Evolution of Acidic Mammalian Chitinase Genes (CHIA) Is Related to Body Mass and Insectivory in Primates
Evolution of Acidic Mammalian Chitinase Genes (CHIA) Is Related to Body Mass and Insectivory in Primates
复制标题
DOI：
10.1093/molbev/msx312
复制
发表时间：
2018-03-01
影响因子：
10.7
通讯作者：
Tosi, Anthony J.
中科院分区：
文献类型：
--
作者：
Janiak, Mareike C.;Chaney, Morgan E.;Tosi, Anthony J.
昆虫是许多灵长类动物的重要食物来源，但节肢动物的几丁质外骨骼长期以来被认为是大多数哺乳动物消化酶不能消化的。然而，最近发现小鼠和食虫蝙蝠产生酶酸性哺乳动物几丁质酶（AMCase）消化昆虫外骨骼。在这里，我们报告的基因CHIA和它的旁系同源，编码AMCase，在非人灵长类动物的比较样本。我们的研究结果表明，早期灵长类动物可能有三个CHIA基因，这表明昆虫是灵长类祖先饮食的重要组成部分。除了一些例外，大多数现存的灵长类动物物种只保留一个功能性的CHIA paralys。例外包括两种colobine物种，其中所有CHIA基因都有过早的终止密码子，以及几种保留两个功能基因的新世界猴物种。在我们的样本中，最食虫的物种也具有最多的功能性CHIA基因。树鼩和耳尾保留三个功能CHIA旁系同源物，而Tarsius syrichta有总共五个，其中两个可能是复制特定的眼镜猴血统。选择分析表明，CHIA基因在昆虫消费量较高的物种中受到更强烈的选择，在体型较小的物种中也是如此。
Insects are an important food resource for many primates, but the chitinous exoskeletons of arthropods have long been considered to be indigestible by the digestive enzymes of most mammals. However, recently mice and insectivorous bats were found to produce the enzyme acidic mammalian chitinase (AMCase) to digest insect exoskeletons. Here, we report on the gene CHIA and its paralogs, which encode AMCase, in a comparative sample of nonhuman primates. Our results show that early primates likely had three CHIA genes, suggesting that insects were an important component of the ancestral primate diet. With some exceptions, most extant primate species retain only one functional CHIA paralog. The exceptions include two colobine species, in which all CHIA genes have premature stop codons, and several New World monkey species that retain two functional genes. The most insectivorous species in our sample also have the largest number of functional CHIA genes. Tupaia chinensis and Otolemur garnettii retain three functional CHIA paralogs, whereas Tarsius syrichta has a total of five, two of which may be duplications specific to the tarsier lineage. Selection analyses indicate that CHIA genes are under more intense selection in species with higher insect consumption, as well as in smaller-bodied species (