Symbiotic microorganisms exert multifaceted impacts on the physiology of their animal hosts. Recent discoveries have shown the gut microbiota influence host brain function and behavior, but the host and microbial molecular factors required to actuate these effects are largely unknown. To uncover molecular mechanisms that underlie the gut-microbiota-brain axis, we used Drosophila melanogaster and its bacterial microbiota as a model to identify microbiota-dependent gene expression changes in the host brain and head. Specifically, we employed RNA-seq and nanoString nCounter technology to identify Drosophila genes that exhibit altered transcript levels in fly heads upon elimination of the microbiota. The identified genes, some of which exhibited sex-specific differences, have demonstrated or inferred functional roles in the immune response, metabolism, neuronal activity, and stress resistance. Overall, this study reveals microbiota-responsive genes in the fly head, an anatomical structure not previously investigated in this context. Our results serve as a foundation for future investigations of how microbe-driven gene expression changes impact Drosophila biology.

Symbiotic microorganisms exert multifaceted impacts on the physiology of their animal hosts. Recent discoveries have shown the gut microbiota influence host brain function and behavior, but the host and microbial molecular factors required to actuate these effects are largely unknown. To uncover molecular mechanisms that underlie the gut-microbiota-brain axis, we usedDrosophila melanogasterand its bacterial microbiota as a model to identify microbiota-dependent gene expression changes in the host brain and head. Specifically, we employed RNA-seq and nanoString nCounter technology to identifyDrosophilagenes that exhibit altered transcript levels in fly heads upon elimination of the microbiota. The identified genes, some of which exhibited sex-specific differences, have demonstrated or inferred functional roles in the immune response, metabolism, neuronal activity, and stress resistance. Overall, this study reveals microbiota-responsive genes in the fly head, an anatomical structure not previously investigated in this context. Our results serve as a foundation for future investigations of how microbe-driven gene expression changes impactDrosophilabiology.

The gut microbiota impacts diverse aspects of host biology including metabolism, immunity, and behavior, but the scope of those effects and their underlying molecular mechanisms are poorly understood. To address these gaps, we used Two-dimensional Difference Gel Electrophoresis (2D-DIGE) to identify proteomic differences in male and female Drosophila heads raised with a conventional microbiota and those raised in a sterile environment (axenic). We discovered 22 microbiota-dependent protein differences, and identified a specific elevation in Alcohol Dehydrogenase (ADH) in axenic male flies. Because ADH is a key enzyme in alcohol metabolism, we asked whether physiological and behavioral responses to alcohol were altered in axenic males. Here we show that alcohol induced hyperactivity, the first response to alcohol exposure, is significantly increased in axenic males, requires ADH activity, and is modified by genetic background. While ADH activity is required, we did not detect significant microbe-dependent differences in systemic ADH activity or ethanol level. Like other animals, Drosophila exhibit a preference for ethanol consumption, and here we show significant microbiota-dependent differences in ethanol preference specifically in males. This work demonstrates that male Drosophila’s association with their microbiota affects their physiological and behavioral responses to ethanol.

The actin cortex that lines the plasma membrane of most eukaryotic cells resists external mechanical forces and plays critical roles in a variety of cellular processes including morphogenesis, cytokinesis, and cell migration. Despite its ubiquity and significance, we understand relatively little about the composition, dynamics, and structure of the actin cortex. Adenomatous polyposis coli (APC) proteins regulate the actin and microtubule cytoskeletons through a variety of mechanisms, and in some contexts, APC proteins are cortically enriched. Here we show that APC2 regulates cortical actin dynamics in the follicular epithelium and the nurse cells of the Drosophila ovary and in addition affects the distribution of cortical actin at the apical side of the follicular epithelium. To understand how APC2 influences these properties of the actin cortex, we investigated the mechanisms controlling the cortical localization of APC2 in S2 cultured cells. We previously showed that the N-terminal half of APC2 containing the Armadillo repeats and the C-terminal 30 amino acids (C30) are together necessary and sufficient for APC2's cortical localization. Our work presented here supports a model that cortical localization of APC2 is governed in part by self-association through the N-terminal APC Self-Association Domain (ASAD) and a highly conserved coiled-coil within the C30 domain.