Department of Ecology, Tibetan Centre for Ecology and Conservation at WHU-TU, Hubei Key Laboratory of Cell Homeostasis, College of Life Sciences, Wuhan University, Wuhan, China.
Research Center for Ecology, College of Science, Tibet University, Lhasa, China.
Integr Zool. 2021 Sep;16(5):659-669. doi: 10.1111/1749-4877.12509. Epub 2020 Dec 12.
Bats represent the largest dietary radiation in a single mammalian order, and have become an emerging model group for studying dietary evolution. Taste receptor genes have proven to be molecular signatures of dietary diversification in bats. For example, all 3 extant species of vampire bats have lost many bitter taste receptor genes (Tas2rs) in association with their dietary shift from insectivory to sanguivory. Indeed, only 8 full-length Tas2rs were identified from the high-quality genome of the common vampire bat (Desmodus rotundus). However, it is presently unknown whether these bitter receptors are functional, since the sense of taste is less important in vampire bats, which have an extremely narrow diet and rely on other senses for acquiring food. Here, we applied a molecular evolutionary analysis of Tas2rs in the common vampire bat compared with non-vampire bats. Furthermore, we provided the first attempt to deorphanize all bitter receptors of the vampire bat using a cell-based assay. We found that all Tas2r genes in the vampire bat have a level of selective pressure similar to that in non-vampire bats, suggesting that this species must have retained some bitter taste functions. We demonstrated that 5 of the 8 bitter receptors in the vampire bat can be activated by some bitter compounds, and observed that the vampire bat generally can not detect naturally occurring bitter compounds examined in this study. Our study demonstrates functional retention of bitter taste in vampire bats as suggested by cell-based functional assays, calling for an in-depth study of extra-oral functions of bitter taste receptors.
蝙蝠代表了单目哺乳动物中最大的辐射性饮食，并且已经成为研究饮食进化的新兴模式群体。味觉受体基因已被证明是蝙蝠饮食多样化的分子特征。例如，所有 3 种现存的吸血蝙蝠都失去了许多苦味味觉受体基因（Tas2rs），与它们从食虫性转变为吸血性的饮食转变有关。事实上，从普通吸血蝙蝠（Desmodus rotundus）的高质量基因组中仅鉴定出 8 个全长 Tas2rs。然而，目前尚不清楚这些苦味受体是否具有功能，因为在吸血蝙蝠中，味觉的作用较小，它们的饮食非常狭窄，并且依靠其他感官来获取食物。在这里，我们对普通吸血蝙蝠与非吸血蝙蝠的 Tas2rs 进行了分子进化分析。此外，我们首次尝试使用基于细胞的测定法对吸血蝙蝠的所有苦味受体进行去孤儿化。我们发现吸血蝙蝠中的所有 Tas2r 基因都具有与非吸血蝙蝠相似的选择压力水平，这表明该物种必须保留了某些苦味功能。我们证明了吸血蝙蝠中的 8 个苦味受体中的 5 个可以被一些苦味化合物激活，并且观察到吸血蝙蝠通常无法检测到本研究中检查的天然存在的苦味化合物。我们的研究通过基于细胞的功能测定证明了吸血蝙蝠中苦味味觉的功能保留，这呼吁对苦味受体的口腔外功能进行深入研究。
