Characterization of hybrid triploid loach (Misgurnus anguillicaudatus) karyotype by C-banding and fluorescence in situ hybridization with rDNA

The embryonic chromosomes of hybrid triploid loach (4n♀×2n♂), Misgurnus anguillicaudatus, were examined by C-banding and fluorescence in situ hybridization (FISH).The characteristics of C-band of hybrid triploid loach were discussed for the first time, so as to provide the basis for identifying chromosomes accurately.Meanwhile, the number and position of ribosomal 5.8S+28S rDNA in the metaphase chromosomes of hybrid triploid loach embryos were studied.The results of C-banding in embryonic chromosomes of hybrid triploid loach show that, C-bands were classified into types of terminals and centromeres, but no middle type of arm was observed.The type of terminals were located on terminal of short arm of M1, whereas, compared with the type of centromeres, bigger and more obvious C-band was found on terminal of short arm of M1.While the other M chromosomes and SM chromosomes and T chromosomes only have centromeric C-band.The results of FISH show that, ribosomal 5.8S+28S rDNA was clearly localized in the region of terminal of middle centromere (M) of the metaphase chromosome of the hybrid triploid loach.Three hybrid signals could be detected in metaphase chromosomes of hybrid triploid loach.The results further confirmed that the hybrid triploid loach is a genetic triploid with three sets of chromosomes from the aspect of molecular cytogenetics.