洞庭湖水系沅水和澧水野鲫的染色体组型及资源保护

鲫(Carassius auratus)是洞庭湖水系一种重要的经济鱼类。为了解洞庭湖水系野鲫的细胞遗传背景,采用PHA和秋水仙素活体注射法,对沅水和澧水采集的野鲫样本逐一进行肾细胞染色体制片及组型分析。结果发现,在两条河流的野鲫群体中均检测出染色体数为100和基本染色体数为150的两种不同倍性个体,其中,两条河流染色体数为100的二倍体鲫组型公式为2N=28M+22SM+28ST+22T,NF=150;基本染色体数为150的三倍体鲫组型公式为3N=42M+33SM+42ST+33T,NF=225。在沅水和澧水不同采样点随机采集的共100尾野鲫中,检测出的三倍体比例(85%)远高于二倍体(15%),且二倍体与三倍体鲫个体在形态特征上不存在明显差异(P0.05)。两种不同倍性鲫在同一水体的共存对于鲫的遗传进化与选育具有一定的理论和实践意义,而二倍体鲫种群的大量减少,则提示我们应该从染色体组遗传多样性角度加强对洞庭湖水系二倍体野鲫资源的保护。

Karyotype and Resource Protection of the Wild Crucian Carps (Carassius auratus) in the Dongting Lake Water System

Crucian Carp (Carassius auratus)is an important economic fishes in the Dongting Lake water system. In order to realize their cells genetic background, the chromosomes number and karyotype of the wild Crucian Carps collected from the Yuanshui River and Lishui River of the Dongting Lake water system were analyzed one by one using chromosomes of kidney cell-PHA culture in vivo prepared by flame-drying technique. The results show that there are two different ploidy levels Crucian Carps which the chromosomes number are 100 and 150±, respectively in both the Yuanshui River and Lishui River. The karyotype formula of 100 chromosomes is 2N=28M+22SM+28ST+22T, NF=150; and the karyotype formula of 150 basic chromosomes is 3N=42M+33SM+42ST+33T,NF=225. With the 100 wild Crucian Carps from different sample points of the Yuanshui River and Lishui River, the proportion of the triploid Crucian Carps (85%)is sharply higher than that of the diploid Crucian Carps (15%), and the morphological characteristics of the diploids and the triploids have no significant differences (P>0.05). The Crucian Carps with two different ploidy levels coexisting in the same water system will have certain theoretical and practical significance to their evolutionary study and genetic breeding, and the huge reduction of the diploid Crucian Carps suggested that resources protection of them in the sight of chromosome set genetic diversity should be strengthened.