同源雌核发育银鲫子代微卫星杂合位点的分离

Segregation of microsatellite heterozygous loci in homologous gynogenetic silver crucian carp(C.a.gibelio Bloch) offspring

使用14对银鲫(Carassius autatus gibelioBloch)微卫星引物对同源雌核发育的银鲫子代及其亲本进行多态性研究,探讨雌核发育银鲫的母本微卫星杂合位点在同源传代中是否有分离的情况发生。在所选用的14对微卫星引物中,有8对在父母本间检测出不同的多态性,在所检测的第1组银鲫自交的子代中,只有1个个体在所检测的8个微卫星位点均存在变异,有明显的父本特异性条带出现,表现出了大量父本遗传信息,出现率为4.55%;在第2组检测到1个个体只在SCM13位点上出现母本部分特异性条带的缺失、弱化,而在其他位点上没有发现变异,出现率为1.52%。此结果表明,雌核发育银鲫卵子大部分在配子发生过程中没有发生减数分裂,即使用同源精子刺激,也行雌核发育生殖;但是,有极少数卵子在配子发生过程中,可能发生了部分减数分裂,具有部分融合同源精子的能力,从而在子代中检测到父本以及在融合过程中重组来的特异条带,用微卫星分子标记证实了银鲫两种生殖方式的存在,即雌核发育生殖和两性融合生殖。

The silver crucian carp （Carassius auratus gibelio Bloch） is a triploidy gynogenetic species, which provides a unique model system for understanding evolutionary genetics and for elucidating the regulatory mechanisms underlying diverse reproduction modes in vertebrates. In this study, PCR was performed on homologous gynogenetic parents and its offspring by 14 pairs of microsatellite primers, which was expected to disclose the segregation of maternal heterozygous loci in generation passage. There were two groups of parents and its offspring to test in this study. Eight microsatellite loci showed different polymorphism between father and mother in selected 14 loci. In group Ⅰ, only one individual, that occupied 4.55 % of the population, was detected to show the obvious specific bands of paternal in each of the 8 loci, which showed abundant paternal genetic information. Meanwhile, an individual represented the deletion and weakening of partly maternal specific bands in microsatellite locus SCM13 in group Ⅱ, which occupied 1.25 % of the population. It was concluded that meiosis did not happen during the most process of gametogenesis in gynogenetic silver crucian carp eggs, even when they were stimulated by homologous sperms. However, minority eggs maybe complete meiosis partly at gametogenesis that can lead to fusing the homologous sperms partly. In this case, the specific bands from pater and recombination during the fusion can be detected in filial generation. It is confirmed that there exist two reproduction modes in silver crucian carp including gynogenesis and amphimixis by microsatellite molecular markers.