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 May 29th, 2026 - Physiology and Metabolism

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Soto, J., Pinilla, F., Olguin, P., Castaneda, L. E. (2025). Genetic Architecture of the Thermal Tolerance Landscape in Drosophila melanogaster. Mol Ecol, 34(7):e17697 PubMed ID: 40035350
Summary:
Increased environmental temperatures associated with global warming strongly impact natural populations of ectothermic species. Therefore, it is crucial to understand the genetic basis and evolutionary potential of heat tolerance. However, heat tolerance and its genetic components depend on the methodology, making it difficult to predict the adaptive responses to global warming. This study measured the knockdown time for 100 lines from the Drosophila Genetic Reference Panel (DGRP) at four different static temperatures, and their thermal-death-time (TDT) curves, which incorporate the magnitude and the time of exposure to thermal stress, were estimated to determine the genetic basis of the thermal tolerance landscape. Through quantitative genetic analyses, the knockdown time showed a significant heritability at different temperatures and that its genetic correlations decreased as temperatures differences increased. Significant genotype-by-sex and genotype-by-environment interactions were noted for heat tolerance. Genetic variability was discovered for the two parameters of TDT: CT(max) and thermal sensitivity. Taking advantage of the DGRP, a GWAS was performed and multiple variants were identified associated with the TDT parameters, which mapped to genes related to signalling and developmental functions. Functional validations were performed for some candidate genes using RNAi, which revealed that genes such as mam, KNCQ, or robo3 affect the knockdown time at a specific temperature but are not associated with the TDT parameters. In conclusion, the thermal tolerance landscape display genetic variation and plastic responses, which may facilitate the adaptation of Drosophila populations to a changing world.

Franchet, A., Haller, S., Yamba, M., Barbier, V., Thomaz-Vieira, A., Leclerc, V., Becker, S., Lee, K. Z., Orlov, I., Spehner, D., Daeffler, L., Ferrandon, D. (2025). Nora virus proliferates in dividing intestinal stem cells and sensitizes flies to intestinal infection and oxidative stress. bioRxiv, PubMed ID: 39975242
Summary:
The digestive tract represents the most complex interface of an organism with its biotope. Food may be contaminated by pathogens and toxicants while an abundant and complex microbiota strives in the gut lumen. The organism must defend itself against potentially noxious biotic or abiotic stresses while preserving its microbiota, provided it plays a beneficial role. The presence of intestinal viruses adds another layer of complexity. Starting from a differential sensitivity of two lines from the same Drosophila wild-type strain to ingested Pseudomonas aeruginosa, this study reports that the presence of Nora virus in the gut epithelium promotes the sensitivity to this bacterial pathogen as well as to an ingested oxidizing xenobiotic. The genotype, age, nature of the ingested food and to a limited extent the microbiota are relevant parameters that influence the effects of Nora virus on host fitness. Mechanistically, the initial presence of viral proteins was detected essentially in progenitor cells. Upon stress such as infection, exposure to xenobiotics, aging or feeding on a rich-food diet, the virus is then detected in enterocytes, which correlates with a disruption of the intestinal barrier function in aged flies. Finally, this study showed that the virus proliferates only when ISCs are induced to divide and that blocking either enterocyte apoptosis or JAK/STAT-driven ISC division leads to a drastically reduced Nora virus titer. In conclusion, it is important to check that experimental strains are devoid of intestinal viruses when monitoring survival/life span of fly lines or when investigating the homeostasis of the intestinal epithelium as these viruses can constitute significant confounding factors.

Jelena, R., Jelena, T., Marija, R., Tanja, L., Tatjana, S., Bojan, B., Biljana, B. N., Pavkovic-Lucic, S. (2025). Different Long-Term Nutritional Regimens of Drosophila melanogaster Shape Its Microbiota and Associated Metabolic Activity in a Sex-Specific Manner. Insects, 16(2) PubMed ID: 40003771
Summary:
The dietary habits of fruit flies profoundly influence their fitness, morphology, and physiology yet the mechanisms underlying these effects remain incompletely understood. To address this gap, the relationship between dietary regimens and the composition and function of adult Drosophila melanogaster microbiota was investigated in the present study. The adult fly microbiota communities that were reared for long time on five different diets were characterized by means of 16S rRNA sequencing. Obtained results revealed distinct community structures associated with each dietary regimen, which was additionally corroborated through machine learning-based analysis. In general, sugar-rich diets correlate with microbial ecosystems of higher richness/diversity. Dominance of the phyla Proteobacteria and Firmicutes in the microbiota was confirmed irrespective of diet, with the varying proportions of the most abundant families: Acetobacteraceae, Lactobacillaceae, Moraxellaceae, Bradyrhizobiaceae, and Leucostonocaceae. Bacterial families of lower abundance also emerged as differentially present among the studied fly groups. Additionally, functional prediction provided initial clues into how nutrient availability might modulate the metabolic traits of adult fly microbiota in a sex-specific manner to meet host metabolic needs. Overall, the presented findings highlight the intricate interplay between diet, microbiota composition, and host phenotype in fruit flies, underscoring the importance of diet as a determinant of host-microbiota interactions.

Frappaolo, A., Zaccagnini, G., Riparbelli, M. G., Colotti, G., Callaini, G., Giansanti, M. G. (2025). PACS deficiency disrupts Golgi architecture and causes cytokinesis failures and seizure-like phenotype in Drosophila melanogaster. Open Biol, 15(2):240267 PubMed ID: 39999877:
Summary:
The PACS (phosphofurin acidic cluster sorting protein) proteins are membrane trafficking regulators, required for maintaining cellular homeostasis and preventing disease states. Mutations in human PACS1 and PACS2 cause human neurodevelopmental disorders, characterized by epileptic seizures and neurodevelopmental delay. In vertebrates, functional analysis of PACS proteins is complicated by the presence of two paralogues which can compensate for the loss of each other. This study characterized the unique fly homologue of human PACS proteins. Drosophila PACS (dPACS) is required for cell division in dividing spermatocytes and neuroblasts. In primary spermatocytes, dPACS colocalizes with GOLPH3 at the Golgi stacks and is essential for maintaining Golgi architecture. In dividing cells, dPACS is necessary for central spindle stability and contractile ring constriction. dPACS and GOLPH3 proteins form a complex and are mutually dependent for localization to the cleavage site. We propose that dPACS, by associating with GOLPH3, mediates the flow of vesicle trafficking that supports furrow ingression during cytokinesis. Furthermore, loss of dPACS leads to defects in tubulin acetylation and severe bang sensitivity, a phenotype associated with seizures in flies. Together these findings suggest that a Drosophila PACS disease model may contribute to understanding the molecular mechanisms underpinning human PACS syndromes. ]

Yang, D., Xiu, M., Jiang, X., Kang, Q., Fu, J., Zhou, S., Liu, Y., He, J. (2025). Caffeic Acid Alleviates Chronic Sleep Deprivation-Induced Intestinal Damage by Inhibiting the IMD Pathway in Drosophila. J Inflamm Res, 18:3485-3498 PubMed ID: 40093942
Summary:
Sleep is vital for maintaining the health of the organism. Chronic sleep deprivation (CSD) is a key contributor to significant health risks, including the induction of gastrointestinal disorders. However, the mechanism of CSD caused intestinal damage remains unclear. Drosophila melanogaster as an in vivo model was used to investigate the mechanism of CSD-induced intestinal injury, as well as the ameliorative effect of caffeic acid. CSD resulted in reduced survival and severely affected intestinal homeostasis in flies, as evidenced by disruption of intestinal acid-base homeostasis, increased feeding, increased intestinal permeability and shortened intestinal length. Meanwhile, the expressions of the immune deficiency (IMD) pathway-related genes PGRP-SB1, Dpt, AttA, AttB and Mtk were significantly up-regulated in the intestine of CSD flies. On the other hand, Caffeic acid supplementation restored intestinal acid-base homeostasis and intake, while improving intestinal barrier permeability and intestinal length, and effectively reducing intestinal damage. In addition, administration of caffeic acid decreased the expressions of PGRP-SB1, Dpt, AttA and Mtk genes in the CSD flies gut. These results suggested that CSD could disrupt gut homeostasis in adult flies by overactivating the IMD pathway, while Caffeic acid has an obvious protective role on the gut homeostasis.

Vachias, C., Tourlonias, C., Grelee, L., Gueguen, N., Renaud, Y., Venugopal, P., Richard, G., Pouchin, P., Brasset, E., Mirouse, V. (2025). Gap junctions allow transfer of metabolites between germ cells and somatic cells to promote germ cell growth in the Drosophila ovary. LoS Biol, 23(2):e3003045 PubMed ID: 39965028
Summary:
Gap junctions allow the exchange of small molecules between cells. How this function could be used to promote cell growth is not yet fully understood. During Drosophila ovarian follicle development, germ cells, which are surrounded by epithelial somatic cells, undergo massive growth. We found that this growth depends on gap junctions between these cell populations, with a requirement for Innexin4 and Innexin2, in the germ cells and the somatic cells, respectively. Translatomic analyses revealed that somatic cells express enzymes and transporters involved in amino acid metabolism that are absent in germ cells. Among them, we identified a putative amino acid transporter required for germline growth. Its ectopic expression in the germline can partially compensate for its absence or the one of Innexin2 in somatic cells. Moreover, affecting either gap junctions or the import of some amino acids in somatic cells induces P-bodies in the germ cells, a feature usually associated with an arrest of translation. Finally, in somatic cells, innexin2 expression and gap junction assembly are regulated by the insulin receptor/PI3K kinase pathway, linking the growth of the two tissues. Overall, these results support the view that metabolic transfer through gap junction promotes cell growth and illustrate how such a mechanism can be integrated into a developmental program, coupling growth control by extrinsic systemic signals with the intrinsic coordination between cell populations.

Wednesday May 27th - Larval and Adult Neural Development, Structure and Function

Meece, M., Rathore, S., Zagazeta, D., Buschbeck, E. K. (2025). Assessing recovery of Drosophila melanogaster photoreceptors with different wavelengths of red and infrared light J Exp Biol, 228(6) PubMed ID: 39957476
Summary:
It has previously been shown that near-infrared light can positively affect the physiology of damaged tissue. This is likely mediated by the modulation of metabolic activity via cytochrome c oxidase (COX), the rate of ATP production and the generation of reactive oxygen species. It has been suggested that this process is influenced by the wavelength of near-infrared light, with different wavelengths having different efficacy. The impact of these effects on retinal health is not yet well understood. To answer this question, photoreceptor damage was first induced in the eyes of white mutant D. melanogaster through prolonged exposure to bright light. Then the recovery of retinal health following exposure to different wavelengths of near-infrared light (670, 750, 810, 850 and 950 nm) was investigated over the course of 10 days. Retinal health was assessed through electroretinograms and fluorescence imaging of live photoreceptors. All treatments except for 950 nm light facilitated the recovery of the electroretinogram response in previously light-damaged flies - though efficacy varied across treatments. All near-infrared light-exposed groups showed at least some improvement in retinal organization and auto-fluorescence compared with an untreated recovery control. These results do not stem from a fly-specific artifact relating to opsin photoconversion. Finally, use was made of a bioassay to show enhanced ATP levels in light treatments. This study represents a much-needed direct comparison of the effect of light of a multitude of different wavelengths and contributes to an emerging body of literature that highlights the promise of phototherapy.

Nelson, N., Miller, V., Broadie, K. (2025). Neuron-to-glia and glia-to-glia signaling directs critical period experience-dependent synapse pruning. Front Cell Dev Biol, 13:1540052 PubMed ID: 40040788
Summary:
Experience-dependent glial synapse pruning plays a pivotal role in sculpting brain circuit connectivity during early-life critical periods of development. Recent advances suggest a layered cascade of intercellular communication between neurons and glial phagocytes orchestrates this precise, targeted synapse elimination. This study focused on studies from the powerful Drosophila forward genetic model, with reference to complementary findings from mouse work. Both neuron-to-glia and glia-to-glia intercellular signaling pathways directing experience-dependent glial synapse pruning are presented. A putative hierarchy is discussed of secreted long-distance cues and cell surface short-distance cues that act to sequentially orchestrate glia activation, infiltration, target recognition, engulfment, and then phagocytosis for synapse pruning. Ligand-receptor partners mediating these stages in different contexts are discussed from recent Drosophila and mouse studies. Signaling cues include phospholipids, small neurotransmitters, insulin-like peptides, and proteins. Conserved receptors for these ligands are discussed, together with mechanisms where the receptor identity remains unknown. Potential mechanisms are proposed for the tight temporal-restriction of heightened experience-dependent glial synapse elimination during early-life critical periods, as well as potential means to re-open such plasticity at maturity.

Scholz-Carlson, E., Iyer, A. R., Nern, A., Ewer, J., Fernandez, M. P. (2025). Synaptic Targets of Circadian Clock Neurons Influence Core Clock Parameters bioRxiv, PubMed ID: 39975067
Summary:
Neuronal connectivity in the circadian clock network is essential for robust endogenous timekeeping. In the Drosophila circadian clock network, four pairs of small ventral lateral neurons (sLN(v)s) serve as critical pacemakers. Peptidergic communication via sLN(v) release of the key output neuropeptide Pigment Dispersing Factor (PDF) has been well characterized. In contrast, little is known about the role of the synaptic connections that sLN(v)s form with downstream neurons. Connectomic analyses revealed that the sLN(v)s form strong synaptic connections with a group of previously uncharacterized neurons, SLP316. This study shows that silencing synaptic output in the SLP316 neurons via tetanus toxin (TNT) expression shortens the free-running period, whereas hyper-exciting them by expressing the Na[+] channel NaChBac results in period lengthening. Under light-dark cycles, silencing SLP316 neurons also causes lower daytime activity and higher daytime sleep. These results revealed that the main postsynaptic partners of the Drosophila pacemaker neurons are a non-clock neuronal cell type that regulates the timing of sleep and activity.

Samara, E., Schilling, T., Ribeiro, I. M. A., Haag, J., Leonte, M. B., Borst, A. (2025). Columnar cholinergic neurotransmission onto T5 cells of Drosophila Curr Biol, 35(6):1269-1284.e1266 PubMed ID: 40020661
Summary:
Several nicotinic and muscarinic acetylcholine receptors (AChRs) are expressed in the brain of Drosophila melanogaster. However, the contribution of different AChRs to visual information processing remains poorly understood. T5 cells are the primary motion-sensing neurons in the OFF pathway and receive input from four different columnar cholinergic neurons, Tm1, Tm2, Tm4, and Tm9. It was reasoned that different AChRs in T5 postsynaptic sites might contribute to direction selectivity, a central feature of motion detection. The nicotinic nAChRα1, nAChRα3, nAChRα4, nAChRα5, nAChRα7, and nAChα1 subunits localize on T5 dendrites. By targeting synaptic markers specifically to each cholinergic input neuron, a prevalence was found of the nAChRα5 in Tm1, Tm2, and Tm4-to-T5 synapses and of nAChRα7 in Tm9-to-T5 synapses. Knockdown of nAChRα4, nAChRα5, nAChRα, or mAChR-B individually in T5 cells alters the optomotor response and reduces T5 directional selectivity. These findings indicate the contribution of a consortium of postsynaptic receptors to input visual processing and, thus, to the computation of motion direction in T5 cells.

Naik, S., Biswal, S. S., Mishra, M. (2025). The Mechanism Behind the Therapeutic Role of Alpha-Tocopherol in Mitigating Hypobaric Hypoxia-Induced Eye Defect in Drosophila melanogaster Dev Neurobiol, 85(2):e22963 PubMed ID: 39992680
Summary:
Hypoxia, or low oxygen levels, is linked to several pathological disorders, including retinopathies. Retina being a metabolically active tissue, low oxygen levels resulted in retinal degradation. The developmental perspective of hypobaric hypoxia (HBH)-induced eye development remains elusive. Drosophila is used as our model organism to investigate the impact of HBH on eye development and alpha-tocopherol as a potential inhibitor. To induce the hypoxic condition, Drosophila was exposed to hypobaric pressure (120 mbar). Hypoxia induces eye defects in different developmental stages of Drosophila as revealed by histological staining. Biochemical estimation disclosed the presence of reactive oxygen species (ROS) during hypoxia, which led to cellular injury and DNA damage. Quantitative PCR reveals the upregulation of Puf, Wge, and Twr genes and the downregulation of Rh1 and Rh6 involved in eye development. All these defects are brought back to normal levels after treatment with alpha-tocopherol. This research provides a foundation for understanding ocular developmental problems caused by oxygen deprivation and alpha-tocopherol as a crucial therapeutic approach to the treatment of HBH.

Morano, N. C., Lopez, D. H., Meltzer, H., Sergeeva, A. P., Katsamba, P. S., Rostam, K. D., Gupta, H. P., Becker, J. E., Bornstein, B., Cosmanescu, F., Schuldiner, O., Honig, B., Mann, R. S., Shapiro, L. (2025). Members of the DIP and Dpr adhesion protein families use cis inhibition to shape neural development in Drosophila. PLoS Biol, 23(3):e3003030 PubMed ID: 40029885
Summary:
In Drosophila, two interacting adhesion protein families, Defective proboscis responses (Dprs) and Dpr interacting proteins (DIPs), coordinate the assembly of neural networks. While intercellular DIP::Dpr interactions have been well characterized, DIPs and Dprs are often co-expressed within the same cells, raising the question as to whether they also interact in cis. This study shows, in cultured cells and in vivo, that DIP-α and DIP-δ can interact in cis with their ligands, Dpr6/10 and Dpr12, respectively. When co-expressed in cis with their cognate partners, these Dprs regulate the extent of trans binding, presumably through competitive cis interactions. The neurodevelopmental effects of cis inhibition in fly motor neurons and in the mushroom body are demonstrated. It was further shown that a long disordered region of DIP-α at the C-terminus is required for cis but not trans interactions, likely because it alleviates geometric constraints on cis binding. Thus, the balance between cis and trans interactions plays a role in controlling neural development.

Monday May 25th - Disease Models

Nisha, Thapliyal, D., Gohil, B., Modak, A. S., Singh, N. T., Mukherjee, C., Ahuja, S., Sahu, B. S., Singh, M. D. (2025). Downregulation of Pten Improves Huntington's Disease Phenotype by Reducing Htt Aggregates and Cell Death. Mol Neurobiol, 62(7):8752-8767 PubMed ID: 40042729
Summary:
Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder that stems from the expansion of CAG repeats within the coding region of Huntingtin (HTT) gene. Currently, there exists no effective therapeutic intervention that can prevent the progression of the disease. This study aims to identify a novel genetic modifier with therapeutic potential. Transgenic flies were used containing HTT.ex1.Q93 and mRFP-HTT.588.Q138 constructs, which encode mutant pathogenic Huntingtin (Htt) proteins featuring 93 and 138 polyglutamine (Q) repeats respectively. The resultant mutant proteins cause the loss of photoreceptor neurons in the eye and a progressive loss of neuronal tissues in the brain and motor neurons in Drosophila. Several findings have demonstrated the association of HD with growth factor signaling defects. Phosphatase and tensin homolog (Pten) have been implicated in the negative regulation of the Insulin signaling/receptor tyrosine signaling pathway which regulates the growth and survival of cells. This study downregulated Pten and found a significant improvement in morphological phenotypes in the eye, brain, and motor neurons. These findings were further correlated with the enhancement of the functional vision and climbing ability of the flies. Reduction was found in both Htt aggregate and caspase levels which are involved in the apoptotic pathway. In alignment with the genetic modulation of Pten, the protective role of Pten inhibition was elucidated through the utilization of VO-OHpic. VO-OHpic improved the climbing ability of flies and reduced the poly(Q) aggregates and apoptosis levels. A similar reduction in Htt aggregates was observed in the mouse neuronal inducible HD cell line model. This study illustrates that Pten inhibition is a potential therapeutic approach for HD.

Rai, P., Kumar, R. (2025). H50Q mutation in alpha-Synuclein impairs the insulin signaling pathway and induces neuroinflammation in the Drosophila model. Exp Cell Res, 447(1):114460 PubMed ID: 39986600
Summary:
H50Q mutations in the SNCA gene, also known as also known as the α-Synuclein (α-Syn), have been causally linked to familial Parkinson's disease (PD). PD is primarily characterized by the progressive loss of dopaminergic neurons in the substantia nigra region of the brain. α-Syn- plays a pivotal role in the formation of Lewy bodies (LB), a prominent pathological marker in PD. Growing evidence has highlighted the involvement of the insulin signaling pathway dysfunction in various neurodegenerative models. This study aimed to explore how the H50Q mutation in α-Syn influences the insulin signaling pathway and the overall lifespan of fruit flies afflicted with PD. It has been established that a mutation in α-Syn affects mitochondrial function and increases oxidative stress, ultimately contributing to the death of dopaminergic neurons. The impairment of mitochondrial function disrupts metabolism and exerts an adverse effect on the insulin signaling pathway. Furthermore, the unfolded protein response of the endoplasmic reticulum (ER) was investigated and a decrease was observed in the expression of PERK (Protein kinase R-like ER kinase) during ER stress. These findings confirm the intricate interplay between the insulin signaling pathway and the activation of the PERK-ER stress pathway. However, the degeneration of neurons triggers a neuroinflammatory response, which are found to be mitigated by the improvement of insulin signaling and the PERK-ER stress-related pathway. The results of this study shed light on the novel regulatory role of PERK within the insulin signaling pathway and suggest its potential as a therapeutic candidate for modulating neuroinflammation in the context of α-Syn -associated PD pathology.

Ranxhi, B., Bangash, Z. R., Chbihi, Z. M., Todi, S. V., LeWitt, P. A., Tsou, W. L. (2025). The effect of AKT inhibition in alpha-synuclein-dependent neurodegeneration Front Mol Neurosci, 18:1524044 PubMed ID: 39974188
Summary:
Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting millions of individuals worldwide. A hallmark of PD pathology is the accumulation of α-synuclein (α-Syn), a small protein known to support neuronal development and function. However, in PD, α-Syn cumulatively misfolds into toxic aggregates that disrupt cellular processes and contribute to neuronal damage and neurodegeneration. Previous studies implicated the AKT signaling pathway in α-Syn toxicity in cellular models of PD, suggesting AKT as a potential therapeutic target. This study investigated the effect of AKT inhibition in a Drosophila model of synucleinopathy. Administration of the AKT inhibitor, A-443654 led to mild improvements in both survival and motor function in flies expressing human α-Syn. Genetic studies revealed that reduction of AKT levels decreased α-Syn protein levels, concomitant with improved physiological outcomes. The protective effects of AKT reduction appear to operate through the fly ortholog of NF-kappa;B, Relish, suggesting a link between AKT and NF-kappaB in regulating α-Syn levels. These findings highlight the AKT cascade as a potential therapeutic target for synucleinopathies and provide insights into mechanisms that could be utilized to reduce α-Syn toxicity in PD and related disorders, such as multiple system atrophy.

Spargo, T. P., Sands, C. F., Juan, I. R., Mitchell, J., Ravanmehr, V., Butts, J. C., De-Paula, R. B., Kim, Y., Hu, F., Wang, Q., Vitsios, D., Garg, M., Middleton, L., Tyrlik, M., Messa, M., Del Angel, G., Calame, D. G., Saade, H., Robak, L., Hollis, B., Cuddapah, V. A., Zoghbi, H. Y., Shulman, J. M., Petrovski, S., Al-Ramahi, I., Tachmazidou, I., Dhindsa, R. S. (2025). Haploinsufficiency of ITSN1 is associated with a substantial increased risk of Parkinson's disease. Cell Rep, 44(3):115355 PubMed ID: 40056900
Summary:
Despite its significant heritability, the genetic basis of Parkinson's disease (PD) remains incompletely understood. In analyzing whole-genome sequence data from 3,809 PD cases and 247,101 controls in the UK Biobank, this study discovered that protein-truncating variants in ITSN1 confer a substantially increased risk of PD (p = 6.1 x 10^-7. This association was replicated in three independent datasets totaling 8,407 cases and 413,432 controls (combined p = 4.5 × 10^-12). Notably, ITSN1 haploinsufficiency has also been associated with autism spectrum disorder, suggesting variable penetrance/expressivity. In Drosophila, loss of the ITSN1 ortholog Dap160 exacerbates α-synuclein-induced neuronal toxicity and motor deficits, and in vitro assays further suggest a physical interaction between ITSN1 and α-synuclein. These results firmly establish ITSN1 as a PD risk gene with an effect size exceeding previously established loci, implicate vesicular trafficking dysfunction in PD pathogenesis, and potentially open new avenues for therapeutic development.

Neophytou, C., Teloni, S., Koumouri, M., Stefanutti, M., Gianni, P., Yilmaz, V., Strati, K., Apidianakis, Y. (2025). Aberrant enterocyte progenitor clustering as an early life biomarker of Drosophila aging. iScience, 28(3):111967 PubMed ID: 40060901
Summary:
Stem cell accumulation and mutation-derived tumors are two hallmarks of Drosophila midgut aging. They imply a decline in stem cell signaling homeostasis late in life and a robust homeostasis in young adults. Contrary to this, spontaneously developing stem-like cells were found that vary in size and ploidy, have a stem-enteroblast mixed identity, achieve higher mitotic rate per cell, exhibit DNA replication stress, and are inherently prone to clustering. Reduction of mitosis or DNA replication stress lessens the production of these cells but does not explain the loss of their proper differentiation. However, young enterocyte progenitors also display epigenetic plasticity in Notch signaling network genes and Notch locus instability. Strikingly, reinforcing Notch signaling in enteroblasts, alleviates dysplasia and extends overall survival and survival to infection. Thus, Notch signaling between prospective stem cells and enteroblasts is never sufficiently on, producing stem-enteroblast mixed identity cells that cluster and compromise homeostasis and overall aging.

Li, Y., Wu, T., Li, Y., Xu, C., Zhou, C., Li, Z., Shang, W., Wang, L., Liu, Z., Wang, J., Liu, Y., Fang, F., Yang, B., Tong, C. (2025). Ectopic protein lysine methacrylation contributes to defects caused by loss of HIBCH or ECHS1. Cell Rep, 44(3):115379 PubMed ID: 40056416
Summary:
The absence of HIBCH or ECHS1, two Leigh syndrome genes, in cultured cells results in abnormal mitochondrial morphology and respiratory defects. Fly eyes lacking either protein exhibit age-dependent degeneration. Elevated lysine methacrylation (Kmea) is observed in both HIBCH- and ECHS1-deficient cells and fly tissues. Quantitative mass spectrometry reveals that many proteins are ectopically modified by Kmea in these cells. Mimicking Kmea in proteins like CH60, FKBP4, BIP, LDHB, or DHRS2 replicates the mitochondrial morphology changes seen in HIBCH- or ECHS1-deficient cells. Reducing Kmea modification partially rescues mitochondrial morphology changes in cells and eye degeneration in flies. Fibroblasts from patients with HIBCH or ECHS1 mutations show similar mitochondrial changes and elevated Kmea, which are significantly reversed by administering N-acetyl-L-cysteine to reduce Kmea levels. It is proposed that ectopic Kmea modification mediates the defects caused by HIBCH- or ECHS1-deficiency. Reducing Kmea modification provides a new approach for treating HIBCH- or ECHS1-related Leigh syndrome.

Wednesday May 20th - Behavior

Nisha, Thapliyal, D., Gohil, B., Modak, A. S., Singh, N. T., Mukherjee, C., Ahuja, S., Sahu, B. S., Singh, M. D. (2025). Downregulation of Pten Improves Huntington's Disease Phenotype by Reducing Htt Aggregates and Cell Death. Mol Neurobiol, 62(7):8752-8767 PubMed ID: 40042729 Journal & PubMed ID:
Summary:
Huntington's disease (HD) is a dominantly inherited neurodegenerative disorder that stems from the expansion of CAG repeats within the coding region of Huntingtin (HTT) gene. Currently, there exists no effective therapeutic intervention that can prevent the progression of the disease. This study aims to identify a novel genetic modifier with therapeutic potential. Transgenic flies were used containing HTT.ex1.Q93 and mRFP-HTT.588.Q138 constructs, which encode mutant pathogenic Huntingtin (Htt) proteins featuring 93 and 138 polyglutamine (Q) repeats respectively. The resultant mutant proteins cause the loss of photoreceptor neurons in the eye and a progressive loss of neuronal tissues in the brain and motor neurons in Drosophila. Several findings have demonstrated the association of HD with growth factor signaling defects. Phosphatase and tensin homolog (Pten) have been implicated in the negative regulation of the Insulin signaling/receptor tyrosine signaling pathway which regulates the growth and survival of cells. This study downregulated Pten and found a significant improvement in morphological phenotypes in the eye, brain, and motor neurons. These findings were further correlated with the enhancement of the functional vision and climbing ability of the flies. Reduction was found in both Htt aggregate and caspase levels which are involved in the apoptotic pathway. In alignment with the genetic modulation of Pten, the protective role of Pten inhibition was elucidated through the utilization of VO-OHpic. VO-OHpic improved the climbing ability of flies and reduced the poly(Q) aggregates and apoptosis levels. A similar reduction in Htt aggregates was observed in the mouse neuronal inducible HD cell line model. This study illustrates that Pten inhibition is a potential therapeutic approach for HD.

Wednesday May 20th - Behavior

Capek, M., Arenas, O. M., Alpert, M. H., Zaharieva, E. E., Mendez-Gonzalez, I. D., Simoes, J. M., Gil, H., Acosta, A., Su, Y., Para, A., Gallio, M. (2025). Evolution of temperature preference in flies of the genus Drosophila. Nature, 641(8062):447-455 PubMed ID: 40044866
Summary:
The preference for a particular thermal range is a key determinant of the distribution of animal species. However, little is known about how temperature preference behaviour evolves during the colonization of new environments. This study shows that at least two distinct neurobiological mechanisms drive the evolution of temperature preference in flies of the genus Drosophila. Fly species from mild climates (D. melanogaster and D. persimilis) avoid both innocuous and noxious heat, and this study shows that the thermal activation threshold of the molecular heat receptor Gr28b.d precisely matches species-specific thresholds of behavioural heat avoidance. We find that desert-dwelling D. mojavensis are instead actively attracted to innocuous heat. Notably, heat attraction is also mediated by Gr28b.d (and by the antennal neurons that express it) and matches its threshold of heat activation. Rather, the switch in valence from heat aversion to attraction correlates with specific changes in thermosensory input to the lateral horn, the main target of central thermosensory pathways and a region of the fly brain implicated in the processing of innate valence. Together, these results demonstrate that, in Drosophila, the adaptation to different thermal niches involves changes in thermal preference behaviour, and that this can be accomplished using distinct neurobiological solutions, ranging from shifts in the activation threshold of peripheral thermosensory receptor proteins to a substantial change in the way temperature valence is processed in the brain.

Bragina, J. V., Goncharova, A. A., Besedina, N. G., Danilenkova, L. V., Kamysheva, E. A., Kamyshev, N. G. (2025). Genetic Control of Social Experience-Dependent Changes in Locomotor Activity in Drosophila melanogaster Males. Arch Insect Biochem Physiol, 118(2):e70022 PubMed ID: 39966324
Summary:
In animals, social experience plays an important role in the adaptive modification of behavior. Previous social experience changes locomotor activity in Drosophila melanogaster. In females, suppression of locomotion is observed only when flies are in aggregations, but males retain a reduced level of locomotor activity up to 5 days after being isolated from the group. The mechanisms underlying such behavioral plasticity still largely are unknown. This study aimed to identify new candidate genes involved in the social experience-dependent modification of locomotor activity. The effect of social experience on spontaneous locomotor activity in various mutant males, including those with impaired learning and memory, circadian rhythms, some biochemical pathways, and sensory systems. The results of the present study indicate that the biogenic amines and olfactory perception appear to play key roles in social experience-induced changes in locomotor activity. Also, a screen was performed of the collection of mutants carrying random autosomal insertions of PdL transposon. Five candidate genes were isolated, of which two genes, Dek and Hel89B, encode proteins related to the formation of the epigenetic code, implying that epigenetic factors regulating gene expression may be involved in social experience-dependent modification of locomotor behavior.

Rorsman, H. O., Muller, M. A., Liu, P. Z., Sanchez, L. G., Kempf, A., Gerbig, S., Spengler, B., Miesenbock, G. (2025). Sleep pressure accumulates in a voltage-gated lipid peroxidation memory. Nature, 641(8061):232-239 PubMed ID: 40108451
Summary:
Voltage-gated potassium (K(V)) channels contain cytoplasmically exposed β-subunits whose aldo-keto reductase activity is required for the homeostatic regulation of sleep. This study shows that Hyperkinetic, the β-subunit of the K(V)1 channel Shaker in Drosophila, forms a dynamic lipid peroxidation memory. Information is stored in the oxidation state of Hyperkinetic's nicotinamide adenine dinucleotide phosphate (NADPH) cofactor, which changes when lipid-derived carbonyls, such as 4-oxo-2-nonenal or an endogenous analogue generated by illuminating a membrane-bound photosensitizer, abstract an electron pair. NADP(+) remains locked in the active site of K(V)β until membrane depolarization permits its release and replacement with NADPH. Sleep-inducing neurons use this voltage-gated oxidoreductase cycle to encode their recent lipid peroxidation history in the collective binary states of their K(V)β subunits; this biochemical memory influences-and is erased by-spike discharges driving sleep. The presence of a lipid peroxidation sensor at the core of homeostatic sleep control suggests that sleep protects neuronal membranes against oxidative damage. Indeed, brain phospholipids are depleted of vulnerable polyunsaturated fatty acyl chains after enforced waking, and slowing the removal of their carbonylic breakdown products increases the demand for sleep.

Manoli, G., Lankinen, P., Bertolini, E., Helfrich-Forster, C. (2025). Correlation between circadian and photoperiodic latitudinal clines in Drosophila littoralis Open Biol, 15(3):240403 PubMed ID: 40037533
Summary:
Insects can survive harsh conditions, including Arctic winters, by entering a hormonally induced state of dormancy, known as diapause. Diapause is triggered by environmental cues such as shortening of the photoperiod (lengthening of the night). The time of entry into diapause depends on the latitude of the insects' habitat, and this applies even within a species: populations living at higher latitudes enter diapause earlier in the year than populations living at lower latitudes. A long-standing question in biology is whether the internal circadian clock, which governs daily behaviour and serves as a reference clock to measure night length, shows similar latitudinal adaptations. To address this question, the onset of diapause and various behavioural and molecular parameters were examined of the circadian clock in the cosmopolitan fly, Drosophila littoralis, a species distributed throughout Europe from the Black Sea (41° N) to Arctic regions (69° N). All clock parameters examined showed the same correlation with latitude as the critical night length for diapause induction. It is concluded that the circadian clock has adapted to the latitude and that this may result in the observed latitudinal differences in the onset of diapause.

Chen, J., Zhu, P., Jin, S., Zhang, Z., Jiang, S., Li, S., Liu, S., Peng, Q., Pan, Y. (2025). A hormone-to-neuropeptide pathway inhibits sexual receptivity in immature Drosophila females Proc Natl Acad Sci U S A, 122(8):e2418481122 PubMed ID: 39982743
Summary:
Newborns, typically asexual, undergo a process of sexual transition to reach sexual maturity, but the regulatory mechanism underlying this transition is not clear. How female sexual behavior is modulated during sexual transition by hormones and neuromodulators in Drosophila was examined. Leucokinin (LK) inhibits female receptivity specifically during a sexual transition period in immature females, but not in younger or mature females. Moreover, the steroid hormone ecdysone, which is mainly synthesized in the female ovary during sexual maturation, acts on LK neurons via the ecdysone receptor to suppress sexual receptivity. It was further found that LK suppresses female receptivity through its receptor LKR in central pC1 neurons, a decision center for female sexual behavior. These findings reveal a hormone-to-neuropeptide pathway that specifically inhibits sexual behavior during sexual maturation in female Drosophila, shedding light on how hormones and neuromodulators coordinate sexual development and behaviors.

Canic, T., Lopez, J., Ortiz-Vega, N., Zhai, R. G., Syed, S. (2025). High-resolution, high-throughput analysis of Drosophila geotactic behavior J Exp Biol, 228(4) PubMed ID: 39976165
Summary:
Drosophila's innate response to gravity, geotaxis, has been used to assess the impact of aging and disease on motor performance. Despite its rich history, fly geotaxis continues to be largely measured manually and assessed through simplistic metrics, limiting analytic insights into the behavior. A fully programmable apparatus was constructed and a multi-object tracking software was developed capable of following sub-second movements of individual flies, thus allowing quantitative analysis of geotaxis. The apparatus monitors 10 fly cohorts simultaneously, with each cohort consisting of up to 7 flies. The software tracks single flies during the entire run with ∼97% accuracy, yielding detailed climbing curve, speed and movement direction with 1/30 s resolution. Our tracking permits the construction of multi-variable metrics and the detection of transitory movement phenotypes, such as slips and falls. The platform is therefore poised to advance Drosophila geotaxis assay into a comprehensive assessment of locomotor behavior.

Tuesday May 19th - Evolution

Sabaris, G., Schuettengruber, B., Papadopoulos, G. L., Coronado-Zamora, M., Fitz-James, M. H., Gonzalez, J., Cavalli, G. (2025). A mechanistic basis for genetic assimilation in natural fly populations. Proc Natl Acad Sci U S A, 122(11):e2415982122 PubMed ID: 40063800
Summary:
Genetic assimilation is a process by which a trait originally driven by the environment becomes independent of the initial cue and is expressed constitutively in a population. More than seven decades have passed since Waddington's pioneering demonstration of the acquisition of morphological traits through genetic assimilation, but the underlying mechanism remains unknown. This study addressed this gap by performing combined genomic analyses of Waddington's genetic assimilation experiments using the ectopic veins (EV) phenocopy in Drosophila as a model. This study reveals the assimilation of EV in both outbred and inbred fly natural populations, despite their limited genetic diversity. Key changes were identified in the expression of developmental genes and pinpointed selected alleles involved in EV assimilation. The assimilation of EV is mainly driven by the selection of regulatory alleles already present in the ancestral populations, including the downregulation of the receptor tyrosine kinase gene Cad96Ca by the insertion of a transposable element in its 3' untranslated region. The genetic variation at this locus in the inbred population is maintained by a large chromosomal inversion. In outbred populations, the evolution of EV results from a polygenic response shaped by the selective environment. These results support a model in which selection for multiple preexisting alleles in the ancestral population, rather than stress-induced genetic or epigenetic variation, drives the evolution of EV in natural fly populations.

Liao, A., Kawecki, T. J. (2025). Context- and sex-dependent links between sire sexual success and offspring pathogen resistance. Evolution, 79(6):983-994 PubMed ID: 40048651
Summary:
Sexual selection has been proposed to promote genetic variants that improve resistance to pathogens (a variant of the "good genes" hypothesis). Two key mechanisms linking sexual success and pathogen resistance have been proposed: the "condition-dependent" scenario, where general health improves both sexual traits and pathogen resistance, and the "context-dependent" scenario, where resistance to specific pathogens benefits sexual success only in certain environments. Few studies distinguish between these two mechanisms. Here, we used Drosophila melanogaster in an experiment designed to test for additive genetic relationship between males' sexual success and the resistance of its offspring to the fungal pathogen Metarhizium brunneum, and to investigate if this relationship depends on pathogen exposure during sexual selection as well as on offspring sex. In the absence of the pathogen, more sexually successful males sired less pathogen-resistant offspring, whereas no relationship was detected when sires competed for paternity after pathogen exposure. For daughters, the relationship tended to be negative irrespective of sire's pathogen exposure. Thus, while this study confirmed that sexual selection may act on genes affecting resistance in a context- and sex-dependent manner, no circumstances were found under which it promoted resistance, in contradiction to the "good genes" hypothesis.

De Nardo, A. N., Meena, A., Maggu, K., Eggs, B., Sbilordo, S. H., Lupold, S. (2025). Experimental evolution reveals trade-offs between sexual selection and heat tolerance in Drosophila prolongata. Evolution, 79(5):823-836. PubMed ID: 39964947
Summary:
Sexual selection promotes traits that enhance mating or fertilization success, but these traits can be very costly under harsh environmental conditions. The extent to which differential investment in costly traits under varying intensities of sexual selection is related to their susceptibility to environmental stress remains unclear. This study explored how experimental evolution under different operational sex ratios (OSRs) shapes traits and reproductive success of male Drosophila prolongata, and how developmental and/or adult heat stress affect the expression of these traits. This study found males from even and slightly male-biased OSRs to be larger and display greater reduction in body size under developmental heat stress, suggesting pre-mating sexual selection on body size and condition-dependent thermal sensitivity. These populations also exhibited consistently high mating and fertilization success across temperatures, potentially indicating selection for robust phenotypes with "good genes" that perform well regardless of temperature. Conversely, males from strongly male-biased OSR populations experienced more pronounced decline in sperm competitiveness following exposure to developmental or adult heat stress. These results highlight how environmental stressors differentially impact populations, shaped by varying strengths of pre- and post-mating sexual selection. These observed patterns suggest potential interactions between past selection and the ability to adapt to changing environments.

Loh, L. S., DeMarr, K. A., Tsimba, M., Heryanto, C., Berrio, A., Patel, N. H., Martin, A., McMillan, W. O., Wray, G. A., Hanly, J. J. (2025). Lepidopteran scale cells derive from sensory organ precursors through a canonical lineage. Development, 152(5) PubMed ID: 40052482
Summary:
The success of butterflies and moths is tightly linked to the origin of scales within the group. A long-standing hypothesis postulates that scales are homologous to the well-described mechanosensory bristles found in the fruit fly Drosophila melanogaster, as both derive from an epithelial precursor. Previous histological and candidate gene approaches identified parallels in genes involved in scale and bristle development. This study provides developmental and transcriptomic evidence that the differentiation of lepidopteran scales derives from the sensory organ precursor (SOP). Live imaging in lepidopteran pupae shows that SOP cells undergo two asymmetric divisions that first abrogate the neurogenic lineage, and then lead to a differentiated scale precursor and its associated socket cell. Single-nucleus RNA sequencing using early pupal wings revealed differential gene expression patterns that mirror SOP development, suggesting a shared developmental program. Additionally, we recovered a newly associated gene, the transcription factor Pdm3, involved in the proper differentiation of butterfly wing scales. Altogether, these data open up avenues for understanding scale type specification and development, and illustrate how single-cell transcriptomics provide a powerful platform for understanding evolution of cell types.

Verdonk, H., Pivirotto, A., Pavinato, V., Hey, J., Pond, S. L. K. (2025). A New Comparative Framework for Estimating Selection on Synonymous Substitutions Mol Biol Evol, 42(4) PubMed ID: 40129111
Summary:
Selection on synonymous codon usage is a well-known and widespread phenomenon, yet existing models often do not account for it or its effect on synonymous substitution rates. This article developed and expand the capabilities of multiclass synonymous substitution (MSS) models, which account for such selection by partitioning synonymous substitutions into 2 or more classes and estimating a relative substitution rate for each class, while accounting for important confounders like mutation bias. Extensive heterogeneity was identified among relative synonymous substitution rates in an empirical dataset of ~12,000 gene alignments from 12 Drosophila species. Model performance was evaluated using data simulated under a forward population genetic simulation, demonstrating that MSS models are robust to model misspecification. MSS rates are significantly correlated with other covariates of selection on codon usage (population-level polymorphism data and tRNA abundance data), suggesting that models can detect weak signatures of selection on codon usage. With the MSS model, we can now study selection on synonymous substitutions in diverse taxa, independent of any a priori assumptions about the forces driving that selection.

Lollar, M. J., Kim, E., Stern, D. L., Pool, J. E. (2025). Courtship song differs between African and European populations of Drosophila melanogaster and involves a strong effect locus, G3 (Bethesda), 15(5) PubMed ID: 40053835
Summary:
The courtship song of Drosophila melanogaster has long served as an excellent model system for studies of animal communication and differences in courtship song have been demonstrated among populations and between species. Here, we report that flies of African and European origin, which diverged ∼13,000 years ago, show significant genetic differentiation in the use of slow vs fast pulse song. Using a combination of quantitative trait mapping and population genetic analysis, this study detected a single strong quantitative trait locus underlying this trait and w candidate genes were identified that may contribute to the evolution of this trait. Song trait variation between parental strains of the recombinant inbred panel enabled detection of genomic intervals associated with 6 additional song traits, some of which include known courtship-related genes. These findings improve the prospects for further genetic insights into the evolution of reproductive behavior and the biology underlying courtship song.

Monday May 18th - Larval and Adult Neural Development, Structure, and Function

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). Gradients of Cell Recognition Molecules Wire Visuomotor Transformation bioRxiv, PubMed ID: 39974884
Summary:
Converting sensory information into motor commands is fundamental to most of our actions. In Drosophila, visuomotor transformations are mediated by Visual Projection Neurons (VPNs). These neurons encode object location and motion to drive directional behaviors through a synaptic gradient mechanism . However, the molecular origins of such graded connectivity remain unknown; this question in a VPN cell type called LPLC2 (lobula plate-lobula columnar type 2 neurons), which integrates looming motion and transforms it into an escape response through two separate dorsoventral synaptic gradients at its inputs and outputs. Two corresponding dorsoventral expression gradients of cell recognition molecules within the LPLC2 population that regulate this synaptic connectivity. Dpr13 (Defective proboscis extension response 13)) determines synaptic outputs of LPLC2 axons by interacting with its binding partner, DIP-epsilon (see Dips and Dprs)), expressed in the Giant Fiber - a neuron that mediates escape. Similarly, Beat-VI regulates synaptic inputs onto LPLC2 dendrites by interacting with Side-II expressed in upstream motion-detecting neurons. Behavioral, physiological, and molecular experiments demonstrate that these coordinated molecular gradients regulate synaptic connectivity, enabling the accurate transformation of visual features into motor commands. As continuous variation in gene expression within a neuronal type is also observed in the mammalian brain, graded expression of cell recognition molecules may represent a common mechanism underlying synaptic specificity.

Hamlin, V., Ansaf, H., Heffern, R., Williams-Simon, P. A., King, E. G. (2025). Multiple methods for assessing learning and memory in Drosophila melanogaster demonstrates the highly complex, context-dependent genetic underpinnings of cognitive traits. bioRxiv, PubMed ID: 40060392
Summary:
Learning and memory are fundamental for an individual to be able to respond to changing stimuli in their environment. Between individuals variation is seen in their ability to perform learning and memory tasks, however, it is still largely unknown what genetic factors may impact this variability. To gain better insight to the genetic components impacting variation in learning and memory, recombinant inbred lines (RILs) were used from the Drosophila synthetic population resource (DSPR), a multiparent mapping population exhibiting natural variation in many traits. Using a reward based associative learning and memory assay, flies were trained to associate an odor with a sucrose reward under starvation condition and measured olfactory learning and memory ability in y-mazes for 50 DSPR RILs. While no significant QTLs were found for olfactory learning or memory, suggestive regions were found that may be contributing to variability in performance when trained to different odors. Evidence is provided that performance with specific odors should be considered different phenotypes and introduce new methods for analysis for olfactory y-maze assays with multiple decision points. Additionally, we compare our data to previously collected place learning and memory data to show there is limited correlation in performance outcomes.

Li, Z., Lyu, C., Xu, C., Hu, Y., Luginbuhl, D. J., Caspi-Lebovic, A. B., Priest, J. M., Ozkan, E., Luo, L. (2025). Repulsive interactions instruct synaptic partner matching in an olfactory circuit bioRxiv, PubMed ID: 40060423
Summary:
Neurons exhibit extraordinary precision in selecting synaptic partners. Whereas cell-surface proteins (CSPs) mediating attractive interactions between developing axons and dendrites have been shown to instruct synaptic partner matching, it is less clear the degree to which repulsive interactions play a role. Using a genetic screen guided by single cell transcriptomes, this study identified three CSP pairs-Toll2-Ptp10D, Fili-Kek1, and Hbs/Sns-Kirre-in mediating repulsive interactions between non-partner olfactory receptor neuron (ORN) axons and projection neuron (PN) dendrites in the developing Drosophila olfactory circuit. Each CSP pair exhibits inverse expression patterns in the select PN-ORN partners. Loss of each CSP in ORNs led to similar synaptic partner matching deficits as the loss of its partner CSP in PNs, and mistargeting phenotypes caused by overexpressing one CSP could be suppressed by loss of its partner CSP. Each CSP pair is also differentially expressed in other brain regions. Together, these data reveal that multiple repulsive CSP pairs work together to ensure precise synaptic partner matching during development by preventing neurons from forming connections with non-cognate partners.

Ispizua, J. I., Rodriguez-Caron, M., Tassara, F. J., Kim, K. Y., Insussarry Perkins, C., Barzi, M., Carpio-Romero, C., Vasquez, M. F., Hansen, C. N., Gargiulo, J., Rosato, E., de la Iglesia, H., Ellisman, M. H., Ceriani, M. F. (2025). Daily ultrastructural remodeling of clock neurons bioRxiv, PubMed ID: 39990321
Summary:
In Drosophila, about 250 clock neurons in the brain form a network that orchestrates circadian rhythmicity. Among them, eight small Lateral ventral Neurons (s-LNvs) play a critical role, synchronizing the circadian ensemble via the neuropeptide Pigment-Dispersing Factor (PDF). Moreover, their neurites show daily variations in morphology, PDF levels, synaptic markers and connectivity. This process, called circadian structural plasticity, is ill-defined at the subcellular level. This study presents 3D volumes of the s-LNv terminals generated by Serial Block-face Scanning Electron Microscopy (SBEM) at three key time points, two hours before lights-ON, two hours after lights-ON, and two hours after lights-OFF. A reduction is reported in the number of neuronal varicosities at night, which reflects (and probably regulates) the cycling of the components found therein. Indeed, in the morning more presynaptic sites and increased accumulation and release of dense core vesicles were observed. These rhythms were paralleled by periodic changes in mitochondrial structure that suggest daily modulation of their activity. It is proposed that circadian plasticity of the functionally relevant structures within presynaptic varicosities cyclically modulates the influence of the s-LNvs on the clock network.

Hardin, K. R., Penas, A. B., Joubert, S., Ye, C., Myers, K. R., Zheng, J. Q. (2025). A Critical Role for the Fascin Family of Actin Bundling Proteins in Axon Development, Brain Wiring and Function bioRxiv, PubMed ID: 40027761
Summary:
Actin-based cell motility drives many neurodevelopmental events including guided axonal growth. Fascin is a major family of F-actin bundling proteins, but its role in axon development in vivo and brain wiring remains unclear. This study reports that fascin is required for axon development, brain wiring and function. Fascin is enriched in the motile filopodia of axonal growth cones and its inhibition impairs axonal extension and branching of hippocampal neurons in culture. Evidence is provided that fascin is essential for axon development and brain wiring in vivo using Drosophila melanogaster as a model. Drosophila expresses a single ortholog of mammalian fascin called Singed (SN), which is expressed in the mushroom body (MB) of the central nervous system. Loss of SN causes severe MB disruption, marked by α- and β-lobe defects indicative of altered axonal guidance. SN-null flies also exhibit defective sensorimotor behaviors as assessed by the negative geotaxis assay. MB-specific expression of SN in SN-null flies rescues MB structure and sensorimotor deficits, indicating that SN functions autonomously in MB neurons. Together, these data from primary neuronal culture and in vivo models highlight a critical role for fascin in brain development and function.

Grzejda, D., Hess, A., Rezansoff, A., Gorey, S., Carrasco, J., Alfonso-Gonzalez, C., Tsagkris, S., Neuhaus, L., Shi, M., Ozbulut, H. C., Vogtle, F. N., Vlachos, A., Hilgers, V. (2025). Pumilio differentially binds to mRNA 3' UTR isoforms to regulate localization of synaptic proteins EMBO Rep, 26(7):1792-1815 PubMed ID: 39984683
Summary:
In neuronal cells, the regulation of RNA is crucial for the spatiotemporal control of gene expression, but how the correct localization, levels, and function of synaptic proteins are achieved is not well understood. This study globally investigateD the role of alternative 3' UTRs in regulating RNA localization in the synaptic regions of the Drosophila brain. We identify direct mRNA targets of the translational repressor Pumilio, finding that mRNAs bound by Pumilio encode proteins enriched in synaptosomes. Pumilio differentially binds to RNA isoforms of the same gene, favoring long, neuronal 3' UTRs. These longer 3' UTRs tend to remain in the neuronal soma, whereas shorter UTR isoforms localize to the synapse. In cultured pumilio mutant neurons, axon outgrowth defects are accompanied by mRNA isoform mislocalization, and proteins encoded by these Pumilio target mRNAs display excessive abundance at synaptic boutons. Our study identifies an important mechanism for the spatiotemporal regulation of protein function in neurons.

Wednesday May 13th - Stress

Onkar, A., Sheshadri, D., Nagarajan, K., Ganesh, S. (2025). Inactivation of Laforin Phosphatase and Increased Glucose Uptake Underlie Glycogen Synthase-Mediated Neuronal Survival Under Oxidative Stress. Mol Neurobiol, PubMed ID: 40261604
Summary:
Recent studies demonstrate that exposure of neurons to physiological stressors triggers glycogen synthase (GS) activation and glycogen synthesis as a transient cell survival mechanism. However, the mechanisms that regulate glycogen synthesis during stress and its role in neuronal physiology remain unclear. This study investigated the mechanisms that guide GS activation and glycogen accumulation under oxidative stress conditions as a model stressor. Neuronal cell lines were used to demonstrate that hydrogen peroxide-induced oxidative stress activates GS and glycogen synthesis in neuronal cells. We further demonstrate that the stress-induced glycogen accumulation is dependent on the membrane localization of the Glut3 glucose transporters and increased glucose uptake during stress. The stress-induced activation of glycogen synthesis, however, is independent of intracellular glucose level, suggesting a parallel mechanism for activating GS and glucose uptake in neurons under physiological stress.Oxidative stress results in the inactivation of laforin phosphatase, leading to the membrane localization of Glut3 and activation of GS. Using the Drosophila model, it was demonstrated that increased GS activity and concomitant glycogen accumulation are pro-survival mechanisms for neurons under oxidative stress. This study thus offers novel insights into the pathways that regulate glycogen metabolism in neurons under oxidative stress and underscores their importance for neuronal survival.

Zanco, B., Morimoto, J., Cockerell, F., Mirth, C., Sgro, C. M. (2025). Nutritional optima for life-history traits vary with temperature and across locally-adapted populations. J Insect Physiol, 163:104815 PubMed ID: 40334813
Summary:
As the climate changes, populations must overcome more frequent and more extreme exposure to a wide range of stressors. However, knowledge of how locally-adapted populations respond to combinations of stressors remains incomplete. Recent studies show that elevated temperatures can interact with nutrition to accentuate the negative effects of a poor diet, suggesting higher costs of nutritional stress when individuals experience temperatures outside of their locally-adapted conditions. This can translate into reduced nutrient optima under thermal stress in life-history trait landscapes, a hypothesis that remains to be tested. This study used the Geometric Framework for Nutrition to test this hypothesis using two locally-adapted populations of Drosophila melanogaster from opposing ends of a well-characterised adaptive gradient along the east coast of Australia (tropical vs. temperate). The negative effects of nutritional stress were significantly greater in the tropical population under warmer temperatures. In contrast, the temperate population was able to utilise a broader nutritional space to maintain high viability and a large wing size across the range of fluctuating temperatures. These findings reveal the ways in which local adaptation impacts how populations navigate and explore the nutritional space in response to increasingly stressful thermal conditions. These data suggest that certain populations may be better able to cope with increasingly stressful and variable environments, while others may be more vulnerable to local extinctions.

Zhang, W., Ai, Z., Zhu, G., Yang, M., Liu, Y., Xu, H., Zheng, Q., Song, Y., Su, D. (2025). Drosophila model of depression-like behavior: systematic investigation of external stress parameters and intrinsic susceptibility Pharmacol Biochem Behav, 252:174014 PubMed ID: 40262700
Summary:
Currently, Drosophila is widely used to study brain diseases. Unfortunately, Drosophila still lacks a mature and stable model for research on depression. This study addressed this issue by systematically exploring external stress and intrinsic susceptibility factors (Drosophila strains, adult/larval forms) that may influence the establishment and reproducibility of the stress-induced model. On this basis, the parameters are optimized. The results indicate Drosophila strains and forms are critical factors influencing model establishment, while external stress is the primary cause affecting the model's mortality rate. Compared with the other four strains, Canton-S are the most susceptible to chronic unpredictable mild stress (CUMS). Larval forms exhibit lower reactivity to external stress compared to adults. Parameter variations greatly influence model mortality rates from cold/heat/starvation stress. The model methodology validation study conducted subsequently through assessments of face, construct, and predictive validity demonstrates that the model exhibits face (neurobehavioral differences), structural (neurotransmitter changes in the Drosophila brain), and predictive (behavioral changes after fluoxetine treatment) validity. Additionally, spatial behavior experiments in Drosophila provide more realistic activity patterns compared to planar behavior, minimizing potential errors in interpreting lateral movements of the Drosophila, and it is recommended that this metric be included in model evaluation. This study presents a comprehensive set of methods for establishing and evaluating a depression-like behavior model and offers greater convenience for research on the pathogenesis of depression, as well as the screening, efficacy evaluation, and mechanistic studies of antidepressant drugs.

Hopkins, T., Ragsdale, C., Seo, J. (2025). Elevated ambient temperature reduces fat storage through the FoxO-mediated insulin signaling pathway PLoS One, 20(2):e0317971 PubMed ID: 40009607
Summary:
Temperature profoundly impacts all living organisms, influencing development, growth, longevity, and metabolism. Specifically, when adult flies are exposed to high temperatures, there is a notable reduction in their body fat content. This study investigated the roles of the insulin signaling pathway in temperature-mediated fat storage. This pathway is not only highly conserved from insects to mammals but also crucial in regulating lipid metabolism, cell proliferation, and tissue growth. The Forkhead box O (FoxO) protein functions as a key downstream signaling molecule in this pathway, mediating the inhibitory effects of insulin signaling. At elevated temperatures, direct targets of FoxO, such as insulin receptor (InR), Thor (Drosophila eukaryotic initiation factor 4E binding protein), and FoxO itself, are significantly upregulated, which indicates an inhibition of insulin signaling. Interestingly, this inhibition seems to occur independently of Drosophila insulin-like peptide (Ilp) stimuli, as not all Ilp transcripts were reduced at elevated temperatures. Furthermore, when S2R + Drosophila cells are incubated at high temperatures, there is a marked decrease in Akt phosphorylation, directly supporting the notion that elevated temperatures can inhibit insulin signaling in a cell-autonomous manner, independent of Ilp levels. Subsequent experiments demonstrated that either constitutively active InR or knockdown of FoxO prevents the reduction of body fat at high temperatures. Together, these findings highlight the critical role of the insulin signaling-FoxO branch in regulating lipid homeostasis under heat stress conditions.

Li, S., Yang, H., Duan, Y., Wu, L., Hu, C., Yu, B., Zhao, Y. (2025). Role of heat shock proteins in response to temperature stress and their effect on apoptosis in Drosophila melanogaster Int J Biol Macromol, 306(Pt 1):141320 PubMed ID: 39984102
Summary:
Temperature is a key ecological factor influencing insect development and survival. Temperature stress triggers insect cell apoptosis. However, factors surrounding the response of insects to various temperature stresses at different developmental stages remain unclear. The molecular mechanisms by which these factors reduce apoptosis are also not well understood. In this study, transcriptome sequencing and differential expression analysis were conducted on the W¹¹¹⁸ strain of Drosophila melanogaster at various developmental stages under different temperature treatments (6 6deg;C, 26 °C, 36 °/37 °C). The analysis revealed that DmenHSP68 is a differentially expressed gene for different developmental stages and under different temperature stresses. The RNA interference (RNAi) suppression of DmenDNAJA1Hsp68 (HSP70 family), and DmenHSP83 (HSP90 family) significantly decreased adult survival rates under temperature stress. RT-PCR results showed a significant upregulation of apoptosis-related genes. The levels of apoptosis markers, such as reactive oxygen species (ROS), cytochrome c (Cytc) levels, and Caspase-3 activity significantly increased, while adenosine triphosphate (ATP) levels significantly decreased. This study provides a theoretical foundation for further elucidation of the molecular mechanisms underlying apoptosis in Drosophila under different temperature stresses.

Ricolo, D., Casanova, J., Giannios, P. (2025). Drosophila and human Headcase define a new family of ribonucleotide granule proteins required for stress response Sci Adv, 11(13):eads2086 PubMed ID: 40153502
Summary:
Cells have means to adapt to environmental stresses such as temperature fluctuations, toxins, or nutrient availability. Stress responses, being dynamic, extend beyond transcriptional control and encompass post-transcriptional mechanisms allowing for rapid changes in protein synthesis. Previous research has established headcase as a fundamental gene for stress responses and survival of the Drosophila adult progenitor cells (APCs). However, the molecular role of Headcase has remained elusive. This study identified Headcase as a component of ribonucleoprotein (RNP) granules. Headcase is required for proper RNP granule formation and remodeling upon stress and is crucial for translation control. Likewise, the human Headcase homolog (HECA) is identified as a component of RNP granules and has similar roles in translational regulation and stress protection. Thus, Headcase proteins define a new family contributing to specific roles among the RNP heterogeneous network.

Tuesday May 12th - RNAs and Transposons

Briney, C. A., Henriksen, J. C., Lin, C., Jones, L. A., Benner, L., Rains, A. B., Gutierrez, R., Gafken, P. R., Rissland, O. S. (2025). Muskelin is a substrate adaptor of the highly regulated Drosophila embryonic CTLH E3 ligase. EMBO Rep, 26(6):1647-1669 PubMed ID: 39979464
Summary:
The maternal-to-zygotic transition (MZT) is a conserved developmental process where the maternally-derived protein and mRNA cache is replaced with newly made zygotic gene products. Previously work has shown that in Drosophila the deposited RNA-binding proteins ME31B, Cup, and Trailer Hitch are ubiquitylated by the CTLH E3 ligase and cleared. However, the organization and regulation of the CTLH complex remain poorly understood in flies because Drosophila lacks an identifiable substrate adaptor, and the mechanisms restricting the degradation of ME31B and its cofactors to the MZT are unknown.This study shows that the developmental regulation of the CTLH complex is multi-pronged, including transcriptional control by OVO and autoinhibition of the E3 ligase. One major regulatory target is the subunit Muskelin, which we demonstrate is a substrate adaptor for the Drosophila CTLH complex. Finally, Muskelin was found to have few targets beyond the three known RNA-binding proteins, showing exquisite target specificity. Thus, multiple levels of integrated regulation restrict the activity of the embryonic CTLH complex to early embryogenesis, during which time it regulates three important RNA-binding proteins.

Blumenstiel, J. P., Kingan, S. B., Garrigan, D., Hill, T., Vedanayagam, J. (2025). Nested likelihood-ratio testing of the nonsynonymous:synonymous ratio suggests greater adaptation in the piRNA machinery of Drosophila melanogaster compared with Drosophila ananassae and Drosophila willistoni, two species with higher repeat content. G3 (Bethesda), 15(4) PubMed ID: 39982380
Summary:
Numerous studies have revealed a signature of strong adaptive evolution in the piwi-interacting RNA (piRNA) machinery of Drosophila melanogaster, but the cause of this pattern is not understood. Several hypotheses have been proposed. One hypothesis is that transposable element (TE) families and the piRNA machinery are co-evolving under an evolutionary arms race, perhaps due to antagonism by TEs against the piRNA machinery. A related, though not co-evolutionary, hypothesis is that recurrent TE invasion drives the piRNA machinery to adapt to novel TE strategies. A third hypothesis is that ongoing fluctuation in TE abundance leads to adaptation in the piRNA machinery that must constantly adjust between sensitivity for detecting new elements and specificity to avoid the cost of off-target gene silencing. Rapid evolution of the piRNA machinery may also be driven independently of TEs, and instead from other functions such as the role of piRNAs in suppressing sex-chromosome meiotic drive. We sought to evaluate the impact of TE abundance on adaptive evolution of the piRNA machinery in D. melanogaster and 2 species with higher repeat content-Drosophila ananassae and Drosophila willistoni. This comparison was achieved by employing a likelihood-based hypothesis testing framework based on the McDonald-Kreitman test. It is possible to reject a faster rate of adaptive evolution in the piRNA machinery of these 2 species. The high rate of adaptation in D. melanogaster is either driven by a recent influx of TEs that have occurred during range expansion or selection on other functions of the piRNA machinery.

Yu, J., Kawasaki, F., Izumi, N., Kiuchi, T., Katsuma, S., Tomari, Y., Shoji, K. (2025). Autonomous shaping of the piRNA sequence repertoire by competition between adjacent ping-pong amplification sites. Mol Cell, 85(6):1134-1146. PubMed ID: 40118041
Summary:
PIWI-interacting RNAs (piRNAs) are crucial for silencing transposable elements (TEs). In many species, piRNAs are generated via a complex process known as the ping-pong pathway, coupling TE cleavage with piRNA amplification. However, the biological significance of this complexity remains unclear. This study systematically compared piRNA profiles in two related silkworm cell lines and found significant changes in their sequence repertoire. Importantly, the changeability of this repertoire negatively correlated with the piRNA biogenesis efficiency, a trend also observed in Drosophila stocks and single silkworm eggs. This can be explained by competition between adjacent ping-pong sites, supported by mathematical modeling. Moreover, this competition can rationalize how piRNAs autonomously avoid deleterious mismatches to target TEs in silkworms, flies, and mice. These findings unveil the intrinsic plasticity and adaptability of the piRNA system to combat diverse TE sequences and highlight the universal power of competition and self-amplification to drive autonomous optimization.

Klumpe, S., Senti, K. A., Beck, F., Sachweh, J., Hampoelz, B., Ronchi, P., Oorschot, V., Brandstetter, M., Yeroslaviz, A., Briggs, J. A. G., Brennecke, J., Beck, M., Plitzko, J. M. (2025). In-cell structure and snapshots of copia retrotransposons in intact tissue by cryo-ET. Cell, 188(8):2094-2110. PubMed ID: 40049165
Summary:
Long terminal repeat (LTR) retrotransposons belong to the transposable elements (TEs), autonomously replicating genetic elements that integrate into the host's genome. Among animals, Drosophila melanogaster serves as an important model organism for TE research and contains several LTR retrotransposons, including the Ty1-copia family, which is evolutionarily related to retroviruses and forms virus-like particles (VLPs). This study used cryo-focused ion beam (FIB) milling and lift-out approaches to visualize copia VLPs in ovarian cells and intact egg chambers, resolving the in situ copia capsid structure to 7.7 Å resolution by cryoelectron tomography (cryo-ET). Although cytoplasmic copia VLPs vary in size, nuclear VLPs are homogeneous and form densely packed clusters, supporting a model in which nuclear import acts as a size selector. Analyzing flies deficient in the TE-suppressing PIWI-interacting RNA (piRNA) pathway, copia's translocation into the nucleus during spermatogenesis was observed. These findings provide insights into the replication cycle and cellular structural biology of an active LTR retrotransposon.

Cao, N., Wang, J., Deng, T., Fan, B., Su, S., Ma, J., Wang, H. W. (2025). Structural basis of endo-siRNA processing by Drosophila Dicer-2 and Loqs-PD Nucleic Acids Res, 53(4) PubMed ID: 39988314
Summary:
Endogenous small interfering RNAs (endo-siRNAs or esiRNAs) originate from either elongated endogenous transcripts capable of forming complex fold-back structures or from double-stranded regions generated through intermolecular base pairing of convergently transcribed mRNAs. The mechanism of maturation and functionality of esiRNAs exhibit significant variation across diverse species. In Drosophila melanogaster, esiRNAs reside in both somatic and germline cells, where they serve as post-transcriptional modulators for specific target RNAs. Their maturation process critically relies on Dicer-2 (Dcr-2), with the assistance of its cofactor Loqs-PD. In this study, we have successfully elucidated the cryo-EM structures of Dcr-2/Loqs-PD complex bound to esiRNA precursors (pre-esiRNAs) in various states. These structural and biochemical results reveal that ATP is essential for the cleavage of esiRNAs by the Dcr-2/Loqs-PD complex, a process analogous to the cleavage of double-stranded RNA (dsRNA). When Loqs-PD is present, pre-esiRNAs are preferentially loaded onto the Helicase domain of Dcr-2. Moreover, as the Helicase domain exhibits a preference for binding to the rigid end of double-stranded RNA, Dcr-2 tends to cleave pre-esiRNA from the small closed loop end, rather than the loose and flexible open end.

Grzejda, D., Hess, A., Rezansoff, A., Gorey, S., Carrasco, J., Alfonso-Gonzalez, C., Tsagkris, S., Neuhaus, L., Shi, M., Ozbulut, H. C., Vogtle, F. N., Vlachos, A., Hilgers, V. (2025). Pumilio differentially binds to mRNA 3' UTR isoforms to regulate localization of synaptic proteins EMBO Rep, 26(7):1792-1815 PubMed ID: 39984683
Summary:
In neuronal cells, the regulation of RNA is crucial for the spatiotemporal control of gene expression, but how the correct localization, levels, and function of synaptic proteins are achieved is not well understood. This study globally investigateD the role of alternative 3' UTRs in regulating RNA localization in the synaptic regions of the Drosophila brain. Direct mRNA targets of the translational repressor Pumilio were identified, finding that mRNAs bound by Pumilio encode proteins enriched in synaptosomes. Pumilio differentially binds to RNA isoforms of the same gene, favoring long, neuronal 3' UTRs. These longer 3' UTRs tend to remain in the neuronal soma, whereas shorter UTR isoforms localize to the synapse. In cultured pumilio mutant neurons, axon outgrowth defects are accompanied by mRNA isoform mislocalization, and proteins encoded by these Pumilio target mRNAs display excessive abundance at synaptic boutons. This study identifies an important mechanism for the spatiotemporal regulation of protein function in neurons.

Monday May 12th - Disease Models

Chakraborty, A., Mitra, J., Malojirao, V. H., Kodavati, M., Mandal, S. M., Gill, S. K., Sreenivasmurthy, S. G., Vasquez, V., Mankevich, M., Bosch, L. V. D., Garruto, R. M., Robey, I. F., Krishnan, B., Ghosh, G., Hegde, M., Hazra, T. (2025). Fructose-2,6-bisphosphate restores TDP-43 pathology-driven genome repair deficiency in motor neuron diseases bioRxiv, PubMed ID: 39990425
Summary:
TAR DNA-binding protein 43 (TDP-43) proteinopathy plays a critical role in neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia (FTD). In recent discovery, it was identified that TDP-43 plays an essential role in DNA double-strand break (DSB) repair via the non-homologous end joining (NHEJ) pathway. This study found persistent DNA damage in the brains of ALS/FTD patients, primarily in the transcribed regions of the genome. The underlying mechanism was further investigated and found that polynucleotide kinase 3'-phosphatase (PNKP) activity was severely impaired in the nuclear extracts of both patient brains and TDP-43-depleted cells. PNKP is a key player in DSB repair within the transcribed genome, where its 3'-P termini processing activity is crucial for preventing persistent DNA damage and neuronal death. The inactivation of PNKP in ALS/FTD was due to reduced levels of its interacting partner, phosphofructo-2-kinase fructose 2,6 bisphosphatase (PFKFB3), and its biosynthetic product, fructose-2,6-bisphosphate (F2,6BP), an allosteric modulator of glycolysis. Recent work has shown that F2,6BP acts as a positive modulator of PNKP activity in vivo. Notably, exogenous supplementation with F2,6BP restored PNKP activity in nuclear extracts from ALS/FTD brain samples and patient-derived induced pluripotent stem (iPS) cells harboring pathological mutations. Furthermore, supplementation of F2,6BP restores genome integrity and partially rescues motor phenotype in a Drosophila model of ALS. These findings underscore the possibility of exploring the therapeutic potential of F2,6BP or its analogs in TDP-43 pathology-associated motor neuron diseases.

Karunaraj, P., Cao, E., Singh, H., Luf, M., Baker, S. J., Reddy, E. P., Pfleger, C. M. (2025). A Drosophila model for Costello Syndrome caused by Ras mutation K117R. bioRxiv, PubMed ID: 39974993
Summary:
Germline mutations that increase signaling through the Ras pathway can cause developmental disorders called RASopathies. The RASopathy Costello syndrome has been described to present with hallmarks that include short stature, intellectual disability, cardiac issues, and characteristic facial abnormalities and has been associated with gain-of-function mutations in HRas. The most common HRas mutations in Costello Syndrome occur at G12 and G13, but there are also other rare mutation sites such as K117 including HRas (K117R) . Ras (K117R) mutations are also found in colorectal cancer. Drosophila studies modeling gain-of-function in Ras primarily utilize the common cancer-associated mutation G12V, and previous Drosophila RASopathy models assessing Ras gain-of-function mutations have used human sequences for KRas G12D and HRas G12S. To augment these studies, this study characterized the phenotype of engineering the rare gain-of-function mutation K117R in the Drosophila Ras sequence. Constitutive low-level expression of Ras (K117R) increased lethality and reduced body size while also causing rough eye and ectopic wing vein phenotypes in those flies that survived to adulthood. Ras pathway inhibitors Trametinib and Rigosertib suppressed the lethality but not the reduced size phenotypes. Trametinib strongly suppressed the K117R wing vein phenotype whereas Rigosertib had only subtle effects. Trametinib is a direct MEK inhibitor. Rigosertib has been reported to have strong effects on PI3K signaling and to indirectly inhibit the Raf-ERK branch. Therefore, this data is consistent with an interpretation that some lethality in the fly Ras (K117R) model depends on elevated signaling through the Raf-ERK branch and potentially some lethality depends on the PI3K branch. In contrast, the lack of effects on the reduced size phenotypes would be consistent with small stature resulting from Raf- and PI3K-independent processes. This model can be useful for future mechanistic analysis and pharmacological screening and evaluation.

Hanson, K. M., Macdonald, S. J. (2025). Dynamic changes in gene expression through aging in Drosophila melanogaster heads G3 (Bethesda), 15(4) PubMed ID: 39992875
Summary:
Work in many systems has shown large-scale changes in gene expression during aging. However, many studies employ just two arbitrarily chosen timepoints to measure expression and can only observe an increase or a decrease in expression between "young" and "old" animals, failing to capture any dynamic, nonlinear changes that occur throughout the aging process. RNA sequencing was used to measure expression in male head tissue at 15 timepoints through the lifespan of an inbred Drosophila melanogaster strain. >6,000 significant, age-related genes were identified, nearly all of which have been seen in previous Drosophila aging expression studies and that include several known to harbor lifespan-altering mutations. This gene set was grouped into 28 clusters via their temporal expression change, observing a diversity of trajectories; some clusters show a linear change over time, while others show more complex, nonlinear patterns. Notably, reanalysis of the dataset comparing the earliest and latest timepoints-mimicking a 2-timepoint design-revealed fewer differentially expressed genes (around 4,500). Additionally, those genes exhibiting complex expression trajectories in multitimepoint analysis were most impacted in this reanalysis; their identification, and the inferred change in gene expression with age, was often dependent on the timepoints chosen. Informed by our trajectory-based clusters, a series of gene enrichment analyses was executed, identifying enriched functions/pathways in all clusters, including the commonly seen increase in stress- and immune-related gene expression with age. Finally, a pair of accessible Shiny apps, a framework for creating interactive web applications directly from R or Python without requiring web development skills, was developed to enable exploration of differential expression and gene enrichment results.

Doran, M. H., Rynkiewicz, M. J., Despond, E., Viswanathan, M. C., Madan, A., Chitre, K., Fenwick, A. J., Sousa, D., Lehman, W., Dawson, J. F., Cammarato, A. (2025). The hypertrophic cardiomyopathy-associated A331P actin variant enhances basal contractile activity and elicits resting muscle dysfunction iScience, 28(2):111816 PubMed ID: 39981516
Summary:
Previous studies aimed at defining the mechanistic basis of hypertrophic cardiomyopathy caused by A331P cardiac actin have reported conflicting results. The mutation is located along an actin surface strand, proximal to residues that interact with tropomyosin. These F-actin-tropomyosin associations are vital for proper contractile inhibition. To help resolve disease pathogenesis, we implemented a multidisciplinary approach. Transgenic Drosophila, expressing A331P actin, displayed skeletal muscle hypercontraction and elevated basal myocardial activity. A331P thin filaments, reconstituted using recombinant human cardiac actin, exhibited higher in vitro myosin-based sliding speeds, exclusively at low Ca(2+) concentrations. Cryo-EM-based reconstructions revealed no detectable A331P-related structural perturbations in F-actin. In silico, however, the P331-containing actin surface strand was less mobile and established diminished van der Waal's attractive forces with tropomyosin, which correlated with greater variability in inhibitory tropomyosin positioning. Such mutation-induced effects potentially elevate resting contractile activity among the models and may stimulate pathology in patients.

Holmes, B. B., Weigel, T. K., Chung, J. M., Kaufman, S. K., Apresa, B. I., Byrnes, J. R., Kumru, K. S., Vaquer-Alicea, J., Gupta, A., Rose, I. V. L., Zhang, Y., Nana, A. L., Alter, D., Grinberg, L. T., Spina, S., Leung, K. K., Condello, C., Kampmann, M., Seeley, W. W., Coutinho-Budd, J. C., Wells, J. A. (2025). β-Amyloid Induces Microglial Expression of GPC4 and APOE Leading to Increased Neuronal Tau Pathology and Toxicity. bioRxiv, PubMed ID: 40060520
Summary:
To elucidate the impact of Aβ pathology on microglia in Alzheimer's disease pathogenesis, this study profiled the microglia surfaceome following treatment with Aβ fibrils. The findings reveal that Aβ-associated human microglia upregulate Glypican 4 (GPC4), a GPI-anchored heparan sulfate proteoglycan (HSPG). In a Drosophila amyloidosis model, glial GPC4 expression exacerbates motor deficits and reduces lifespan, indicating that glial GPC4 contributes to a toxic cellular program during neurodegeneration. In cell culture, GPC4 enhances microglia phagocytosis of tau aggregates, and shed GPC4 can act in trans to facilitate tau aggregate uptake and seeding in neurons. Additionally, these data demonstrate that GPC4-mediated effects are amplified in the presence of APOE. These studies offer a mechanistic framework linking Aβ and tau pathology through microglial HSPGs and Apolipoprotein E (APOE).

Giblin, A., Cammack, A. J., Blomberg, N., Anoar, S., Mikheenko, A., Carcole, M., Atilano, M. L., Hull, A., Shen, D., Wei, X., Coneys, R., Zhou, L., Mohammed, Y., Olivier-Jimenez, D., Wang, L. Y., Kinghorn, K. J., Niccoli, T., Coyne, A. N., van der Kant, R., Lashley, T., Giera, M., Partridge, L., Isaacs, A. M. (2025). Neuronal polyunsaturated fatty acids are protective in ALS/FTD Nat Neurosci, 28(4):737-747 PubMed ID: 40000803
Summary:
This study reports a conserved transcriptomic signature of reduced fatty acid and lipid metabolism gene expression in a Drosophila model of C9orf72 repeat expansion, the most common genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), and in human postmortem ALS spinal cord. Lipidomics was performed on C9 ALS/FTD Drosophila, induced pluripotent stem (iPS) cell neurons and postmortem FTD brain tissue. This revealed a common and specific reduction in phospholipid species containing polyunsaturated fatty acids (PUFAs). Feeding C9 ALS/FTD flies PUFAs yielded a modest increase in survival. However, increasing PUFA levels specifically in neurons of C9 ALS/FTD flies, by overexpressing fatty acid desaturase enzymes, led to a substantial extension of lifespan. Neuronal overexpression of fatty acid desaturases also suppressed stressor-induced neuronal death in iPS cell neurons of patients with both C9 and TDP-43 ALS/FTD. These data implicate neuronal fatty acid saturation in the pathogenesis of ALS/FTD and suggest that interventions to increase neuronal PUFA levels may be beneficial.

Friday May 8th - Cytoskeleton

Kahawatte, S., Macke, A. C., St Clair, C., Dima, R. I. (2025). A Major Disease-Related Point Mutation in Spastin Dramatically Alters the Dynamics and Allostery of the Motor. J Biochemistry, 64(6):1293-1307 PubMed ID: 40009545
Summary:
Spastin is a microtubule-severing AAA+ ATPase that is highly expressed in neuronal cells and plays a crucial role in axonal growth, branching, and regeneration. This machine oligomerizes into hexamers in the presence of ATP and microtubule carboxy-terminal tails (CTTs). Conformational changes in Spastin hexamers, powered by ATP hydrolysis, apply forces to the microtubule, ultimately leading to the severing of the filament. Mutations disrupt the normal function of spastin, impairing its ability to sever microtubules effectively and leading to abnormal microtubule dynamics in neurons characteristic of the set of neurodegenerative disorders called hereditary spastic paraplegias (HSP). Experimental studies have identified the HSP-related R591S (a key Hereditary Spastic Paraplegia (HSP)-related mutation that severely impairs the protein's ability to sever microtubules) mutation as playing a crucial role in Spastin. Given its significant role in HSP, this study employed a combination of molecular dynamics simulations with machine learning and graph network-based approaches to identify and quantify the perturbations caused by the R591S HSP mutation on Spastin's dynamics and allostery with functional implications. The functional hexamer, upon HSP-related mutation, loses the ability to execute the primary motion associated with the severing action. The study of allosteric changes upon the mutation showed that the regions that are most perturbed are those involved in the formation of the interprotomer contacts. The mutation induces rigidity in the allosteric networks of the motor, making it more likely to experience loss of function as applied perturbations would not be easily dissipated by passing through a variety of alternative paths as in the wild-type (WT) Spastin.

Verma, D., Sarkar, B., Singh, J., Singh, A., Mutsuddi, M., Mukherjee, A. (2025). Loss of non-muscle myosin II Zipper leads to apoptosis-induced compensatory proliferation in Drosophila Biochim Biophys Acta Mol Cell Res, 1872(5):119939 PubMed ID: 40157509
Summary:
Drosophila Non-muscle myosin II Zipper (Zip) belongs to a functionally divergent class of molecular motors that play a vital role in various cellular processes including cell adhesion, cell migration, cell protrusion, and maintenance of polarity via its cross-linking property with actin. To further determine its role in cell proliferation and apoptosis, Zip loss of function studies were carried out that led to compromised epithelial integrity in Drosophila wing imaginal discs as evident from the perturbed expression pattern of cell-cell junction proteins Cadherin, Actin, and Armadillo. Disruption of these adhesion proteins resulted in the cells undergoing apoptosis as evident from the increased level of effector caspase, cDcp-1. The induction of cell death due to the loss of function of Zip was accompanied by proliferation as apparent from increased PH3 staining. The control of apoptosis-induced compensatory proliferation lies under the caspase cascade. Experiments were carried out that suggested that the apical caspase Dronc is responsible for the apoptosis-induced compensatory proliferation due to the loss of Zip function and not the effector caspase Drice/Dcp-1. Further, it was observed that Dronc leads to the subsequent activation of Jun N-terminal kinase pathway (JNK) pathway and Wingless (Wg) mitogen that diffuse to the neighboring cells and prompt them to undergo cell division. Taken together, these results suggest that loss of function of Zip leads to apoptosis-induced compensatory proliferation.

Quiniou, M., Burns, M. C., McDermott, A., Jaworek, K., Scott, S. J., Wakefield, J. G., Borgal, L. (2025). The PP2A-B56 Binding Site LxxIxE Contributes to Asp-Mediated Spindle Pole Stability Cytoskeleton (Hoboken), PubMed ID: 40072232
Summary:
The organization of microtubules into a mitotic spindle is critical for animal cell proliferation and involves the cooperation of hundreds of proteins whose molecular roles and regulation are not fully understood. The protein product of the Drosophila gene abnormal spindle, Asp, is a microtubule-associated protein required for correct mitotic spindle formation. To better understand the contribution of Asp to microtubule organization during spindle formation, flies were reverse-engineered to express a version of Asp (Asp^LIE), predicted to have lost its ability to bind the phosphatase trimer PP2A-B56. The Asp^LIE mutation reduced an interaction with the Drosophila PP2A-B56 regulatory subunit Widerborst (Wdb), as well as other proteins with known roles in spindle formation. Asp^LIE flies exhibited less robust microtubule minus-end cohesion at neural stem cell spindle poles, which was accompanied by a substantial developmental delay but no microcephaly. Predictive structural modeling suggests that the presence of Wdb alters the conformation of an Asp interaction with a tubulin dimer in a manner similar to that of the Asp^LIE mutation. Protein localization in the Drosophila embryo, in addition to in vitro microtubule organization experiments, suggests that a role of PP2A may be to prevent Asp from contributing to microtubule cross-linking at spindle microtubule plus ends. Together, these findings add new insights to mechanisms underlying microtubule organization within the mitotic spindle.

Pissarek, H., Huang, N., Frasch, L. H., Aberle, H., Frasch, M. (2025). Formin 3 stabilizes the cytoskeleton of Drosophila tendon cells, thus enabling them to resist muscle tensile forces. J Cell Sci, 138(7) PubMed ID: 40084430
Summary:
The cytoskeleton of Drosophila tendon cells features specialized F-actin and microtubule arrays that endow these cells with resistance to the tensile forces exerted by the attached muscles. In a forward genetic screen for mutants with neuromuscular junction and muscle morphology phenotypes in larvae, this study identified formin 3 (form3) as a crucial component for stabilizing these cytoskeletal arrays under muscle tension. form3 mutants exhibit severely stretched tendon cells in contact with directly attached larval body wall muscles, leading to muscle retraction and rounding. Both the actomyosin and microtubule arrays are expanded likewise in these mutants and can separate laterally in extreme cases. Analysis of a natively HA-tagged, functional version of Form3 reveals that Form3 is distributed along the length of these cytoskeletal arrays. Based on thesa findings and existing data on vertebrate and Caenorhabditis elegans orthologs of form3, it is proposed that the primary function of Form3 in this context is to co-bundle actin filaments and microtubules, thus maximizing the rigidity of these cytoskeletal structures against muscle tensile forces.

Brunet, M., Thomas, J., Lapart, J. A., Kruttli, L., Laporte, M. H., Riparbelli, M. G., Callaini, G., Durand, B., Morel, V. (2025). Drosophila Alms1 proteins regulate centriolar cartwheel assembly by enabling Plk4-Ana2 amplification loop. Embo j, 44(8):2366-2395 PubMed ID: 40021845
Summary:
Centrioles play a central role in cell division by recruiting pericentriolar material (PCM) to form the centrosome. Alterations in centriole number or function lead to various diseases including cancer or microcephaly. Centriole duplication is a highly conserved mechanism in eukaryotes. The two Drosophila orthologs of the Alstrom syndrome protein 1 (Alms1a and Alms1b) are unexpected novel players of centriole duplication in fly. Using Ultrastructure Expansion Microscopy, this study revealed that Alms1a is a PCM protein that is loaded proximally on centrioles at the onset of procentriole formation, whereas Alms1b caps the base of mature centrioles. Chronic loss of Alms1 proteins (with RNA null alleles) affects PCM maturation, whereas their acute loss (in RNAi KD) completely disrupts procentriole formation before Sas-6 cartwheel assembly. Alms1 proteins are required for the amplification of the Plk4-Ana2 pool at the duplication site and the subsequent Sas-6 recruitment. Thus, Alms1 proteins are novel critical but highly buffered regulators of PCM and cartwheel assembly in flies.

Tootle, T. L. (2025). Prostaglandins limit nuclear actin rod formation during Drosophila oogenesis MicroPubl Biol, 2025 PubMed ID: 40255252
Summary:
Expression of GFP-Actin results in nuclear actin rod formation during specific stages of Drosophila melanogaster oogenesis. Loss of prostaglandin (PG) synthesis and signaling results in an increased frequency of cells with nuclear actin rods; there are less rods per cell, but the rods are longer. These findings suggest that loss of PGs results in increased nuclear actin and are consistent with prior findings assessing the roles of PGs in modulating endogenous nuclear actin. Thus, GFP-Actin rod formation can be used as a tool to screen for new regulators of nuclear actin.

Monday May 4th - Enhancers and Transcriptinal Regulations

Dunipace, L., McGehee, J. M., Irizarry, J., Stathopoulos, A. (2025). The proximal enhancer of the snail gene mediates negative autoregulatory feedback in Drosophila melanogaster. Genetics, 230(2) PubMed ID: 40147870
Summary:
Autoregulatory feedback is a mechanism in which a gene product regulates its own expression, stabilizing gene activity amid noise and environmental changes. In Drosophila melanogaster, the gene snail encodes a key transcriptional repressor that regulates the expression of many genes during early embryogenesis, including its own expression. This study focuses on Snail occupancy at both distal and proximal enhancers of the snail gene to understand the cis-regulatory mechanisms involved in autoregulatory control. The coordinated action of these enhancers results in precisely constrained levels of snail expression during early embryogenesis. Using genome editing by CRISPR/Cas9, this study found that deletion of each enhancer individually is compatible with embryonic viability under normal conditions. However, the double mutant is lethal, suggesting a functional interplay between the 2 enhancers. To gain further insight, snail gene expression levels were assayed in fixed embryos. The results revealed that negative autoregulation of snail relies on the proximal enhancer. Moreover, increasing the affinity of binding sites for Dorsal, a transcriptional activator, in the proximal enhancer impaired this autoregulation, suggesting that Snail acts locally to counterbalance Dorsal's input. A mathematical model of snail autoregulatory control further supports our findings, reinforcing the view that the proximal enhancer mediates negative autoregulatory feedback, and implicating the distal enhancer in positive autoregulatory feedback. In summary, Snail's role at the proximal enhancer is pivotal for negative autoregulatory control and essential for balancing the activation mediated by the distal enhancer.

Osadchiy, I., Umnova, A., Pokholkova, G. V., Golovnin, A., Gvozdev, V. A., Zhimulev, I. F., Georgiev, P., Maksimenko, O. (2025). Drosophila architectural proteins M1BP and Opbp cooperatively form the active promoter of a ribosomal protein gene. Epigenetics Chromatin, 18(1):20 PubMed ID: 40241195
Summary:
In Drosophila, architectural proteins are frequently found in promoters, including those of genes with extremely high expression levels, such as ribosomal protein genes (RPGs). The involvement of several of these proteins in gene regulation in Drosophila has been shown, but the exact mechanisms of their possible cooperative action have not been fully elucidated. This study dissected the contribution of the architectural proteins Opbp and Mibp, which are co-localized at several RPG promoters near the transcription start site, to promoter functioning. Opbp was found to have two domains that directly interact with CP190, Putzig (Pzg), and Chromator (Chro) proteins, the cofactors which are required for the activation of housekeeping (hk) gene promoters. These domains have redundant functions in vivo and can tether the cofactors forming open chromatin regions when are artificially recruited to the "closed" chromatin. Additionally, interactions were observed between and the same cofactors. In the transgene assay, the transcription driven by the 192-bp part of Rpl27A RPG promoter is fully dependent on the presence of at least one Opbp or M1BP binding site and it is sufficient for the very high activity of this promoter integrated into the hk gene cluster and moderate expression outside the cluster, while presence of both sites even more facilitates transcription. This study demonstrates that different architectural proteins can work independently and in cooperation and fulfill partially redundant functions in the activation of RPG promoters.

Fujioka, M., Ke, W., Schedl, P., Jaynes, J. B. (2025). The homie insulator has sub-elements with different insulating and long-range pairing properties Genetics, 229(4) PubMed ID: 39999387
Summary:
Chromatin insulators are major determinants of chromosome architecture. Specific architectures induced by insulators profoundly influence nuclear processes, including how enhancers and promoters interact over long distances and between homologous chromosomes. Insulators can pair with copies of themselves in trans to facilitate homolog pairing. They can also pair with other insulators, sometimes with great specificity, inducing long-range chromosomal loops. Contrary to their canonical function of enhancer blocking, these loops can bring distant enhancers and promoters together to activate gene expression, while at the same time blocking other interactions in cis. The details of these effects depend on the choice of pairing partner, and on the orientation specificity of pairing, implicating the 3D architecture as a major functional determinant. This study dissected the homie insulator from the Drosophila even skipped (eve) locus, to understand its substructure. Pairing function was tested based on homie-carrying transgenes interacting with endogenous eve. The assay is sensitive to both pairing strength and orientation. Using this assay, a Su(Hw) binding site in homie were found to be required for efficient long-range interaction, although some activity remains without it. This binding site also contributes to the canonical insulator activities of enhancer blocking and barrier function. Based on this and other results from this functional dissection, each of the canonical insulator activities, chromosomal loop formation, enhancer blocking, and barrier activity, are partially separable. These results show the complexity inherent in insulator functions, which can be provided by an array of different proteins with both shared and distinct properties.

Cardamone, F., Piva, A., Loser, E., Eichenberger, B., Romero-Mulero, M. C., Zenk, F., Shields, E. J., Cabezas-Wallscheid, N., Bonasio, R., Tiana, G., Zhan, Y., Iovino, N. (2025). Chromatin landscape at cis-regulatory elements orchestrates cell fate decisions in early embryogenesis Nat Commun, 16(1):3007 PubMed ID: 40148291
Summary:
The establishment of germ layers during early development is crucial for body formation. The Drosophila zygote serves as a model for investigating these transitions in relation to the chromatin landscape. However, the cellular heterogeneity of the blastoderm embryo poses a challenge for gaining mechanistic insights. Using 10× Multiome, the in vivo epigenomic and transcriptomic states were simultaneously analyzed of wild-type, E(z)-, and CBP-depleted embryos during zygotic genome activation at single-cell resolution. Pre-zygotic H3K27me3 was found to safeguard tissue-specific gene expression by modulating cis-regulatory elements. Furthermore, CBP was demonstrated to be essential for cell fate specification functioning as a transcriptional activator by stabilizing transcriptional factors binding at key developmental genes. Surprisingly, while CBP depletion leads to transcriptional arrest, chromatin accessibility continues to progress independently through the retention of stalled RNA Polymerase II. This study reveals fundamental principles of chromatin-mediated gene regulation essential for establishing and maintaining cellular identities during early embryogenesis.

Sipani, R., Rawal, Y., Barman, J., Abburi, P., Kurlawala, V., Joshi, R. (2025). Drosophila grainyhead gene and its neural stem cell specific enhancers show epigenetic synchrony in the cells of the central nervous system. Dev Biol, 522:227-239 PubMed ID: 40154783
Summary:
Enhancers are the epicentres of tissue-specific gene regulation. In this study used the central nervous system (CNS) specific expression of the Drosophila grainyhead (grh) gene to make a case for deleting the enhancers in a sensitised background of other enhancer deletion, to functionally validate their role in tissue-specific gene regulation. Novel enhancers for grh were identified and subsequently two of them were delete to establish their collective importance in regulating grh expression in CNS. This showed that grh relies on multiple enhancers for its robust expression in neural stem cells (NSCs), with different combinations of enhancers playing a critical role in regulating its expression in various subset of these cells. These enhancers and the grh gene show epigenetic synchrony across the three cell types (NSCs, intermediate progenitors and neurons) of the developing CNS; and grh is not transcribed in intermediate progenitor cells, which inherits the Grh protein from the NSCs. This could be a general mechanism for regulating the expression of cell fate determinant protein in intermediate progenitor cells. Lastly, the results underline that enhancer redundancy results in phenotypic robustness in grh gene expression, which seems to be a consequence of the cumulative activity of multiple enhancers.

Sigalova, O. M., Forneris, M., Stojanovska, F., Zhao, B., Viales, R. R., Rabinowitz, A., Hammal, F., Ballester, B., Zaugg, J. B., Furlong, E. E. M. (2025). Integrating genetic variation with deep learning provides context for variants impacting transcription factor binding during embryogenesis. Genome Res, 35(5):1138-1153 PubMed ID: 40234030
Summary:
Understanding how genetic variation impacts transcription factor (TF) binding remains a major challenge, limiting the ability to model disease-associated variants. This study used a highly controlled system of F(1) crosses with extensive genetic diversity to profile allele-specific binding of four TFs at several time points during Drosophila embryogenesis. Using a combined haplotype test, this study identified 9%-18% of TF-bound regions impacted by genetic variation even for essential regulators. By expanding WASP (a tool for allele-specific read mapping) to examine indels, detection of allelically imbalanced peaks was increased by 30%-50%. This fine-grained "mutagenesis" can reconstruct functionalized binding motifs for all factors. To prioritize causal variants, a convolutional neural network (Basenji) was trained to accurately predict binding from DNA sequence. The model can also predict measured allelic imbalance for strong effect variants, providing a mechanistic interpretation for how the variant impacts binding. This reveals unexpected relationships between TFs, including potential cooperative pairs, and mechanisms of tissue-specific recruitment of the ubiquitous factor CTCF.

Friday, May 1st - Larval and Adult Neural Development, Structure, and Function

Nern, A., Loesche, F., Takemura, S. Y., Burnett, L. E., Dreher, M., Gruntman, E., Hoeller, J., Huang, G. B., Januszewski, M., ...., Knecht, C., Korff, W., Plaza, S. M., Romani, S., Saalfeld, S., Scheffer, L. K., Berg, S., Rubin, G. M., Reiser, M. B. (2025). Connectome-driven neural inventory of a complete visual system. Nature, 641(8065):1225-1237 PubMed ID: 40140576
Summary:
Vision provides animals with detailed information about their surroundings and conveys diverse features such as colour, form and movement across the visual scene. Computing these parallel spatial features requires a large and diverse network of neurons. Consequently, from flies to humans, visual regions in the brain constitute half its volume. These visual regions often have marked structure-function relationships, with neurons organized along spatial maps and with shapes that directly relate to their roles in visual processing. More than a century of anatomical studies have catalogued in detail cell types in fly visual systems, and parallel behavioural and physiological experiments have examined the visual capabilities of flies. To unravel the diversity of a complex visual system, careful mapping of the neural architecture matched to tools for targeted exploration of this circuitry is essential. This study presents a connectome of the right optic lobe from a male Drosophila melanogaster acquired using focused ion beam milling and scanning electron microscopy. A comprehensive inventory was esStablished of the visual neurons and developed a computational framework to quantify their anatomy. Together, these data establish a basis for interpreting how the shapes of visual neurons relate to spatial vision. By integrating this analysis with connectivity information, neurotransmitter identity and expert curation, the approximately 53,000 neurons were classified into 732 types. These types are systematically described and about half are newly named. Finally, an extensive collection of split-GAL4 lines matched to the neuron-type catalogue. Overall, this comprehensive set of tools and data unlocks new possibilities for systematic investigations of vision in Drosophila and provides a foundation for a deeper understanding of sensory processing.

Manoim-Wolkovitz, J. E., Camchy, T., Rozenfeld, E., Chang, H. H., Lerner, H., Chou, Y. H., Darshan, R., Parnas, M. (2025). Nonlinear high-activity neuronal excitation enhances odor discrimination. Curr Biol, 35(7):1521-1538.e1525 PubMed ID: 40107267
Summary:
Discrimination between different signals is crucial for animals' survival. Inhibition that suppresses weak neural activity is crucial for pattern decorrelation. Understanding of alternative mechanics that allow efficient signal classification remains incomplete.This study shows that Drosophila olfactory receptor neurons (ORNs) have numerous intraglomerular axo-axonal connections mediated by the G protein-coupled receptor (GPCR), muscarinic type B receptor (mAChR-B). Contrary to its usual inhibitory role, mAChR-B participates in ORN excitation. The excitatory effect of mAChR-B only occurs at high ORN firing rates. A computational model demonstrates that nonlinear intraglomerular or global excitation decorrelates the activity patterns of ORNs of different types and improves odor classification and discrimination, while acting in concert with the previously known inhibition. Indeed, knocking down mAChR-B led to increased correlation in odor-induced ORN activity, which was associated with impaired odor discrimination, as shown in behavioral experiments. Furthermore, knockdown (KD) of mAChR-B and the GABAergic GPCR, GABAB-R, has an additive behavioral effect, causing reduced odor discrimination relative to single-KD flies. Together, this study unravels a novel mechanism for neuronal pattern decorrelation, which is based on nonlinear intraglomerular excitation.

Zang, Y., Yoshimoto, M., Igaki, T. (2025). Programmed cell senescence is required for sensory organ development in Drosophila. iScience, 28(3):112048 PubMed ID: 40124515
Summary:
Cellular senescence is an irreversible cell-cycle arrest often associated with cancer and aging, yet its physiological role remains elusive. This study showed developmentally programmed cellular senescence occurs in Drosophila imaginal epithelium. In developing wing discs, two clusters of cells exhibit hallmarks of cellular senescence such as elevated senescence-associated β-galactosidase activity, cell-cycle arrest, heterochromatinization, upregulation of a cyclin-dependent kinase (CDK) inhibitor Dacapo, cellular hypertrophy, Ras signaling activation, and upregulation of an inflammatory cytokine unpaired3, a possible component of the senescence-associated secretory phenotype. Blocking programmed cell senescence by inhibiting Ras signaling or its downstream transcription factor Pointed (Pnt) results in loss of sensory organ campaniform sensilla. Ras-Pnt signaling causes programmed cell senescence through a transcription factor Zfh2, thereby contributing to campaniform sensilla formation via the achaete-scute complex. Our observations uncover the evolutionary conservation of programmed cell senescence in invertebrates, which is required for the induction of the proper number of sensory organs.

Olguin, A. G. R., Rochon, P. L., Theriault, C., Brown, T., Yao, H., Cayouette, M., Cook, E. P., Krishnaswamy, A. (2025). Cadherin 4 assembles a family of color-preferring retinal circuits that respond to light offset. Curr Biol, 35(6):1298-1310.e1297 PubMed ID: 40081378
Summary:
Retinal interneurons and projection neurons (retinal ganglion cells, RGCs) connect in specific combinations in a specialized neuropil called the inner plexiform layer (IPL). The IPL is divided into multiple sublaminae, with neurites of each neuronal type confined to one or a few layers. This laminar specificity is a major determinant of circuit specificity and circuit function. Using a combination of approaches, this study showed that RGCs targeting IPL sublaminae 1 and 3a (s1-s3a) express the cell adhesion molecule cadherin 4 (Cdh4). Using calcium imaging and iterative immunostaining, Cdh4 RGCs were classified into nine types that each encode unique aspects of dark visual stimuli. Cdh4 loss selectively disrupted the layer targeting of these RGCs, reduced their synaptic inputs from interneurons, and severely altered their visual responses. Overexpression of Cdh4 in other retinal neurons directed their neurites to s1-s3a through homophilic interactions. Taken together, these results demonstrate that Cdh4 is a novel layer-targeting system for nearly a quarter of all RGCs.

Casas-Tinto, S., Garcia-Guillen, N., Losada-Perez, M. (2025). Adult neurogenesis through glial transdifferentiation in a CNS injury paradigm. Elife, 13 PubMed ID: 40052673
Summary:
As the global population ages, the prevalence of neurodegenerative disorders is fast increasing. This neurodegeneration as well as other central nervous system (CNS) injuries cause permanent disabilities. Thus, generation of new neurons is the rosetta stone in contemporary neuroscience. Glial cells support CNS homeostasis through evolutionary conserved mechanisms. Upon damage, adult glial cells activate an immune and inflammatory response to clear the injury site from debris and proliferate to restore cell number. This glial regenerative response (GRR) is mediated by the neuropil-associated glia (NG) in Drosophila, equivalent to vertebrate astrocytes, oligodendrocytes (OL), and oligodendrocyte progenitor cells (OPCs). This study examined the contribution of NG lineages and the GRR in response to injury. The results indicate that NG exchanges identities between ensheathing glia (EG) and astrocyte-like glia (ALG). Additionally, NG cells were found to undergo transdifferentiation to yield neurons. Moreover, this transdifferentiation increases in injury conditions. Thus, these data demonstrate that glial cells are able to generate new neurons through direct transdifferentiation. The present work makes a fundamental contribution to the CNS regeneration field and describes a new physiological mechanism to generate new neurons.

Choy, J., Charara, S., Cauwenberghs, K., McKaughan, Q., Kim, K. Y., Ellisman, M. H., Su, C. Y. (2025). Population-level morphological analysis of paired CO (2) - and odor-sensing olfactory neurons in D. melanogaster via volume electron microscopy bioRxiv, PubMed ID: 39974999
Summary:
Dendritic morphology is a defining characteristic of neuronal subtypes. In Drosophila , heterotypic olfactory receptor neurons (ORNs) expressing different receptors display diverse dendritic morphologies, but whether such diversity exists among homotypic ORNs remains unclear. Using serial block-face scanning electron microscopy on cryofixed tissues, this study analyzed the majority of CO (2) -sensing neurons (ab1C) and their odor-sensing neighbors (ab1D) in the D. melanogaster antenna. Surprisingly, ab1C neurons featured flattened, sheet-like dendrites-distinct from the cylindrical branches typical of odor-sensing neurons-and displayed remarkable diversity, ranging from plain sheets to tube-like structures that enclose several neighboring dendrites, forming "dendrite-within-dendrite" structures. Similarly, ab1D dendrites varied from simple, unbranched forms to numerously branched morphologies. These findings suggest that morphological heterogeneity is common even among homotypic ORNs, potentially expanding their functional adaptability and ranges of sensory physiological properties.

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