[Mutation rate and pattern of microsatellites in gynogenetic silver crucian carp (Carassius autatus gibeblio)]

The natural gynogenetic triploid silver crucian carp (Carassius autatus gibeblio Bloch) provides a good system for studying evolutional genetics of the unisexual and polyploidy vertebrate. Microsatellites are abundant across genomes and show high levels of polymorphism and mutational rate, so they have been widely used for studying evolutional biology. In this study, the mutation rate and pattern at 33 microsatellite loci of silver crucian carp were investigated. As a result, it was found that the only one of 22 offspring had 18 mutant alleles at 15 microsatellite loci. The overall mutation rate of the 33 loci was 1.16x10(-2)/locus/generation (95% confidence interval 6.87x10(-3) and 1.83x10(-2)). The mutation rate in the gynogenetic triploid silver crucian carp was obviously higher than other fish, which was closely related to the transitional phase of parthenogenesis and gamogenesis in the natural gynogenetic fish. The repeat numbers had more than 10 times at 13 loci of the mutant alleles, and there was no obviously different in the mutant rate between the 11 compound microsatellite loci (1.31x10(-2) )and the 21 perfect microsatellite loci(1.00x10(-2)) (P = 0.67). The mutant rate had affinity with repeat numbers instead of repeat types and GC content in flanking sequences of microsatellite. The mutation pattern of silver crucian carp was very complexional, as well as some loci did not follow the Stepwise Mutation Model.