Molecular evolution of the semenogelin 1 and 2 and mating system in gibbons
Molecular evolution of the semenogelin 1 and 2 and mating system in gibbons
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长臂猿精蛋白 1 和 2 的分子进化和交配系统
DOI：
10.1002/ajpa.23748
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
T.
中科院分区：
文献类型：
--
作者：
Isshiki;M. & Ishida;T.
精胶蛋白1和2(SEMG1和SEMG2)是灵长类精液凝集蛋白，具有60个氨基酸的重复结构。重复序列的数量因物种而异，并被假设与灵长类精子竞争的水平有关。直到最近，长臂猿还被认为是一夫一妻制的灵长类动物，但现在人们知道，长臂猿的社会结构是灵活的。材料和方法从圈养长臂猿的3个属(Hylobates、Symphalangus和Nomascus)的6个种的50只长臂猿中获得了SEMG1和SEMG2的外显子2的序列。结果观察到了一些突变，这些突变产生了SEMG1中的提前终止密码子，减少了基因组中SEMG2的重复次数，并可能改变了这些蛋白质的编码特性。我们还发现每个基因和属间的核苷酸多样性水平不同。值得注意的是，在诺马斯氏菌中，我们在SEMG1和SEMG2中发现了很高的N/dS比率。诺马斯菌SEMG2的核苷酸多样性也明显低于其他两个属。讨论这些结果与诺马斯菌谱系中存在强烈的正选择是一致的，即使作用于这些基因的确切选择力还不是最终的已知。在长臂猿中，我们无法证明半官方进化系统和交配系统之间的明确关系。
ObjectivesSemenogelin 1 and 2 (SEMG1 and SEMG2) are known as semen coagulating proteins in primates with a repetitive structure of 60‐amino acids. The number of repeats varies among species and is hypothesized to be related to the level of primate sperm competition. Gibbons until recently were thought to be monogamous primates, but it is now known that gibbon social structure is flexible. Thus, hypotheses of the relationship between theSEMGs evolution and mating systems were tested.Materials and methodsThe sequences of the exon 2 of theSEMG1andSEMG2were obtained from 50 captive gibbons comprising six species belonging to three genera (Hylobates,Symphalangus, andNomascus). Then we quantified the levels of polymorphism and estimated rates of protein evolution by calculatingdN/dSratio.ResultsSeveral mutations that create a premature stop codon in theSEMG1and a reduction in the repeats of theSEMG2in the genusHylobateswere observed and may alter the coding properties for these proteins. We also found different level of nucleotide diversity in each gene and between genera. Strikingly, inNomascus leucogenyswe discovered a highdN/dSratio in theSEMG1andSEMG2. TheNomascus SEMG2also showed significantly lower nucleotide diversity than the other two genera.DiscussionThese results are consistent with the presence of a strong positive selection in theNomascuslineage even if the exact selective forces acting on these genes are not yet conclusively known. We were not able to demonstrate, among gibbons, unambiguous relationships between theSEMGsevolution and mating systems.