Zhong Huaming, Shang Shuai, Wu Xiaoyang, Chen Jun, Zhu Wanchao, Yan Jiakuo, Li Haotian, Zhang Honghai
College of Life Science, Qufu Normal University, Qufu, Shandong, China.
Ocean University of China, College of Marine Life Sciences, Qingdao, Shandong, China.
PeerJ. 2017 Aug 18;5:e3708. doi: 10.7717/peerj.3708. eCollection 2017.
As nontraditional model organisms with extreme physiological and morphological phenotypes, snakes are believed to possess an inferior taste system. However, the bitter taste sensation is essential to distinguish the nutritious and poisonous food resources and the genomic evidence of bitter taste in snakes is largely scarce. To explore the genetic basis of the bitter taste of snakes and characterize the evolution of bitter taste receptor genes (s) in reptiles, we identified genes in 19 genomes (species) corresponding to three orders of non-avian reptiles. Our results indicated contractions of gene repertoires in snakes, however dramatic gene expansions have occurred in lizards. Phylogenetic analysis of the s with NJ and BI methods revealed that genes of snake species formed two clades, whereas in lizards the genes clustered into two monophyletic clades and four large clades. Evolutionary changes (birth and death) of intact genes in reptiles were determined by reconciliation analysis. Additionally, the taste signaling pathway calcium homeostasis modulator 1 () gene of snakes was putatively functional, suggesting that snakes still possess bitter taste sensation. Furthermore, Phylogenetically Independent Contrasts (PIC) analyses reviewed a significant correlation between the number of genes and the amount of potential toxins in reptilian diets, suggesting that insectivores such as some lizards may require more s genes than omnivorous and carnivorous reptiles.
作为具有极端生理和形态表型的非传统模式生物，蛇被认为拥有较差的味觉系统。然而，苦味感觉对于区分营养和有毒食物资源至关重要，而蛇类苦味的基因组证据在很大程度上是稀缺的。为了探索蛇类苦味的遗传基础并表征爬行动物中苦味受体基因的进化，我们在对应于三个非鸟类爬行动物目的19个基因组（物种）中鉴定了基因。我们的结果表明蛇类基因库收缩，然而蜥蜴中发生了显著的基因扩张。用NJ和BI方法对这些基因进行系统发育分析表明，蛇类物种的基因形成两个分支，而在蜥蜴中，这些基因聚集成两个单系分支和四个大分支。通过和解分析确定了爬行动物中完整基因的进化变化（产生和消亡）。此外，蛇类的味觉信号通路钙稳态调节剂1（）基因被推测具有功能，这表明蛇仍然具有苦味感觉。此外，系统发育独立对比（PIC）分析表明，基因数量与爬行动物饮食中潜在毒素的量之间存在显著相关性，这表明一些蜥蜴等食虫动物可能比杂食性和肉食性爬行动物需要更多的基因。
