Sugar receptors in Drosophila

Area of Science:

• * Neuroscience and Sensory Biology
• * Molecular and Cellular Biology
• * Animal Behavior

Background:

• * Animals rely on taste to identify food sources and avoid toxins.
• * Fruit flies (Drosophila melanogaster) possess 68 gustatory receptors (GRs) for detecting diverse chemicals.
• * The specific functions of most GRs in feeding behavior remain largely uncharacterized.

Purpose of the Study:

• * To investigate the role of the Gr64 gene family in sugar detection in Drosophila.
• * To determine if Gr64 genes encode receptors for common dietary sugars.
• * To explore the molecular mechanisms underlying gustatory receptor function.

Main Methods:

• * Generation of a Drosophila melanogaster strain with a deletion of all six Gr64 genes (DeltaGr64).
• * Assessment of the proboscis extension reflex (PER) in mutant flies upon stimulation with various sugars.
• * Analysis of gene transcription patterns, including polycistronic mRNA expression.

Main Results:

• * DeltaGr64 mutant flies showed significantly reduced or absent PER responses to glucose, maltose, and sucrose.
• * A notable response to fructose was observed in Gr64 mutant flies.
• * Trehalose detection was abolished in Gr64 mutants, even with a functional Gr5a gene, indicating a requirement for multiple GRs.

Conclusions:

• * The Gr64 gene family encodes receptors responsible for detecting a variety of sugars in Drosophila.
• * Gustatory receptors likely function as multimeric complexes, as evidenced by trehalose detection.
• * Polycistronic mRNA transcription provides a mechanism for co-expressing multiple sugar receptors in taste neurons.