Data Mining for Simple Sequence Repeats in Expressed Sequence Tags from Japanese Flounder (Paralichthys olivaceus)
Based on ESTs of Japanese flounder (Paralichthys olivaceus) in the public database, EST-SSR makers were developed after mining and evaluating SSRs in them by bioinformatics methods. 5 927 non-redundant ESTs of Japanese flounder were screened and 390 SSRs were mined out. The frequency of these EST-SSRs was 7.95% and the average distance of distribution was 7.9 kb in non-redundant ESTs. The dinucleotide repest motif was dominant type (59.02%) with repeat motif AC being the most common (16.91%). The distribution of trinucleotide, tetranucleotide and hexanucleotide repeats were dispersive. 30 primer pairs for EST-SSRs were designed, 27 primer pairs showed the amplification, and 17 primer pairs showed polymorphisms, the rates of polymorphic EST-SSRs were 62.96% with the alleles per locus ranging from 2 to 6 (mean 3.5). The observed (HO) and expected (HE) heterozygosities of these EST-SSRs were 0.280.92 and 0.31550.8033, respectively. Two EST-SSR loci significantly deviated from the HardyWeinberg equilibrium (HWE) expectation, and theremaining 15 loci were in HWE. These new EST-SSR markers would provide sufficient polymorphism for population genetic studies and genome mapping of Japanese flounder.