Lineage‐specific duplication and adaptive evolution of bitter taste receptor genes in bats

Abstract

By generating raw genetic material and diverse biological functions, gene duplication represents a major evolutionary mechanism that is of fundamental importance in ecological adaptation. The lineage-specific duplication events of bitter taste receptor genes (Tas2rs) have been identified in a number of vertebrates, but functional evolution of new Tas2r copies after duplication remains largely unknown. Here, we present the largest data set of bat Tas2rs to date, identified from existing genome sequences of 15 bat species and newly sequenced from 17 bat species, and demonstrate lineage-specific duplications of Tas2r16, Tas2r18 and Tas2r41 that only occurred in Myotis bats. Myotis bats are highly speciose and represent the only mammalian genus that is naturally distributed on every continent except Antarctica. The occupation of such diverse habitats might have driven the Tas2r gene expansion. New copies of Tas2rs in Myotis bats have shown molecular adaptation and functional divergence. For example, three copies of Tas2r16 in Myotis davidii showed differential sensitivities to arbutin and salicin that may occur in their insect prey, as suggested by cell-based functional assays. We hypothesize that functional differences among Tas2r copies in Myotis bats would increase their survival rate through preventing the ingestion of an elevated number of bitter-tasting dietary toxins from their insect prey, which may have facilitated their adaptation to diverse habitats. Our study demonstrates functional changes of new Tas2r copies after lineage-specific duplications in Myotis bats and highlights the potential role of taste perception in exploiting new environments.

Origin and evolution of the major histocompatibility complex class I region in eutherian mammals

“…To obtain the MHCI repertoire for the target species, each genome sequence was analyzed by using an automatic pipeline developed in our laboratory, as described elsewhere (Feng, Zheng, Rossiter, Wang, & Zhao, ; Hong & Zhao, ; Jiao, Wang, Zhang, Jiang, & Zhao, ; Wang & Zhao, ). Briefly, we used full‐length MHCI protein sequences from the human, horse, and bats as queries in TBLASTN searches against each genome assembly, with a cutoff E‐value of 10 −10 .…”

“…To obtain the MHCI repertoire for the target species, each genome sequence was analyzed by using an automatic pipeline developed in our laboratory, as described elsewhere (Feng, Zheng, Rossiter, Wang, & Zhao, 2014;Hong & Zhao, 2014;Jiao, Wang, Zhang, Jiang, & Zhao, 2018;Wang & Zhao, 2015…”

Structure-Function Analyses of Human Bitter Taste Receptors—Where Do We Stand?

“…While the functional profiling of bitter taste receptors in the early years after their discovery was somewhat biased towards human TAS2Rs [ 16 ], more recently other vertebrates’ receptors were more avidly investigated. To date, we know at least one bitter agonist for 21 of the 25 human TAS2Rs [ 16 ], 21 of 35 mouse Tas2rs [ 19 ] and we have such information for several bird species [ 18 ], the domestic cat [ 20 , 21 ], rat [ 22 , 23 ], frog [ 18 ], fish [ 24 ], bat [ 25 ] and some primates [ 26 , 27 , 28 , 29 , 30 , 31 ].…”

Metal Ions Activate the Human Taste Receptor TAS2R7

“…Humans possess 25 functional TAS2Rs. However, the numbers of TAS2R genes vary greatly among mammalian species, ranging from 0 to 54 in amphibian, presumably correlating with the specific ecological niche of a species (Go et al 2005; Liman 2006; Shi and Zhang 2006; Jiang et al 2012; Feng et al 2014; Wang and Zhao 2015; Jiao et al 2018). Most human TAS2Rs have been deorphanized, and their receptive ranges are heterogeneous (Meyerhof et al 2010).…”