利用微卫星遗传标记探讨达氏鳇的多倍体倍性

鲟形目(Acipenseriformes)鱼类是一类多倍体起源的鱼类,种问易于杂交,且由于存在大量微型染色体,其染色体数目和倍性也难于确定.到目前为止包括达氏鳇(Huso dauricus)在内的一些鲟鱼物种基因组大小和染色体倍性仍旧存在争议.本实验采用微卫星遗传标记技术,通过观察9个微卫星位点的等位基因数目,发现达氏鳇在大部分位点中显示的倍性大于二倍性,同时利用多倍体分析软件POLYSAT推断了26尾达氏鳇的个体倍性.结果表明,26尾达氏鳇中有20尾显示为六倍体,占总数的76.92％；4尾显示为八倍体,占总数的15.38％；2尾显示为四倍体,占总数的7.79％.因此,我们认为达氏鳇应该为八倍体物种,结果中出现的四倍体和六倍体个体,是由于这些个体在我们选取的微卫星位点中存在部分纯合等位基因,导致了多数个体显示为六倍体.这一结论与近年来支持达氏鳇为进化性八倍体物种的研究结果一致.

Polyploidy of Huso dauricus as Revealed by Microsatellite Genetic Markers

Acipenseriforme fishes originating from polyploidy fish are easy to undergo interspecific hybridization. Furthermore, their abundant mini-chromosomes make it hard to determine their chromosome number and ploidy. So far, reports about the genome size and chromosome ploidy of some sturgeon species including Kaluga Sturgeon (Huso dauricus), are still controversial. In this study, microsatellite genetic markers were used to observe the number of alleles of nine microsatellite loci, and ploidy patterns of 26 Kaluga individuals were analyzed with the help of polyploidy analysis software POLYSAT. We found that most loci showed greater than diploidy, with 20 of 26 Kaluga individuals were hexaploid, 4 individuals were octoploid, and the remaining 2 were tetraploid. Therefore, Kaluga sturgeon should be classified as octaploid species, and its hexaploidy and tetraploidy might be a result of partial homozygous allele existing in the loci we used in some individuals. Our results support the recent opinion that Kaluga sturgeon belongs to evolutionary octaploid group.