Improvement in group identification of dojo loach, Misgurnus anguillicaudatus, using PCR-restriction fragment length polymorphism

In most Japanese populations of dojo loach ( Misgurnus anguillicaudatus ), gonochoristic diploids of genetically diversified groups (A and B, further subdivided into B1 and B2) are present, whereas unisexual clonal lineages inhabit certain localities in the Hokkaido and Ishikawa Prefectures in Japan. Through a series of genetic studies including DNA markers, the clonal loaches were deemed to originate from a hybridization event(s) between the A and B1 groups. However, combined analyses with other DNA markers are needed to identify each genetic group. In this study, we improved the PCR-restriction fragment length polymorphism (RFLP) analysis of the recombination activating gene 1 ( RAG1 ) gene using digestion with two restriction enzymes, Pvu II and Stu I. The improved RAG1 -RFLP analysis showed different fragment patterns for each group: two fragments (245 and 198 bp) for group A, three fragments (198, 147, and 98 bp) for group B1, and a single fragment (443 bp) for group B2. The clonal loaches exhibited four fragments (245, 198, 147, and 98 bp) derived from both groups A and B1. Moreover, the DNA markers were able to detect two different hybrid genotypes (A × B2 and B1 × B2). Thus, the improved RAG1 -RFLP markers allowed for quick and accurate group identification of the dojo loaches.