Microsatellite DNA polymorphism to reveal genetic divergence in Ayu, Plecoglossus altivelis

Abstract

Six (CA)n and one (CT)n(CA)n microsatellite loci were isolated from a size-selected genomic library of ayu Plecoglossus altivelis altivelis. Primers for PCR amplification were designed for the microsatellite loci and the loci characterized by screening polymorphisms in the amphidromous form of ayu. All loci displayed a high degree of length polymorphism, as observed in the total number of alleles per locus (2-21), and a high degree of heterozygosity ranging from 0.414-1.000. Distinct differences were observed between amphidromous and landlocked populations of ayu, in the frequency distributions of the alleles. The primers developed for ayu Plecoglossus a. altivelis were also tested for their ability to amplify homologous sequences in endangered subspecies of Ryukyu-ayu, Plecoglossus altivelis ryukyuensis. Genetic variability was obviously low in both average number of alleles per locus and average heterozygosities. These microsatellite loci show great potential as indicators for genetic variability and divergence among populations of ayu species.