Standardized Karyotype and Idiogram of Two-Spot Glass Catfish, Ompok bimaculatus (Siluriformes, Siluridae) in Thailand by Conventional and Ag-NOR Staining Techniques

抄録

Standardized karyotype and idiogram of the two-spot glass catfish (Ompok bimaculatus) from Chi basin, Maha Sarakham Province, northeast Thailand, were studied. Kidney cell samples were taken from 5 male and 5 female fish. The mitotic chromosome preparations were prepared directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of O. bimaculatus was 2n=50, the fundamental number (NF) was 90 in both males and females. The types of chromosomes were 10 large metacentric, 2 large submetacentric, 4 large acrocentric, 2 large telocentric, 4 medium metacentric, 18 medium submetacentric, 2 medium acrocentric, 2 medium telocentric, and 6 small telocentric chromosomes. The region adjacent to telomere of the short arm of submetacentric chromosome pair 4 showed clearly observable nucleolar organizer regions (NORs). The karyotype formula for O. bimaculatus could be deduced as:
2n (diploid) 50=L^m₁₀+L^sm₂+L^a₄+L^t₂+M^m₄+M^sm₁₈+M^a₂+M^t₂+S^t₆