新疆额尔齐斯河水系银鲫克隆多样性研究

STUDIES ON CLONAL DIVERSITY OF GIBEL CARP,CARASSIUS AURATUS GIBELIO,FROM THE IRTYSH RIVER WATER SYSTEM IN XINJIANG PROVINCE

银鲫(Carassius auratus gibelio Bloch)由于其独特的遗传背景和繁殖方式而成为研究进化遗传学和选择育种的一个独特的模式生物。到目前为止,我们对新疆额尔齐斯河水系银鲫群体的多样性状况一直知之甚少。为了更好地了解额尔齐斯河水系银鲫群体的克隆多样性状况,本研究中,我们采集了来自新疆额尔齐斯河水系的4个鲫鱼群体。通过流式细胞术分析血细胞样品,结果证实这些鲫鱼均为三倍体银鲫。通过血清转铁蛋白电泳表型分析,我们从这些银鲫群体中鉴定出总共8个不同的克隆。在这些鉴定的克隆中,有4个克隆(克隆A、J、M和S)同于以前鉴定的克隆,而另外的4个克隆是新发现的。克隆A和M分布最广,出现在所调查的4个群体中;克隆J出现在2个不同的群体中;其余的5个克隆中每个克隆均为单个群体所拥有。不同克隆在群体中的这种分布谱式可能反映了银鲫的各个克隆可在不同水体之间迁移以及同一克隆在不同水体中生存能力存在有差异。在取样的银鲫群体中,发现有一个群体的克隆多样性水平明显低于其他3个群体,而这后3个群体的克隆多样性水平是与已报道过的银鲫群体相似的。这一结果可能暗示着修建水利工程和过度捕捞等人类活动的不利影响。本研究所揭示的克隆多样性将有助于进化遗传学和选择育种研究。同时,也反映了保护额尔齐斯河水系银鲫克隆多样性的重要性。

Gibel carp, Carassius auratus gibelio Bloch, as a subspecies of Carassius auratus, has a wide geographic distribution from northern Europe to Asia. As a new culture target, it has been used widely for aquaculture practice in recent 30 years in China, and its production capacity has increased up to 2 billion kilograms annually. Gibel carp possess several interesting characteristics： 1 ） It is a triploid fish with more than 150 chromosomes, 2） It exists as a bisexual population with predominantly more females （an 80 ： 20 female ： male ratio） in natural habitats, 3） It has dual reproductive modes of gynogenesis and bisexual reproduction, 4） Various gynogenetic clones have been identified. These features make gibel carp a promising study model for evolutionary genetics, developmental biology and selective breeding. Recently, we have detected clonal diversity of gibel carp in Fangzheng stock hatchery of Heilongjiang Province and Qihe stock hatchery of Henan Province. Up to now, however, little information had been known about the status of gibel carp populations from the Irtysh River water system in Xinjiang Province. In order to obtain a better understanding of the status of clonal diversity of the gibel carp populations, four populations of Carassius auratus were collected from the Irtysh River water system in this study. Flow cytometry was applied to analyze their blood cells, revealing that all of them were triploid gibel carp. Then, a total of eight different clones were clearly discriminated from these gibel carp populations by analysis of serum transferrin phenotypes. Among them, four clones were identical to those identified previously, whereas, the other four were new. Clones A and M were the most wide-ranging, occurring in all of the four populations. Clone J appeared in two populations. Each of the other five clones was specific to single population. These distribution patterns of different clones within populations might reflect clones being able to migrate and differences in viability of a clone among different water bodies. Among these sampled populations of gibel carp, one had the level of clonal diversity obviously lower than those in the other three, similar to those in populations reported, probably suggesting negative effects of human activities such as hydraulic engineering construction and overharvesting. The clonal diversity revealed in this study will likely benefit evolutionary genetics and selective breeding studies. At the same time, this work also highlights the significance of protecting clonal diversity of gibel carp in the Irtysh River water system.