Alisson Marques Gontijo

Mutations and polymorphisms in the Rho guanine nucleotide exchange factor 10 (ARHGEF10) locus are associated with behavioral and locomotor dysfunctions in humans, including psychiatric disorders and polyneuropathies that show age- and sex-specific prevalence. ARHGEF10 encodes a conserved guanine exchange factor that activates Rho GTPases and has proposed roles in cell migration and adhesion, but the relevant cell types and mechanisms underlying its age- and sex-dependent effects remain unclear. Drosophila darhgef10 gene is the single orthologue of vertebrate ARHGEF10 and its paralogue ARHGEF10L. Here, to gain insight into possible age- and sex-dependent ARHGEF10 neuromuscular functions, we generated darhgef10 knockout flies and quantified induced walking kinematics with high-speed imaging and coarse spontaneous behaviors—walking, micromovements, and sleep—in open arenas. Mutants of both sexes exhibited abnormal walking kinematics, which worsened with age in females. Cell-type-specific knockdowns indicated these phenotypes arose primarily from neuronal, rather than glial or muscle, requirements. Loss of darhgef10 also caused sexually dimorphic neurodevelopmental and post-adult-onset behavioral effects: females were more susceptible to total darhgef10 reduction, showing decreased wakefulness and speed. In contrast, darhgef10 isoform imbalance—rather than total loss—drove stronger locomotor effects in males, suggesting complex activity regulation. These sexually dimorphic effects were also largely explained by neuronal darhgef10 activity. Accordingly, dArhgef10 expression was detected in the developing nervous system, where motor neuron-targeted knockdown demonstrated a cell-autonomous requirement in establishing adult muscle innervation patterns. ARHGEF10 thus plays an ancient, conserved role in neurons that promotes proper wakefulness and locomotor activity in an age- and sex-dependent manner.

Maintaining organismal homeostasis requires mechanisms that coordinate the metabolic needs of individual organs with whole animal nutrient intake. Although nutrient sensors and central pathways regulating hunger have been extensively characterized, how peripheral organ physiology influences nutrient specific appetites remains poorly understood. Here, we identify a previously unrecognized signalling axis, originated in the ovary, that modulates yeast appetite in Drosophila melanogaster . Through a targeted germline RNAi screen, we find that specific perturbations in oogenesis consistently and selectively increase yeast appetite. The manipulations increasing yeast appetite disrupt oogenesis progression, producing a shared signature of increased vitellogenic follicle accumulation and reduced number of mature (stage14) oocytes. This shift is accompanied by decreased expression of the relaxin-like hormone Dilp8, and loss of Dilp8 recapitulates the feeding phenotype. We show that this ovarian regulation of nutrient specific appetite is independent of amino acid state but requires mating, indicating integration with Sex Peptide–mediated reproductive activation. Together, our findings uncover a novel mechanism that couples oogenesis progression to nutrient selection, emphasizing the importance of the ovary as an active regulator of whole organism nutritional decisions. This work provides a conceptual framework for how reproductive tissues communicate their physiological demands to other organs and raises the possibility that analogous ovary-derived signals may shape nutrient specific appetite and metabolic states in other animals. Graphical Created in BioRender. Francisco, A. (2026) https://BioRender.com/pwalhtl

Ovulation enables mature oocytes to exit the ovary for potential fertilization. In Drosophila, ovulation is induced by mating but also occurs spontaneously in virgins, with rates varying widely in natural populations: short oocyte retention is ancestral, while longer retention is favored in colder climates. The molecular regulation of spontaneous ovulation remains unclear. Here, we show that disrupting the relaxin/insulin-like peptide Dilp8 or its receptor Lgr3 (an ortholog of vertebrate RXFP1/2) in follicle cells or specific neurons, respectively, delays ovulation, slows average egg transit time in the reproductive tract, and facilitates oogenesis progression beyond approximately two mature oocytes per ovariole, leading to mature follicle accumulation in the ovary. Mating largely rescues these defects, suggesting the pathway is dispensable post-mating. Dilp8-Lgr3 signaling ensures high oocyte quality by promoting elimination of lower-quality aging oocytes and by antagonizing oogenesis progression via an undefined mechanism downstream of Lgr3-positive neurons. Our findings provide a molecular basis for oocyte retention time regulation in Drosophila involving ovarian-nervous system cross-talk, and bring further support for an ancient, conserved role for relaxin-like signaling in regulating ovulation and overall female reproductive physiology.

Mutations and polymorphisms in the Rho guanine nucleotide exchange factor 10 (ARHGEF10) locus are associated with behavioral and locomotor dysfunctions in humans, including psychiatric disorders and polyneuropathies that show age- and sex-specific prevalence. ARHGEF10 encodes a conserved guanine exchange factor that activates Rho GTPases and has proposed roles in cell migration and adhesion, but the relevant cell types and mechanisms underlying its age- and sex-dependent effects remain unclear. Drosophila darhgef10 gene is the single orthologue of vertebrate ARHGEF10 and its paralogue ARHGEF10L . Here, to gain more direct insight into possible age- and sex-dependent ARHGEF10 neuromuscular functions, we generated darhgef10 knock-out flies and quantified induced walking kinematics with high-speed imaging and coarse spontaneous behaviors—walking, micromovements, rest, and sleep—in open arenas. Mutants of both sexes exhibited abnormal walking kinematics, which worsened with age in females. Cell-type-specific knockdowns indicated that locomotor phenotypes arose primarily from neuronal, rather than glial or muscle, requirements. dArhgef10 was especially critical in glutamatergic motor neurons of aged females. dArhgef10 was also required for wakefulness and activity initiation in females but, surprisingly, not in males. Genetic rescue and isoform expression analyses suggested that sexually-dimorphic expression of long isoforms RC and/or RD underlies at least part of the sex-specific requirements of dArhgef10 in locomotor behavior control, revealing unanticipated complexity in its activity regulation. Collectively, our results suggest ARHGEF10 plays an ancient, conserved role in neurons that promotes proper wakefulness and locomotor activity in an age- and sex-dependent manner.

mariner is a transposable element of the Tc1/mariner superfamily that is widely distributed in various species. It was discovered in Drosophila mauritiana owing to a white-peach eye color mutation, and since then it has been used as a research tool in many systems and species. mariner element mobilization consists of cut-and-paste transposon excision and insertion. Here, apart from giving a historical overview of the discovery, distribution, and classification of mariner elements, we address the factors responsible for their particularly high somatic mobilization activity, with a focus on stress responses. We also address the usage of mariner transposases as research tools and how somatic mobilization can currently be detected.

Ovulation allows mature oocytes to exit the ovary for potential fertilization. In Drosophila , ovulation can be induced by mating or occur spontaneously in lower amounts in virgin females. Virgin ovulation rates show high populational variation, with short oocyte retention times being ancestral, and long retention being selected for in colder climates. The molecular mechanisms controlling virgin ovulation rates are poorly understood. Here, we show that reduced activity of the Drosophila insulin-like peptide 8 (Dilp8), a relaxin-like peptide secreted from terminal follicle cells of the ovary, slows virgin ovulation and ovulated egg genital tract transit by a factor of ∼5-6. These phenotypes are largely rescued by mating, suggesting other mechanisms override the Dilp8-Lgr3 pathway post-mating. Knockdown of the Dilp8 receptor, Lgr3— an orthologue of vertebrate relaxin RXFP1/2 receptors—in at least two subsets of reproductive-tract-innervating neurons, one of which are octopaminergic, produces similar phenotypes. Dilp8-Lgr3 signaling in virgin females ensures high oocyte quality by promoting the elimination of aging oocytes and by systemically antagonizing insulin signaling, which is critical for oogenesis progression beyond previtellogenic stages. We hypothesize this latter Dilp8 activity factors in oocyte stock size in the nutrient-availability-based decision to invest in producing more oocytes or not, ensuring oocyte overstocking in virgins only occurs in highly favorable nutritional conditions. Our findings provide a molecular basis for oocyte retention time regulation in Drosophila virgins, and bring further support for an ancient, conserved role for relaxin-like signaling in regulating ovulation and overall female reproductive physiology. Significance statement: Ovulation enables mature oocytes to exit the ovary for potential fertilization. In Drosophila , ovulation is induced by mating but also occurs spontaneously in virgins, with rates varying widely in natural populations: short oocyte retention is ancestral, while longer retention is favored in colder climates. The molecular regulation of virgin ovulation remains unclear. Here, we show that disrupting the Drosophila relaxin/insulin-like peptide Dilp8 or its receptor Lgr3—an orthologue of vertebrate RXFP1/2—in follicle cells or specific neurons delays ovulation, slows egg transit, and reduces oocyte quality. Mating largely rescues these defects, suggesting the pathway is dispensable post-mating. Our findings reveal a molecular mechanism for oocyte retention in Drosophila virgins and support an ancient, conserved role for relaxin-like signaling in ovulation.

At the end of their growth phase, Drosophila larvae remodel their bodies, glue themselves to a substrate, and harden their cuticle in preparation for metamorphosis. This process—termed pupariation—is triggered by a surge in the hormone ecdysone. Substrate attachment is achieved by a pupariation subprogram called glue expulsion and spreading behavior (GSB). An epidermis-to-CNS Dilp8-Lgr3 relaxin signaling event that occurs downstream of ecdysone is critical for unlocking progression of the pupariation motor program toward GSB, but the factors and circuits acting downstream of Lgr3 signaling remain unknown. Here, using cell-type-specific RNA interference and behavioral monitoring, we identify Myoinhibiting peptide (Mip) as a neuromodulator of multiple GSB action components, such as tetanic contraction, peristaltic contraction alternation, and head-waving. Mip is required in a pair of brain descending neurons, which act temporally downstream of Dilp8-Lgr3 signaling. Mip modulates GSB via ventral nerve cord neurons expressing its conserved receptor, sex peptide receptor (SPR). Silencing of Mip descending neurons by hyperpolarization completely abrogates GSB, while their optogenetic activation at a restricted competence time window triggers GSB-like behavior. Hence, Mip descending neurons have at least two functions: to act as GSB command neurons and to secrete Mip to modulate GSB action components. Our results provide insight into conserved aspects of Mip-SPR signaling in animals, reveal the complexity of GSB control, and contribute to the understanding of how multistep innate behaviors are coordinated in time and with other developmental processes through command neurons and neuropeptidergic signaling.

The ability to achieve a species-specific size and proportion despite developmental or environmental perturbations is termed developmental stability. The molecular and cellular processes behind this are best understood in insects. In Drosophila, a peripheral-tissue stress signal, the relaxin/insulin-like peptide Dilp8, promotes developmental stability during larval development via its neuronal receptor, Lgr3, an ortholog of vertebrate relaxin receptors. Lgr3 signaling is widely accepted to occur in–and to activate (depolarize)–the central brain growth-coordinating interneurons (PIL/GCL neurons). Here, using neurogenetic approaches, we confirm the requirement of Lgr3 in PIL/GCL neurons, but unexpectedly find that they require both silenced (hyperpolarized) and active (depolarized) states for an appropriate response to Dilp8. These results are most simply explained if Lgr3 activation by Dilp8 triggers PIL/GCL-neuron oscillatory activity, and such oscillations promote developmental stability. PIL/GCL neurons express and require Cyclin A–which can form cell-cycle oscillator complexes with cyclin-dependent kinases–for their response to Dilp8, independently of Rca1 (regulator of CycA)/Emi1 (early mitotic inhibitor). This opens the possibility that cell-cycle machinery can be co-opted for postmitotic neuron oscillations, adding to an increasing list of postmitotic roles for cyclins. Neuroanatomically, we show that PIL/GCL neurons form reciprocally-innervating loops, which are common architectures in oscillating circuits and central pattern generators. The role of PIL/GCL neurons in developmental stability mirrors other homeostasis-regulating, peptide-driven oscillatory circuits found in the vertebrate hypothalamus, a developmentally-homologous region to the one occupied by PIL/GCL neurons in the fly brain.

At the end of their growth phase, Drosophila larvae remodel their bodies, firmly glue themselves to a substrate, and harden their cuticle in preparation for metamorphosis. This process is termed pupariation and it is triggered by a surge in the steroid hormone ecdysone. Substrate attachment is achieved by a recently-described pupariation subprogram called glue expulsion and spreading behavior (GSB). An epidermis-to-CNS Dilp8-Lgr3 relaxin signaling event that occurs downstream of ecdysone after pupariation initiation is critical for unlocking progression of the pupariation motor program towards GSB, but the factors and circuits acting downstream of Lgr3 signaling remain unknown. Here, we screened for such factors using cell type-specific RNA interference (RNAi) and behavioral monitoring. We identify Myoinhibiting peptide (Mip) and its highly conserved neuronal receptor, Sex peptide receptor (SPR), as a critical neuropeptidergic signaling pathway required to trigger and modulate multiple action components of GSB. In addition, we find that Mip is specifically required in a pair of descending neurons, whose optogenetic activation at a specific competence window triggers GSB-like behavior and whose neurogenetic silencing completely abrogates GSB without overtly affecting other pupariation components. This strongly suggests that these descending Mip neurons are developmentally-regulated GSB command neurons. Dissection of the GSB action components via muscle calcium-level monitoring coupled with cell-type specific RNAi indicates that Mip acts on multiple SPR-positive neuronal populations, which collectively define and pattern the sequence and timing of GSB actions. Hence, we have identified a pair of descending command neurons that utilize both synaptic transmission and neuropeptidergic signaling to trigger and modulate a complex innate behavior in Drosophila . Our results advance our molecular and cellular understanding of pupariation control, reveal the complexity of glue expulsion and spreading behavior control, provide insight into conserved aspects of Mip-SPR signaling in animals, and contribute to the understanding of how multi-step innate behaviors are coordinated in time and with other developmental processes through command neurons and neuropeptidergic signaling.