Publications - Page 3/3

The detection and discrimination of chemical compounds in potential foods are essential sensory processes when animals feed The fruit fly Drosophila melanogaster employs 68 different gustatory receptors GRs for the detection of mostly nonvolatile chemicals that include sugars a diverse group of toxic compounds present in many inedible plants and spoiled foods and pheromones 1-6 With the exception of a trehalose GR5a and a caffeine GR66a receptor 7-9 the functions of GRs involved in feeding are unknown Here we show that the Gr64 genes encode receptors for numerous sugars We generated a fly strain that contained a deletion for all six Gr64 genes DeltaGr64 and showed that these flies exhibit no or a significantly diminished proboscis extension reflex PER response when stimulated with glucose maltose sucrose and several other sugars The only considerable response was detected when Gr64 mutant flies were stimulated with fructose Interestingly response to trehalose is also abolished in these flies even though they contain a functional Gr5a gene which has been previously shown to encode a receptor for this sugar 8 9 This observation indicates that two or more Gr genes are necessary for trehalose detection suggesting that GRs function as multimeric receptor complexes Finally we present evidence that some members of the Gr64 gene family are transcribed as a polycistronic mRNA providing a mechanism for the coexpression of multiple sugar receptors in the same taste neurons

Sugar receptors in Drosophila.