Complex evolutionary history of the vertebrate sweet/umami taste receptor genes
Complex evolutionary history of the vertebrate sweet/umami taste receptor genes
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DOI：
10.1007/s11434-013-5811-5
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发表时间：
2013-06-01
影响因子：
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通讯作者：
Zhao HuaBin
中科院分区：
文献类型：
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作者：
Feng Ping;Zhao HuaBin
适应性进化在味觉受体的功能分化和特化中起作用，味觉被认为与摄食生态密切相关。为了研究摄食生态是否塑造了脊椎动物味觉受体基因的进化，我们在这里重点研究了编码umami(Tas1r1和Tas1r3异源二聚体)和Sweet(Tas1r2和Tas1r3异源二聚体)味觉受体的Tas1r基因家族。通过搜索目前可用的48种脊椎动物的基因组序列，包括38种哺乳动物、1种爬行动物、3种鸟类、1种青蛙和5种鱼，我们发现Tas1Rs的三个成员在大多数物种中都是完整的，这表明大多数脊椎动物都保持着鲜味和甜味。有趣的是，在一些具有不同取食偏好和不同系统发育位置的物种中也发现了Tas1Rs的缺失和假基因，这表明无论它们的饮食如何，这些动物都普遍丧失了鲜味和/或甜味。连同之前显示其他脊椎动物味觉丧失的发现，我们未能确定可能导致味觉丧失的常见饮食因素。我们的结果报告表明，Tas1Rs的进化比我们以前认识到的要复杂得多，并强调了分析从草案基因组序列预测的序列的警告。未来更好地了解味觉受体功能的工作将有助于揭示是什么生态因素推动了脊椎动物Tas1r的进化史。
Adaptive evolution plays a role in the functional divergence and specialization of taste receptors and the sense of taste is thought to be closely related to feeding ecology. To examine whether feeding ecology has shaped the evolution of taste receptor genes in vertebrates, we here focus on Tas1r gene family that encodes umami (Tas1r1 and Tas1r3 heterodimer) and sweet (Tas1r2 and Tas1r3 heterodimer) taste receptors. By searching currently available genome sequences in 48 vertebrates that contain 38 mammals, 1 reptile, 3 birds, 1 frog, and 5 fishes, we found all three members of Tas1rs are intact in most species, suggesting umami and sweet tastes are maintained in most vertebrates. Interestingly, the absence and pseudogenization of Tas1rs were also discovered in a number of species with diverse feeding preferences and distinct phylogenetic positions, indicating widespread losses of umami and/or sweet tastes in these animals, irrespective of their diet. Together with previous findings showing losses of tastes in other vertebrates, we failed to identify common dietary factors that could result in the taste losses. Our results report here suggest the evolution of Tas1rs is more complex than we previously appreciated and highlight the caveat of analyzing sequences predicted from draft genome sequences. Future work for a better understanding of taste receptor function would help uncover what ecological factors have driven the evolution history of Tas1rs in vertebrates.