L. Dunipace et al., Spatially restricted expression of candidate taste receptors in the Drosophila gustatory system, CURR BIOL, 11(11), 2001, pp. 822-835
Background: Taste is an important sensory modality in most animals. In Dros
ophila, taste is perceived by gustatory neurons located in sensilla distrib
uted on several different appendages throughout the body of the animal. Her
e we show that the gustatory receptors are encoded by a family of at least
54 genes (GF genes), most of which are expressed exclusively in a small sub
set of taste sensilla located in narrowly defined regions of the fly's body
.
Results: BLAST searches with the predicted amino acid sequences of 6 7-tran
smembrane-receptor genes of unknown function and 20 previously identified,
putative gustatory receptor genes led to the identification of a large gene
family comprising at least 54 genes, We investigated the expression of eig
ht genes by using a Gal4 reporter gene assay and found that five of them we
re expressed in the gustatory system of the fly, Four genes were expressed
in 1%-4% of taste sensilla, located in well-defined regions of the probosci
s, the legs, or both, The fifth gene was expressed in about 20% of taste se
nsilla in all major gustatory organs, including the taste bristles on the a
nterior wing margin. Axon-tracing experiments demonstrated that neurons exp
ressing a given Gr gene project their axons to a spatially restricted domai
n of the subesophageal ganglion in the fly brain.
Conclusions: Our findings suggest that each taste sensillum represents a di
screte, functional unit expressing at least one Gr receptor and that most G
r genes are expressed in spatially restricted domains of the gustatory syst
em. These observations imply the potential for high taste discrimination of
the Drosophila brain.