created and receptor activation was followed throughout Drosophila development. Alk(Tango) reports Alk activation in embryonic and larval tissues previously linked to Alk signaling. Remarkably, Alk(Tango) was active in the heartjeb expression in pericardial cells coincided with Alk(Tango) activity. Perturbation of cardiac Alk signaling leads to decreased adult survival as well as lower fitness and increased lethality in response to heat stress. In keeping with a role for Alk, heart measurements reveal arrythmia and irregular muscle contraction upon ligand stimulation. Finally, activation of cardiac Alk signaling induces hyperplasia in the accessory wing hearts of adult flies.

Friday, November 29h - Signaling

Kassel, S., Yuan, K., Bunnag, N., Neitzel, L. R., Lu, W., Schwarzkopf, A., Maines, B., Loberg, M. A., Xu, G., Adams, A., McCray, A. D., Cho, A., Rockouski, M., Orton, G., Goldsmith, L., Aronno, M. M. A., Spencer, Z. T., Khan, O. M., Ye, F., Williams, C., Lebensohn, A. M., Rohatgi, R., Wang, X., Weiss, V. L., Hong, C. C., Kettenbach, A. N., Robbins, D. J., Ahmed, Y., Lee, E. (2025). The TRIP12 E3 ligase induces SWI/SNF component BRG1-β-catenin interaction to promote Wnt signaling. Nat Commun, 16(1):5248 PubMed ID: 40473626
Summary:
SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes displace nucleosomes to promote the access of transcription factors to enhancers and promoters. Despite the critical roles of SWI/SNF in animal development and tumorigenesis, how signaling pathways recruit SWI/SNF complexes to their target genes is unclear. Here, we demonstrate that target gene activation mediated by β-catenin, the essential transcriptional coactivator in the Wnt signal transduction pathway, requires ubiquitylation of the SWI/SNF component Brahma-related gene-1 (BRG1) by the E3 ubiquitin ligase Thyroid Hormone Receptor Interactor 12 (TRIP12). TRIP12 depletion in Drosophila, zebrafish, mouse organoids, and human cells attenuates Wnt signaling. Genetic epistasis experiments place TRIP12 activity downstream of the β-catenin destruction complex. TRIP12 interacts with and ubiquitylates BRG1, and BRG1 depletion blocks TRIP12-mediated Wnt pathway activation. TRIP12 promotes BRG1 binding to β-catenin in the presence of Wnt. Our findings support a model in which TRIP12 ubiquitylates BRG1 in the presence of Wnt and promotes its interaction with β-catenin in the nucleus, in order to recruit SWI/SNF to Wnt target genes. Our studies suggest a general mechanism by which cell signaling induces the interaction between BRG1 and pathway-specific transcription factors to recruit SWI/SNF complexes to their appropriate target genes.

Wolfstetter, G., Masudi, T., Uckun, E., Zhu, J. Y., Yi, M., Anthonydhason, V., Guan, J., Sonnenberg, H., Han, Z., Palmer, R. H. (2025). Alk(Tango) reveals a role for Jeb/Alk signaling in the Drosophila heart. Cell Commun Signal, 23(1):229 PubMed ID: 40382638
Summary:
Anaplastic lymphoma kinase (Alk) signaling is important in a variety of biological contexts such as cell type specification, regulation of metabolic and endocrine programs, behavior, and cancer. In this work, a Tango GPCR assay-based, dimerization-sensitive Alk activity reporter (Alk(Tango)) was created and receptor activation was followed throughout Drosophila development. Alk(Tango) reports Alk activation in embryonic and larval tissues previously linked to Alk signaling. Remarkably, Alk(Tango) was active in the heartjeb expression in pericardial cells coincided with Alk(Tango) activity. Perturbation of cardiac Alk signaling leads to decreased adult survival as well as lower fitness and increased lethality in response to heat stress. In keeping with a role for Alk, heart measurements reveal arrythmia and irregular muscle contraction upon ligand stimulation. Finally, activation of cardiac Alk signaling induces hyperplasia in the accessory wing hearts of adult flies.

Tuesday November 25th - Larval and Adult Neural Structure, Development, and Function

Nemat, R. A., Chaya, T., Atheby, A. C., Lawal, H. O. (2025). Altered Vesicular Acetylcholine Transporter Expression Regulates Acetylcholine Abundance in the Brain of Drosophila melanogaster. J Neurochem, 169(6):e70109 PubMed ID: 40452408
Summary:
The neurotransmitter acetylcholine (ACh) plays a central role in the regulation of vital neurological processes like cognition. As a result, increases or decreases in neuronal cholinergic signaling lead to an impairment in learning and memory. Although much about how acetylcholine is regulated is known, the mechanism through which alterations in cholinergic signaling affect changes in ACh-linked behavior is not fully understood. Importantly, the nature of the relationship between vesicular acetylcholine packaging and its release at the synaptic cleft is also unclear. This study involves an interest in using the vesicular acetylcholine transporter (VAChT), which mediates the packaging and transport of acetylcholine (ACh) for exocytotic release, to elucidate the ways in which ACh loading alters its release and metabolism. Both an overexpression of VAChT and two Vacht mutant lines, Vacht(2) and Vacht(8), were used to increase or decrease the gene's expression respectively. Taking a combined immunohistochemical and biochemical approach,the expression of ACh was measured in VAChT overexpressors and followed up with an assay for ACh levels as a means of quantifying ACh storage and those of choline, its degradation product. Consistent with its well-known role in mediating ACh release, the VAChT overexpression line has elevated total head ACh levels in females but not males while Vacht mutants show strong reductions. By contrast, choline levels are elevated in VAChT overexpressors but unchanged in Vacht mutants. These findings are supported by immunolocalization studies in the fly brain in which the VAChT overexpressors show both elevated ACh in and around ACh neurons and an increased localization to synaptic release sites. When we analyzed the immunostaining studies by sex, we found that in contrast to the neurochemical studies, both males and females had elevated ACh levels, while the two Vacht mutants had reductions in that neurotransmitter's levels. By our estimation, these data represent the first time that acetylcholine has been measured directly in VAChT overexpression and Vacht mutants in Drosophila and demonstrate a consistency with findings from mammalian studies.

Lee, G. G., Peterson, A. J., Kim, M. J., Shimell, M., O'Connor, M. B., Park, J. H. (2025). Linking expression and function of Drosophila type-I TGF-β receptor baboon isoforms: Multiple roles of BaboA isoform in shaping of the adult central nervous system. PLoS One, 20(5):e0318406 PubMed ID: 40445987
Summary:
Evolutionarily conserved transforming growth factor β (TGF-β) signaling is used in both vertebrates and invertebrates to regulate a variety of developmental and cellular processes. The baboon (babo) gene encoding a Drosophila type-I TGF-β receptor produces three isoforms via alternative splicing: BaboA, BaboB, and BaboC. This study generated three fly lines, each carrying an isoform-specific GFP tag, and another line with a GFP conjugated at the C-terminus common to all isoforms. Using these lines, the following was assessed: (1) whether the tagged proteins function properly in rescue assays and (2) how the isoform expression is regulated in various tissues including the central nervous system (CNS). A Gal4 knock-in line in the babo locus was also characterized for reporter expression, mutant phenotypes, and isoform-specific knockdown phenotypes. The C-terminal tag does not interrupt the subcellular targeting and functions of the tagged isoforms, but the internal isoform tags do so in a cell- and isoform-specific fashion. Nevertheless, our results demonstrated that these tags faithfully reflect endogenous expression of individual isoforms. Certain cell types express single or multiple isoforms at different levels, suggesting that alternative splicing could determine the isoform types and their levels depending on cell (or tissue) type. The larval CNS displays distinct patterns of two isoforms, BaboA and BaboC. BaboC is mostly expressed in neural cells originating during embryogenesis, while BaboA is broadly expressed in neural cells produced from both embryonic and postembryonic stages. Assays of both isoform-specific mutants and cell-specific knockdown of individual isoforms revealed broad roles played by BaboA in postembryonic neurogenesis and differentiation of precursor neurons, remodeling processes of persisting larval neurons, and metamorphic CNS reorganization, which are essential for establishing of the adult CNS. Taken together, this study demonstrates that the GFP-tagged lines permit visualization of endogenous expression of individual isoforms, which further provides clues about cell- and stage-specific functions played by each isoform.

Pang, R., Baker, C. A., Murthy, M., Pillow, J. (2025). Inferring neural population codes for Drosophila acoustic communication. Proc Natl Acad Sci U S A, 122(21):e2417733122 PubMed ID: 40388613
Summary:
Social communication between animals is often mediated by sequences of acoustic signals, sometimes spanning long timescales. How auditory neural circuits respond to extended input sequences to guide behavior is not understood. This problem was addressed using Drosophila acoustic communication, a behavior involving the male's production of and female's response to long, highly variable courtship songs. This study asked whether female neural and behavioral responses to song are better described by a linear-nonlinear feature detection model vs. a nonlinear accumulation model. Comparing both models against head-fixed neural recordings and pure-behavioral recordings of unrestrained courtship, this study found that while both models could explain the neural data, the accumulation model better predicted female locomotion during courtship, outperforming several alternative predictors. To understand how the accumulation model encoded song to predict locomotion, the relationship was analyzed between neural activity simulated by the model and female locomotion during courtship-this revealed the model's reliance on heterogeneous nonlinear adaptation and slow integration. Finally, it was asked how adaptation and integration processes could cooperate across the model neural population to encode temporal patterns in song. Simulations revealed how adaptation can transform song inputs prior to integration, allowing fine-scale song information to be retained in the population code for long periods. Thus, modeling fly auditory responses as a nonlinearly adaptive, accumulating population code accounts for female locomotor responses to song during courtship and suggests a biologically plausible mechanism for the online encoding of extended communication sequences.

Guttenplan, K. A., Maxwell, I., Santos, E., Borchardt, L. A., Manzo, E., Abalde-Atristain, L., Kim, R. D., Freeman, M. R. (2025). GPCR signaling gates astrocyte responsiveness to neurotransmitters and control of neuronal activity. Science, 388(6748):763-768 PubMed ID: 40373148
Summary:
How astrocytes regulate neuronal circuits is a fundamental question in neurobiology. Specifically, how astrocytes respond to different neurotransmitters in vivo and how they affect downstream circuit modulation are questions that remain to be fully elucidated. Thia atudy reports a mechanism in Drosophila by which G protein-coupled adrenergic signaling in astrocytes can control-or "gate"-their ability to respond to other neurotransmitters. Astrocytes reliably responded to octopamine and tyramine - the functional homologues of epinephrine/norepinephrine – with whole-cell calcium responses across the entire VNC, but were unresponsive to all other neurotransmitters tested. Further, manipulating this pathway was shown to potently regulates neuronal circuit activity and animal behavior. This gating mechanism is conserved in cultured primary mammalian astrocytes, suggesting that it might be an ancient feature of astrocyte circuit function. Our work establishes a mechanism by which astrocytes dynamically respond to and modulate neuronal activity in different brain regions and in different behavioral states.

Thakur, D., Hunt, S., Tsou, T., Petty, M., Rodriguez, J. M., Montell, C. (2025). Control of odor sensation by light and cryptochrome in the Drosophila antenna. iScience, 28(5):112443 PubMed ID: 40395666
Summary:
Olfaction is employed by the fruit fly, Drosophila melanogaster, to differentiate safe from harmful foods and for other behaviors. This study shows that ultraviolet (UV) or blue light reduces the fly's behavioral aversion and the responses of olfactory receptor neurons (ORNs) to certain repellent odors, such as benzaldehyde. cryptochrome (cry) is expressed in antennal support cells and is required for the light-dependent reduction in aversion. Light activation of Cry creates reactive oxygen species (ROS), and ROS activate the TRPA1 channel. TRPA1 was shown to be required in ORNs for benzaldehyde repulsion and is activated in vitro by benzaldehyde. It is proposed that light-activation of Cry and creation of ROS persistently stimulates and then desensitizes TRPA1, preventing activation by benzaldehyde. Since flies begin feeding at dawn, it is suggested that the light-induced reduction in odor avoidance serves to lower the barrier to feeding following the transition from night to day.

Tenedini, F. M., Yin, C., Huang, J. M., Dhiman, N., Soba, P., Parrish, J. Z. (2025). Inflammatory cytokine upd3 induces axon length-dependent synapse removal by glia. Proc Natl Acad Sci U S A, 122(21):e2422752122 PubMed ID: 40392850
Summary:
Many neurodegenerative disorders (NDDs) preferentially affect neurons with long or complex axonal arbors but the cellular and molecular bases for neurite length-dependent vulnerability of neurons to degeneration is largely unknown. Using Drosophila sensory neurons as a model system this study showed that neuronal activation of the integrated stress response triggers expression of the Interleukin-6 homolog unpaired 3 (upd3), which is both necessary and sufficient for axon length-dependent degeneration of presynapses. Upd3 activates phagocytic glia, triggering phagocytic removal of presynapses preferentially on neurons with long axons, thus revealing an intrinsic axon length-dependent vulnerability to glial insult. Finally, this study found that axon length-dependent presynapse loss in fly models of human neurodevelopmental disorders utilized this pathway, requiring upd3 and glial expression of the phagocytic receptor draper. Our studies identify inflammatory cytokine signaling and glial phagocytosis as key determinants of axon length-dependent vulnerability, thus mechanistically linking these hallmarks of NDDs.

Monday November 24th - Disease Models

Ranxhi, B., Bangash, Z. R., Chbihi, Z. M., Qadri, Z., Islam, N. N., Todi, S. V., LeWitt, P. A., Tsou, W. L. (2025). Regulation of polyamine interconversion enzymes affects α-Synuclein levels and toxicity in a Drosophila model of Parkinson's Disease. Res Sq, PubMed ID: 40470180
Summary:
Parkinson's Disease (PD) is a prevalent neurodegenerative disorder characterized by the accumulation and aggregation of α-synuclein as a defining pathological hallmark. Misfolding and aggregation of α-synuclein disrupt cellular homeostasis, hinder mitochondrial function, and activate neuroinflammatory responses, ultimately resulting in neuronal death. Recent biomarker studies have reported a significant increase in the serum concentrations of three L-ornithine-derived polyamines, correlating with PD progression and its clinical subtypes. However, the precise role of polyamine pathways in PD pathology remains poorly understood. This study explored the impact of modifying polyamine-interconversion enzymes (PAIE) on the α-synucleinopathy phenotype in a Drosophila melanogaster model of Parkinson's Disease (PD). Key degenerative features were assessed, including lifespan, locomotor function, tissue integrity, and α-synuclein accumulation. PAIEs were found play a critical role in modulating α-synuclein toxicity in the PD model. Knockdown of ornithine decarboxylase 1 (ODC1), spermidine synthase (SRM), and spermine oxidase (SMOX) mitigates α-synuclein toxicity, whereas suppression of spermidine/spermine N1-acetyltransferase 1 (SAT1) and spermine synthase (SMS) exacerbates it. Furthermore, the overexpression of SAT1 or SMOX significantly lowers α-synuclein toxicity, emphasizing their potential involvement in PD. These results highlight the importance of polyamine pathways in PD, where PAIEs are essential in managing α-synuclein toxicity, providing a new perspective on targeting PD's fundamental pathology.

Pasam, E. S., Madamanchi, K., Melkani, G. C. (2025). Dissecting Metabolic Control of Behaviors and Physiology During Aging in Drosophila. Res Sq, PubMed ID: 40386389
Summary:
Aging disrupts physiological and behavioral homeostasis, largely driven by one-carbon metabolism, mitochondrial dysfunction, energy sensing, and metabolic imbalance. By using panneuronal and indirect flight muscle (IFM)- specific drivers, the impact of gene knockdown or overexpression on sleep-circadian rhythms, locomotion, and lipid metabolism were assessed in a cell-autonomous and non-cell-autonomous manner to address bidirectional neuro-muscle communications. Knockdown of genes such as SdhD, Marf, and Gnmt leads to decrease in flight performance especially in 6 weeks with both the drivers, which demonstrates cell-autonomous and non-cell autonomous effects of these genes. Negative geotaxis with panneuronal knockdown of Adsl, Gnmt, SdhD, Marf genes showed reduced locomotor performance in age-dependent manner consolidating their non-cell autonomous role and neuro-muscular interaction. Whereas mAcon1, LSD2, Ampkα, Ald, Adsl genes showed reduced flight performance with only IFM specific driver emphasizing the cell-autonomous role. Panneuronal knockdown of Ald, GlyP, mAcon1, and Gnmt genes showed increased total sleep, reduced activity, while Adsl and Ogdh knockdown led to sleep fragmentation, in a mid-age suggests cell autonomous impact. Functional analysis of AMPK signaling via overexpression and knockdown of Ampkα, as well as expression of the yeast ortholog SNF1A and its kinase-dead mutant, revealed kinase-dependent, age- and tissue-specific modulation of sleep and activity rhythms. Lipid analysis showed that panneuronal overexpression of Ampkα altered lipid droplet number and size in the brain, indicating disrupted lipid homeostasis during aging. These findings establish Ampkα as a central regulator of behavioral and metabolic aging, linking neuronal energy sensing, motor function, and lipid dynamics, and offer mechanistic insights into tissue-specific metabolic regulation with potential relevance for interventions targeting age-related decline and neurodegeneration.

Tan, F. H. P., Azzam, G., Najimudin, N., Shamsuddin, S., Zainuddin, A., Kasihmuddin, M. S. M. (2025). Salvianolic acid B ameliorates Aβ42 toxicity in Aβ42-expressing Drosophila model: behavioral and transcriptomic profiling. Metab Brain Dis, 40(5):204 PubMed ID: 40377822
Summary:
Alzheimer's disease (AD) is one of the most common neurodegenerative diseases worldwide. It is characterized by the accumulation of amyloid-beta (Aβ) plaques in which Aβ42 is the most toxic and aggressive species. This work investigates the possibility of salvianolic acid B (SalB), a natural compound with established neuroprotective activity, to counteract the Aβ42-induced toxicity in a Drosophila melanogaster model of AD. SalB's effect was assessed in the Aβ42-expressing Drosophila model by measuring three major AD-related behavioural symptoms: eye morphology (cytotoxicity), lifespan, and locomotor activity. The eye assay, longevity, and locomotion assays were employed, followed by RNA sequencing (RNA-seq) to identify molecular alterations following SalB treatment. Aβ42 expression in the Aβ42-expressing Drosophila model resulted in deformed eye morphology, reduced lifespan, and motor impairment. Treatment with SalB restored part of eye morphology, extended lifespan, and improved locomotion. RNA-seq revealed differential gene expression in oxidative phosphorylation, glutathione metabolism, and detoxification processes, suggesting the involvement of antioxidant defence in SalB-mediated neuroprotection. These findings indicate that SalB could be therapeutic for AD and other neurodegenerative disorders, possibly through the modulation of oxidative stress against Aβ42 toxicity. Further research is warranted to address its mechanisms and other uses in neurodegenerative therapy.

Modafferi, S., Farina, S., Esposito, F., Brandi, O., Di Salvio, M., Della Valle, I., D'Uva, S., Scarian, E., Cicio, G., Riccardi, A., Pisati, F., Garbelli, A., Santini, T., Pansarasa, O., Morlando, M., D'Ambrosi, N., Cozzolino, M., Cestra, G., d'Adda di Fagagna, F., Gioia, U., Francia, S. (2025). DNA damage response defects induced by the formation of TDP-43 and mutant FUS cytoplasmic inclusions and their pharmacological rescue. Cell Death Differ, PubMed ID: 40437235
Summary:
Formation of cytoplasmic inclusions (CIs) of TDP-43 and FUS, along with DNA damage accumulation, is a hallmark of affected motor neurons in Amyotrophic Lateral Sclerosis (ALS). However, the impact of CIs on DNA damage response (DDR) and repair in this pathology remains unprobed. This study shows that CIs of TDP-43 and FUS(P525L), co-localizing with stress granules, lead to a dysfunctional DDR activation associated with physical DNA breakage. Inhibition of the activity of the DDR kinase ATM, but not of ATR, abolishes DDR signaling, indicating that DNA double-strand breaks (DSBs) are the primary source of DDR activation. In addition, cells with TDP-43 and FUS(P525L) CIs exhibit reduced DNA damage-induced RNA synthesis at DSBs. Previous work showed that the two endoribonucleases DROSHA and DICER, also known to interact with TDP-43 and FUS during small RNA processing, contribute to DDR signaling at DSBs. Treatment with enoxacin, which stimulates DDR and repair by boosting the enzymatic activity of DICER, restores a proficient DDR and reduces DNA damage accumulation in cultured cells with CIs and in vivo in a murine model of ALS. In Drosophila melanogaster, Dicer-2 overexpression rescues TDP-43-mediated retinal degeneration. In summary, these results indicate that the harmful effects caused by TDP-43 and FUS CIs include genotoxic stress and that the pharmacological stimulation of the DNA damage signaling and repair counteracts it.

Martin-Carrascosa, M. D. C., Palacios-Martinez, C., Galindo, M. I. (2025). A phylogenetic analysis of the CDKL protein family unravels its evolutionary history and supports the Drosophila model of CDKL5 deficiency disorder. Front Cell Dev Biol, 13:1582684 PubMed ID: 40371392
Summary:
The human CDK-like (CDKL) family of serine‒threonine kinases has five members (CDKL1-5), with a conserved N-terminal kinase domain and variable C-termini. Among these, CDKL5 is of particular interest because of its involvement in CDKL5 deficiency disorder (CDD), a rare epileptic encephalopathy with several comorbidities for which there are no specific treatments. Current CDD vertebrate models are seizure resistant, which could be explained by the genetic background, including leaky expression of other CDKLs. Thus, phylogenetic analysis of the protein family would be valuable for understanding current models and developing new ones. Phylogenetic studies revealed that ancestral CDKLs were present in all major eukaryotic clades and had ciliary/flagellar functions, which may have diversified throughout evolution. The original CDKL, which was likely similar to human CDKL5, gave rise to the remaining family members through successive duplications. In addition, particular clades have undergone further gene duplication and loss, a pattern that suggests some functional redundancy among them. A separate study focusing on the C-terminal tail of CDKL5 suggested that this domain is only functionally relevant in jawed vertebrates. A model of CDD was developed in Drosophila based on downregulation of the single Cdkl gene by RNAi, which results in phenotypes similar to those of CDD patients, that are rescued by re-expression of fly Cdkl and human CDKL5. CDKL proteins contain a conserved kinase domain, originally involved in ciliary maintenance; therefore, invertebrate model organisms can be used to investigate CDKL functions that involve the aforementioned domain.

Park, Y. J., Lu, T. C., Jackson, T., Goodman, L. D., Ran, L., Chen, J., Liang, C. Y., Harrison, E., Ko, C., Chen, X., Wang, B., Hsu, A. L., Ochoa, E., Bieniek, K. F., Yamamoto, S., Zhu, Y., Zheng, H., Qi, Y., Bellen, H. J., Li, H. (2025). Distinct systemic impacts of Aβ42 and Tau revealed by whole-organism snRNA-seq. Neuron, 113(13):2065-2082.e2068. PubMed ID: 40381615
Summary:
Both neuronal and peripheral tissues become disrupted in Alzheimer's disease (AD). However, a comprehensive understanding of how AD impacts different tissues across the whole organism is lacking. Using Drosophila, an AD Fly Cell Atlas (AD-FCA) was generated based on whole-organism single-nucleus transcriptomes of 219 cell types from flies expressing AD-associated proteins, either human amyloid-β 42 peptide (Aβ42) or Tau, in neurons. Aβ42 was found to primarily affect the nervous system, including sensory neurons, while Tau induces accelerated aging in peripheral tissues. A neuronal cluster was identified enriched in Aβ42 flies, which has high lactate dehydrogenase (LDH) expression. This LDH-high cluster is conserved in 5XFAD mouse and human AD datasets. A conserved defect in fat metabolism was identifiedfrom both fly and mouse tauopathy models. The AD-FCA offers new insights into how Aβ42 or Tau systemically and differentially affects a whole organism and provides a valuable resource for understanding brain-body communication in neurodegeneration.

Friday November 21st - Genes, Proteins, RNAs and Enzymes

Moon, M., Yun, J., Pyeon, M., Yun, J., Yang, J., Yeom, H. D., Lee, G., Choi, Y. S., Lee, J., Lee, J. H. (2025). Phenethyl Acetate as an Agonist of Insect Odorant Receptor Co-Receptor (Orco): Molecular Mechanisms and Functional Insights. Int J Mol Sci, 26(11) PubMed ID: 40507781
Summary:
The insect olfactory system is vital for survival, enabling the recognition and discrimination of a wide range of odorants present in the environment. This process is mediated by odorant receptors (Ors) and the highly conserved co-receptor Orco. Insect Ors are structurally distinct from mammalian olfactory receptors, a divergence that presents unique advantages for developing insect-specific pest control strategies. This study explored the molecular-level interactions between insect Ors and volatile organic compounds. Specifically, the response of Ors/Orco to phenethyl acetate (PA), a volatile compound found in the culture media of acetic acid bacteria, was investigated. PA elicited activation in a concentration-dependent, reversible, and voltage-independent manner in Or1a, Or24a, and Or35a when combined with Orco, as well as in Orco homomers. Through molecular docking studies, it was determined that the PA-binding site is localized to the Orco subunit, a highly conserved protein across diverse insect taxa. To further elucidate the role of key residues in the Orco homotetramer receptor, site-directed mutagenesis was performed. A mutational analysis identified W146 and E153 as critical residues for PA binding and activation. A double-mutant Orco receptor (W146A + E153A) exhibited a significant reduction in PA-induced activation compared to the wild-type receptor. These findings indicate that PA functions as an agonist for the Drosophila melanogaster Orco receptor and highlight its potential applications in chemosensory research and insect pest management strategies.

Okasha, M., Chen, J., Ayekoi, A., Jacob, E., Radtke, V., Schmidt, A., Bacher, A., Weber, S., Schleicher, E. (2025). Linear free energy relationship between reduction potential and photoreduction rate: studies on Drosophila cryptochrome. Febs j, PubMed ID: 40372360
Summary:
Cryptochromes are flavin adenine dinucleotide (FAD)-containing blue-light photoreceptors involved in the regulation of the circadian clock and may play a role in magnetic field sensing. The photochemistry of cryptochromes is based on the isoalloxazine moiety, which can be photoreduced and subsequently reoxidized by an electron acceptor such as oxygen, corresponding to a photo-switch between the dark and signaling state. The FAD cofactor of Drosophila cryptochrome was replaced with a series of FAD cofactors modified at the 7α or 8α positions, in order to modulate the chemical properties of the electron acceptor. These modifications were shown to alter the kinetics of the light-dependent reactions. Notably, 7-halogenated FADs form the signaling state more than six times faster compared to the natural FAD cofactor. The more positive reduction potentials as well as the increased intersystem crossing rates due to heavy halogen atoms were identified as reasons for the altered photochemistry. Both parameters show a linear dependence on the reaction kinetics, according to the Hammett relationship. With this knowledge, the photochemistry of cryptochromes may be modified in a defined way without changing its amino acid sequence.

Kim, K. Y., Hwang, Y. L., Yeom, S., Kwon, S. H., Jeon, S. H. (2025). Pss knockdown in the midgut causes growth retardation in Drosophila similar to that in human LMHD. Dev Dyn, PubMed ID: 40401988
Summary:
Phosphatidylserine synthase (PSS), localized in the mitochondrial membrane, synthesizes phosphatidylserine. In humans, mutations in Pss lead to Lenz-Majewski hyperostotic dwarfism, a disorder affecting growth and development. The effects of Pss mutations on the growth of Drosophila melanogaster are not fully known. This study was conducted to investigate the effects of Pss knockdown on the growth and development of D. melanogaster. Enterocyte (EC)-specific Pss knockdown resulted in reduced cell size in the gut via reduced Akt signaling. EC-specific Pss knockdown was associated with a decrease in gut size, a change in gut pH, and reduced food intake. These abnormalities affected normal nutrient metabolism in larvae, leading to decreased secretion of Drosophila insulin-like peptides. Consequently, the reduced systemic Akt signaling at the organismal level resulted not only in impaired gut growth but also in abnormal organismal growth and development. These findings highlight the significant role of the Pss gene in the growth and development of D. melanogaster.

Fletcher, S. J., Bardossy, E. S., Tomé-Poderti, L., Moss, T., Mongelli, V., Frangeul, L., Blanc, H., Verdier, Y., Vinh, J., Mukherjee, S., Saleh, M. C. (2025). Hsc70-4: An unanticipated mediator of dsRNA internalization in Drosophila. Sci Adv, 11(20):eadv1286 PubMed ID: 40378201
Summary:
The small interfering RNA pathway is the primary antiviral defense mechanism in invertebrates and plants. This systemic mechanism relies on the recognition, transport, and internalization of double-stranded RNA (dsRNA). The aim of this study was to identify cell surface proteins that bind extracellular dsRNA and mediate its internalization in Drosophila cells. Coimmunoprecipitation coupled with proteomics analysis were used; silencing heat shock cognate protein 70-4 (Hsc70-4), a constitutively expressed heat shock protein, impairs dsRNA internalization. Unexpectedly, despite lacking a predicted transmembrane domain, Hsc70-4 localizes to the cell membrane via lipid interactions. Antibody blocking experiments revealed an extracellular domain on Hsc70-4 that is essential for dsRNA internalization. Intriguingly, this dsRNA-specific binding capacity of Hsc70-4 functions independently of its chaperone activity. These findings not only highlight Hsc70-4 as a previously uncharacterized and essential component in the dsRNA internalization process but also offer promising insights for advancing RNA interference-based technologies to combat pests and vector-borne diseases.

Krishnan, H., Muzaffar, S., Sharma, S., Ramya, V., Ghosh, A., Sowdhamini, R., Padinjat, R. (2025). Conserved biochemical activity and function of phosphatidylinositol 5 phosphate 4 kinase regulates growth & development. Cell Sci, PubMed ID: 40539330
Summary:
Co-ordination of function between multiple cells, mediated by hormones or growth factors, is a critical requirement for multi-cellularity. Phosphoinositides, generated by lipid kinase activity, are second messengers that mediate such signalling. Phosphatidylinositol 5 phosphate 4-kinase (PIP4K) is a lipid kinase that phosphorylates phosphatidylinositol 5-phosphate (PI5P) to generate phosphatidylinositol 4,5 bisphosphate [PI(4,5)P2]. A comprehensive bioinformatics analysis of the tree of life, revealed that PIP4K is a metazoan-specific enzyme, but with homologs in choanoflagellates. This study found that PIP4K from the sponge Amphimedon queenslandica (AqPIP4K), regarded as the earliest evolved metazoan, shows biochemical activity highly conserved with human PIP4K. Further, AqPIP4K was able to rescue the reduced cell size, growth and development of a Drosophila PIP4K mutant. These phenotypes are regulated through activity of the insulin receptor, a member of the receptor tyrosine kinase family, that is unique to metazoans. Overall, this work defines PIP4K as part of a signal transduction motif required to regulate receptor tyrosine kinase signalling for intercellular communication in the earliest forms of metazoans.

Hu, J., Li, X., Lomaev, D., Vorobyeva, N. E., Levine, M., Erokhin, M., Chetverina, D. (2025). Vostok: A looping factor for the organization of the regulatory genome in the Drosophila brain. Mol Cell, 85(12):2442-2451.e2445 PubMed ID: 40499548
Summary:
Drosophila tethering elements mediate long-range enhancer-promoter interactions and connect the promoters of distant paralogous genes. Micro-C maps identified 645 such loops in the Drosophila larval brain, spanning distances of 25 to 250 kb. This study demonstrates that the MADF-containing Vostok protein acts as a looping factor. It binds to GCAACA motifs that are overrepresented in brain tethering elements. There is a loss of 47 (7%) of the loops in Vostok mutants, resulting in diminished expression of associated genes. Vostok is largely independent of another looping factor, GAGA-associated factor (GAF). Only 9 loops are disrupted in both Vostok and GAF mutants, raising the possibility of a combinatorial code for tether-tether interactions. This is supported by the reliance of two previously identified meta-loops spanning 6 Mb on both GAF and Vostok. The prospects of using different combinations of looping factors to engineer 3D associations in animal genomes is discussed.

Wednesday November 19th - Disease Models

Huang, R. N., Luo, S. Y., Huang, T., Li, X. S., Zhou, F. C., Yin, W. H., Chen, Z. R., Yuan, S. Z., Li, L. Y., Tang, B., Qiao, J. D. (2025). The interaction of UBR4, LRP1, and OPHN1 in refractory epilepsy: Drosophila model to investigate the oligogenic effect on epilepsy. Neurobiol Dis, 212:106955 PubMed ID: 40374006
Summary:
Refractory epilepsy is an intractable neurological disorder that can be associated with oligogenic/polygenic etiologies. Through trio-based whole-exome sequencing analysis, a clinical case of refractory epilepsy was identified with three candidate gene variants: UBR4, LRP1, and OPHN1. Utilizing the Gal4-UAS system and double-balancer tool, single, double, and triple knockdown Drosophila models were created to investigate the interactions of the three candidate genes. Seizure behavioral experiments combined with logistic regression analysis revealed the individual epileptogenicity and significant synergistic epileptogenic effects of the three mutations. By constructing a SHAP-XGBoost machine learning model integrating seizure behavior data with knockdown efficiency metrics, it was discovered that LRP1 mutation served as the primary effector in the oligogenic system. Based on transcriptome analysis, main related processes of oxidative stress and metabolic imbalance together with expressional dysregulation separately of 48, 52, and 43 epilepsy-associated genes were discovered to confirm the epileptogenicity of OPHN1 knockdown, UBR4-LRP1 knockdown, and UBR4-LRP1-OPHN1 knockdown respectively. Up-regulation of COX7AL and ND-B8 enriched in metabolic pathways and down-regulation of Diedel enriched in extracellular space component were indicated to be responsible for the significant epileptogenicity of the oligogenic knockdown. For this clinical instance, epileptic pharmacoresistance was considered to be triggered by a combination of KIF gene family, SLC gene family, and ASIC gene family. This study established a novel framework to clarify the multiple genetic structure of epileptogenicity in refractory epilepsy with oligogenic background, which could be critical to translational medicine and precision therapy development.

Li, J., Song, J., Yan, B., Wu, H., Banerjee, M., Magnuson, L., Liu, Y., Zhang, S., Liu, J., Wang, C., Gao, T., Jia, J., Weiss, H. L., Evers, B. M. (2025). Neurotensin inhibits AMPK activity and concurrently enhances FABP1 expression in small intestinal epithelial cells associated with obesity and aging. Exp Mol Med, 57(6):1189-1201 PubMed ID: 40451927
Summary:
Previous work has demonstrated that neurotensin, a 13-amino-acid gut hormone peptide, enhances small intestinal epithelial cell fatty acid uptake through inhibition of AMPK. Utilizing Drosophila and mouse models in vivo, as well as mouse and human small intestinal epithelial organoids or monolayers ex vivo, it was determine the targets of neurotensin and AMPK associated with obesity and aging. High-fat diet and aging decreased AMPK and insulin signaling, which was prevented by neurotensin deficiency. High-fat diet feeding increased FABP1 protein expression in wild-type mice; this effect was attenuated in neurotensin-deficient mice. AICAR and metformin increased AMPK phosphorylation in young but not in aged small intestinal epithelial cells. By contrast, AICAR and metformin inhibited FABP1 mRNA and protein expression. Moreover, cytosolic colocalization of AMPKα1 and FABP1 was noted in IEC-6 cells. AMPK phosphorylation and FABP1 expression was decreased in aged wild-type small intestinal epithelial cells; however, this effect was reversed in neurotensin-deficient cells. Results from human duodenal organoids confirm the effects of neurotensin, palmitic acid and metformin on AMPK phosphorylation and FABP1. Finally, overexpressing neurotensin in enteroendocrine cells reduced the lifespan of Drosophila; neurotensin deficiency extended the lifespan of mice fed a high-fat diet. These findings indicate that neurotensin inhibits AMPK and increases FABP1 in small intestinal epithelial cells under conditions of obesity. Neurotensin deficiency preserves AMPK and FABP1 levels, thus attenuating some of the negative effects of obesity and aging.

Marnas, P., Lupold, S., Giannakou, L., Giannopoulos, A. S., Hatzoglou, C., Gourgoulianis, K. I., Zarogiannis, S. G., Rouka, E. (2025). Modeling COPD in Drosophila melanogaster by cigarette smoke inhalation: functional changes and alterations in the expression of COPD-relevant orthologous genes. Am J Physiol Regul Integr Comp Physiol, 329(1):R13-r19. PubMed ID: 40392629
Summary:
Chronic obstructive pulmonary disease (COPD) ranks as the fourth leading cause of mortality worldwide. Long-term exposure to airway irritants such as smoking and air pollution is the main risk factor for developing the disease. Expanding on previous in silico findings on COPD-relevant orthologous genes between humans and Drosophila melanogaster, this study experimentally investigated the contribution of cigarette smoke (CS) inhalation exposure to the induction of COPD-related physiological and transcriptomic modifications. Adult flies 2-4 days old were exposed to CS via inhalation for 20 min over five consecutive days. The metabolic rate, locomotor activity, body mass, total body length, and the expression of COPD-specific genes were measured and compared between the exposed and unexposed groups. CS inhalation exposure significantly increased the metabolic rate and decreased the locomotor activity, body weight, and total body length. Transcriptomic changes were more profound in females, indicating sex-specific differences in CS-induced molecular responses. Functional enrichment analyses of the differentially expressed COPD-relevant genes in females pointed toward ABC transporters, miR-313 microRNA, abnormal developmental rate, DNA repair, and cell differentiation. These results indicate that D. melanogaster is a powerful model organism for studying the pathophysiological changes associated with COPD. Future work should focus on establishing tracheolar-related changes that would reflect histopathological perturbations similar to COPD patients' airways.

Long, J., Jones, S. G., Serna, A., van Reijmersdal, B., Kampshoff, F., Aibar, S., Verstreken, P., Huynen, M. A., Luhy, K., Coll-Tane, M., Schenck, A. (2025). A conserved epilepsy-associated gene co-expression module identifies increased metabolic rate as a shared pathomechanism. Dis Model Mech, PubMed ID: 40401642
Summary:
Epilepsy is a mechanistically complex, incompletely understood neurological disorder. To uncover novel converging mechanisms in epilepsy, Drosophila whole-brain single-cell RNA sequencing was used to refine and characterize a previously proposed human epilepsy-associated gene co-expression network (GCN). A conserved co-expressed module of 26 genes was identified, that comprises fly orthologs of 13 epilepsy-associated genes and integrates synaptic and metabolic functions. Over one-third of the Drosophila pan-neuronal knockdown models targeting this module exhibited altered seizure-like behaviors in response to mechanical or heat stress. These knockdown models recapitulated seizures associated with four epilepsy-associated genes, identified two novel epilepsy candidate genes, and three genes of which knockdown conferred seizure protection. Most knockdown models with altered seizure susceptibility showed changes in metabolic rate and levels of phosphorylated adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy homeostasis. Enhancing AMPK activity increased seizure resistance in a dose-dependent manner. Our findings show that Drosophila single-cell expression data and behavior can aid functional validation of human GCNs and highlight a role for metabolism in modifying seizure susceptibility.

Jiang, H., Satoh, Y., Yamamura, R., Ooshio, T., Luo, Y., Hai, H., Otsuka, T., Hata, S., Sato, R., Hirata, T., Osawa, T., Goda, K., Sonoshita, M. (2025). Inhibition of NAD-GPx4 axis and MEK triggers ferroptosis to suppress pancreatic ductal adenocarcinoma. Mol Ther, PubMed ID: 40450524
Summary:
Pancreatic ductal adenocarcinoma (PDAC) ranks among the most lethal malignancies, highlighting the critical need for innovative therapeutic strategies. This study examined the roles of nicotinamide adenine dinucleotide (NAD) synthesis pathway in PDAC. Targeting the NAD synthesis pathway significantly mitigated lethality in a Drosophila model that recapitulated the PDAC genotype. Within this pathway, we identified Glutathione peroxidase 4 (GPx4) as a critical effector responsible for scavenging reactive oxygen species (ROS). The combined application of GPx4 and Mitogen-activated protein kinase kinase (MEK) inhibitors, namely ML210 and trametinib, respectively, reduced lethality and tumor-like phenotypes in these flies. Notably, this combination treatment synergistically suppressed the proliferation of human PDAC cells and their corresponding xenografts in mice by inducing ROS accumulation, which triggered ferroptosis. These results suggest that inducing ferroptosis could represent a promising therapeutic strategy for PDAC.

Liu, Z., Du, G., Chen, Y., Chen, H. (2025). Age-associated decline of Coenzyme A leads to intestinal stem cells dysfunction via disturbing iron homeostasis. PLoS Genet, 21(6):e1011704 PubMed ID: 40446021
Summary:
The decline in adult stem cell performance is closely linked to tissue malfunction and the rising incidence of age-related diseases. To investigate the molecular basis of these impairments, a screening strategy identified reduced activity in the pantothenate/coenzyme A (CoA) pathway within aged ISCs. Furthermore, exogenous CoA supplementation restructured intestinal stem cells, reversing age-induced hyperproliferation and intestinal dysfunction, and thus extending Drosophila lifespan by curbing excessive iron accumulation in ISCs. These findings uncover a new mechanism of stem cell aging and propose that pantothenate and CoA could be potential therapeutic targets for treating age-related diseases and enhancing healthy aging in humans.

Monday November 17th - Adult Physiology and Metabolism

Lee, S. H., Hwang, D., Lee, J. W., Goo, T. W., Yun, E. Y. (2025). The Identification of a Glucuronyltransferase-Related Gene, GlcAT-S, with Putative Mucus Protection and Anti-Inflammatory Effects from Gut-Damaged Drosophila by Dextran Sulfate Sodium (DSS). Biology (Basel), 14(5) PubMed ID: 40427702
Summary:
The intestinal epithelium, which is protected by mucosal surfaces composed of mucins and other glycoproteins, functions as a selective barrier that absorbs nutrients while preventing the translocation of harmful substances. To understand the mechanisms between mucosal disruption and tissue inflammation, a mucus-disrupting agent, dextran sodium sulfate, were orally administrated to Drosophila melanogaster and 63 differentially expressed genes (DEGs) were screened. Through a database search using bioinformatics tools (CHEA3 and WebGestalt), ELK1 was identified as a potential key transcription factor for the selected DEGs, and among the 63 DEGs, ELK1-related genes, B3GAT3, FIBP, and TENT2 (GlcAT-S, Fibp, and Wisp in Drosophila), were selected as the relevant genes that respond to mucus disruption. Enterocyte (EC)-specific GlcAT-S knockdown was confirmed by RNAi significantly reduced gut length and increased intestinal stem cell proliferation in Drosophila. Additionally, in EC-specific GlcAT-S-knockdown flies, it was observed that the mucus-production-related genes, Muc68D and Mur29B, were specifically reduced, whereas the inflammatory cytokines egr and upd3 were overexpressed. This study provides evidence that GlcAT-S is involved in the regulation of intestinal inflammation in Drosophila and plays a protective role against mucus disruption. These findings suggest that GlcAT-S may be a potential therapeutic target for the treatment of intestinal inflammatory diseases such as IBD.

Hamilton, W., Massey, J., Hardy, E., Lopez-Madrigal, S., Phelps, M., Martin, M., Newton, I. (2025). Wolbachia uses ankyrin repeats to target specific fly proteins. bioRxiv, PubMed ID: 40463106
Summary:
Arthropods, the most diverse phylum on Earth, are hosts to a plethora of bacterial parasites that secrete various effectors of unknown function during infection. The most prevalent of these is the intracellular bacterium Wolbachia pipientis. The microbe infects between 40-60% of insect species, causes important reproductive manipulations, and limits virus replication in arthropod vectors, becoming a promising biocontrol agent. Understanding the molecular basis of Wolbachia infection and Wolbachia-induced phenotypes is critical to the use of Wolbachia in vector control. These Wolbachia ankyrin repeat proteins (WARPs) represent a highly dynamic and diverse part of the Wolbachia pangenome and remain thus far, largely uncharacterized. Molecular and genetic screens were performed to identify interactions between Wolbachia wMel WARPs and their target host proteins in Drosophila melanogaster. The results identify strong interactions of two Wolbachia proteins, WARP434 and WARP754, with two host targets (CG11327 and Ptp61F, respectively). Heterologous expression of these two WARPs is extremely toxic in Drosophila tissues and the toxicity is dependent on the ankyrin repeat domain of each WARP. Importantly, knockdown of the host targets alleviates toxicity, confirming WARP/target interactions. Finally, antibodies targeting both WARPs show expression by Wolbachia during infection of Drosophila cells. Understanding how Wolbachia manipulates its host biology and which host pathways it targets during infection will help divine how the most prevalent intracellular bacterial parasite on Earth interacts with its insect hosts at the molecular level. Our screen is the first step towards that goal.

Lemoine, M. M., Wohner, T., Kaltenpoth, M. (2025). Microbial Community Dynamics in Natural Drosophila melanogaster Populations Across Seasons. Environ Microbiol, 27(6):e70104 PubMed ID: 40456535
Summary:
Many insects benefit from gut microbes that contribute to digestion, detoxification, nutrient supplementation or defence. Although abiotic and biotic factors are known to shape insect-associated microbial communities, the seasonal dynamics and their potential impact on host fitness remain poorly studied. This study investigated the temporal changes in bacterial and fungal communities associated with the model organism Drosophila melanogaster over 5 months. The results reveal high inter-individual variation, but also consistent changes in microbial communities of three wild D. melanogaster populations from early spring to late summer. These changes were driven by specific indicator species, particularly Acetobacteraceae bacteria (Gluconobacter and Komagataeibacter) and Saccharomycetales yeasts (Pichia, Starmerella, Kregervanrija, Hanseniaspora, Saccharomycopsis, Priceomyces and Dipodascopsis). The temporal dynamics were not accompanied by differences in the total bacterial or fungal abundance, and alpha-diversity only changed across sampling months for the fungal but not the bacterial communities. While the changes in D. melanogaster-associated microbial communities are likely driven by the exposure to seasonally changing microbial environments and diets, they may have important impacts on host fitness. Elucidating the potential adaptive value of seasonally changing microbial communities will enhance understanding of how symbiotic microbes may contribute to ecological niche shifts and geographic range expansions in insects.

Lin, Z., He, Z., Guo, J., Ji, X., Hu, Z., Tang, Y., Wei, C., Liu, J., Wu, W., Ma, J., Jiao, R. (2025). Xgr is involved in body size control in Drosophila through promoting glucose uptake in the Malpighian tubules. J Genet Genomics, PubMed ID: 40441601
Summary:
Body size control is fundamental to development and requires proper energy engagement. One of the key energy sensing factors is AMP-activated protein kinase (AMPK), which regulates glucose uptake to ensure ATP production and nutrition supply during development. This study identified that the mutation of xgr (CG42249), a gene encoding an ATPase, results in a reduced body size in Drosophila. Xgr is primarily expressed in the epithelial cells of the Malpighian tubules and the midguts. Loss of xgr leads to the inactivation of the AMPK signaling due to an increased ATP level. Glucose reabsorption in the Malpighian tubules is significantly reduced, as the Glut1 translocation to the plasma membrane is significantly disrupted in the absence of Xgr function. These results suggest that Xgr function in the Malpighian tubules is essential to systemic glucose supply and energy homeostasis at the organismal level, thereby impacting body size. These findings provide a mechanistic connection between energy homeostasis and animal size control during development.

Lago Solis, B., Koch, R., Nagoshi, E. (2025).. Circadian clock-independent ultradian rhythms in lipid metabolism in the Drosophila fat body.. J Biol Chem, 301(6):110245 PubMed ID: 40383146
Summary:
The role of circadian clocks in regulating metabolic processes is well known; however, their impact on metabolic states across species and life stages remains largely unexplored. This study investigates the relationship between circadian rhythms and metabolic regulation in the Drosophila larval fat body, a metabolic hub analogous to the mammalian liver and adipose tissue. Surprisingly, the fat body of period null mutants, which lack a functional circadian clock in all tissues, exhibited 12-h rhythms in gene expression, particularly those involved in peroxisome function, lipid metabolism, and oxidative stress response. These transcriptomic rhythms were aligned with 12-h oscillations in peroxisome biogenesis and activity, reactive oxygen species levels, and lipid peroxidation. Furthermore, period mutants exhibited 12-h rhythms in body fat storage, ultimately leading to a net reduction in body fat levels. Collectively, these results identify clock-independent ultradian rhythms in lipid metabolism that are essential for larval survival and development.

De Backer, J. F., Karges, T., Papst, J., Panar, Z. N., Coman, C., Ahrends, R., Xu, Y., Garcia-Ccceres, C., Grunwald Kadow, I. C. (2025). Adenosine signaling in glia modulates metabolic state-dependent behavior in Drosophila.Cell Rep, 44(6):115765 PubMed ID: 40445832
Summary:
An animal's metabolic state strongly influences its behavior. Hungry animals prioritize food-seeking and feeding behaviors, while sated animals suppress these behaviors to engage in other activities. Additionally, neuronal activity and synaptic transmission are among the most energy-expensive processes. However, neurons do not uptake nutrients from the circulation. Instead, glia fulfill this highly evolutionarily conserved function in addition to modulating neuronal activity and behavior. However, how different glia subtypes sense metabolic state and modulate behavior is incompletely understood. This study unraveled two types of glia-mediated modulation of metabolic-state-dependent behavior. In food-deprived flies, astrocyte-like and perineurial glia promote foraging and feeding, respectively, while cortex glia suppress these behaviors. We further show that adenosine and adenosine receptors modulate intracellular calcium levels in these glia subtypes, which ultimately controls behavior. This study reveals a mechanism of how different glia subtypes sense an animal's metabolic state and modulate its behavior accordingly.

Thursday November 13th - Behavior

Amos, L., Wigby, S., Dougherty, L. R. (2025). Short-term increases in rival number improves single mating productivity in male Drosophila. Behav Ecol, 36(3):araf032 PubMed ID: 40375890
Summary:
In variable environments, animals can change their reproductive behaviors and physiology to maximize reproductive returns. Natural environments vary in multifaceted ways, and animals may need to integrate multiple social or physical cues to adopt the most effective behavioral strategy. In a fully factorial 2x 2x 2x experiment, this study exposed males to three factors: the number of rivals (10 or 30), food availability (present/absent) and mechanical shaking (present/absent). After 60 min of exposure, the male's mating latency, copulation duration and the number of offspring produced after a single mating were recorded. Latency of the males partner to remate with a stock male 24 h later was also recorded. When rival number was increased from 10 per vial to 30 per vial, males sired more offspring. Males also varied their copulation duration and mating latency in response to the number of rivals, but in a condition-dependent manner. In the absence of vortexing, males mated for a shorter time when kept with 30 rivals, but the opposite was observed when males were vortexed. When males were fed and held in groups of 30, they took longer to begin mating compared to the other treatments. These findings are consistent with the idea that male Drosophila integrate social cues to respond to levels of sperm competition and plastically allocate their ejaculate, but we have demonstrated that they can occur more rapidly (1 h) than previously thought (>24 h). Overall, these data highlight that combinatorial approaches can reveal new relationships between environment and behavior.

Gopfert, M., Yang, J., Rabadiya, D., Riedel, D., Moussian, B., Behr, M. (2025). Exoskeletal cuticle proteins enable Drosophila locomotion. Acta Biomater, PubMed ID: 40412508
Summary:
Exo- and Endoskeleton function enables muscle-mediated locomotion in animals. In mammals, the defective protein matrix of bones found in systematic skeletal disorders such as osteoporosis causes fractures and severe skeletal deformations under high muscle tension. This study identified an analogous mechanism for integrating muscle-mediated tension into the apical extracellular matrix (aECM) of the invertebrate body wall exoskeleton. Obstructor chitin-binding proteins, the chitin deacetylases, Chitinases, and the matrix-protecting proteins Knickkopf and Retroactive are epidermally expressed during late embryogenesis. Their control of forming epidermal chitinous structures protects the exoskeletal aECM from collapsing when embryos start moving and hatch as larvae. In a larval locomotion assay we tested the function of these cuticle related genes. Gene mutations and knockdowns caused changes in normal movement behavior and lower the speed of larvae. Moreover, the transmembrane Zona Pellucida domain protein Piopio provides the adhesion between the epidermal apical membrane and the overlaying chitinous aECM in a matriptase-dependent manner. A failure of Piopio and chitin-associated proteins leads to exoskeletal deformations and detachment from the epidermal membrane, destabilizing muscle forces and impairing larval mobility. The data identifies a protein network that transforms the chitinous aECM into a stable exoskeleton that directly resists muscle impact at epidermal tendon cells, thereby serving locomotion. Demonstrating the importance of these proteins in producing aECM as a three-dimensional cuticular scaffold for exoskeletal function opens up opportunities for the development of biomimetic applications of synthetic materials.

Karashchuk, L., Li, J. S., Chou, G. M., Walling-Bell, S., Brunton, S. L., Tuthill, J. C., Brunton, B. W. (2025). Sensorimotor delays constrain robust locomotion in a 3D kinematic model of fly walking.Elife, 13 PubMed ID: 40372779
Summary:
Walking animals must maintain stability in the presence of external perturbations, despite significant temporal delays in neural signaling and muscle actuation. A 3D kinematic model with a layered control architecture was developed to investigate how sensorimotor delays constrain the robustness of walking behavior in the fruit fly, Drosophila. Motivated by the anatomical architecture of insect locomotor control circuits, this model consists of three component layers: a neural network that generates realistic 3D joint kinematics for each leg, an optimal controller that executes the joint kinematics while accounting for delays, and an inter-leg coordinator. The model generates realistic simulated walking that resembles real fly walking kinematics and sustains walking even when subjected to unexpected perturbations, generalizing beyond its training data. However, it was found that the model's robustness to perturbations deteriorates when sensorimotor delay parameters exceed the physiological range. These results suggest that fly sensorimotor control circuits operate close to the temporal limit at which they can detect and respond to external perturbations. More broadly, this study showed how a modular, layered model architecture can be used to investigate physiological constraints on animal behavior.

Subasi, B. S., Finsterbusch, A. L., Buge, M., Armitage, S. A. O. (2025). Two matings lead to more copulatory wounding than a single mating in female Drosophila melanogaster. Proc Biol Sci, 292(2049):20250523 PubMed ID: 40527456
Summary:
Copulation can result in males inflicting wounds to the female genitalia, so-called traumatic mating. Such wounds are potentially costly as they could be entry points for infections, and they have been associated with a shorter lifespan in insect species. In many species of insects, females mate with more than one male, which leads to the question of whether the number of matings affects the amount of genital damage that females suffer from those matings. This study tested whether copulation frequency affects the number or size of genital wounds in Drosophila melanogaster. Females that mated twice had more genital wounds and a larger total area of wounding, compared with females that mated once. However, females that refused to mate a second time had a similar area of wounding to females that mated twice. Wounds to the ventral abdomen also increased with increased mating frequency. The results show that polyandry can result in increased female copulatory wounding in this species. The extent to which the wounds are costly for females is currently unknown. Investigating genital and abdominal wounds is crucial to a better understanding of the consequences of sexual conflict and the selective pressures shaping mating behaviour.

Guerrero, C. Y. P., Cusick, M. R., Samaras, A. J., Shamon, N. S., Cavanaugh, D. J. (2025). The cell-intrinsic circadian clock is dispensable for lateral posterior clock neuron regulation of Drosophila rest-activity rhythms. Neurobiol Sleep Circadian Rhythms, 18:100124 PubMed ID: 40386580
Summary:
Circadian control of behavior arises from intercommunication among a distributed network of circadian clock neurons in the brain. Single-cell sequencing and brain connectome data support the division of the ~240 brain clock neurons in Drosophila into ~20 subclusters, and functional studies demonstrate that these populations differentially contribute to behavioral outputs. This study used genetic tools that enable highly selective, cell-specific manipulations to investigate the role of molecular clock function and neuronal activity within the lateral posterior clock neurons (LPNs) in the regulation of rest-activity rhythms. Genetic silencing of these neurons, which compromises signaling with downstream neuronal targets, substantially reduces the strength of free-running rest-activity rhythms. In contrast, locomotor activity patterns are robust to CRISPR-mediated disruption of molecular clock cycling within the LPNs. It is concluded that the LPNs act as driven oscillators that retain the capacity to transmit circadian information in the absence of cell-intrinsic molecular clocks.

Ladd, C. E., Simpson, J. H. (2025). Behavior choices amongst grooming, feeding, and courting in Drosophila show contextual flexibility, not an absolute hierarchy of needs.bioRxiv, PubMed ID: 40463182
Summary:
To determine the algorithmic rules and neural circuits controlling selection amongst competing behaviors, we established assays where adult Drosophila melanogaster choose between grooming and feeding, grooming and courting, or feeding and courting. There is not an absolute hierarchy: while flies typically perform grooming first, they can choose to feed if sufficiently starved, or court if an appropriate female is available. Flies alternate between competing behaviors, performing short bouts of each action rather than completely satisfying one drive before transitioning to another. And no evidence was found for a common genetic or neuronal locus that affects all decisions, suggesting that the fly may select the best course of action by discrete circuits regulating each pairwise comparison. Our results add to a growing body of work on decision-making in Drosophila and provide a foundation for future investigation of the exact neural circuits required to achieve appropriate choices.

Wednesday November 12th - Gonads

Galvin, J., Yedigarian, S., Rahman, M., Borziak, K., DeNieu, M., Larson, E. L., Manier, M. K. (2025). Sperm length and seminal fluid proteins promote male reproductive success in D. melanogaster. J Evol Biol, PubMed ID: 40434825
Summary:
Spermatozoal morphology is highly variable both within and among species, often corresponding to variation in the shape of the female sperm storage organs in ways that can significantly impact fertilization success. In an effort to understand genetic mechanisms of sperm length variation, this study compared gene expression patterns in the testes of Drosophila melanogaster males that produce either long or short sperm. Genes upregulated in long sperm testes are enriched for long noncoding RNAs (lncRNAs) and seminal fluid proteins (Sfps). Transferred in seminal fluid to the female during mating, Sfps are secreted by the male accessory glands and affect female remating rate, physiology, and behavior with concomitant advantages for male reproductive success. While sperm and Sfps are both critical for male reproductive success, they are largely considered to be functionally, genetically, and developmentally independent and despite being upregulated in long sperm testes, Sfps have no known function in testis tissue. Knockouts of two Sfps upregulated in long sperm males, Sex Peptide (SP) and ovulin (Acp26Aa) resulted in shorter sperm, which altogether suggests that Sfps may play a role in the development of sperm length during spermatogenesis. Consistent with this, knockout of accessory gland function did not affect sperm length, suggesting that accessory gland expression had no influence on spermatogenic processes. Long sperm males were better able to delay female remating. These results might suggest that long sperm males have a double advantage in sperm competition by both delaying female remating, likely through transfer of more Sfps, and by resisting sperm displacement. However, this stud found that the delay in female remating does not necessarily translate to more progeny or higher paternity success. Thus, this study found that multiple components of the ejaculate promote male reproductive success at different stages of reproduction, but the realized fitness advantages in sperm competition are uncertain.

Harris, D. E., Kim, J. J., Stern, S. R., Vicars, H. M., Matias, N. R., Gallicchio, L., Baker, C. C., Fuller, M. T. (2025). An RNA-binding regulatory cascade controls the switch from proliferation to differentiation in the Drosophila male germ cell lineage. Proc Natl Acad Sci U S A, 122(20):e2418279122 PubMed ID: 40377994
Summary:
The switch from precursor cell proliferation to onset of differentiation in adult stem cell lineages must be carefully regulated to produce sufficient progeny to maintain and repair tissues, yet prevent overproliferation that may enable oncogenesis. In the Drosophila male germ cell lineage, spermatogonia produced by germ line stem cells undergo a limited number of transit amplifying mitotic divisions before switching to the spermatocyte program that sets up meiosis and eventual spermatid differentiation. The number of transit amplifying divisions is set by accumulation of the Bag-of-marbles (Bam) protein to a critical threshold. In bam mutants, spermatogonia proliferate through several extra rounds of mitosis and then die without becoming spermatocytes. This study shows that a key role of Bam for the mitosis to differentiation switch is repressing expression of Held Out Wings (how), homolog of mammalian Quaking. Knockdown of how in germ cells was sufficient to allow spermatogonia mutant for bam or its partner benign gonial cell neoplasm to differentiate, while forced expression of nuclear-targeted How protein in spermatogonia wild-type for bam resulted in continued proliferation at the expense of differentiation. These findings suggest that Bam targets how RNA for degradation by acting as an adapter to recruit the CCR4-NOT deadenylation complex via binding its subunit, Caf40. As How is itself an RNA-binding protein with roles in RNA processing, these findings reveal that the switch from proliferation to meiosis and differentiation in the Drosophila male germ line adult stem cell lineage is regulated by a cascade of RNA-binding proteins.

Azlan, A., Fukunaga, R. (2025). MYCBP interacts with Sakura and Otu and is essential for germline stem cell renewal and differentiation and oogenesis. bioRxiv, PubMed ID: 40631179
Summary:
The self-renewal and differentiation of germline stem cells (GSCs) are tightly regulated during oogenesis. The Drosophila female germline provides a powerful model to study these regulatory mechanisms. Sakura (also known as Bourbon/CG14545) has been identified as a crucial factor for maintenance and differentiation of GSCs and oogenesis, and Sakura has been shown to binds to Ovarian Tumor (Otu), another essential regulator of these processes. This study identified Mhcbp (c-Myc binding protein) as an additional essential component of this regulatory network. MYCBP physically associates with itself, Sakura, and Otu, forming binary and ternary complexes including a MYCBP•Sakura•Otu complex. MYCBP is highly expressed in the ovary, and Mycbp null mutant females exhibit rudimentary ovaries with germline-less and tumorous ovarioles, fail to produce eggs, and are completely sterile. Germline-specific depletion of Mycbp disrupts Dpp/BMP signaling, causing aberrant expression of bag-of-marbles (bam) and leading to defective differentiation and GSC loss. In addition, Mycbp is required for female-specific splicing of sex-lethal (sxl), a master regulator of sex identity determination. These phenotypes closely resemble those observed those of sakura and otu mutants. Together, these findings reveal that MYCBP functions in concert with Sakura and Otu to coordinate self-renewal and differentiation of GSCs and oogenesis in Drosophila.

Hohne, M. Y., Milani, W., Ramlow, K., Bogdan, S. (2025). The tumor suppressor RASSF8: A WAVE interaction partner controlling migration and cohesion of invasive border cells in Drosophila.Proc Natl Acad Sci U S A, 122(23):e2426702122 PubMed ID: 40465620
Summary:
Collective cell migration is a key driver of tissue morphogenesis and cancer invasion. This study identified the tumor suppressor Ras association domain-containing protein 8 (RASSF8) as a WAVE interactor required for border cell migration. RASSF8 colocalizes with F-actin and cell adhesion molecules at border cell- border cell contacts. Loss of RASSF8 function results in border cell cohesion defects, a phenotype associated with changes in the localization of the Echinoid (Ed) and Coracle (Cora). Cell-type-specific RNA interference (RNAi) experiments suggest that cohesion defects are caused by changes in localization of Ed rather than E-cadherin. Gain-of-function experiments further revealed reciprocal functional interactions between RASSF8 and WAVE controlling collective border cell movement. Thus, a dual function is proposed of RASSF8 in coordinating border cell cluster behavior. RASSF8 is thought to regulate the collective movement of border cells by restricting WAVE function, while it controls the epithelial cluster integrity by regulating cell-cell adhesion and septate junction molecules such as Ed and Cora.

Ghosh, G. , Sas, D., Nandi, A., De, S., Gangappa, S. N., Prasad, M. (2025). Ecdysone regulates phagocytic cell fate of epithelial cells in developing Drosophila eggs. J Cell Biol, 224(8) PubMed ID: 40434296
Summary:
Acquisition of nonprofessional phagocytic cell fate plays an important role in sculpting functional metazoan organs and maintaining overall tissue homeostasis. Though physiologically highly relevant, how the normal epithelial cells acquire phagocytic fate is still mostly unclear. This study employed the Drosophila ovary model to demonstrate that the classical ecdysone signaling in the somatic epithelial follicle cells (AFCs) aids the removal of germline nurse cells (NCs) in late oogenesis. Live-cell imaging data reveal a novel phenomenon wherein collective behavior of 4-5 AFCs is required for clearing a single NC. By employing classical genetics, molecular biology, and yeast one-hybrid assay, this study demonstrated that ecdysone modulates the phagocytic disposition of AFCs at two levels. It regulates the epithelial-mesenchymal transition of the AFCs through Serpent and modulates the phagocytic behavior of the AFCs through Croquemort and Draper. These data provide unprecedented novel molecular insights into how ecdysone signaling reprograms AFCs toward a phagocytic fate.

Hofe, P., Gardner, T., DiNardo, S., Anllo, L. (2025). Tbx1 ortholog org-1 is required to establish testis stem cell niche identity in Drosophila. bioRxiv, PubMed ID: 40463141
Summary:
Stem cells require signals from a cellular microenvironment known as the niche that regulates identity, location, and division of stem cells. Niche cell identity must be properly specified during development to form a tissue capable of functioning in the adult. This study shows that the Tbx1 ortholog org1 is expressed in Drosophila testis niche cells in response to Slit and FGF signals. org1 is expressed during niche development and is required to specify niche cell identity. org1 mutants specified fewer niche cells, and those cells showed disruption of niche-specific markers, including loss of the niche adhesion protein Fas3 and reduced hedgehog expression.org1 expression in somatic gonadal precursors is capable of inducing formation of additional niche cells. Disrupted niche identity in org1 mutants resulted in niche assembly and functionality defects. The conserved transcription factor islet is expressed in response to org1 and show that islet functions downstream to mediate niche identity and assembly. This work identifies a novel role for org1 in niche establishment.

Tuesday November 11th - Cell Cycle

Gonzalez-Baez, L., Mortati, E., Mitchell, L., Losick, V. P. (2025). Melanization regulates wound healing by limiting polyploid cell growth in the Drosophila epithelium. Genetics, PubMed ID: 40472338
Summary:
Wound healing requires a localized response that restricts growth, remodeling, and inflammation to the site of injury. In the fruit fly, Drosophila melanogaster, the epithelium heals puncture wounds through cell growth instead of cell division. Epithelial cells on wound margin both fuse and duplicate their genome to generate a multinucleated, polyploid cell essential for tissue repair. Despite the essential role of polyploidy in wound healing, the signals that initiate and regulate the extent of cell growth at the wound site remain poorly understood. One of the first steps in wound healing requires the deposit of melanin at the site of injury, which persists as a melanin scar. The melanin scar forms within hours after a puncture wound and is dependent on the activation of three prophenoloxidase genes (PPO1, PPO2, and PPO3). Using a triple loss of function mutant (PPOnull), a novel role was uncovered for melanization in regulating wound healing by limiting polyploid cell growth post injury. Thus, melanization is required for efficient wound closure and its loss leads to an unexpected exacerbation of polyploid cell growth in the surrounding epithelial cells. This occurs, in part, through the early entry of epithelial cells into the endocycle, which may be due to altered gene expression as a result of delayed JNK signaling and other pathways. In conclusion, this study has found that polyploid cell growth requires melanization at the injury site to control the extent of cell growth and regulate wound repair.

Ramesh, N. A., Buttitta, L. (2025). A window of cell cycle plasticity enables imperfect regeneration of an adult postmitotic organ in Drosophila. bioRxiv, PubMed ID: 40501567
Summary:
The Drosophila ejaculatory duct (ED) is a secretory tissue of the male somatic reproductive system responsible for producing components of the seminal fluid which support fertility, serve antimicrobial functions and influence the physiological changes in the female after mating. The ED is a simple organ made up of secretory epithelial cells that are encased by extracellular matrix and a layer of innervated contractile muscle. These secretory cells are post-mitotic and lack known stem cells or progenitors in the adult, but they are not fully quiescent. They undergo a variant cell cycle called endoreplication immediately post-eclosion to increase organ size and protein synthesis capacity. Polyploid and post-mitotic tissues often face unique challenges in response to cell loss due to their inability to proliferate. This study shows that the adult ED is capable of significant recovery after cell loss due to a combination of increased nuclear and cellular hypertrophy that partially restores tissue mass and organ function. The early cell cycle plasticity of this adult tissue is critical for this recovery, as older tissues that have few or no endocycles exhibit reduced capacity for recovery after cell loss. Together, these findings establish the Drosophila ED as a model to study post-mitotic polyploid tissue repair and highlight a combination of endocycles and hypertrophy as a key mechanism for functional regeneration in the absence of mitosis.

Cho, C. Y., O'Farrell, P. H. (2025). A mitotic bookmark coordinates transcription and replication. bioRxiv, PubMed ID: 40631093
Summary:
Collisions between advancing replication forks and elongating transcripts pose a universal threat. During the rapid nuclear division cycles in early Drosophila embryos, coordinating transcription and replication is critical to reduce the risk of collisions. In each cycle, replication begins immediately after mitosis, while transcription starts 3 minutes later, overlapping with replication for the remainder of interphase. Previous work showed that transcription depends on the coactivator Brd4, which forms hubs at active genes. Brd4 persists on mitotic chromosomes as bookmarks of transcriptional activity and, upon anaphase entry, recruits the replication activator Cdc7 to specify early-replicating genomic regions in the following interphase. Additionally, Cdc7 activity removes Brd4 bookmarks such that post-mitotic transcription occurs only after a new round of Brd4 hub assembly. Early initiation of replication while deferring initiation of transcription is proposed to allow unimpeded transcriptional elongation behind advancing replication forks. Supporting this, inhibiting Cdc7 delayed replication, stabilized Brd4 bookmarks, and resulted in premature transcription with elongation defects. We propose that Cdc7 triggers a functional switch in Brd4 that enforces temporal ordering of the initiation of transcription and replication, thereby minimizing collisions. This switching process might underlie the widespread correlation between transcriptional activity and early replication.

Lin, H. C., Golic, M. M., Hill, H. J., Lemons, K. F., Vuong, T. T., Smith, M., Golic, F., Golic, K. G. (2024). Drosophila ring chromosomes interact with sisters and homologs to produce anaphase bridges in mitosis. bioRxiv, PubMed ID: 39149325
Summary:
Ring chromosomes are known in many eukaryotic organisms, including humans. They are typically associated with a variety of maladies, including abnormal development and lethality. Underlying these phenotypes are anaphase chromatin bridges that can lead to chromosome loss, nondisjunction and breakage. By cytological examination of ring chromosomes in Drosophila melanogaster this study identified five causes for anaphase bridges produced by ring chromosomes. Catenation of sister chromatids is the most common cause and these bridges frequently resolve during anaphase, presumably by the action of topoisomerase II. Sister chromatid exchange and chromosome breakage followed by sister chromatid union also produce anaphase bridges. Mitotic recombination with the homolog was rare, but was another route to generation of anaphase bridges. Most surprising, was the discovery of homolog capture, where the ring chromosome was connected to its linear homolog in anaphase. It is hypothesized that this is a remnant of mitotic pairing and that the linear chromosome is connected to the ring by multiple wraps produced through the action of topoisomerase II during establishment of homolog pairing. In support, it was shown in a ring/ring homozygote the two rings are frequently catenated in mitotic metaphase, a configuration that requires breaking and rejoining of at least one chromosome.

Valles, A. M., Rubin, T., Macaisne, N., Dal Toe, L., Molla-Herman, A., Antoniewski, C., Huynh, J. R. (2024). Transcriptomic analysis of meiotic genes during the mitosis-to-meiosis transition in Drosophila females. Genetics, PubMed iD: 39225982
Summary:
Germline cells produce gametes, which are specialized cells essential for sexual reproduction. Germline cells first amplify through several rounds of mitosis before switching to the meiotic program, which requires specific sets of proteins for DNA recombination, chromosome pairing, and segregation. Surprisingly, previous study found that some proteins of the synaptonemal complex, a prophase i meiotic structure, are already expressed and required in the mitotic region of Drosophila females. To assess if additional meiotic genes were expressed earlier than expected, mitotic and meiotic cell populations were isolated to compare their RNA content. This transcriptomic analysis reveals that all known meiosis i genes are already expressed in the mitotic region; however, only some of them are translated. As a case study, this study focused on mei-W68, the Drosophila homolog of Spo11, to assess its expression at both the mRNA and protein levels and used different mutant alleles to assay for a premeiotic function. No functional role for Mei-W68 was found during homologous chromosome pairing in dividing germ cells. This study paves the way for further functional analysis of meiotic genes expressed in the mitotic region.

Huang, Y. T., Hesting, L. L., Calvi, B. R. (2024). An unscheduled switch to endocycles induces a reversible senescent arrest that impairs growth of the Drosophila wing disc. PLoS Genet, 20(9):e1011387 PubMed iD: 39226333
Summary:
A programmed developmental switch to G / S endocycles results in tissue growth through an increase in cell size. Unscheduled, induced endocycling cells (iECs) promote wound healing but also contribute to cancer. Much remains unknown, however, about how these iECs affect tissue growth. Using the D. melanogaster wing disc as model, populations of iECs were found initially increase in size but then subsequently undergo a heterogenous arrest that causes severe tissue undergrowth. iECs acquired DNA damage and activated a Jun N-terminal kinase (JNK) pathway, but, unlike other stressed cells, were apoptosis-resistant and not eliminated from the epithelium. instead, iECs entered a JNK-dependent and reversible senescent-like arrest. Senescent iECs promoted division of diploid neighbors, but this compensatory proliferation did not rescue tissue growth. This study has uncovered unique attributes of iECs and their effects on tissue growth that have important implications for understanding their roles in wound healing and cancer.

Friday, November 7th - Larval and Adult Neural Structure, Development and Function

Epiney, D. G., Chaya, G. M., Dillon, N. R., Lai, S. L., Doe, C. Q. (2025). Single nuclei RNA-sequencing of adult brain neurons derived from type 2 neuroblasts reveals transcriptional complexity in the insect central complex. Elife, 14 PubMed ID: 40371710
Summary:
In both Drosophila and mammals, the brain contains the most diverse population of cell types of any tissue. It is generally accepted that transcriptional diversity is an early step in generating neuronal and glial diversity, followed by the establishment of a unique gene expression profile that determines morphology, connectivity, and function. In Drosophila, there are two types of neural stem cells, called Type 1 (T1) and Type 2 (T2) neuroblasts. The diversity of T2-derived neurons contributes a large portion of the central complex (CX), a conserved brain region that plays a role in sensorimotor integration. Recent work has revealed much of the connectome of the CX, but how this connectome is assembled remains unclear. Mapping the transcriptional diversity of T2-derived neurons is a necessary step in linking transcriptional profile to the assembly of the adult brain. This study performed single nuclei RNA sequencing of T2 neuroblast-derived adult neurons and glia. Clusters were identified containing all known classes of glia, clusters that are male/female enriched, and 161 neuron-specific clusters. Neurotransmitter and neuropeptide expression were mapped and unique transcription factor combinatorial codes were identified for each cluster. This is a necessary step that directs functional studies to determine whether each transcription factor combinatorial code specifies a distinct neuron type within the CX. Several columnar neuron subtypes were mapped to distinct clusters, and two neuronal classes (NPF+ and AstA+) were identified that both map to two closely related clusters. These data support the hypothesis that each transcriptional cluster represents one or a few closely related neuron subtypes.

Deng, X., Suito, T., Tominaga, M., Sokabe, T. (2025). Monoacylglycerol acyltransferase maintains ionotropic receptor expression for cool temperature sensing and avoidance in Drosophila. Commun Biol, 8(1):765 PubMed ID: 40442407
Summary:
Sensory inputs of temperature dynamics in the environment are essential for appropriate physiological outputs. The responsiveness of sensory neurons is maintained by functional thermosensor expression. However, the mechanism by which their expression is regulated is unclear. This study identified a monoacylglycerol acyltransferase-coding gene named bishu-1 encoding a monoacylglycerol acyltransferase (MGAT)-coding gene that is crucial for cool temperature sensing and avoidance. It is an ortholog of the human diacylglycerol acyltransferase 2 (DGAT2) family of enzymes. The name "bishu" is a Chinese word for "summering," referring to the behavior of escaping heat. bishu-1 contributes to maintaining the responsiveness of cool temperature sensing neurons in Drosophila. bishu-1 mutation leads to abnormal thermal avoidance in a cool temperature range. Cooling-induced responses in dorsal organ cool cells (specialized thermosensory neurons in Drosophila larvae that detect cool temperatures and mediate cool avoidance behavior). Dorsal organ cool cells are weakened by the absence of bishu-1, and this is associated with reduced transcription of the ionotropic receptors IR25a and IR21a and a transcription factor Broad. These findings unveil a novel link between lipid metabolism and thermosensor function, thus providing new insights into mechanisms underlying the appropriate maintenance of sensory inputs.

Chai, C. M., Morrow, C. M., Parikh, D. D., Von Reyn, C. R., Leonardo, A., Card, G. M. (2025). Shorter-duration escapes driven by Drosophila giant interneurons promote survival during predation. Proc Biol Sci, 292(2047):20241724 PubMed ID: 40425165
Summary:
Large axon-diameter descending neurons are metabolically costly but transmit information rapidly from sensory neurons in the brain to motor neurons in the nerve cord. They have thus endured as a common feature of escape circuits in many animal species where speed is paramount. Though often considered isolated command neurons triggering fast-reaction-time, all-or-none escape responses, giant neurons are one of multiple parallel pathways enabling selection between behavioural alternatives. Such degeneracy among escape circuits makes it unclear if and how giant neurons benefit prey fitness. This study competed Drosophila melanogaster flies with genetically silenced giant fibres (GFs) against flies with functional GFs in an arena with wild-caught damselfly predators; GF silencing was found to decrease prey survival. Kinematic analysis of damselfly attack trajectories shows that decreased prey survival results from predator capture of GF-silenced flies during some attack speeds and approach distances that would normally elicit successful escapes. In previous studies with a virtual looming stimulus, a model was proposed in which GFs enforce the selection of a short-duration take-off sequence as opposed to reducing reaction time. These findings demonstrate that, during real predation scenarios, the GFs indeed promote prey survival by influencing action selection as a means to increase escape probability.

Benton, R., Mermet, J., Jang, A., Endo, K., Cruchet, S., Menuz, K. (2025). An integrated anatomical, functional and evolutionary view of the Drosophila olfactory system. EMBO Rep, 26(12):3204-3225 PubMed ID: 40389758
Summary:
The Drosophila melanogaster olfactory system is one of the most intensively studied parts of the nervous system in any animal. Composed of ~50 independent olfactory neuron classes, with several associated hygrosensory and thermosensory pathways, it has been subject to diverse types of experimental analyses. However, synthesizing the available information is limited by the incomplete data and inconsistent nomenclature found in the literature. This work first "complete" the peripheral sensory map through the identification of a previously uncharacterized antennal sensory neuron population expressing Or46aB, and the definition of an exceptional "hybrid" olfactory neuron class comprising functional Or and Ir receptors. Second, this study surveyed developmental, anatomical, connectomic, functional, and evolutionary studies to generate an integrated dataset and associated visualizations of these sensory neuron pathways, creating an unprecedented resource. Third, the utility of the dataset is illustrated to reveal relationships between different organizational properties of this sensory system, and the new questions these stimulate. Such examples emphasize the power of this resource to promote further understanding of the construction, function, and evolution of these neural circuits.

Guerrero, C. Y. P., Cusick, M. R., Samaras, A. J., Shamon, N. S., Cavanaugh, D. J. (2025). The cell-intrinsic circadian clock is dispensable for lateral posterior clock neuron regulation of Drosophila rest-activity rhythms. Neurobiol Sleep Circadian Rhythms, 18:100124 PubMed ID: 40386580
Summary:
Circadian control of behavior arises from intercommunication among a distributed network of circadian clock neurons in the brain. Single-cell sequencing and brain connectome data support the division of the ∼240 brain clock neurons in Drosophila into ∼20 subclusters, and functional studies demonstrate that these populations differentially contribute to behavioral outputs. This study used genetic tools that enable highly selective, cell-specific manipulations to investigate the role of molecular clock function and neuronal activity within the lateral posterior clock neurons (LPNs) in the regulation of rest-activity rhythms. Genetic silencing of these neurons, which compromises signaling with downstream neuronal targets, substantially reduces the strength of free-running rest-activity rhythms. In contrast, locomotor activity patterns are robust to CRISPR-mediated disruption of molecular clock cycling within the LPNs. It is concluded that the LPNs act as driven oscillators that retain the capacity to transmit circadian information in the absence of cell-intrinsic molecular clocks.

Currier, T. A., Clandinin, T. R. (2025). Infrequent strong connections constrain connectomic predictions of neuronal function. Cell, PubMed ID: 40460825
Summary:
How does circuit wiring constrain neural computation? Recent work has leveraged connectomic datasets to predict the functions of cells and circuits in the brains of multiple species. However, many of these hypotheses have not been compared with physiological measurements, obscuring the limits of connectome-based functional predictions. To explore these limits, this study characterized the visual responses of 43 cell types in the fruit fly and quantitatively compared them with connectomic predictions. These predictions are accurate for some response properties, such as orientation tuning, but are surprisingly poor for other properties, such as receptive field size. Importantly, strong synaptic inputs are more functionally homogeneous than expected by chance and exert a disproportionately large influence on postsynaptic responses. Finally, the subset of connections was quantitatively defined that best describe the functional differences between cell types. These results establish a powerful set of constraints for improving the accuracy of connectomic predictions.

Thursday, November 6th - Disease Models

Lushchak, O., Strilbytska, O., Petakh, P., Kamyshnyi, O., Koliada, O., Semaniuk, U. (2025). Reproduction and preference to macronutrients have different relations to biological or chronological age in Drosophila. Biogerontology, 26(3):116 PubMed ID: 40418386
Summary:
Varied factors and interventions were shown to extend the lifespan. An understanding of the mechanisms behind the beneficial effects might extend understanding of how interventions work. However, in most studies, groups are compared at distinct time points representing chronological age. This setup does not take into account that organisms of the same chronological age are different biologically. In other words, they have a different biological age that reflects varied physiological traits. This study has compared reproduction and consumption of specific macronutrients for flies in according quartiles (Q) of chronological and biological age. Quartiles of chronological age were obtained by dividing the total lifespan of the cohort into 4 parts. Quartiles of biological age were estimated as time points of 75, 50, 25 and 0% survival of the cohort. The decline in carbohydrate or protein consumption was shown to be stronger in the case of chronological rather than biological age. However, flies of biological or chronological quartile 4 consumed virtually the same amounts of macronutrients. The decline in reproduction was significantly reduced in relation to biological age. Thus, the decline was about 38-68% when within chronological quartiles 2 and 1 but only 4-31% for biological ones. The reproductive capacity was reduced by 86-93% in flies of chronological Q4 as compared to a 60-77% decrease for those of biological. Starting from quartile 2 biologically aged flies laid significantly higher number of eggs than flies of the same chronological quartile. These results point out the significant difference in flies of the same biological and chronological quartile and raise the question about the suitability of comparison traits of organisms with different lifespans same chronological age.

Abolaji, A. O., Adedara, A. O., Madu, J. C., Owalude, O. T., Ogunyemi, O. M., Omoboyowa, D. A., Omage, F. B., Whitworth, A. J., Aschner, M. (2025). Experimental and computational insights into the therapeutic mechanisms of resveratrol in a Drosophila alpha-synuclein model of Parkinson's disease. Sci Rep, 15(1):17769 PubMed ID: 40404673
Summary:
Parkinson's disease (PD) is a multifactorial neurodegenerative disorder driven by genetic predisposition and environmental exposure. Given its well-documented antioxidative and neuroprotective properties, resveratrol is increasingly being considered for its potential to counteract the neuronal damage characteristic of Parkinson's disease. This study investigated the therapeutic action of resveratrol in a transgenic Drosophila melanogaster model expressing human α-synuclein (SNCA, PD flies), in combination with network pharmacology and molecular docking analyses. The PD flies were fed diet supplemented with resveratrol, to evaluate lifespan. This was followed by a 21-day treatment of PD flies with similar concentrations of resveratrol in the diet to evaluate cognitive function, oxidative stress, and antioxidant biomarkers, using Levodope (0.1 mM) as positive control. The results showed that resveratrol supplementation in the diet significantly improved lifespan, locomotor activity, acetylcholinesterase and catalase activities, and thiol content compared to untreated PD flies. Furthermore, resveratrol reduced nitric oxide (nitrite/nitrate), malondialdehyde, and total hydroperoxide levels, and enhanced cellular metabolic activity and upregulated Sod1 mRNA expression. The network pharmacology and molecular docking analyses identified key molecular targets that may account for the therapeutic action of resveratrol, including B-Cell Lymphoma 2, Monoamine Oxidase (MAO); in flies, MAO-Like, Dopa Decarboxylase, Protein Kinase A and Glycogen Synthase Kinase-3 (GSK-3). Among these, MAO and GSK-3 emerged as top targets as indicated by network prominence and strong binding interactions. Additionally, the binding interaction of resveratrol to SNCA at specific sites suggests a potential role in inhibiting its aggregation, which is a hallmark of PD pathology. Overall, resveratrol supplementation in the diet may be beneficial for PD management by modulating dopamine metabolism, apoptosis, oxidative stress, and cell survival.

Cong, F., Bao, H., Wang, X., Tang, Y., Bao, Y., Poulton, J. S., Liu, X., Wong, A. C., Ji, X., Deng, W. M. (2025). Translocation of gut bacteria promotes tumor-associated mortality by inducing immune-activated renal damage. Embo j, 44(13):3586-3613 PubMed ID: 40404992
Summary:
Paraneoplastic syndrome represents severe and complex systemic clinical symptoms manifesting in multiple organs of cancer patients, but its cause and cellular underpinnings remain little explored. This study, establishing a Drosophila model of paraneoplastic syndrome triggered by tumor transplantation, found that the innate immune response, initiated by translocated commensal bacteria from a compromised intestine, significantly contributes to reduced lifespan in tumor-bearing hosts. The data identify the renal system as a central hub of this paraneoplastic syndrome model, wherein the pericardial nephrocytes undergo severe damage due to an elevated immune response triggered by gut dysbiosis and bacterial translocation. This innate immune response-induced nephrocyte damage is a major contributor to reduced longevity in tumor-bearing hosts, as blocking the NF-kB/Imd pathway in nephrocytes or removing gut bacteria via germ-free derivation or antibiotic treatment ameliorates nephrocyte deterioration and extends the lifespan of tumor-bearing flies. Consistently, treatment with a detoxifying drug also extended the lifespan of the tumor hosts. These findings highlight a critical role of the gut-kidney axis in the paraneoplastic complications observed in cancer-bearing flies, suggesting potential therapeutic targets for mitigating similar complications in cancer patients.

Leventhal, M. J., Zanella, C. A., Kang, B., Peng, J., Gritsch, D., Liao, Z., Bukhari, H., Wang, T., Pao, P. C., Danquah, S., Benetatos, J., Nehme, R., Farhi, S., Tsai, L. H., Dong, X., Scherzer, C. R., Feany, M. B., Fraenkel, E. (2025). An integrative systems-biology approach defines mechanisms of Alzheimer's disease neurodegeneration. Nat Commun, 16(1):4441 PubMed ID: 40393985
Summary:
Despite years of intense investigation, the mechanisms underlying neuronal death in Alzheimer's disease, remain incompletely understood. To define relevant pathways, this study conducted an unbiased, genome-scale forward genetic screen for age-associated neurodegeneration in Drosophila. Poteomics, phosphoproteomics, and metabolomics were also measured in Drosophila models of Alzheimer's disease, and Alzheimer's genetic variants were identified that modify gene expression in disease-vulnerable neurons in humans. A network model was then used to integrate these data with previously published Alzheimer's disease proteomics, lipidomics and genomics. This study computationally predicted and experimentally confirmed that RNA-binding protein HNRNPA2B1 and methylphosphate capping enzyme MEPCE enhance toxicity of the Tau protein, a pathological feature of Alzheimer's disease. Furthermore, the screen hits CSNK2A1 and NOTCH1 were shown to regulate DNA damage in Drosophila and human stem cell-derived neural progenitor cells. This study identifies candidate pathways that could be targeted to ameliorate neurodegeneration in Alzheimer's disease.

Choi, B., Cho, K. S. (2025). Role of neuronal fabp in autophagy and amyloid-β pathology in a Drosophila model of Alzheimer disease. Autophagy Rep, 4(1):2466120 PubMed ID: 40395994
Summary:
FABP3 and FABP7 are members of the fatty acid-binding protein (FABP) family that transport fatty acids to intracellular organelles, which are elevated in patients with Alzheimer disease (AD). However, their role in the disease pathogenesis remain poorly understood. In a Drosophila model of AD, neuronal fabp knockdown inhibited autophagic flux and increased amyloid-beta (Aβ) aggregation, exacerbating neurodegeneration. Conversely, fabp overexpression had the opposite effect and improved memory. The modulation of Ecdysone-induced protein 75B (Eip75B) levels, the Drosophila homolog of peroxisome proliferator-activated receptor, a lipid-activated nuclear receptor that functions as a transcription factor, affected the expression of autophagy-related genes and the role of fabp in Aβ pathology. These results suggest that fabp regulates Aβ pathology through autophagy by modulating Eip75B and highlight the importance of proper fatty acid transport in neurons for autophagy regulation and Aβ pathogenesis.

White, M. A., Crowley, L., Massenzio, F., Li, X., Niblock, M., Coleman, M. P., Barmada, S. J., Sreedharan, J. (2025). Inhibiting glycogen synthase kinase 3 suppresses TDP-43-mediated neurotoxicity in a caspase-dependent manner. Res Sq, PubMed ID: 40502782
Summary:
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are progressive and ultimately fatal diseases characterised by 43-kDa TAR DNA-binding protein (TDP-43) pathology. Current disease modifying drugs have modest effects and novel therapies are sorely needed. Previously showed that deletion of glycogen synthase kinase-3 (GSK3) suppresses TDP-43-mediated motor neuron degeneration in Drosophila. This studyinvestigated the potential of GSK3 inhibition to ameliorate TDP-43-mediated toxicity in mammalian neurons. Expression of TDP-43 both activated GSK3 and promoted caspase mediated cleavage of TDP-43. Conversely, GSK3 inhibition reduced the abundance of full-length and cleaved TDP-43 in neurons expressing wild-type or disease-associated mutant TDP-43, ultimately ameliorating neurotoxicity. These results suggest that TDP-43 turnover is promoted by GSK3 inhibition in a caspase-dependent manner, and that targeting GSK3 activity has therapeutic value.

Wednesday, November 5th - Adult physiology and metabolism

Cerny, J., Krishnan, N., Prokupkova, N., Sterbova, H., Kodrik, D. (2025). Elimination of certain honeybee venom activities by adipokinetic hormone. Sci Rep, 15(1):18638 PubMed ID: 40436933
Summary:
The primary aim of this study was to analyse the influence of honeybee venom on various aspects of Drosophila melanogaster physiology and to assess the efficacy of adipokinetic hormone (AKH) in mitigating venom toxicity. The harmful effects of venom on the thoracic muscles and central nervous system of Drosophila was monitored, as well as the potential use of AKH to counteract these effects. The results demonstrated that envenomation altered AKH levels in the Drosophila CNS, promoted cell metabolism, as evidenced by an increase in citrate synthase activity in muscles, and improved relative cell viability in both organs incubated in vitro. Furthermore, venom treatment reduced the activity of two key antioxidative stress enzymes, superoxide dismutase and catalase, and modified the expression of six genes encoding immune system components (Keap1, Relish, Nox, Eiger, Gadd45, and Domeless) in both organs. The venom also disrupted muscle cell ultrastructure, specifically myofibrils, and increased the release of arginine kinase into the incubation medium. Notably, when administered alongside the venom, AKH influenced the majority of these changes. AKH was the most effective in minimising damage to the ultrastructure of muscle cells and preventing the release of arginine kinase from muscles to the medium; however, in other parameters, the effect was modest or minimal. Given that honeybee venom often affects humans, understanding its actions and potential ways to reduce or eliminate them is valuable and could lead to the development of pharmacologically important compounds that may have clinical relevance.

Azmin, M. R., Habibie, H., Filmaharani, F., Roosevelt, A., Nurhidayah, A., Pratama, M. R., Hardiyanti, W., Latada, N. P., Mudjahid, M., Yuliana, D., Nainu, F. (2025). Aspirin-Mediated Reduction of Glucose Level and Inflammation in Drosophila melanogaster. ACS Omega, 10(18):18622-18628. PubMed ID: 40385166
Summary:
Diabetes mellitus (DM), particularly type 2 diabetes mellitus (T2DM), is a global health challenge marked by chronic hyperglycemia and inflammation, which contributes to both metabolic dysregulation and associated complications. Inflammation exacerbates T2DM by activating immune signaling pathways and promoting insulin resistance. This study aims to investigate the interplay between hyperglycemia and inflammation and to explore the therapeutic potential of aspirin in mitigating these processes using Drosophila melanogaster as a model organism. The PGRP-LB^Δ strain, which exhibits dysregulated immune responses due to the loss of the PGRP-LB gene, leading to a phenotype resembling human autoinflammatory conditions. Larvae of the PGRP-LB^Delta; were fed a high-sucrose diet to induce increased glucose levels, mimicking the metabolic disturbances of T2DM. Aspirin, at different concentrations, was administered to assess its effects on high glucose level-induced inflammation. The results demonstrated that aspirin significantly improved hemolymph glucose levels, larval size, weight, and development. Additionally, aspirin enhanced larval mobility and reduced glucose level-associated immune dysfunction, as evidenced by changes in the expression of key immune and insulin-related genes. These findings highlight the utility of D. melanogaster as an effective and cost-efficient model to investigate the molecular mechanisms of T2DM and inflammation. The study also provides preliminary evidence for the potential of aspirin as an anti-inflammatory agent to modulate glucose levels and inflammation in T2DM, offering a promising avenue for therapeutic development.

Musachio, E., Almeida, F. P., Poetini, M. R., Janner, D. E., Alves, D., Guerra, G., Prigol, M. (2025). 7-chloro-4-(phenylselanyl)quinoline exerts protective effect on acrylamide-induced neurotoxicity in the fly Drosophila melanogaster through modulation of acetylcholinesterase and oxidative stress. Comp Biochem Physiol C Toxicol Pharmacol, 296:110257 PubMed ID: 40562182
Summary:
This study aimed to evaluate the neuroprotective action of 7-chloro-4-(phenylselanyl)quinoline (4-PSQ) through the activity of the enzyme acetylcholinesterase (AChE), oxidative and behavioral parameters associated with acrylamide-induced neurotoxicity (ACR) in Drosophila melanogaster flies. The flies were divided into Control, 4-PSQ (25 μM), ACR (5mM) and ACR + 4PSQ (concomitantly) groups, and remained in treatments for 4 days. All analyses were performed with head samples. It was observed that flies belonging to the ACR + 4-PSQ group presented levels of reactive species and lipid peroxidation similar to the control, and similarly aligned the activity of the enzyme's superoxide dismutase, catalase and glutathione S-transferase, culminating in the preservation of mitochondrial and cellular metabolic capacity. There was a positive modulation of the activity of the AChE enzyme, which was attributed to the conservation of locomotor and exploratory behaviors, configuring the neuroprotective role of 4-PSQ. Together, these results may have reflected in the survival of the flies, which obtained a rate similar to the control. Considering the presence of ACR in the population's life, it was applied to the induction of a neurotoxicity model in Drosophila melanogaster, and thus, these results are scientifically relevant, as they conclude that 4-PSQ presented antioxidant and neuroprotective action.

Price, D. K., West, K., Cevallos-Zea, M., Cahan, S. H., Nunez, J. C. B., Longman, E. K., Yew, J. Y., Mederios, M. J. (2025). Microbiome composition shapes temperature tolerance in a Hawaiian picture-winged Drosophila. bioRxiv, PubMed ID: 40501599
Summary:
Hawaiian picture-winged Drosophila are undergoing rapid biodiversity loss, with twelve species listed as endangered and others in decline. Gut microbiota are increasingly recognized as contributors to host adaptation that are capable of influencing stress tolerance, reproduction, and other fitness-related traits. This study investigated the role of microbial communities in local adaptation using two populations of Drosophila basisetae from Hawaiian rainforests at 900 m and 1200 m elevation. Microbiome profiling of wild flies by high throughput amplicon sequencing revealed distinct bacterial and fungal communities between sites. Whole-genome resequencing of the two Drosophila populations identified weak but significant population genetic structure, with evidence of admixture and gene flow. Despite this connectivity, 16 outlier SNPs across 18 genes showed patterns consistent with divergent selection, suggesting localized adaptation. To test microbiome effects on host physiology experimentally, this study conducted a fully factorial research design with microbiome inoculations in laboratory-reared flies acclimated to 18 deg;C (control) or 24 °C (stressful). Flies treated with low-elevation microbiota had higher survival across temperatures, whereas those treated with high-elevation microbiota produced more eggs, indicating microbiome-mediated differences in reproductive investment. Activity levels at 18 ° were higher when flies received microbiota from their native population. Measures of critical thermal maximum (CTmax) and male accessory gland size showed complex interactions among microbiome source, temperature, and fly population. These results indicate that microbes may modulate host thermal tolerance and reproduction in environmentally-dependent and population-specific ways.

Alassaf, M., Madan, A., Ranganathan, S., Marschall, S., Wong, J. J., Goldberg, Z. H., Brent, A. E., Rajan, A. (2025). Adipocyte metabolic state regulates glial phagocytic function. Cell Rep, 44(5):115704 PubMed ID: 40372917
Summary:
Excess dietary sugar profoundly impacts organismal metabolism and health, yet it remains unclear how metabolic adaptations in adipose tissue influence other organs, including the brain. This study shows that a high-sugar diet (HSD) in Drosophila reduces adipocyte glycolysis and mitochondrial pyruvate uptake, shifting metabolism toward fatty acid and ketogenesis. These metabolic changes trigger mitochondrial oxidation and elevate antioxidant responses. Adipocyte-specific manipulations of glycolysis, lipid metabolism, or mitochondrial dynamics non-autonomously modulate Draper expression in brain ensheathing glia, key cells responsible for neuronal debris clearance. Adipocyte-derived ApoB-containing lipoproteins maintain basal Draper levels in glia via LpR1, critical for effective glial phagocytic activity. Accordingly, reducing ApoB or LpR1 impairs glial clearance of degenerating neuronal debris after injury. Collectively, these findings demonstrate that dietary sugar-induced shifts in adipocyte metabolism substantially influence brain health by modulating glial phagocytosis, identifying adipocyte-derived ApoB lipoproteins as essential systemic mediators linking metabolic state with neuroprotective functions.

Sheng, Y., Xu, Z., Li, Y., Chen, J., Pang, L., Lu, Y., Dong, Z., Zhang, Q., Zhang, J., Feng, T., Shi, W., Wang, Y., Chen, X., Shen, X. X., Huang, J. (2025). Fruit flies exploit behavioral fever as a defense strategy against parasitic insects. Sci Adv, 11(24):eadw0191 PubMed ID: 40498848
Summary:
Behavioral fever, a thermoregulatory response in which ectothermic animals seek warmer environments to elevate body temperature and combat parasite infections, is well documented against microparasites. However, its role and mechanisms against macroparasites remain largely unknown. This study shows that Drosophila hosts use behavioral fever to defend against Leptopilina parasitoid wasps. This thermal preference increases wasp mortality and enhances host survival. Behavioral fever is mediated by up-regulation of Heat shock protein 70 (Hsp70) genes in infected hosts as Hsp70 loss abolishes behavioral fever, whereas its overexpression induces heat-seeking behavior. It was further found that behavioral fever up-regulates immune genes in infected hosts, including 12 antimicrobial peptide (AMP) genes, which disrupt the gut microbiota homeostasis of parasitoid wasps and, in turn, lead to substantial wasp mortality. These findings elucidate the detailed mechanisms of behavioral fever in Drosophila hosts, advancing understanding of ectothermic animal defenses against macroparasites.

Tuesday, November 3rd - Adult Neural Development, Structure, and Function

Kim, H. S., Santana, G. M., Sancer, G., Emonet, T., Jeanne, J. M. (2025). Divergent synaptic dynamics originate parallel pathways for computation and behavior in an olfactory circuit. Curr Biol, 35(13):3146-3162.e3148 PubMed ID: 40541186
Summary:
To enable diverse sensory processing and behavior, central circuits use divergent connectivity to create parallel pathways. However, linking synaptic and cellular mechanisms to the circuit-level segregation of computation has been challenging. This study investigated the generation of parallel processing pathways in the Drosophila olfactory system, where glomerular projection neurons (PNs) diverge onto many lateral horn neurons (LHNs). The effects of a single PN's activity on two of its target LHNs were compared. One LHN type generates sustained responses to odor and adapts divisively. The other generates transient responses and adapts subtractively. The distinct odor-coding dynamics originate from differences in the dynamics of PN synapses targeting each LHN type. Sustained LHN responses arise from synapses that recover from depression quickly enough to maintain ongoing transmission. Divisive adaptation is due to slow cellular gain control implemented by the Na(+)/K(+) ATPase in the postsynaptic neuron. Transient LHN responses arise from synapses that recover from depression too slowly to maintain ongoing transmission but that also facilitate when PN spike rate increases. Interfering with facilitation via the calcium buffer EGTA or interfering with the presynaptic priming factor Unc13B diminishes the magnitude of initial transient responses. Subtractive adaptation is due to the nonlinearity imposed by the spike threshold in the postsynaptic neuron. Transient LHNs make corresponding transient contributions to behavioral odor attraction in walking flies, whereas sustained LHNs may make sustained, but nuanced, contributions. Subcellular presynaptic specialization is thus a compact and efficient way to originate parallel information streams for specialized computation and behavior.

Patel, A. A., Cardona, A., Cox, D. N. (2025). Neural substrates of cold nociception in Drosophila larva. Elife, 12 PubMed ID: 40512662
Summary:
Metazoans detect and differentiate between innocuous (non-painful) and/or noxious (harmful) environmental cues using primary sensory neurons, which serve as the first node in a neural network that computes stimulus-specific behaviors to either navigate away from injury-causing conditions or to perform protective behaviors that mitigate extensive injury. The ability of an animal to detect and respond to various sensory stimuli depends upon molecular diversity in the primary sensors and the underlying neural circuitry responsible for the relevant behavioral action selection. Recent studies in Drosophila larvae have revealed that somatosensory class III multidendritic (CIII md) neurons function as multimodal sensors regulating distinct behavioral responses to innocuous mechanical and nociceptive thermal stimuli. Recent advances in circuit bases of behavior have identified and functionally validated Drosophila larval somatosensory circuitry involved in innocuous (mechanical) and noxious (heat and mechanical) cues. However, central processing of cold nociceptive cues remained unexplored. This study implicates multisensory integrators (Basins), premotor (Down-and-Back), and projection (A09e and TePns) neurons as neural substrates required for cold-evoked behavioral and calcium responses. Neural silencing of cell types downstream of CIII md neurons led to significant reductions in cold-evoked behaviors, and neural co-activation of CIII md neurons plus additional cell types facilitated larval contraction (CT) responses. Further, this study demonstrated that optogenetic activation of CIII md neurons evokes calcium increases in these neurons. Finally, the premotor to motor neuron network underlying cold-evoked CT was characterized and the muscular basis of CT response was delineated. Collectively, this study demonstrated how Drosophila larvae process cold stimuli through functionally diverse somatosensory circuitry responsible for generating stimulus-specific behaviors.

Richter, V., Rist, A., Kislinger, G., Laumann, M., Schoofs, A., Miroschnikow, A., Pankratz, M. J., Cardona, A., Thum, A. S. (2025). Morphology and ultrastructure of external sense organs of Drosophila larvae. Elife, 12 PubMed ID: 40522083
Summary:
Sensory perception is the ability through which an organism is able to process sensory stimuli from the environment. This stimulus is transmitted from the peripheral sensory organs to the central nervous system, where it is interpreted. Drosophila melanogaster larvae possess peripheral sense organs on their head, thoracic, and abdominal segments. These are specialized to receive diverse environmental information, such as olfactory, gustatory, temperature, or mechanosensory signals. This work completes the description of the morphology of external larval sensilla and provide a comprehensive map of the ultrastructure of the different types of sensilla that comprise them. This was achieved by 3D electron microscopic analysis of partial and whole body volumes, which contain high-resolution and complete three-dimensional data of the anatomy of the sensilla and adjacent ganglia. This analysis revealed three main types of sensilla on thoracic and abdominal segments: the papilla sensillum, the hair sensillum, and the knob sensillum. They occur solitary or organized in compound sensilla such as the thoracic keilin's organ or the terminal sensory cones. A spatial map defining these sensilla is prsented by their position on thoracic and abdominal segments. Furthermore, we the sensilla at the larval head and the last fused abdominal segments were identified and named. Mechanosensation dominates in the larval peripheral nervous system, as most sensilla have corresponding structural properties. The result of this work, the construction of a complete structural and neuronal map of the external larval sensilla, provides the basis for following molecular and functional studies to understand which sensory strategies the Drosophila larva employs to orient itself in its natural environment.

Andersen, M. K., Robertson, R. M., MacMillan, H. A. (2025). Temperature sensitivity of spreading depolarization in the CNS of Drosophila melanogaster. Am J Physiol Regul Integr Comp Physiol, 329(1):R134-r149 PubMed ID: 40392029
Summary:
During exposure to extreme stress, the central nervous system (CNS) of mammals and insects fails through a phenomenon known as spreading depolarization (SD). SD is characterized by an abrupt disruption of ion gradients across neural and glial membranes that spreads through the CNS, silencing neural activity. In humans, SD is associated with neuropathological conditions like migraine and stroke, while it coincides with critical thermal limits for activity in insects. In the latter, SD is conveniently monitored by recording the transperineurial potential (TPP), which this study used to explore the plasticity and temperature dependence of SD thresholds and electrophysiological parameters in fruit flies (Drosophila melanogaster). Specifically, the effects of thermal acclimation on the characteristics of TPP changes during cold-induced SD were characterized, after which SD was induced with anoxia at different temperatures in both acclimation groups to examine the interactive effects of temperature and acclimation status. Lastly, how these affect the rate of SD propagation across the fly CNS was investigated. Cold acclimation enhanced resistance to both cold and anoxic SD, and our TPP measurements revealed independent and interactive effects of temperature and acclimation on the TPP and SD propagation. This suggests that thermodynamic processes and physiological mechanisms interact to modulate the thermal threshold for activity through SD and its electrophysiological phenomenology. These findings are discussed in relation to conceptual models for SD and established mechanisms for variation in the thermal threshold for SD, and it is emphasized that future comparative or cross-species studies or translations must account for thermodynamic effects to improve inferences based on electrophysiology.

Cheng, L. S., Charng, C. C., Chen, R. H., Feng, K. L., Chiang, A. S., Lo, C. C., Lee, T. K. (2025). Hybrid neural networks in the mushroom body drive olfactory preference in Drosophila. Sci Adv, 11(22):eadq9893 PubMed ID: 40446049
Summary:
In Drosophila melanogaster, olfactory encoding in the mushroom body (MB) involves thousands of Kenyon cells (KCs) processing inputs from hundreds of projection neurons (PNs). Recent data challenge the notion of random PN-to-KC connectivity, revealing preferential connections between food-related PNs and specific KCs. This study further uncovers a broader picture-an L-shaped hybrid network, supported by spatial patterning: Food-related PNs diverge across KC classes, whereas pheromone-sensitive PNs converge on γ KCs. α/β KCs specialize in food odors, whereas γ KCs integrate diverse inputs. Such spatial arrangement extends further to the antennal lobe (AL) and lateral horn (LH), shaping a systematic olfactory landscape. Moreover, functional validations align with computational predictions of KC odor encoding based on the hybrid connectivity, correlating PN-KC activity with behavioral preferences. In addition, simulations showcase the network's augmented sensitivity and precise discrimination abilities, underscoring the computational benefits of this hybrid architecture in olfactory processing.

Miao, H., Kim, W. J. (2025). Electrical silencing of dendritic arborization neurons rescues toxic polyglutamine-induced locomotion defect. Fly (Austin), 19(1):2519687 PubMed ID: 40519063
Summary:
This study investigates the effects of polyglutamine (polyQ) expansions on the locomotion of Drosophila larvae, focusing on the role of class IV dendritic arborization (da) neurons. PolyQ expansions are associated with neurodegenerative diseases like Huntington's disease, and Drosophila is a valuable model organism for studying these diseases due to its genetic tractability and short generation time. Expressing a polyQ protein in class IV da neurons caused significant locomotion deficits. Specifically, larvae with polyQ expression exhibited slower crawling speed and increased turn frequency, indicating impaired movement. The most intriguing finding of this study was that electrically silencing class IV da neurons completely rescued the locomotion deficits caused by polyQ expression. By expressing a potassium channel that makes the neurons less active, the locomotion defects were effectively reversed. This suggests that modulating the activity of these neurons could be a promising therapeutic approach for treating polyQ diseases. These findings have significant implications for understanding polyQ diseases and developing new therapeutic approaches. By electrically silencing these neurons,the harmful effects of polyQ-induced cation channels, which are thought to disrupt cellular function, may be prevented. This opens up exciting possibilities for exploring electrical silencing as a potential treatment for polyQ diseases, offering hope for future therapies that target the underlying mechanisms of these devastating conditions.

Monday, November 3rd - Synapse and Vesicles

Dombrovski, M., Zang, Y., Frighetto, G., Vaccari, A., Jang, H., Mirshahidi, P. S., Xie, F., Sanfilippo, P., Hina, B. W., Rehan, A., Hussein, R. H., Mirshahidi, P. S., Lee, C., Morris, A., Frye, M. A., von Reyn, C. R., Kurmangaliyev, Y. Z., Card, G. M., Zipursky, S. L. (2025). Molecular gradients shape synaptic specificity of a visuomotor transformation. Nature, PubMed ID: 40468081
Summary:
How does the brain convert visual input into specific motor actions? In Drosophila, visual projection neurons (VPNs) perform this visuomotor transformation by converting retinal positional information into synapse number in the brain. The molecular basis of this phenomenon remains unknown. This issue was addressed in LPLC2 (lobula plate/lobula columnar, type II)), a VPN type that detects looming motion and preferentially drives escape behaviour to stimuli approaching from the dorsal visual field with progressively weaker responses ventrally. This correlates with a dorsoventral gradient of synaptic inputs into and outputs from LPLC2. This study reports that LPLC2 neurons sampling different regions of visual space exhibit graded expression of cell recognition molecules matching these synaptic gradients. Dpr13 shapes LPLC2 outputs by binding DIP-ε in premotor descending neurons mediating escape. Beat-VI shapes LPLC2 inputs by binding Side-II in upstream motion-detecting neurons. Gain-of-function and loss-of-function experiments show that these molecular gradients act instructively to determine synapse number. These patterns, in turn, fine-tune the perception of the stimulus and drive the behavioural response. Similar transcriptomic variation within neuronal types is observed in the vertebrate brain and may shape synapse number via gradients of cell recognition molecules acting through both genetically hard-wired programs and experience.

Zhou, Y., Yang, X., Xu, W., Shen, S., Fan, W., Meng, G., Cheng, Y., Lu, Y., Wei, Y. (2025). Rag GTPases control lysosomal acidification by regulating v-ATPase assembly in Drosophila. J Biol Chem, 301(7):110400 PubMed ID: 40543592
Summary:
The Rag GTPases play an important role in sensing amino acids and activating the target of rapamycin complex 1, a master regulator of cell metabolism. Previous work has shown that GDP-bound RagA stimulates lysosome acidification and autophagic degradation, which are essential for young egg chamber survival under starvation in Drosophila. However, the underlying mechanism is unclear. This study demonstrates that the GDP-bound RagA breaks the physical interaction between cytosolic chaperonin-containing tailless complex polypeptide 1 (CCT) and vacuolar H+-ATPase (v-ATPase) subunit V1, and thus promotes the assembly of active v-ATPase and increases the lysosomal acidification. Consistently, knockdown of CCT complex components rescued the accumulation of defective autolysosomes in RagA RNAi. Moreover, the knockdown of Lamtor4, a component of lysosomal adaptor and MAPK and mTOR activator (LAMTOR) that anchors Rag GTPases to the lysosome, resulted in autolysosome accumulation, suggesting that Rag GTPases regulate lysosomal acidification depend on their lysosomal localization. Knockdown of the CCT complex components attenuated the autophagic defects in Lamtor 4 RNAi. This work highlights the interaction between CCT and v-ATPase in regulating lysosomal acidification.

Chen, J., Lin, J., He, K., Wang, L., Han, Y., Qiu, C., Dickman, D. (2025). Resolving synaptic events using subsynaptically targeted GCaMP8 variants. bioRxiv, PubMed ID: 40611906
Summary:
While genetically encoded Ca(2+) indicators are valuable for visualizing neural activity, their speed and sensitivity have had limited performance when compared to chemical dyes and electrophysiology, particularly at synaptic compartments. This study addressed these limitations by engineering a suite of next-generation GCaMP8-based indicators, targeted to presynaptic boutons, active zones, and postsynaptic compartments at the Drosophila neuromuscular junction. These sensors were validated to be superior to previous versions. Next, a new Python-based analysis program, CaFire, was developed that enables the automated quantification of evoked and spontaneous Ca(2+) signals. Using CaFire, this study showed a ratiometric presynaptic GCaMP8m sensor accurately captures physiologically-relevant presynaptic Ca(2+) changes with superior sensitivity and similar kinetics compared to chemical dyes. Moreover, the ability of an active zone-targeted, ratiometric GCaMP8f sensor to report differences in Ca2+ between release sites was tested. Finally, a newly engineered postsynaptic GCaMP8m, positioned near glutamate receptors, detects quantal events with temporal and signal resolution comparable to electrophysiological recordings. These next generation indicators and analytical methods demonstrate that GCaMP8 sensors, targeted to synaptic compartments, can now achieve the speed and sensitivity necessary to resolve Ca(2+) dynamics at levels previously only attainable with chemical dyes or electrophysiology.

Ermanoska, B., Baets, J., Rodal, A. A. (2025). Nonmuscle myosin II regulates presynaptic actin and neuronal mechanobiology in Drosophila. J Cell Biol, 224(9) PubMed ID: 40644605
Summary:
Neuromuscular junctions (NMJs) are evolutionarily ancient, specialized contacts between neurons and muscles. They experience lifelong strain, yet the mechanism preserving their integrity under mechanical load remains unclear. This study identified a novel actomyosin structure at Drosophila larval NMJs, consisting of a long-lived, low-turnover presynaptic actin core that colocalizes with nonmuscle myosin II (NMII) and becomes disorganized upon manipulating neuronal NMII levels or activity. Intriguingly, neuronal NMII depletion altered postsynaptic NMII levels and organization near synapses, suggesting transsynaptic propagation of actomyosin rearrangements. Under these conditions, integrin adhesion receptors were reduced on both sides of the synapse, indicating disrupted neuron-muscle connections. Notably, axon severing mimics these effects, while axonal stretching reorganizes integrins without disrupting the actin core, suggesting that presynaptic actomyosin and integrin organization are highly sensitive to mechanical cues and dynamically adjust to both loss and gain of tension. This study reveals a presynaptic actomyosin assembly that maintains mechanical continuity between neurons and muscle, potentially enabling mechanotransduction at the NMJ through integrin-mediated adhesion.

Aghi, K., Schultz, R., Stowers, R. S., Liu, W. Y., MendonCa, P. R. F., Li, R., Bakshinska, D., Newman, Z. L., Isacoff, E. Y. (2025). Balanced synapse-to-synapse short-term plasticity ensures constant transmitter release. Curr Biol, 35(12):2881-2892.e2886 PubMed ID: 40466645
Summary:
Synaptic strength can vary greatly between synapses. Optical quantal analysis at Drosophila glutamatergic motor neuron synapses shows that short-term plasticity also varies greatly between synapses, even those made by an individual motor neuron. Strong and weak synapses are randomly distributed in the motor neuron nerve terminal, as are facilitating and depressing synapses. Although synapses exhibit highly heterogeneous basal strength at low-action potential firing frequency and undergo varied plasticity when firing frequency increases, the overall distribution of strength across synapses remains remarkably constant due to a balance between the number of synapses that facilitate versus depress and to their degree of plasticity and basal synaptic weight. Constancy in transmitter release can ensure robustness across changing behavioral conditions.

Chipman, P. H., Lee, U., Orr, B. O., Fetter, R. D., Davis, G. W. (2025). A unifying mechanism for presynaptic homeostatic plasticity at mammalian peripheral and central synapses. Neuron, PubMed ID: 40592327
Summary:
Presynaptic homeostatic plasticity (PHP) is a potent form of adaptive plasticity that has been documented at synapses as diverse as the glutamatergic Drosophila neuromuscular junction (NMJ), cholinergic mammalian NMJ (including human), and glutamatergic synapses in the mammalian brain. This study defines secreted class III semaphorin as a unifying, trans-synaptic signal necessary for PHP at highly divergent synapses. Sema3a drives the rapid induction of PHP at the cholinergic mouse NMJ and synapses in the adult hippocampus (CA1), including cross-modal potentiation of inhibitory transmission. Three-dimensional electron microscopy (EM) reveals Sema3a-dependent active zone expansion, presynaptic stabilization, and the maintenance of synapse organization during PHP. Mechanistically, Sema3a promotes vesicle redistribution from a non-releasing to recycling and readily releasable vesicle pool. Finally, presynaptic-signal transduction is also commonly deployed, requiring activation of PlexinA4 and an integrin beta-1 (ITGB1) co-receptor. The widespread utilization of common PHP mechanisms emphasizes the translational potential of model organisms toward promoting neuronal resilience to combat brain disorders and disease.

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