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July 2025
June2025 May 2025 April 2025 March 2025 February 2025 January 2025 December 2024 November 2024 October 2024 September 2024 August 2024 July 2024 June 2024 May 2024 April 2024 March 2024 February 2024 January 2024 December 2023 November 2023 October 2023 September 2023 August 2023 July 2023 June 2023 December 2022 December 2021 December 2020 December 2019 December 2018 | Kina, H., Izumi, N., Hanyu-Nakamura, K., Yoshitani, T., Yamane, M., Niwa, H., Tomari, Y., Nakamura, A. (2025). Abundant piRNA production mediated by the Drosophila GTSF1 homolog Tpp ensures Aubergine localization and germ plasm assembly.. Proc Natl Acad Sci U S A, 122(24):e2419375122 PubMed ID: 40493187
Summary: Germ cells transmit genetic information to offspring and maintain the genome of the species. In many animals including Drosophila, germ cell formation relies on maternal determinants in the germ plasm. Several proteins present in the germ plasm of oocytes also localize to the perinuclear nuage in nurse cells, where they contribute to the production of PIWI-interacting RNAs (piRNAs). These piRNAs guide the silencing of transposons, thereby protecting the germline genome from invading mobile elements. Aubergine (Aub) is a germ plasm/nuage protein and a piRNA-directed endonuclease that inactivates transposons. Aub is also essential for germ plasm assembly. The Aub-bound piRNAs in the germ plasm are inherited by the progeny germline and serve as templates for piRNA biogenesis in the next generation. Thus, piRNA production in the nurse cell nuage is thought to be coordinated with germ plasm assembly in the oocyte. However, the underlying mechanism remains unclear. This study reports that a maternal factor, named tiny pole plasm (tpp), mediates this coordination. Tpp (Asterix) is a GTSF1 family PIWI cofactor. In tpp- ovaries, the production of piRNAs, particularly Aub-bound piRNAs, is defective, resulting in reduced Aub localization to the germ plasm and impaired germ cell formation. Notably, the levels of piRNA production required for proper Aub localization are much higher than those required for transposon silencing. It is proposed that producing abundant piRNAs beyond what is required for transposon silencing in the ovary promotes germ plasm assembly, thereby enabling the progeny germline to properly silence transposons for species survival. | Akkouche, A., Kneuss, E., Bornelov, S., Renaud, Y., Eastwood, E. L., van Lopik, J., Gueguen, N., Jiang, M., Creixell, P., Maupetit-Mehouas, S., Sobieszek, A., Gui, Y., Czech Nicholson, B., Brasset, E., Hannon, G. J. (2025). Binding of heterochromatin protein Rhino to a subset of piRNA clusters depends on a combination of two histone marks. Nat Struct Mol Biol, PubMed ID: 40527990
Summary: Animal germ cells deploy a specialized small RNA-based silencing system, called the PIWI-interacting RNA (piRNA) pathway, to prevent unwanted expression of transposable elements (TEs) and maintain genome integrity. In Drosophila melanogaster germ cells, the majority of piRNA populations originate from dual-strand piRNA clusters, genomic regions highly enriched in TE fragments, via an elaborate machinery centered on the Heterochromatin Protein 1 homolog, Rhino. Although Rhino binds to peptides carrying tri-methylated H3K9 in vitro, it is not fully understood why in vivo only a fraction of H3K9me3-decorated heterochromatin is occupied by Rhino. Recent work revealed that Rhino is recruited to a subset of piRNA clusters by Kipferl. This study identif a Kipferl-independent mode of Rhino recruitment that, in addition to the previously established role of H3K9me3, also depends on the histone H3 lysine 27 methyltransferase Enhancer of Zeste. At Kipferl-independent sites, Rhino specifically binds to loci marked by both H3K9me3 and H3K27me3 via its chromodomain. Although the exact mechanism of how Rhino binding is influenced by dual histone modifications remains unclear from a structural and biochemical perspective, this work suggests that combinatorial modifications may regulate the specificity of chromatin-binding protein interactions. These findings provide an enhanced understanding of how Rhino targets piRNA source loci, highlighting the sophisticated epigenetic landscape governing TE silencing in Drosophila germ cells. |
| Ascencio, G., Galvan, L., Sanchez, J. M., Nagainis, A., Tam, C., Goins, L. M., Riggs, B. (2025). miR-190 is a Key Regulator in Establishing Cell Polarity and Specification in the Drosophila Nervous System. bioRxiv, PubMed ID: 40501908
Summary: Asymmetric cell division generates cellular diversity in developing tissues, particularly in the CNS. In Drosophila neuroblasts, this process relies on polarity complexes and fate determinants, yet its molecular regulation remains unclear. This study identified miRNA-190 as a key regulator of neuroblast polarity and differentiation. Single-cell RNA sequencing and transcriptome analysis reveal that miR-190 deficiency disrupts CNS cell populations, reducing neurons while increasing neural progenitors and glia. Mechanistically, miR-190 is required for proper localization of the Par complex and basal determinants during mitosis. In miR-190 mutants, these factors mislocalize, leading to defective polarity and fate specification in embryonic neuroblast. qPCR analysis shows that miR-190 targets RhoGAP, which modulates Cdc42 activation and Par-6, crucial factors in neuroblast polarity. We propose a model in which miR-190 ensures proper Cdc42 activation and polarity establishment by targeting transcripts for degradation. miR-190 has been implicated in various cancers, and these findings provide a mechanistic framework for understanding the miR-190 roles in tumorigenesis and its broader involvement in metabolic diseases. | Rivera, A., Lee, J. R., Gupta, S., Yang, L., Goel, R. K., Zaia, J., Lau, N. C. (2024). Traffic Jam activates the Flamenco piRNA cluster locus and the Piwi pathway to ensure transposon silencing and Drosophila fertility. bioRxiv, PubMed iD: 39211177
Summary: Flamenco (Flam) is the most prominent piRNA cluster locus expressed in Drosophila ovarian follicle cells, and it is required for female fertility to silence gypsy/mdg4 transposons. To determine how Flam is regulated, promoter-bashing reporter assays were used in OSS cells to uncover novel enhancer sequences within the first exons of Flam . The enhancer sequence relevance was confirmed in vivo with new Drosophila Flam deletion mutants of these regions that compromised Flam piRNA expression and lowered female fertility from activated transposons. Proteomic analysis of proteins associated with these enhancer sequences discovered the transcription factor Traffic Jam (TJ). Tj knockdowns in OSS cells caused a decrease in Flam transcripts, FlampiRNAs, and multiple Piwi pathway genes. A TJ ChiP-seq analysis from whole flies and OSS cells confirmed TJ binding exactly at the enhancer that was deleted in the new Flam mutant as well as at multiple Piwi pathway gene enhancers. interestingly, TJ also bound the Long Terminal Repeats of transposons that had decreased expression after Tj knockdowns in OSS cells. This study reveals the integral role TJ plays in the on-going arms race between selfish transposons and their suppression by the host Piwi pathway and the Flam piRNA cluster locus. |
| Zak, H., Rozenfeld, E., Levi, M., Deng, P., Gorelick, D., Pozeilov, H., Israel, S., Paas, Y., Paas, Y., Li, J. B., Parnas, M., Shohat-Ophir, G. (2024). A highly conserved A-to-I RNA editing event within the glutamate-gated chloride channel GluClα is necessary for olfactory-based behaviors in Drosophila. Sci Adv, 10(36):eadi9101 PubMed ID: 39231215
Summary: A-to-I RNA editing is a cellular mechanism that generates transcriptomic and proteomic diversity, which is essential for neuronal and immune functions. It involves the conversion of specific adenosines in RNA molecules to inosines, which are recognized as guanosines by cellular machinery. Despite the vast number of editing sites observed across the animal kingdom, pinpointing critical sites and understanding their in vivo functions remains challenging.The function of an evolutionary conserved editing site in Drosophila, located in glutamate-gated chloride channel (GluClα). The findings reveal that flies lacking editing at this site exhibit reduced olfactory responses to odors and impaired pheromone-dependent social interactions. Moreover, this study demonstrated that editing of this site is crucial for the proper processing of olfactory information in projection neurons. These results highlight the value of using evolutionary conservation as a criterion for identifying editing events with potential functional significance and paves the way for elucidating the intricate link between RNA modification, neuronal physiology, and behavior. | Alfonso-Gonzalez, C., Shi, M., Gorey, S., Holec, S., Carrasco, J., Rauer, M., Tsagkris, S., Mateos, F., Hilgers, V. (2025). ELAV mediates circular RNA biogenesis in neurons. Genes Dev, PubMed ID: 40490354
Summary: Circular RNAs (circRNAs) arise from back-splicing of precursor RNAs and accumulate in the nervous systems of animals, where they are thought to regulate gene expression and synaptic function. HThis study showed that neuronal circRNA biosynthesis is mediated by the pan-neuronal RNA-binding protein ELAV. In Drosophila embryos, the circRNA landscape was characterized in normal and elav mutant neurons. Neuronal circRNAs are globally (>75%) depleted upon ELAV knockout, and induction of ELAV expression drives ectopic RNA circularization. In brain tissue, ELAV binds to pre-mRNA introns flanking putative circRNAs and decreases efficiency of linear splicing in favor of intron pairing at reverse complementary matches, inducing circularization. Together, our data demonstrate that ELAV directly modulates splicing decisions to generate the neuronal circRNA landscape. |
Tuesday August 26th - Chromatin |
| Bhatt, A. D., Brown, M. G., Wackford, A. B., Shindo, Y., Amodeo, A. A. (2024). Local nuclear to cytoplasmic ratio regulates chaperone-dependent H3 variant incorporation during zygotic genome activation. bioRxiv, PubMed ID: 39071352
Summary: Early embryos often have relatively unstructured chromatin that lacks active and inactive domains typical of differentiated cells. In many species, these regulatory domains are established during zygotic genome activation (ZGA). In Drosophila, ZGA occurs after 13 fast, reductive, syncytial nuclear divisions during which the nuclear to cytoplasmic (N/C) ratio grows exponentially. These divisions incorporate maternally-loaded, cytoplasmic pools of histones into chromatin. Previous work found that chromatin incorporation of replication-coupled histone A HREF="../polycomb/histh3-1.htm">H3 decreases while its variant H3.3 increases in the cell cycles leading up to ZGA. In other cell types, H3.3 is associated with sites of active transcription as well as heterochromatin, suggesting a link between H3.3 incorporation and ZGA. This study examine the factors that contribute to H3.3 incorporation at ZGA. A more rapid decrease in the nuclear availability was identified of H3 than H3.3 over the final pre-ZGA cycles. An N/C ratio-dependent increase was observed in H3.3 incorporation in mutant embryos with non-uniform local N/C ratios. Chaperone binding, not gene expression, controls incorporation patterns using H3/H3.3 chimeric proteins at the endogenous H3.3A locus. The specificity was tested of the H3.3 chaperone pathways for H3.3 incorporation using Hira (H3.3 chaperone) mutant embryos. Overall, a model in is proposed inwhich local N/C ratios and specific chaperone binding regulate differential incorporation of H3.3 during ZGA. | Crain, A. T., Nevil, M., Leatham-Jensen, M. P., Reeves, K. B., Matera, A. G., McKay, D. J., Duronio, R. J. (2024). Redesigning the Drosophila histone gene cluster: an improved genetic platform for spatiotemporal manipulation of histone function. Genetics, 228(1) PubMed ID: 39039029
Summary: Mutating replication-dependent (RD) histone genes is an important tool for understanding chromatin-based epigenetic regulation. Deploying this tool in metazoans is particularly challenging because RD histones in these organisms are typically encoded by many genes, often located at multiple loci. Such gene arrangements make the ability to generate homogenous histone mutant genotypes by site-specific gene editing quite difficult. Drosophila melanogaster provides a solution to this problem because the RD histone genes are organized into a single large tandem array that can be deleted and replaced with transgenes containing mutant histone genes. In the last ~15 years several different RD histone gene replacement platforms were developed using this simple strategy. However, each platform contains weaknesses that preclude full use of the powerful developmental genetic capabilities available to Drosophila researchers. This study describes the development of a newly engineered platform that rectifies many of these weaknesses. We used CRISPR to precisely delete the RD histone gene array (HisC), replacing it with a multifunctional cassette that permits site-specific insertion of either one or two synthetic gene arrays using selectable markers. This cassette was designed with the ability to selectively delete each of the integrated gene arrays in specific tissues using site-specific recombinases. This study also presents a method for rapidly synthesizing histone gene arrays of any genotype using Golden Gate cloning technologies. These improvements facilitate the generation of histone mutant cells in various tissues at different stages of Drosophila development and provide an opportunity to apply forward genetic strategies to interrogate chromatin structure and gene regulation. |
| Kassel, S., Yuan, K., Bunnag, N., ..., Robbins, D. J., Ahmed, Y., Lee, E. (2025). The TRIP12 E3 ligase induces SWI/SNF component BRG1-beta-catenin interaction to promote Wnt signaling. Nat Commun, 16(1):5248 PubMed ID: 40473626
Summary: SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes displace nucleosomes to promote the access of transcription factors to enhancers and promoters. Despite the critical roles of SWI/SNF in animal development and tumorigenesis, how signaling pathways recruit SWI/SNF complexes to their target genes is unclear. This study demonstrates that target gene activation mediated by β-catenin, the essential transcriptional coactivator in the Wnt signal transduction pathway, requires ubiquitylation of the human SWI/SNF component Brahma-related gene-1 (BRG1) by the E3 ubiquitin ligase Thyroid Hormone Receptor Interactor 12 (TRIP12). TRIP12 depletion in Drosophila, zebrafish, mouse organoids, and human cells attenuates Wnt signaling. Genetic epistasis experiments place TRIP12 activity downstream of the β-catenin destruction complex. TRIP12 interacts with and ubiquitylates BRG1, and BRG1 depletion blocks TRIP12-mediated Wnt pathway activation. TRIP12 promotes BRG1 binding to β-catenin in the presence of Wnt. These findings support a model in which TRIP12 ubiquitylates BRG1 in the presence of Wnt and promotes its interaction with β-catenin in the nucleus, in order to recruit SWI/SNF to Wnt target genes. These studies suggest a general mechanism by which cell signaling induces the interaction between BRG1 and pathway-specific transcription factors to recruit SWI/SNF complexes to their appropriate target genes. | Li, Y. R., Ling, L. B., Chao, A., Fugmann, S. D., Yang, S. Y. (2024). Transient chromatin decompaction at the start of D. melanogaster male embryonic germline development. Life science alliance, 7(10) PubMed ID: 38991729
Summary: Embryonic germ cells develop rapidly to establish the foundation for future developmental trajectories, and in this process, they make critical lineage choices including the configuration of their unique identity and a decision on sex. This study used single-cell genomics patterns for the entire embryonic germline in Drosophila melanogaster along with the somatic gonadal precursors after embryonic gonad coalescence to investigate molecular mechanisms involved in the setting up and regulation of the germline program. Profiling of the early germline chromatin landscape revealed sex- and stage-specific features. In the male germline immediately after zygotic activation, the chromatin structure underwent a brief remodeling phase during which nucleosome density was lower and deconcentrated from promoter regions. These findings echoed enrichment analysis results of genomics data in which top candidates were factors with the ability to mediate large-scale chromatin reorganization. Together, they point to the importance of chromatin regulation in the early germline and raise the possibility of a conserved epigenetic reprogramming-like process required for proper initiation of germline development. |
| Cyrus, S. S., Medina Giro, S., Lian, T., Allan, D. W., Gibson, W. T. (2025). Functional Analysis of Human EED Variants Using Drosophila. Genetics, PubMed ID: 40539649
Summary: The Polycomb Repressive Complex 2 is an epigenetic reader/writer that methylates histone H3K27. Rare germline partial loss of function (pLoF) variants in core members of the complex (EZH2, EED, SUZ12) cause overgrowth and intellectual disability syndromes, whereas somatic variants are implicated in cancer. However, up to 1% of the general population will have a rare variant in one of these genes, most of which would be classified as variants of uncertain significance (VUS). Towards screening these VUS for partial LoF alleles that may contribute to disease, this study reports functional assays in Drosophila to interrogate Embryonic Ectoderm Development (EED) missense variants. The amino acid change(s) of EED variants were mimicked into its Drosophila ortholog, esc, and their function was tested. Known likely benign variants functioned wildtype and known pathogenic variants were LoF. The utility of this calibrated assay was further tested as a scalable approach to assist clinical interpretation of human EED VUS. | Arroyo, O. M., Leatham-Jensen, M. P., McKay, D. J. (2025). An RNAi-based platform for spatiotemporal control of histone gene expression during animal development. Res Sq, PubMed ID: 40502799
Summary: Mutational analysis of histones provides an important means of studying the function of histone post-translational modifications (PTMs) in epigenetic gene regulation. However, several technical challenges have impeded direct tests of histone residue function in metazoans, including the massive abundance of histone gene products, multiple copies of histone genes in the genome, and the necessity of histones for cell viability. This study describes a new experimental approach in Drosophila for selective depletion of the replication-dependent histone H3.2. Using short hairpin RNA (shRNA) transgenes, effective depletion of endogenous H3.2 gene expression was demonstrated, causeing defects in cell proliferation and organ development. It was further shown that a histone replacement transgene, engineered to be insensitive to RNA interference (RNAi) fully rescues shRNA-mediated developmental defects. Last, it was demonstrated that this selective depletion platform recapitulates phenotypes caused by histone gene mutation. It is concluded that shRNA-mediated depletion of endogenous histone H3.2, coupled with histone replacement transgenes engineered to be insensitive to RNAi, is an effective experimental approach for studying the role of histone PTMs in animal development. |
Friday August 22nd - Behavior |
| Jung, N., Xia, C., Jang, Y. H., Kim, H. W., Chung, Y. D., Chon, T. S. (2025). Movement and Dispersion Parameters Characterizing the Group Behavior of Drosophila melanogaster in Micro-Areas of an Observation Arena.. Animals (Basel), 15(11) PubMed ID: 40508981
Summary: In the present study, groups of 10 adult males from wild-type strain Drosophila melanogaster Canton-S and corresponding mutant tab2(201Y) were continuously observed using automatic digitization. Data based on instantaneous movement and cumulated movement positions were obtained for micro-areas providing space for resources (food and moisture) and for activity (edge area and intermediate area [between edge and center-diffusion areas]) within the observation arena for 24 h. The results confirmed the natural tendency of local aggregation among individuals within the observation arena (14 cm × 14 cm) at a relatively low density of ten individuals. For Canton-S, temporal cooccurring patterns among different parameters were observed as time progressed, with two primary patterns identified in the resource supply areas: single peak and double peaks. The single peak was observed with maximum speed and I-index, indicating minimum degree of isolated individuals from groups, during the transition from the photoperiod to the scotoperiod, the amount of time the organism is in the dark. The double peaks occurred before (mid-to-late photoperiod) and after (end of scotoperiod) the single peak, co-occurring temporally with a number of parameters including duration rates, stop number (total occurrence of pauses), stop time (total duration of pauses), mean crowding (MC), and social space index (SSI), indicating local aggregations for feeding in accordance with maximum durations in resource supply areas. Temporally cooccurring trends in parameters were also found with the stop number and SSI in micro-areas associated with activity, indicating that short pauses were needed to keep balance between attraction and repulsion between nearby individuals. Overall, the measured parameters varied depending on the micro-area, light phase, and strain. In particular, behavioral differences were observed for tab2(201Y), including an increase in speed, especially in the areas related to activity during the scotoperiod. Between strains, behavioral differences in the measured parameters were observed less for tab2(201Y) than Canton-S. x | Du, C., Okuwa, S., Jia, L., Rozados Barreiro, M., Scott, S., Sotelo Fonseca, J. E., Mabuchi, Y., Appadoo, S., Garcia, L., Rohrbach, S., Koruk, S., Balkanli, E., Lin, J., Yapici, N., Jones, C. D., Volkan, P. C. (2025). Social experience alters behaviors by reprogramming the Fruitless pathway and circadian state in Drosophila. bioRxiv, PubMed ID: 40502197
Summary: Animals thrive with social interactions and suffer significant adverse mental and physical health consequences when isolated. From flies to humans, social experience affects various cognitive and behavioral processes. This study used fruit flies to show that group housing suppresses male courtship vigor as a result of a decrease in the evoked neural responses in courtship circuits. Bulk tissue RNAseq and single-cell RNAseq from fru - and dsx -positive cells from grouped or isolated male brains revealed that social isolation increases the number of fru- and dsx -positive neurons, elevates fru transcript levels in specific clock neurons, and dsx transcript levels throughout the brain. Knocking down fruM) in the fru -positive neurons in brains decreases courtship in isolated males to levels comparable to those of group-housed males. Furthermore, group housing increases the expression of sr and Hr38 genes encoding neural activity-induced transcription factors in most neurons within social circuits. Knocking down sr in fru positive neurons effectively eliminates the impact of social experience by increasing courtship in group-housed males. Importantly, social experience also alters the expression of Fru (M) /Dsx (M) target genes regulating circadian states throughout the brain. Disrupting circadian gene function also diminishes the effect of group housing on courtship. These findings suggest that group housing/social enrichment suppress courtship by reprogramming the circadian arousal state, whereas courtship-elevating effects of social isolation rely on changes in Fru (M) expression and function. These results are significant as they point to modulation of circadian arousal state as a possible central strategy for mediating the pleiotropic effects of social experience on organismal responses. |
| Pratt, B. G., Lee, S. J., Chou, G. M., Tuthill, J. C. (2024). Miniature linear and split-belt treadmills reveal mechanisms of adaptive motor control in walking Drosophila. Curr Biol, PubMed ID: 39216486
Summary: To navigate complex environments, walking animals must detect and overcome unexpected perturbations. One technical challenge when investigating adaptive locomotion is measuring behavioral responses to precise perturbations during naturalistic walking; another is that manipulating neural activity in sensorimotor circuits often reduces spontaneous locomotion. To overcome these obstacles, this study introduced miniature treadmill systems for coercing locomotion and tracking 3D kinematics of walking Drosophila. By systematically comparing walking in three experimental setups, flies compelled to walk on the linear treadmill were shown to have similar stepping kinematics to freely walking flies, while kinematics of tethered walking flies are subtly different. Genetically silencing mechanosensory neurons altered step kinematics of flies walking on the linear treadmill across all speeds. Flies can maintain a forward heading on a split-belt treadmill by specifically adapting the step distance of their middle legs. These findings suggest that proprioceptive feedback contributes to leg motor control irrespective of walking speed and that the fly's middle legs play a specialized role in stabilizing locomotion. | Byars, A. S. X., Riddle, N. C. (2025). Unpredictable disturbance and its effects on activity behavior and lifespan in Drosophila melanogaster. Biol Open, PubMed ID: 40554766
Summary: Animals exhibit natural movement patterns that are important for their survival and reproduction. Human disturbance can alter these movement patterns. In many natural settings, assessing the long-term impact of these altered movement patterns is difficult. Laboratory studies with model organisms may provide additional insight into the long- term effects of altered movement behaviors, such as those caused by human disturbance. This study investigated how unpredictable disturbance impacts animal activity and lifespan of Drosophila melanogaster. Four strains were selected from the Drosophila Genetics Reference Panel (DGRP) to assess animals with different baseline activity levels. The unpredictable disturbance treatment was simulated using the TreadWheel to administer four randomized 30-minute disturbances daily. Both 5-day and 20-day disturbance treatments altered activity levels, but the response was dependent on sex, genotype, and age of the animals. While altered animal activity was detected in several groups, lifespan generally was not affected, with a few exceptions. Thesse results highlight the complexity involved in predicting individual responses to disturbance but suggest that long-term effects on lifespan are rare in response to short-term disturbance. |
| Cazale-Debat, L., Scheunemann, L., Day, M., Fernandez, D. V. A. T., Dimtsi, A., Zhang, Y., Blackburn, L. A., Ballardini, C., Greenin-Whitehead, K., Reynolds, E., Lin, A. C., Owald, D., Rezaval, C. (2024). Mating proximity blinds threat perception. Nature, PubMed ID: 39198656
Summary: Romantic engagement can bias sensory perception. This 'love blindness' reflects a common behavioural principle across organisms: favouring pursuit of a coveted reward over potential risks. In the case of animal courtship, such sensory biases may support reproductive success but can also expose individuals to danger, such as predation. However, how neural networks balance the trade-off between risk and reward is unknown. This study discovered a dopamine-governed filter mechanism in male Drosophila that reduces threat perception as courtship progresses. We show that during early courtship stages, threat-activated visual neurons inhibit central courtship nodes via specific serotonergic neurons. This serotonergic inhibition prompts flies to abort courtship when they see imminent danger. However, as flies advance in the courtship process, the dopaminergic filter system reduces visual threat responses, shifting the balance from survival to mating. By recording neural activity from males as they approach mating, this study demonstrated that progress in courtship is registered as dopaminergic activity levels ramping up. This dopamine signalling inhibits the visual threat detection pathway via Dop2R receptors, allowing male flies to focus on courtship when they are close to copulation. Thus, dopamine signalling biases sensory perception based on perceived goal proximity, to prioritize between competing behaviours. | Bhatnagar, A., Banerjee, S., Das, S., Saha, S., Murray, G., Ray, S. (2025). Behavioral and Metabolomics Analyses of Drosophila melanogaster with Chronobiotic Melatonin Treatment: Effects on Locomotor Activity, Circadian Integrity, and Metabolic Pathways. Omics, 29(7):320-329 . PubMed ID: 40560839
Summary: Using an integrated approach combining high-throughput locomotor activity monitoring and untargeted metabolomics, the behavioral and metabolic effects of a chronobiotic melatonin was tested. The behavioral activity of fruit flies was recorded using an infrared-based monitoring device, followed by data analysis with open-source data packages ShinyR-DAM and VANESSA. One mM and 4 mM melatonin doses significantly increased Drosophila locomotor activity. Melatonin at a high concentration (4 mM) exhibited a protective effect to reduce mortality in Drosophila. Despite these changes, melatonin preserved the flies' endogenous bimodal activity pattern, maintaining circadian alignment. Metabolomics analysis using high-performance liquid chromatography-mass spectrometry identified differentially abundant metabolites after melatonin administration compared with the vehicle treatment. 20 biologically relevant metabolites were found to br altered by melatonin, including key perturbations in arginine biosynthesis, alanine/aspartate/glutamate metabolism, and pyrimidine pathways. Notably, melatonin upregulated glutamine, a potential indicator of enhanced neurotransmitter synthesis and broadly modulated amino acid and nucleotide metabolism, suggesting dual roles in neuroprotection and energy homeostasis. This high-throughput omics study uncovers melatonin-induced behavioral and metabolic perturbations in Drosophila as a model organism, revealing how melatonin modulates locomotor activity and circadian integrity through specific alterations in metabolism. |
Tuesday August 19th - Genes, Enzymes and Protein Expression, Evolution, Structure, and function |
| Hwang, H. J., Sheard, K. M., Cox, R. T. (2024). Drosophila Clueless ribonucleoprotein particles display novel dynamics that rely on the availability of functional protein and polysome equilibrium. bioRxiv, PubMed ID: 39229069
Summary: The cytoplasm is populated with many ribonucleoprotein (RNP) particles that post-transcriptionally regulate mRNAs. These membraneless organelles assemble and disassemble in response to stress, performing functions such as sequestering stalled translation pre-initiation complexes or mRNA storage, repression and decay. Drosophila Clueless (Clu) is a conserved multi-domain ribonucleoprotein essential for mitochondrial function that forms dynamic particles within the cytoplasm. Unlike well-known RNP particles, stress granules and Processing bodies, Clu particles completely disassemble under nutritional or oxidative stress. However, it is poorly understood how disrupting protein synthesis affects Clu particle dynamics, especially since Clu binds mRNA and ribosomes. This study capitalizes on ex vivo and in vivo imaging of Drosophila oocytes to determine what domains of Clu are necessary for Clu particle assembly, how manipulating translation using translation inhibitors affects particle dynamics, and how Clu particle movement relates to mitochondrial association. Using Clu deletion analysis and live and fixed imaging, this study identified three protein domains in Clu, which are essential for particle assembly. In addition, overexpressing functional Clu disassembled particles, while overexpression of deletion constructs did not. To examine how decreasing translation affects particle dynamics, translation was inhibited in Drosophila germ cells using cycloheximide and puromycin. In contrast to stress granules and Processing bodies, cycloheximide treatment did not disassemble Clu particles yet puromycin treatment did. Surprisingly, cycloheximide stabilized particles in the presence of oxidative and nutritional stress. These findings demonstrate that Clu particles have novel dynamics in response to altered ribosome activity compared to stress granules and Processing bodies and support a model where they function as hubs of translation whose assembly heavily depends on the dynamic availability of polysomes. | Cooke, M. M., Chembars, M. S., Pitts, R. J. (2025). The Dysregulation of Tuning Receptors and Transcription Factors in the Antennae of Orco and Ir8a Mutants in Aedes aegypti Suggests a Chemoreceptor Regulatory Mechanism Involving the MMB/dREAM Complex. Insects, 16(6) PubMed ID: 40559068
Summary: Olfaction has been extensively studied in the yellow fever mosquito, Aedes aegypti. This species uses its sense of smell to find blood hosts and other resources, contributing to its impact as a vector for human pathogens. Two major families of protein-coding genes, the odorant receptors (Ors) and the ionotropic receptors (Irs), provide the mosquito with sensitivities to distinct classes of volatile compounds in the antennae. Individual tuning receptors in both families require co-receptors for functionality: Orco for all Ors, and Ir8a for many Irs, especially ones that are involved in carboxylic acid detection. In Drosophila melanogaster, disruptions of Orco or Ir8a impair receptor function, tuning receptor expression, and membrane localization, leading to general anosmia. In this study it was reasoned that Orco and Ir8a might also be important for coordinated chemosensory receptor expression in the antennal sensory neurons of Ae. aegypti. To test this, RNAseq and differential expression analysis was performed in wildtype versus Orco(-/-) and Ir8a(-/-) mutant adult female antennae. The analyses revealed Or and Ir tuning receptors are broadly under-expressed in Orco(-/-) mutants, while a subset of tuning Irs are under-expressed in Ir8a mutants. Other chemosensory and non-chemosensory genes are also dysregulated in these mutants. Furthermore, differentially expressed transcription factors were found including homologs of the Drosophila melanogaster >Mip120 gene. These data suggest a previously unknown pleiotropic role for the Orco and Ir8a co-receptors in the coordination of expression of chemosensory receptors within the antennae of Ae. aegypti by participating in a feedback loop involving amos and members of the MMB/dREAM complex. |
| Fudo, S., Verkhovskaya, M., Di Scala, C., Rivera, C., Kajander, T. (2025). Biophysical characterization and ion transport with cell-based and proteoliposome reconstitution assays of invertebrate K(+)-Cl(-) cotransporters. FEBS Open Bio, PubMed ID: 40509965
Summary: The cation-chloride cotransporter (CCC) family includes ion symporters that cotransport monovalent cations and Cl(-), playing a crucial role in controlling cytoplasmic ion content. K(+)-Cl(-) cotransporters (KCCs) facilitate the symport of ions across the plasma membrane. The CCCs participate in various physiological processes, such as transepithelial ion transport and regulation of cell volume. Among KCCs, KCC2 has unique and essential functions in the central nervous system. KCC from Drosophila melanogaster (DmKCC) is an ortholog of mammalian KCCs. Its critical role in neuronal transmission has been demonstrated. Also, the cnidarian Hydra vulgaris has a functional KCC (HvKCC). Comparative analyses of these transporters with vertebrate counterparts can provide insights into the mechanism of KCC ion transport, regulation, and evolution. Thus, this study purified DmKCC and HvKCC and characterized their biophysical properties using differential scanning fluorimetry and light scattering. Their functionality was evaluated in cells and a method was developed to study ion transport with flame photometry. Further, a fluorescence-based assay for DmKCC reconstituted into proteoliposomes was developed. The activity of DmKCC was found to be dependent on Ca(2+), which is reminiscent of some other chloride transport protein families and potentially important for the KCC protein family overall. | Chatterjee, M., Yu, X. Y., Brady, N. K., Amendola, C., Hatto, G. C., Reed, R. D. (2025). mirror determines the far posterior domain in butterfly wings. Elife, 13 PubMed ID: 40557921
Summary: Insect wings, a key innovation that contributed to the explosive diversification of insects, are recognized for their remarkable variation and many splendid adaptations. Classical morphological work subdivides insect wings into several distinct domains along the anteroposterior (AP) axis, each of which can evolve relatively independently to produce the myriad forms we see in nature. Important insights into AP subdivision of insect wings come from work in Drosophila melanogaster; however, they do not fully explain the diversity of AP domains observed across broad-winged insects. This study shows that the transcription factor mirror acts as a selector gene to differentiate a far posterior domain in the butterfly wing, classically defined as the vannus, and has effects on wing shape, scale morphology, and color pattern. These results support models of how selector genes may facilitate evolutionarily individuation of distinct AP domains in insect wings outside of Drosophila and suggest that the D. melanogaster wing blade has been reduced to represent only a portion of the archetypal insect wing. |
| Bonchuk, A. N., Balagurov, K. I., Baradaran, R., Boyko, K. M., Sluchanko, N. N., Khrustaleva, A. M., Burtseva, A. D., Arkova, O. V., Khalisova, K. K., Popov, V. O., Naschberger, A., Georgiev, P. G. (2024). The Arthropoda-specific Tramtrack group BTB protein domains use previously unknown interface to form hexamers. Elife, 13 PubMed ID: 39221775
Summary: BTB (Bric-a-brack, Tramtrack and Broad Complex) is a diverse group of protein-protein interaction domains found within metazoan proteins. Transcription factors contain a dimerizing BTB subtype with a characteristic N-terminal extension. The Tramtrack group (TTK) is a distinct type of BTB domain, which can multimerize. Single-particle cryo-EM microscopy revealed that the TTK-type BTB domains assemble into a hexameric structure consisting of three canonical BTB dimers connected through a previously uncharacterized interface. The TTK-type BTB domains are found only in Arthropods and have undergone lineage-specific expansion in modern insects. The Drosophila genome encodes 24 transcription factors with TTK-type BTB domains, whereas only four have non‑TTK‑type BTB domains. Yeast two-hybrid analysis revealed that the TTK-type BTB domains have an unusually broad potential for heteromeric associations presumably through dimer-dimer interaction interface. Thus, the TTK-type BTB domains are a structurally and functionally distinct group of protein domains specific to Arthropodan transcription factors. | Guo, C. J., Zhang, Z., Lu, J. L., Zhong, J., Wu, Y. F., Guo, S. Y., Liu, J. L. (2024). Structural Basis of Bifunctional CTP/dCTP Synthase. J Mol Biol, 436(20):168750 PubMed iD: 39173734
Summary: The final step in the de novo synthesis of cytidine 5'-triphosphate (CTP) is catalyzed by CTP synthase (CTPS), which can form cytoophidia in all three domains of life. Recent work has discovered that CTPS binds to ribonucleotides (NTPs) to form filaments, and have successfully resolved the structures of Drosophila melanogaster CTPS bound with NTPs. Previous biochemical studies have shown that CTPS can bind to deoxyribonucleotides (dNTPs) to produce 2'-deoxycytidine-5'-triphosphate (dCTP). However, the structural basis of CTPS binding to dNTPs is still unclear. This study found that Drosophila CTPS can also form filaments with dNTPs. Using cryo-electron microscopy, it was possible to resolve the structure of Drosophila melanogaster CTPS bound to dNTPs with a resolution of up to 2.7 Å. By combining these structural findings with biochemical analysis, the binding and reaction characteristics of NTPs and dNTPs with CTPS were compared. These results indicate that the same enzyme can act bifunctionally as CTP/dCTP synthase in vitro, and provide a structural basis for these activities. |
Friday August 15th - Larval and Adult Brain - Development, structure and function |
| Calle-Schuler, S. A., Santana-Cruz, A. E., Kmecova, L., Hampel, S., Seeds, A. M. (2025). A comprehensive mechanosensory connectome reveals a somatotopically organized neural circuit architecture controlling stimulus-aimed grooming of the Drosophila head. bioRxiv, PubMed ID: 40501676
Summary: Animals respond to tactile stimulations of the body with location-appropriate behavior, such as aimed grooming. These responses are mediated by mechanosensory neurons distributed across the body, whose axons project into somatotopically organized brain regions corresponding to body location. How mechanosensory neurons interface with brain circuits to transform mechanical stimulations into location-appropriate behavior is unclear. Previous work described the somatotopic organization of bristle mechanosensory neurons (BMNs) around the Drosophila head that elicit a sequence of location-aimed grooming movements. This study used a serial section electron microscopy reconstruction of a full adult fly brain to identify nearly all of BMN pre-and postsynaptic partners, uncovering circuit pathways that control head grooming. Postsynaptic partners dominate the connectome, and are both excitatory and inhibitory. An excitatory hemilineage of cholinergic interneurons (hemilineage 23b: for information on hemilineage 23b neurons, go to Google and enter hemilineage 23b neurons Drosophila) was identified that elicit aimed head grooming and exhibit varied connectivity to BMNs from different head locations, revealing lineage-based development of a somatotopic parallel circuit architecture. Presynaptic partners provide extensive BMN presynaptic inhibition, consistent with models of sensory gain control as a mechanism of suppressing grooming movements and controlling the sequence. This work provides the first comprehensive map of a somatotopically organized connectome, and reveals how this organization could shape grooming. It also reveals the mechanosensory interface with the brain, illuminating fundamental features of mechanosensory processing, including feedforward excitation and inhibition, feedback inhibition, somatotopic circuit organization, and developmental origins. | Dhawan, S., Huang, Z., Dickerson, B. H. (2025). . Neural connectivity of a computational map for fly flight control. bioRxiv, PubMed ID: 40501886
Summary: Nervous systems rely on sensory feature maps, where the tuning of neighboring neurons for some ethologically-relevant parameter varies systematically, to control behavior. Such maps can be organized topographically or based on some computational principle. However, it is unclear how the central organization of a sensory system corresponds to the functional logic of the motor system. This problem is exemplified by insect flight, where sub-millisecond modifications in wing-steering muscle activity are necessary for stability and maneuverability. Although the muscles that control wing motion are anatomically and functionally stratified into distinct motor modules, comparatively little is known about the architecture of the sensory circuits that regulate their precise firing times. This study leveraged an existing volume of an adult female VNC of the fruit fly Drosophila melanogaster to reconstruct the complete population of afferents in the haltere-nature's only biological "gyroscope"-and their synaptic partners. These neurons were morphologically classified into distinct subtypes and design split-GAL4 lines that help us determine the peripheral locations from which each subtype originates. Each subtype, rather than originating from the same anatomical location, was shown to be comprised of multiple regions on the haltere. The flow of rapid mechanosensory feedback was traced from the peripheral haltere receptors to the central motor circuits that control wing kinematics. This work demonstrates how a sensory system's connectivity patterns construct a neural map that may facilitate rapid processing by the motor system. |
| Elkahlah, N., Lin, Y., Shirangi, T. R., Clowney, E. J. (2025). Hierarchical diversification of instinctual behavior neurons by lineage, birth order, and sex. bioRxiv PubMed ID: 40502082
Summary: Brain regions devoted to instinctual behaviors, including the vertebrate hypothalamus and arthropod cerebrum, contain bespoke neural circuits dedicated to perceptual and internal regulation of many behavioral states. These circuits are usually complex in structure and contain an extensive diversity of cell types. The regulatory mechanisms that pattern circuits for instinctual behaviors have been challenging to elucidate. Methods were developed in Drosophila to transcriptionally profile identified neuronal stem cell lineages in the cerebrum. This method was applied to lineages that generate sex-differentiated neurons with known circuit roles. 91 transcription factors were identified that, in combinations of 6-8, delineate cerebral hemilineages - classes of postmitotic neurons born from the same stem cell and sharing Notch status. Hemilineages comprise the major anatomic classes in the cerebrum and these transcription factors are required to generate their gross features. 33 transcription factors were identified characteristic of neuronal birth order within lineages; these subtly differentiate neuronal subtypes to provide common computational modules to circuits regulating different behaviors. Our findings suggest that hemilineage and birth order transcription factors operate in a hierarchical system to build, diversify, and sexually differentiate lineally-related neurons that compose complex instinctual circuits. | Chen, H. Y., Wu, P. S., Li, Z. Y., Liu, Y. C., Yeh, S. R., Duan, B. C., Cheng, K. W., Hsu, C. C., Chiu, Y. L., Lee, W. T., Fan, S. Z., Wang, P. Y. (2025). Gut microbiome and host TOR pathway interact to regulate predator-induced aversive memory in Drosophila melanogaster. Proc Natl Acad Sci U S A, 122(25):e2422928122. PubMed ID: 40540603
Summary: The gut microbiome has emerged as a key factor influencing a wide range of host physiological processes and behaviors, though the mechanisms behind these effects remain only partially understood. This study explored the role of the gut microbiome in memory regulation using a parasitoid wasp-induced oviposition depression paradigm in Drosophila melanogaster. Flies with depleted gut microbiota, either through axenic culture or antibiotic treatment, exhibited significant memory impairments. However, reintroducing the commensal bacterium Lactobacillus plantarum alone was sufficient to restore memory, while coinoculation with Acetobacter pomorum further enhanced memory performance. Hemolymph metabolomic analyses revealed reduced amino acid levels in antibiotic-treated flies, which were linked to impaired Drosophila target of rapamycin (dTOR) signaling. Additionally, genetic manipulation of dTOR or dietary supplementation with branched-chain amino acids either mimicked or rescued the memory deficits caused by antibiotic treatments. These results suggest that the gut microbiome is essential for regulating memory function by maintaining amino acid homeostasis and proper dTOR signaling, with profound implications for advancing knowledge of cognitive regulation. |
| Takagi, S., Sancer, G., Abuin, L., Stupski, S. D., Roman Arguello, J., Prieto-Godino, L. L., Stern, D. L., Cruchet, S., Alvarez-Ocana, R., Wienecke, C. F. R., van Breugel, F., Jeanne, J. M., Auer, T. O., Benton, R. (2024). Olfactory sensory neuron population expansions influence projection neuron adaptation and enhance odour tracking. Nat Commun, 15(1):7041 PubMed ID: 39147786
Summary: The evolutionary expansion of sensory neuron populations detecting important environmental cues is widespread, but functionally enigmatic. This phenomenon was investigated through comparison of homologous olfactory pathways of Drosophila melanogaster and its close relative Drosophila sechellia, an extreme specialist for Morinda citrifolia noni fruit. D. sechellia has evolved species-specific expansions in select, noni-detecting olfactory sensory neuron (OSN) populations, through multigenic changes. Activation and inhibition of defined proportions of neurons demonstrate that OSN number increases contribute to stronger, more persistent, noni-odour tracking behaviour. These expansions result in increased synaptic connections of sensory neurons with their projection neuron (PN) partners, which are conserved in number between species. Surprisingly, having more OSNs does not lead to greater odour-evoked PN sensitivity or reliability. Rather, pathways with increased sensory pooling exhibit reduced PN adaptation, likely through weakened lateral inhibition. Thia work reveals an unexpected functional impact of sensory neuron population expansions to explain ecologically-relevant, species-specific behaviour. | Wang, H., Bollepogu Raja, K. K., Yeung, K., Morrison, C. A., Terrizzano, A., Khodadadi-Jamayran, A., Chen, P., Jordan, A., Fritsch, C., Sprecher, S. G., Mardon, G., Treisman, J. E. (2024). Synergistic activation by Glass and Pointed promotes neuronal identity in the Drosophila eye disc. Nat Commun, 15(1):7091 PubMed iD: 39154080
Summary: The integration of extrinsic signaling with cell-intrinsic transcription factors can direct progenitor cells to differentiate into distinct cell fates. in the developing Drosophila eye, differentiation of photoreceptors R1-R7 requires EGFR signaling mediated by the transcription factor Pointed, and single-cell RNA-Seq analysis shows that the same photoreceptors require the eye-specific transcription factor Glass. Ectopic expression of Glass and activation of EGFR signaling synergistically induce neuronal gene expression in the wing disc in a Pointed-dependent manner. Targeted DamiD reveals that Glass and Pointed share many binding sites in the genome of developing photoreceptors. Comparison with transcriptomic data shows that Pointed and Glass induce photoreceptor differentiation through intermediate transcription factors, including the redundant homologs Scratch and Scrape, as well as directly activating neuronal effector genes. These data reveal synergistic activation of a multi-layered transcriptional network as the mechanism by which EGFR signaling induces neuronal identity in Glass-expressing cells. |
Thursday August 14th - Immune Respons |
| Wang, X., Qu, Q., Li, Z., Lu, S., Ferrandon, D., Xi, L. (2024). An unusual Toll/MyD88-mediated Drosophila host defence against Talaromyces marneffei. Fly (Austin), 18(1):2398300 PubMed iD: 39239739
Summary: Talaromycosis, caused by Talaromyces marneffei (T. marneffei, formerly known as Penicillium marneffei), is an opportunistic invasive mycosis endemic in tropical and subtropical areas of Asia with high mortality rate. Despite various infection models established to study the immunological interaction between T. marneffei and the host, the pathogenicity of this fungus is not yet fully understood. So far, Drosophila melanogaster, a well-established genetic model organism to study innate immunity, has not been used in related research on T. marneffei. This study provide the initial characterization of a systemic infection model of T. marneffei in the D. melanogaster host. Survival curves and fungal loads were tested as well as Toll pathway activation was quantified by RT-qPCR of several antimicrobial peptide (AMP) genes including Drosomycin, Metchnikowin, and Bomanin Short 1. Whereas most wild-type flies were able to overcome the infection, MyD88 or Toll mutant flies failed to prevent fungal dissemination and proliferation and ultimately succumbed to this challenge. Unexpectedly, the induction of classical Toll pathway activation readouts, Drosomycin and Bomanin Short 1, by live or killed T. marneffei was quite limited in wild-type flies, suggesting that the fungus largely escapes detection by the systemic immune system. This unusual situation of a poor systemic activation of the Toll pathway and a strong susceptibility phenotype of MyD88/Toll might be accounted for by a requirement for this host defence in only specific tissues, a hypothesis that remains to be rigorously tested. | Chauhan, M., Martinak, P. E., Hollenberg, B. M., Goodman, A. G. (2024). Drosophila melanogaster Toll-9 elicits antiviral immunity against Drosophila C virus. bioRxiv, PubMed ID: 38948804
Summary: The Toll pathway plays a pivotal role in innate immune responses against pathogens. The evolutionary conserved pathogen recognition receptors (PRRs), including Toll like receptors (TLRs), play a crucial role in recognition of pathogen associated molecular patterns (PAMPs). The Drosophila genome encodes nine Toll receptors that are orthologous to mammalian TLRs. While mammalian TLRs directly recognize PAMPs, most Drosophila Tolls recognize the proteolytically cleaved ligand Spatzle to activate downstream signaling cascades. This study demonstrated that Toll-9 is crucial for antiviral immunity against Drosophila C virus (DCV), a natural pathogen of Drosophila A transposable element insertion in the Toll-9 gene renders the flies more susceptible to DCV. The stable expression of Toll-9 in S2 cells confers resistance against DCV infection by upregulation of the RNAi pathway. Toll-9 promotes the dephosphorylation of AKT, resulting in the induction of antiviral RNAi genes to inhibit DCV replication. Toll-9 localizes to the endosome where it binds dsRNA, suggesting its role to detect viral dsRNA. Toll-9 also induces apoptosis during DCV infection, contributing to its antiviral role. Together, this work identifies the role of Toll-9 in antiviral immunity against DCV infection through its ability to bind dsRNA and induce AKT-mediated RNAi antiviral immunity. |
| Nawar, N., Rits, E., Cohen, L., Wunderlich, Z. (2025). Heterogeneous NF-kappaB activation and enhancer features shape transcription in Drosophila immunity. bioRxiv, PubMed ID: 40475619
Summary: Conserved NF-kappaB signaling pathways shape immune responses in animals. In mammals, NF-kappaB activation patterns and downstream transcription vary with stimulus, cell type, and stochastic differences among identically treated cells. Whether animals without adaptive immunity exhibit similar heterogeneity or rely on distinct immune strategies remains unknown. This studied engineered Drosophila melanogaster S2* reporter cells as an immune-responsive model to monitor the dynamics of an NF-kappaB transcription factor, Relish, and downstream transcription in single, living cells. Following immune stimulation, Relish exhibits diverse nuclear localization dynamics that fall into distinct categories, with both the fraction of responsive cells and their activation speed rising with stimulus dose. Pre-stimulus features, including Relish nuclear fraction, predict a cell's responsiveness to stimulation. Simultaneous measurement of Relish and downstream transcription revealed that the probability of transcriptional bursts from immune-responsive enhancers correlates with Relish nuclear fraction. The number of NF-kappaB binding sites tunes transcriptional activity among immune enhancers. This study uncovers heterogeneity in NF-kappaB activation and target gene expression within Drosophila, illustrating how dynamic NF-kappaB behavior and enhancer architecture tune gene regulation. | Azizpor, P., Okakpu, O. K., Parks, S. C., Chavez, D., Eyabi, F., Martinez-Beltran, S., Nguyen, S., Dillman, A. R. (2024). Polyunsaturated fatty acids stimulate immunity and eicosanoid production in Drosophila melanogaster. Journal of lipid research, 65(9):100608 PubMed ID: 39069231
Summary: Eicosanoids are a class of molecules derived from C20 polyunsaturated fatty acids (PUFAs) that play a vital role in mammalian and insect biological systems, including development, reproduction, and immunity. Recent research has shown that insects have significant but lower levels of C20 PUFAs in circulation in comparison to C18 PUFAs. It has been previously hypothesized in insects that eicosanoids are synthesized from C18 precursors, such as linoleic acid (LA), to produce downstream eicosanoids. This study shows that introduction of arachidonic acid (AA) stimulates production of cyclooxygenase, lipoxygenase, and cytochrome P450-derived eicosanoids. Downstream immune readouts showed that LA stimulates phagocytosis by hemocytes, while both LA and AA stimulate increased antimicrobial peptide production when D. melanogaster is exposed to a heat-killed bacterial pathogen. In totality, this work identifies PUFAs that are involved in insect immunity and adds evidence to the notion that Drosophila utilizes immunostimulatory lipid signaling to mitigate bacterial infections. Understanding of immune signaling in the fly and its analogies to mammalian systems will increase the power and value of Drosophila as a model organism in immune studies. |
| Wang, Z., Li, S., Zhang, S., Zhang, T., Wu, Y., Liu, A., Wang, K., Ji, X., Cao, H., Zhang, Y., Tan, E. K., Wang, Y., Wang, Y., Liu, W. (2024). Hosts manipulate lifestyle switch and pathogenicity heterogeneity of opportunistic pathogens in the single-cell resolution. Elife, 13 PubMed ID: 39190452
Summary: Host-microbe interactions are virtually bidirectional, but how the host affects their microbiome is poorly understood. This study reports that the host is a critical modulator to regulate the lifestyle switch and pathogenicity heterogeneity of the opportunistic pathogens Serratia marcescens utilizing the Drosophila and bacterium model system. First, it was found that Drosophila larvae efficiently outcompete S. marcescens and typically drive a bacterial switch from pathogenicity to commensalism toward the fly. Furthermore, Drosophila larvae reshape the transcriptomic and metabolic profiles of S. marcescens characterized by a lifestyle switch. More importantly, the host alters pathogenicity and heterogeneity of S. marcescens in the single-cell resolution. Finally, larvae-derived antimicrobial peptides were found to be required to recapitulate the response of S. marcescens to larvae. Altogether, these findings provide an insight into the pivotal roles of the host in harnessing the life history and heterogeneity of symbiotic bacterial cells, advancing knowledge of the reciprocal relationships between the host and pathogen. | Burgmer, S., Meyer Zu Altenschildesche, F. L., Gyenis, A., Lee, H. J., Vilchez, D., Giavalisco, P., Fichant, A., Uhlirova, M., Storelli, G. (2025). Endosymbiont control through non-canonical immune signaling and gut metabolic remodeling. Cell Rep, 44(6):115811 PubMed ID: 40483691
Summary: Animals coexist with bacteria and need to keep these microorganisms under tight control. To achieve such control, pattern recognition receptors (PRRs) sense bacterial cues and induce the production of antimicrobials. This study uncovered a metabolic arm in the control of symbionts by PRRs. In Drosophila, the PRRs PGRP-LC and PGRP-LE act independently of canonical NF-kappaB signaling to repress essential metabolic functions in the gut, such as digestion and central carbon metabolism. This metabolic switch affects commensal populations and drastically reduces intestinal and systemic populations of the intracellular parasite Wolbachia. It is proposed that intestinal metabolic remodeling complements immune responses by imposing nutrient restriction on intracellular bacteria, whose lifestyle protects them from antimicrobials. These findings reveal a role for PRRs in bacterial control beyond canonical immune pathways and provide insights into how microbial signals modulate symbiotic populations but also nutrition and metabolism in animals. |
Wednesday August 13th - Enhancers and Transcriptional Regulation |
| Duan, Q., Okuwa, S., Estrella, R., Yeung, C., Chen, Y. D., Rio, L. Q., Vien, K. M., Volkan, P. C. (2025). Deciphering the combinatorial expression pattern and genetic regulatory mechanisms of Beats and Sides in the olfactory circuits of Drosophila. bioRxiv, PubMed ID: 40502011
Summary: Over the past decades, many critical molecular players have been uncovered to control distinct steps in olfactory circuit assembly in Drosophila. Among these, multi-member gene families of cell surface proteins are of interest because they can act as neuron-specific identification/recognition tags in combinations and contribute to circuit assembly in complex brains through their heterophilic or homophilic interactions. Recently, a multi-protein interactome has been described between the Beat and Side families of IgSF proteins. This study used the publicly available single-cell RNA-seq datasets and newly generated gene trap transgenic driver lines to probe the in vivo spatial expression pattern of the beat/side gene families in odorant receptor neurons (ORNs) and their synaptic target projection neurons (PNs). The results revealed that each ORN and its synaptic target PN class expresses a class-specific combination of beat/side genes, hierarchically regulated by lineage-specific genetic programs. Though ORNs or PNs from closer lineages tend to possess more similar beat/side profiles, many examples were found of divergence from this pattern among closely related ORNs and closely related PNs. To explore whether the class-specific combination of beats/sides defines ORN-PN matching specificity, presynaptic beat-IIa and postsynaptic side-IV were perturbed in two ORN-PN partners. However, disruption of Beat-IIa-Side-IV interaction did not produce any significant mistargeting in these two examined glomeruli. Though without affecting general glomerular targeting, knockdown of side in ORNs leads to the reduction of synaptic development. Interestingly, conserved expression patterns of beat/side orthologs were found across ORNs in ants and mosquitoes, indicating the shared regulatory strategies specifying the expression of these duplicated paralogs in insect evolution. Overall, this comprehensive analysis of expression patterns lays a foundation for indepth functional investigations into how Beat/Side combinatorial expression contributes to olfactory circuit assembly. | Ainsworth, J., Zhao, Y., Gao, K., Gravina, N. M., Goldberg, Z. H., Pinkerton, C., Rifkin, S. A., Ernst, A. M., Garcia, H. G., Perry, M. W. (2025). Cell fate ratios are encoded by transcriptional dynamics in the Drosophila retina. Curr Biol, 35(12):2946-2959. PubMed ID: 40499552
Summary: Although transcription happens in bursts, it is unclear whether variation in the rate and pattern of bursting matters during animal development. This study examined whether the amount and timing of transcription influence the ratio of cell types produced during stochastic patterning of the Drosophila retina. This system is balanced between 2 outcomes: ~70% of R7 photoreceptors (PRs) express Rhodopsin 4 (Rh4), and the rest express Rhodopsin 3 (Rh3). Cell fate depends on the cell-intrinsic binary decision to express the transcription factor spineless (Ss). Changing the ss bursting pattern by replacing the ss core promoter led to a different ratio of R7 PR types. It is hypothesized that random variation in the timing of transcriptional initiation followed by autoregulation might control the outcome. Instead, the decision was found to occur before R7 specification and before protein is made, with no feedback via Ss protein. Surprisingly, this happens in a field of progenitor cells that give rise to all retina cell types, which all initially transcribe ss. A subset stops transcribing ss over time. Those that become R7s and maintain ss transcription take the Ss-ON/Rh4 fate. Live imaging of ss transcription suggests increased time spent in off periods could decrease the probability of new transcription and therefore the Ss-ON ratio. Transiently increasing continuity of transcription produces all Ss-ON outcomes, while introducing longer gaps lowers the ratio. Targeting CBP to the ss locus increases the ratio, indicating a repressive role for chromatin state during periods when transcription is inactive. It is concluded the ratio is set by the amount and dynamics of ss transcription. |
| Fogarty, E. A., Buchert, E. M., Ma, Y., Nicely, A. B., Buttitta, L. A. (2024). Transcriptional repression and enhancer decommissioning silence cell cycle genes in postmitotic tissues. G3 (Bethesda), PubMed iD: 39171889
Summary: The mechanisms that maintain a non-cycling status in postmitotic tissues are not well understood. Many cell cycle genes have promoters and enhancers that remain accessible even when cells are terminally differentiated and in a non-cycling state, suggesting their repression must be maintained long term. in contrast, enhancer decommissioning has been observed for rate-limiting cell cycle genes in the Drosophila wing, a tissue where the cells die soon after eclosion, but it has been unclear if this also occurs in other contexts of terminal differentiation. This study showed that enhancer decommissioning also occurs at specific, rate-limiting cell cycle genes in the long-lived tissues of the Drosophila eye and brain, and it is proposed this loss of chromatin accessibility may help maintain a robust postmitotic state. The decommissioned enhancers were examined at specific rate-limiting cell cycle genes and show that they encode for dynamic temporal and spatial expression patterns that include shared, as well as tissue-specific elements, resulting in broad gene expression with developmentally controlled temporal regulation. This analysis was extended to cell cycle gene expression and chromatin accessibility in the mammalian retina using a published dataset; the principles of cell cycle gene regulation identified in terminally differentiating Drosophila tissues are conserved in the differentiating mammalian retina. A robust, non-cycling status is proposed to be maintained in long-lived postmitotic tissues through a combination of stable repression at most cell cycle genes, alongside enhancer decommissioning at specific rate-limiting cell cycle genes. | Denaud, S., Bardou, M., Papadopoulos, G. L., Grob, S., Di Stefano, M., Sabaris, G., Nollmann, M., Schuettengruber, B., Cavalli, G. (2024). A PRE loop at the dac locus acts as a topological chromatin structure that restricts and specifies enhancer-promoter communication. Nat Struct Mol Biol, PubMed ID: 39152239
Summary: Three-dimensional (3D) genome folding has a fundamental role in the regulation of developmental genes by facilitating or constraining chromatin interactions between cis-regulatory elements (CREs). Polycomb response elements (PREs) are a specific kind of CRE involved in the memory of transcriptional states in Drosophila melanogaster. PREs act as nucleation sites for Polycomb group (PcG) proteins, which deposit the repressive histone mark H3K27me3, leading to the formation of a class of topologically associating domain (TAD) called a Polycomb domain. PREs can establish looping contacts that stabilize the gene repression of key developmental genes during development. However, the mechanism by which PRE loops fine-tune gene expression is unknown. Using clustered regularly interspaced short palindromic repeats and Cas9 genome engineering, this study specifically perturbed PRE contacts or enhancer function and used complementary approaches including 4C-seq, Hi-C and Hi-M to analyze how chromatin architecture perturbation affects gene expression. These results suggest that the PRE loop at the dac gene locus acts as a constitutive 3D chromatin scaffold during Drosophila development that forms independently of gene expression states and has a versatile function; it restricts enhancer-promoter communication and contributes to enhancer specificity. |
| Dima, S. S., Reeves, G. T. (2025). Bulk-level maps of pioneer factor binding dynamics during the Drosophila maternal-to-zygotic transition. Development, 152(13) PubMed ID: 40512118
Summary: Gene regulation by transcription factors (TFs) binding cognate sequences is of paramount importance. For example, the TFs Zelda (Zld) and GAGA factor (GAF) are widely acknowledged for pioneering gene activation during zygotic genome activation (ZGA) in Drosophila. However, quantitative dose/response relationships between bulk TF concentration and DNA binding, an event tied to transcriptional activity, remain elusive. This study mapped these relationships during ZGA: a crucial step in metazoan development. To map the dose/response relationship between nuclear concentration and DNA binding, raster image correlation spectroscopy, a method that can measure biophysical parameters of fluorescent molecules, was performed. Although Zld concentration increases during nuclear cycles 10 to 14 was found, its binding in the transcriptionally active regions decreases, consistent with its function as an activator for early genes. In contrast, GAF-DNA binding is nearly linear with its concentration, which sharply increases during the major wave, implicating its involvement in the major wave. This study provides key insights into the properties of the two factors and puts forward a quantitative approach that can be used for other TFs to study transcriptional regulation. | Tullius, T. W., Isaac, R. S., Dubocanin, D., Ranchalis, J., Churchman, L. S., Stergachis, A. B. (2024). RNA polymerases reshape chromatin architecture and couple transcription on individual fibers. Mol Cell, 84(17):3209-3222. PubMed ID: 39191261
Summary: RNA polymerases must initiate and pause within a complex chromatin environment, surrounded by nucleosomes and other transcriptional machinery. This environment creates a spatial arrangement along individual chromatin fibers ripe for both competition and coordination, yet these relationships remain largely unknown owing to the inherent limitations of traditional structural and sequencing methodologies. To address this, long-read chromatin fiber sequencing (Fiber-seq) was employed in Drosophila to visualize RNA polymerase (Pol) within its native chromatin context with single-molecule precision along up to 30 kb fibers. Fiber-seq was demonstrated to enable the identification of individual Pol II, nucleosome, and transcription factor footprints, revealing Pol II pausing-driven destabilization of downstream nucleosomes. Furthermore, this study demonstrated pervasive direct distance-dependent transcriptional coupling between nearby Pol II genes, Pol III genes, and transcribed enhancers, modulated by local chromatin architecture. Overall, transcription initiation reshapes surrounding nucleosome architecture and couples nearby transcriptional machinery along individual chromatin fibers. |
Tuesday August 12th - Physiology and Metabolism |
| De Donno, M. D., Mercuri, E., Balena, B., Zangaro, F., Bozzetti, M. P., Specchia, V. (2025). Mechanistic insights into cadmium-related premature aging in Drosophila model. Front Neurosci, 19:1605687 PubMed ID: 40535972
Summary: The intricate and multifaceted relationship between environmental pollutants, particularly heavy metals such as cadmium, and human health has been extensively documented, with a significant focus on their neurotoxic effects. Notably, the connection between cadmium exposure and Alzheimer's disease is becoming increasingly evident, prompting a deeper investigation into the underlying mechanisms at play. Despite the growing body of evidence linking cadmium to neurodegeneration and although harmful molecular activities of cadmium in cells have been demonstrated, the precise molecular mechanism induced by this toxic metal within neuronal cells remains largely enigmatic. This study aims to shed light on these mechanistic processes by utilizing Drosophila melanogaster. Through a carefully designed approach, chronic exposure to cadmium was simulated, which allowed observation of the resulting effects on the flies over time. The findings revealed that chronic cadmium exposure led to premature aging in flies, characterized by neurodegeneration and an exacerbation of complex neurological phenotypes. Notably, these included significant impairments in learning and memory, which are critical cognitive functions often compromised in neurodegenerative conditions. With the aim of exploring the mechanistic underpinnings of these observations, this s determined that cadmium impairs RNP formation and could disrupt the delicate process of liquid-liquid phase separation within neuronal cells. This disruption appears to play a pivotal role in initiating the cascade of events that contribute to neurodegeneration. Liquid-liquid phase separation is essential for the proper organization of cellular components and the maintenance of neuronal health; thus, cadmium's interference in this process may provide a crucial insight into its neurotoxic effects. | Di Dio, C., Porrazzo, A., De Gregorio, A., Morciano, P., Tabocchini, M. A., Cenci, G., Cipressa, F., Esposito, G. (2025). TIn vivo study of the radioadaptive response and low-dose hyper-radiosensitivity for chromosome breaks induced by gamma rays in wild-type Drosophila melanogaster larval neuroblasts: Dose and dose rate dependence. PLoS One, 20(6):e0325608 PubMed ID: 40489495
Summary: Although the biological effects of low doses/dose rates of ionising radiation have been extensively studied both in vitro and in vivo, there are still knowledge gaps to be filled. For example, the mechanisms underlying the phenomena of radioadaptive responses and hypersensitivity to low doses of radiation are still not fully understood. This study aims to investigate the phenomenon of radioadaptive response in Drosophila melanogaster larval neuroblasts, focusing on the influence of different gamma priming doses and priming dose rates. This study examined the modulation of cytogenetic damage, specifically the frequency of chromosome breaks, induced by a challenging dose of 10 Gy following different priming doses (0-2.7 Gy) delivered at dose rates ranging from 1.4 to 17 mGy/h. The findings reveal the presence of a distinct window in which radioadaptive responses occurs, notably above a certain threshold dose when delivered at a rate of 1.4 mGy/h. Consistently with previous results, this study confirmed that the maximal protection was observed at a priming dose of 0.4 Gy delivered at 2.5 mGy/h. Additionally, the occurrence of chromosome breaks was studied after irradiating larval neuroblasts at doses ranging from 0.7 to 10 Gy. Notably, in this case a low-dose hyper-radiosensitivity phenomenon was observed up to 2.7 Gy, followed by increased resistance above 2.7 Gy. These results provide insight into the complex cellular responses to low-dose/dose rate radiation and have implications in various fields, including radiation protection, diagnostics, theragnostics and biodosimetry. |
| Bhattacharya, D., Abaquita, T. L. A., Gorska-Andrzejak, J., Pyza, E. (2025). The Influence of Caffeine on Siesta and Nighttime Sleep in Drosophila melanogaster. Dev Neurobiol, 85(3):e22987 PubMed ID: 40525487
Summary: Caffeine, a plant-derived psychostimulant, has been demonstrated to reduce sleep and increase dopaminergic neuron activity in mammals through competitive antagonism at adenosine receptors (AdoRs). However, the extent to which it influences daytime sleep (siesta) as much as nighttime sleep and the involvement of the adenosine signaling pathway in this process remain unsolved. It is similarly unclear whether the influence of caffeine varies with age and depends on sex and what type of cells it affects most; the clock cells that are involved in sleep timing and regulation or dopaminergic neurons, which are crucial for voluntary movement. To address this question, the role of caffeine has been investigated in Drosophila melanogaster (wild-type Canton-S flies), which has also been observed to reduce sleep in response to caffeine. The siesta and nighttime sleep of 3-, 30-, and 50-day-old males and females of Canton-S Drosophila were examined. Furthermore, transgenic flies with overexpressed or silenced dAdoR in all neurons (elav-expressing cells), the circadian clock cells (tim-expressing cells), and dopaminergic neurons (th-expressing cells) were studied. Females exhibited greater sensitivity to caffeine than males, and older flies slept longer during the day than young flies. However, caffeine treatment resulted in reducing siesta in flies with overexpression of dAdoR in all neurons, tim-, and th-expressing cells. Conversely, silencing of dAdoR increased siesta. Therefore, the observed differences in the daytime sleep of Drosophila appeared to depend on signaling through AdoRs. | Wang, R., Zhu, Q., Huang, H., Yang, M., Wang, X., Dong, Y., Li, Y., Guan, Y., Zhong, L., Niu, Y. (2024). Periodic protein-restricted diets extend the lifespan of high-fat diet-induced Drosophila melanogaster males. Aging Cell:e14327 PubMed ID: 39207121
Summary: Research has shown that sustained protein restriction can improve the effects of a high-fat diet on health and extend lifespan. However, long-term adherence to a protein-restricted diet is challenging. Therefore, this study used a fly model to investigate whether periodic protein restriction (PPR) could also mitigate the potential adverse effects of a high-fat diet and extend healthy lifespan. This study's results showed that PPR reduced body weight, lipid levels, and oxidative stress induced by a high-fat diet in flies and significantly extended the healthy lifespan of male flies. Lipid metabolism and transcriptome results revealed that the common differences between the PPR group and the control group and high-fat group showed a significant decrease in palmitic acid in the PPR group; the enriched common differential pathways Toll and Imd were significantly inhibited in the PPR group. Further analysis indicated a significant positive correlation between palmitic acid levels and gene expression in the Toll and Imd pathways. This suggests that PPR effectively improves fruit fly lipid metabolism, reduces palmitic acid levels, and thereby suppresses the Toll and Imd pathways to extend the healthy lifespan of flies. This study provides a theoretical basis for the long-term effects of PPR on health and offers a new dietary adjustment option for maintaining health in the long term. |
| Deng, X., Wang, W., Peng, D., Zhang, L., Ma, Z., Fu, J., Tong, C., Xu, Y. (2025). Optogenetic perturbation of lipid droplet localization affects lipid metabolism and development in Drosophila. J Lipid Res:100848 PubMed ID: 40545239
Summary: Lipid droplets (LDs) are dynamic organelles crucial for lipid storage and homeostasis. Despite extensive documentation of their importance, the causal relationship between LD localization and function in health and disease remains inadequately understood. This study developed optogenetics-based tools, termed 'Opto-LDs', which facilitate the interaction between LDs and motor proteins in a light-dependent manner, enabling precise control of LD localization within cells. Utilizing these optogenetic modules, this study demonstrated that light-induced relocation of LDs to the periphery of hepatocytes results in elevated very-low-density lipoprotein (VLDL) secretion, recapturing the beneficial effect of insulin in vitro. Furthermore, studies in transgenic Drosophila revealed that proper LD localization is critical for embryonic development, with mistargeting of LDs significantly affecting egg success of hatching into first instar larvae. In summary, this work underscores the great importance of LD localization in lipid metabolism and development, and the developed tools offer valuable insights into the functions of LDs in health and disease. | Boumard, B., Le Meur, G., Aboutine, L., Stefanutti, M., Maalouf, T., El-Hajj, M., Choi, B. J., Bauer, R., Bardin, A. J. (2025). Cell-type-specific nucleotide sharing through gap junctions impacts sensitivity to replication stress in Drosophila. Dev Cell, PubMed ID: 40480229
Summary: Cell proliferation, which underlies tissue growth and homeostasis, requires high levels of metabolites such as deoxynucleotides (dNTPs). The dNTP pool is known to be tightly and cell-autonomously regulated via de novo synthesis and salvage pathways. Tis study demonstrated that nucleotides can also be provided to cells non-autonomously by surrounding cells within a tissue. Using Drosophila epithelial tissues as models, this study found that adult intestinal stem cells (ISCs) are highly sensitive to nucleotide depletion, whereas wing progenitor cells are not. Wing progenitor cells share nucleotides through gap junction connections, allowing buffering of replication stress induced by nucleotide pool depletion. Adult ISCs, however, lack gap junctions and cannot receive dNTPs from neighbors. Collectively, these data suggest that gap-junction-dependent sharing between cells can contribute to dNTP pool homeostasis in vivo. It is proposed that inherent differences in cellular gap junction permeability can influence sensitivity to fluctuations in intracellular dNTP levels. |
Thursday August 7th - Adult Development |
| Li, J., Ning, C., Liu, Y., Deng, B., Wang, B., Shi, K., Wang, R., Fang, R., Zhou, C. (2024). The function of juvenile-adult transition axis in female sexual receptivity of Drosophila melanogaster. Elife, 12 PubMed ID: 39240259
Summary: Female sexual receptivity is essential for reproduction of a species. Neuropeptides play the main role in regulating female receptivity. However, whether neuropeptides regulate female sexual receptivity during the neurodevelopment is unknown. This study found the peptide hormone prothoracicotropic hormone (A hrefPTTH), which belongs to the insect PG (prothoracic gland) axis, negatively regulated virgin female receptivity through ecdysone during neurodevelopment in Drosophila melanogaster. This study identified PTTH neurons as doublesex-positive neurons, they regulated virgin female receptivity before the metamorphosis during the third-instar larval stage. PTTH deletion resulted in the increased EcR-A expression in the whole newly formed prepupae. Furthermore, the ecdysone receptor EcR-A in pC1 neurons positively regulated virgin female receptivity during metamorphosis. The decreased EcR-A in pC1 neurons induced abnormal morphological development of pC1 neurons without changing neural activity. Among all subtypes of pC1 neurons, the function of EcR-A in pC1b neurons was necessary for virgin female copulation rate (for information on pC1b neurons, go to Google and enter pC1b neurons Drosophila). These suggested that the changes of synaptic connections between pC1b and other neurons decreased female copulation rate. Moreover, female receptivity significantly decreased when the expression of PTTH receptor Torso was reduced in pC1 neurons. This suggested that PTTH not only regulates female receptivity through ecdysone but also through affecting female receptivity associated neurons directly. The PG axis has similar functional strategy as the hypothalamic-pituitary-gonadal axis in mammals to trigger the juvenile-adult transition. This work suggests a general mechanism underlying which the neurodevelopment during maturation regulates female sexual receptivity. | Aldrich, J. C., Vanderlinden, L. A., Jacobsen, T. L., Wood, C., Saba, L. M., Britt, S. G. (2024). Genome-Wide Association Study and transcriptome analysis reveals a complex gene network that regulates opsin gene expression and cell fate determination in Drosophila R7 photoreceptor cells. bioRxiv, PubMed ID: 39149333
Summary: An animal's ability to discriminate between differing wavelengths of light (i.e., color vision) is mediated, in part, by a subset of photoreceptor cells that express opsins with distinct absorption spectra. In Drosophila R7 photoreceptors, expression of the rhodopsin molecules, Rh3 or Rh4, is determined by a stochastic process mediated by the transcription factor Spineless. The goal of this study was to identify additional factors that regulate R7 cell fate and opsin choice using a Genome Wide Association Study (GWAS) paired with transcriptome analysis via RNA-Seq. Rh3 and Rh4 expression was examined in a subset of fully-sequenced inbred strains from the Drosophila Genetic Reference Panel,performed, and a GWAS was performed to identify 42 naturally-occurring polymorphisms-in proximity to 28 candidate genes-that significantly influence R7 opsin expression. Network analysis revealed multiple potential interactions between the associated candidate genes, spineless and its partners. GWAS candidates were further validated in a secondary RNAi screen which identified 12 lines that significantly reduce the proportion of Rh3 expressing R7 photoreceptors. Finally, using RNA-Seq, all but four of the GWAS candidates were demonstrated to be expressed in the pupal retina at a critical developmental time point and that five are among the 917 differentially expressed genes in sevenless mutants, which lack R7 cells. Collectively, these results suggest that the relatively simple, binary cell fate decision underlying R7 opsin expression is modulated by a larger, more complex network of regulatory factors. Of particular interest are a subset of candidate genes with previously characterized neuronal functions including neurogenesis, neurodegeneration, photoreceptor development, axon growth and guidance, synaptogenesis, and synaptic function. |
| Ramesh, N. A., Box, A. M., Buttitta, L. A. (2024). Post-eclosion growth in the Drosophila Ejaculatory Duct is driven by Juvenile Hormone signaling and is essential for male fertility. bioRxiv, PubMed ID: 39185157
Summary: The Drosophila Ejaculatory duct (ED) is a secretory tissue of the somatic male reproductive system. The ED is involved in the secretion of seminal fluid components and ED-specific antimicrobial peptides that aid in fertility and the female post-mating response. The ED is composed of secretory epithelial cells surrounded by a layer of innervated contractile muscle. The ED grows in young adult males during the first 24h post-eclosion, but the cell cycle status of the ED secretory cells and the role of post-eclosion ED growth have been unexplored. This study showed that secretory cells of the adult Drosophila ED undergo variant cell cycles lacking mitosis called the endocycle, that lead to an increase in the cell and organ size of the ED post eclosion. The cells largely exit the endocycle by day 3 of adulthood, when the growth of the ED ceases, resulting in a tissue containing cells of ploidies ranging from 8C-32C. The size of the ED directly correlates with the ploidy of the secretory cells, with additional ectopic endocycles increasing organ size. When endoreplication is compromised in ED secretory cells, it leads to reduced organ size, reduced protein synthesis and compromised fertility. Evidence is provided that the growth and endocycling in the young adult male ED is dependent on Juvenile hormone (JH) signaling, and hormone-induced early adult endocycling is suggested to be required for optimal fertility and function of the ED tissue. Use of the ED as a post-mitotic tissue model to study the role of polyploidy in regulating secretory tissue growth and function is proposed. | Zhang, F., Luo, W., Liu, S., Zhao, L., Su, Y. (2024). Protein phosphatase 2A regulates blood cell proliferation and differentiation in Drosophila larval lymph glands. Febs j, PubMed ID: 39185698
Summary: Protein phosphatase 2A (PP2A), one of the most abundant protein phosphatases, has divergent functions in multiple types of cells. Its inactivation has been closely associated with leukemia diseases. However, the physiological function of PP2A for hematopoiesis has been poorly understood in organisms. Drosophila hematopoiesis parallels the vertebrate counterpart in developmental and functional features but involves a much simpler hematopoietic system. Utilizing the Drosophila major larval hematopoietic organ lymph gland, the function of PP2A for hematopoiesis in vivo was studied. By knocking down the expression of Pp2A-29B that encodes the scaffold subunit of the PP2A holoenzyme complex, this study found that PP2A silencing in the differentiating hemocytes resulted in their excessive proliferation. Furthermore, this PP2A inhibition downregulated the expression of Smoothened (Smo), a crucial component in the Hedgehog pathway, and smo overexpression was able to rescue the phenotypes of PP2A depletion, indicating that Smo functions as a downstream effector of PP2A to restrict the hemocyte proliferation. PDGF/VEGF-receptor (Pvr) overexpression also restored the Smo expression and lymph gland morphology of PP2A silencing, suggesting a PP2A-Pvr-Smo axis to regulate lymph gland growth and hemocyte proliferation. Moreover, inhibiting PP2A activity in the blood progenitor cells promoted their differentiation, but which was independent with Smo. Together, these data suggested that PP2A plays a dual role in the Drosophila lymph gland by preserving the progenitor population and restraining the hemocyte proliferation, to properly regulate the hematopoietic process. |
| Bose, A., Schuster, K., Kodali, C., Sonam, S., Smith-Bolton, R. K. (2025). The pioneer transcription factor Zelda controls the exit from regeneration and restoration of patterning in Drosophila. Sci Adv, 11(23):eads5743 PubMed ID: 40479065
Summary: Many animals can regenerate tissues after injury. While the initiation of regeneration has been studied extensively, how the damage response ends and normal gene expression returns is unclear. This study found that in Drosophila wing imaginal discs, the pioneer transcription factor Zelda controls the exit from regeneration and return to normal gene expression. Optogenetic inactivation of Zelda during regeneration disrupted patterning, induced cell fate errors, and caused morphological defects yet had no effect on normal wing development. Using Cleavage Under Targets & Release Using Nuclease, this study identified targets of Zelda important for the end of regeneration, including genes that control wing margin and vein specification, compartment identity, and cell adhesion. GAGA factor and Fork head similarly coordinate patterning after regeneration, and chromatin regions bound by Zelda increase in accessibility during regeneration. Thus, Zelda orchestrates the transition from regeneration to normal gene expression, highlighting a fundamental difference between developmental and regeneration patterning in the wing disc. | Campbell, J. B., Shingelton, A. W., Greenlee, K. J., Gray, A. E., Smith, H. C., Callier, V., Lundquist, T., Harrison, J. F. (2024). HIF-signaling in the prothoracic gland regulates growth and development in hypoxia but not normoxia in Drosophila. The Journal of experimental biology, PubMed ID: 39206603
Summary: The developmental regulation of body size is a fundamental life-history characteristic that in most animals is tied to the transition from juvenile to adult form. In holometabolous insects this transition is ostensibly initiated at the attainment of a critical weight in the final larval instar. It has been hypothesized that the size-sensing mechanism used to determine attainment of critical weight exploits oxygen limitation as a larvae grows beyond the oxygen-delivery capacity of its fixed tracheal system; that is, developmentally-induced cellular hypoxia initiates the synthesis of the molting hormone ecdysone by the prothoracic gland. This hypothesis was in Drosophila by assaying cellular hypoxia throughout the third-larval instar at 21 and 10 kPa O2, using the activity of the HIF-signalling pathway as a measure of hypoxia. While HIF-signalling was elevated at low levels of environmental O2 it did not markedly increase during development at either oxygen level, and was only suppressed by hyperoxia after feeding had ceased. Further, changes in HIF-signalling in the prothoracic gland alone did not alter body size or developmental time in a way that would be expected if cellular hypoxia in the prothoracic gland was part of the critical weight mechanism. These data do show, however, that reduced HIF-signalling in the prothoracic gland decreases survival and retards development at 10 kPa O2, suggesting that prothoracic HIF-signaling is a necessary part of the beneficial plasticity mechanism that controls growth and development in response to low oxygen level. |
Friday August 1st - Gonads |
| Zhang, R., Shi, P., Xu, S., Ming, Z., Liu, Z., He, Y., Dai, J., Matunis, E., Xu, J., Ma, Q. (2024). Soma-germline communication drives sex maintenance in the Drosophila testis. National science review, 11(8):nwae215 PubMed ID: 39183747
Summary: In adult gonads, disruption of somatic sexual identity leads to defective gametogenesis and infertility. However, the underlying mechanisms by which somatic signals regulate germline cells to achieve proper gametogenesis remain unclear. In a previous study, the chinmoSex Transformation) (chinmoST) mutant Drosophila testis phenotype was introduced as a valuable model for investigating the mechanisms underlying sex maintenance. In chinmoST testes, depletion of the Janus Kinase-Signal Transducer and Activator of Transcription downstream effector Chinmo from somatic cyst stem cells (CySCs) feminizes somatic cyst cells and arrests germline differentiation. This study usef single-cell RNA sequencing to uncover chinmoST -specific cell populations and their transcriptomic changes during sex transformation. Comparative analysis of intercellular communication networks between wild-type and chinmoST testes revealed disruptions in several soma-germline signaling pathways in chinmoST testes. Notably, the insulin signaling pathway exhibited significant enhancement in germline stem cells (GSCs). Chinmo cleavage under targets and tagmentation (CUT&Tag) assay revealed that Chinmo directly regulates two male sex determination factors, doublesex (dsx) and fruitless (fru), as well as Ecdysone-inducible gene L2 (ImpL2), a negative regulator of the insulin signaling pathway. Further genetic manipulations confirmed that the impaired gametogenesis observed in chinmoST testes was partly contributed by dysregulation of the insulin signaling pathway. In summary, this study demonstrates that somatic sex maintenance promotes normal spermatogenesis through Chinmo-mediated conserved sex determination and the insulin signaling pathway. This work offers new insights into the complex mechanisms of somatic stem cell sex maintenance and soma-germline communication at the single-cell level. Additionally, these discoveries highlight the potential significance of stem cell sex instability as a novel mechanism contributing to testicular tumorigenesis. | Anderson, M. T., Horne-Badovinac, S. (2025). A complex relationship between the architecture of the basement membrane, its mechanical properties, and its ability to shape the Drosophila egg. Matrix Biol, PubMed ID: 40518025
Summary: Basement membranes (BMs) are planar extracellular matrices that line the basal surfaces of epithelia and are essential components of most organs. During development, BMs can also play instructive roles in shaping the tissues to which they belong, but how they do so is incompletely understood. The Drosophila egg chamber has become a premier system to study this aspect of BM biology due to the ostensible simplicity of the BM's role in morphogenesis. The prevailing model posits that the egg chamber outer layer of epithelial cells creates a symmetric stiffness gradient in the surrounding BM that preferentially channels egg chamber growth along one axis to create the elongated shape of the egg. There is evidence that the stiffening of the BM depends, in part, on a polarized array of fibrils that form within the BM network, and yet the exact role the BM fibrils play in egg chamber elongation has remained unclear. This study used genetic conditions that abrogate fibril formation to different extents to probe the relationship between the BM's fibril content, its mechanical properties, and the shape of the egg. The results of these experiments are consistent with a model in which BM fibrils influence egg shape by directly augmenting the mechanical properties of the BM. However, this study then examined a final genetic condition that does not fit this simple narrative. It is proposed that the role of the BM in conferring final egg shape is more complicated than previously thought and that some approaches used to study this role should be re-evaluated for their efficacy. |
| Bischoff, M. C., Norton, J. E., Clark, S. E., Peifer, M. (2025). Plexin/Semaphorin antagonism orchestrates collective cell migration and organ sculpting by regulating epithelial-mesenchymal balance. Sci Adv, 11(25):eadu3741 PubMed ID: 40532000
Summary: Cell behavior emerges from the intracellular distribution of properties such as protrusion, contractility, and adhesion. Thus, characteristic emergent rules of collective migration can arise from cell-cell contacts locally tweaking architecture, orchestrating self-regulation during development, wound healing, and cancer progression. The Drosophila testis-nascent-myotube system allows dissection of contact-dependent migration in vivo at high resolution. This study describes a role for the axon guidance factor Plexin A in collective cell migration: maintaining cell-cell interfaces at a precise point on the mesenchymal-to-epithelial continuum. This is crucial for testis myotubes (muscle cells that migrate from the genital disc onto the developing testes during metamorphosis) to migrate as a continuous sheet, allowing normal sculpting-morphogenesis. Cells must maintain filopodial N-cadherin-based junctions and remain ECM-tethered near cell-cell contacts to spread while collectively moving. These data further suggest Semaphorin 1b is a Plexin A antagonist, fine-tuning activation. This reveals a contact-dependent mechanism to maintain sheet integrity during migration, driving organ morphogenesis. This is relevant for mesenchymal organ sculpting in other migratory contexts such as angiogenesis. | Andreatta, G., Montagnese, S., Costa, R. (2025). Cold-Sensing TRP Channels and Temperature Preference Modulate Ovarian Development in the Model Organism Drosophila melanogaster. Int J Mol Sci, 26(12) PubMed ID: 40565102
Summary: Temperature is perceived primarily via transient receptor potential (TRP) channels, which are integral to the molecular machinery sensing environmental and cellular signals. Functional evidence of TRP channel involvement in regulating cold-induced developmental/reproductive responses remains scarce. This study shows that mutations affecting cold-sensing TRP channels antagonize the reduction in development induced by low temperatures (reproductive dormancy) in Drosophila melanogaster. More specifically, mutants for brv1, trp, and trpl significantly lowered dormancy levels at 12 °C and exhibited well-developed oocytes characterized by advanced vitellogenesis. Similarly, functional knockouts for norpA, a gene encoding a phospholipase C acting downstream to Trp and Trpl, exhibited a reduced dormancy response, suggesting that Ca(2+) signaling is key to relaying cold-sensing stimuli during dormancy induction and maintenance. Finally, mutants with an altered temperature preference (i.e., exhibiting impaired cold or warm avoidance) differentially responded to the cold, either lowering or increasing dormancy levels. In summary, this phenotypic analysis provides functional evidence of developmental/reproductive modulation by specific cold-sensing TRP channels in Drosophila melanogaster and indicates that temperature preference affects developmental processes. |
| Martin-Diaz, J., Herrera, S. C. (2024). A stem cell activation state coupling spermatogenesis with social interactions in Drosophila males. Cell Rep, 43(8):114647 PubMed iD: 39153199
Summary: Reproduction is paramount to animals. For it to be successful, a coordination of social behavior, physiology, and gamete production is necessary. How are social cues perceived and how do they affect physiology and gametogenesis? While females, ranging from insects to mammals, have provided multiple insights about this coordination, its existence remains largely unknown in males. By using the Drosophila male as a model, this study described a phenomenon by which the availability of potential mating partners triggers an activation state on the stem cell populations of the testis, boosting spermatogenesis. Reliance of spermatogenesis on pheromonal communication, even in the absence of mating or other interactions with females was identified. Finally, the interorgan communication signaling network responsible-muscle-secreted tumor necrosis factor alpha (TNF-α)/Eiger and neuronally secreted octopamine trigger, respectively, the Jun N-terminal kinase (JNK) pathway and a change in calcium dynamics in the cyst stem cells. As a consequence, germ line stem cells increase their proliferation. | Miao, Y. H., Dou, W. H., Liu, J., Huang, D. W., Xiao, J. H. (2024). Single-cell transcriptome sequencing reveals that Wolbachia induces gene expression changes in Drosophila ovary cells to favor its own maternal transmission. mBio:e0147324 PubMed ID: 39194189
Summary: Wolbachia is an obligate endosymbiont that is maternally inherited and widely distributed in arthropods and nematodes. It remains in the mature eggs of female hosts over generations through multiple strategies and manipulates the reproduction system of the host to enhance its spreading efficiency. However, the transmission of Wolbachia within the host's ovaries and its effects on ovarian cells during oogenesis, have not been extensively studied. Single-cell RNA sequencing was used to comparatively analyze cell-typing and gene expression in Drosophila ovaries infected and uninfected with Wolbachia. The findings indicate that Wolbachia significantly affects the transcription of host genes involved in the extracellular matrix, cytoskeleton organization, and cytomembrane mobility in multiple cell types, which may make host ovarian cells more conducive for the transmission of Wolbachia from extracellular to intracellular. Moreover, the genes nos and orb, which are related to the synthesis of ribonucleoprotein complexes, are specifically upregulated in early germline cells of ovaries infected with Wolbachia, revealing that Wolbachia can increase the possibility of its localization to the host oocytes by enhancing the binding with host ribonucleoprotein-complex processing bodies (P-bodies). All these findings provide novel insights into the maternal transmission of Wolbachia between host ovarian cells. |
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