Identification and functional expression of putative gustatory receptor genes among mega and micro bats
Taste, a form of chemoreception among invertebrates and vertebrates provide dietary information and is crucial for survival. All tastes contribute to a combination of five basic modalities: sweet, bitter, salty, sour and umami. Upon chemical stimulation, each of these tastes that are mediated by receptors, detect variety of substances ranging from simple ions to complex organic molecules. Molecular studies reveal that the TAS1R gene repertoire constitutes three genes, namely, TAS1R1, TAS1R2, and TAS1R3. These genes are expressed in mammals as Class C G-protein coupled receptors, out of which TAS1R2 and TAS1R3 form heterodimeric complexes to function as sweet taste receptor, while TAS1R2 is found to be the sole sweet-specific taste receptor in mammals. Therefore, our study is mainly focused on the sweet taste specific receptor gene TAS1R2 in bat species due to their diverse dietary preferences. By using bioinformatics approach, we have identified that bats TAS1R2 gene shares 80-98% sequence homology and similar domain organization with mouse, chimpanzee and human. Taking the above information into account, we find TAS1R2 gene as an interesting candidate to investigate the role and expression pattern in bats with the following objectives 1) To identify the expression pattern of gustatory receptor gene in different bat species and 2) To understand the molecular mechanism of gustatory receptor gene in bats. This proposed work employs integrated disciplines including behaviour, molecular biology and luciferase reporter assay to unravel taste signal transduction and to comprehensively understand the genes involved in gustation.
Keywords: bats, gustatory receptors, GPCR, TAS1R2 gene