猴科动物苦觉受体基因的进化及其生态学意义

Taste perception plays an important role in animal feeding, both the relation between taste and diet and the evolutionary pattern of taste receptor genes are of great interest to evolutionary biologists. Much poisonous and harmful substance tastes bitter, and they can be detected by bitter receptor, so bitter taste can protect animal from ingesting poisonous and harmful substance. As for fruit-eating and leaves-eating animals, the bitter substance which they encounter is not the same, so we raise three questions: 1. Whether the numbers of bitter receptor gene are different in fruit-eating and leaves-eating animals? 2. Whether the bitter receptor genes responsive to fruit-eating and leaves-eating respectively are the same? 3. Furthermore, what are the bitter receptor genes’ evolutionary patterns in Cercopithecidae species? To answer these questions, this study focus on four Cercopithecidae species which distribute in Nonggang Nature Reserve, Guangxi, China, and they feed on fruit and leaves, respectively. First of all, we intend to find out all the bitter receptor genes (T2Rs) through the primates with known genomic sequences by bioinformatics methods, and then based on these sequences we design primers to amplify and sequence the T2Rs of the above four Cercopithecidae species. The known sequences of T2Rs in Cercopithecidae species will be added to the newly available T2Rs sequences, and along with the diet of each species, we will carry out the comparable analyses. This study will reveal the evolutionary pattern of bitter receptor genes in Cercopithecidae species, meanwhile, it will provide a case study for the relation between taste and diet.

味觉在动物取食过程中起重要作用，味觉与食性的关系、味觉受体基因的进化规律一直是进化生物学家感兴趣的问题。大多数有毒有害物质都是苦味的，能被苦觉受体所识别，所以苦觉能防止动物摄入有毒有害物质。对于食果和食叶的动物，它们所遇到的苦味物质不尽相同，那么它们的苦觉受体基因在数量上是否存在差异、对应两种食性的苦觉受体基因是否相同，进一步，猴科动物的苦觉受体基因进化模式如何，这些都是本项目所关注的问题。为了探讨上述问题，本研究以分布在广西弄岗自然保护区的食果和食叶的四种猴科动物为具体研究对象，拟通过生物信息学的方法从基因组序列已知的灵长类中找出所有的苦觉受体基因T2Rs，以它们为模板设计引物扩增这四种猴科动物的T2Rs，将所得到的新序列结合基因组已知的猴科动物的T2Rs、以及不同物种的食性，进行比较分析。本研究将揭示猴科动物苦觉受体基因的进化模式，同时为味觉与食性的进化关系提供一个具体研究案例。

本研究主要对灵长类特别是猴科动物苦味受体基因的进化进行研究，找出不同食性物种苦味受体基因数与食性之间的进化关联。本研究对猴科的5个物种(白头叶猴、黑叶猴、猕猴、白臀叶猴、熊猴)的T2Rs进行扩增，分别得到33,31,33,29,33个苦味受体基因，对已有全基因组序列信息的 19 个灵长类进行 T2Rs 查找，得 825 条序列。结合已有研究中发表的 14 个灵长类的 T2Rs 进行数据分析，本研究发现，1)很多物种都有着共同的完整基因，而一些特定的基因在有的物种中是假基因，在另一些物种中是完整基因，推测与其食物成分的分化或者食性的差异有关；2）白头叶猴、黑叶猴、熊猴、猕猴和白臀叶猴都存在同一T2R基因有多个拷贝的现象，这可能与它们取食特定的食物有关。本研究为揭示灵长类苦味受体基因与食性的关系提供研究实例，进一步为揭示植食性物种在应对不同苦味物质成分或者比例时的苦味受体分化机制提供研究基础。