Biology subjects

Audette, K.

Publications and source records attributed to Audette, K..

3 recordsLinked to original sources

bioRxiv2025

Amino acids activate parallel chemosensory pathways in Drosophila

Amino acids (AAs) are essential dietary macronutrients that impact an organisms fitness in a concentration-dependent manner, but the mechanisms mediating AA detection to drive consumption are less clear. In Drosophila, we identified the full repertoire of taste cells and receptors involved in feeding initiation towards a glutamate-rich AA mixture, tryptone, using in vivo calcium imaging and the proboscis extension response (PER). We found that AA attraction occurs through sweet cells, whereas feeding aversion is mediated through Ionotropic Receptor 94e (IR94e) cells and bitter cells, dependent on concentration. Further, our results corroborate previous findings that ionotropic receptors IR76b, IR51b, and IR94e detect AAs in their respective cell types. Additionally, we describe a new role for the appetitive IR56d receptor and bitter gustatory receptors in detecting AAs. This work establishes a cellular and molecular framework of AA feeding initiation and highlights redundancy in aversive pathways that regulate AA feeding.

neuroscience↗

bioRxiv2025

Artificial sweeteners differentially activate sweet and bitter gustatory neurons in Drosophila

Artificial sweeteners are highly sweet, non-nutritive compounds that have become increasingly popular over recent decades despite research suggesting that their consumption has unintended consequences. Specifically, there is evidence suggesting that some of these chemicals interact with bitter taste receptors, implying that sweeteners likely generate complex chemosensory signals. Here, we report the basic sensory characteristics of sweeteners in Drosophila, a common model system used to study the impacts of diet, and find that all noncaloric sweeteners inhibited appetitive feeding responses at higher concentrations. At a cellular level, we found that sucralose and rebaudioside A co-activated sweet and bitter gustatory receptor neurons (GRNs), two populations that reciprocally impact feeding behavior, while aspartame only activated bitter cells. We assessed the behavioral impacts of sweet and bitter co-activation and found that low concentrations of sucralose signal appetitive feeding while high concentrations signal feeding aversion. Finally, silencing bitter GRNs reduced the aversive signal elicited by high concentrations of sucralose and significantly increased sucralose feeding behaviors. Together, we conclude that artificial sweeteners generate a gustatory signal that is more complex than "sweetness" alone, and this bitter co-activation has behaviorally relevant effects on feeding that may help flies flexibly respond to these unique compounds.

neuroscience↗

bioRxiv2024

Taste cells expressing Ionotropic Receptor 94e reciprocally impact feeding and egg laying in Drosophila

Chemosensory cells across the body of Drosophila melanogaster evaluate the environment and play a crucial role in neural circuits that prioritize feeding, mating, or egg laying. Previous mapping of gustatory receptor neurons (GRNs) on the fly labellum identified a set of neurons in L-type sensilla defined by expression of Ionotropic Receptor 94e (IR94e), but the impact of IR94e GRNs on behavior remained unclear. To understand their behavioral output, we used optogenetics and chemogenetics to activate IR94e neurons and found that they drive mild suppression of feeding but enhanced egg laying. In vivo calcium imaging revealed that IR94e GRNs respond strongly to certain amino acids, including glutamate. Furthermore, we found that IR94e is necessary and sufficient for the detection of amino acid ligands, and co-receptors IR25a and IR76b are also required for IR94e GRN activation. Finally, IR94e mutants show behavioral changes to solutions containing amino acids, including increased consumption and decreased egg laying. Overall, our results suggest that IR94e GRNs on the fly labellum discourage feeding and encourage egg laying as part of an important behavioral switch in response to certain chemical cues.

neuroscience↗