A First Chromosomal Characterization of NORs in Splendid Snakehead Fish, Channa lucius (Perciformes, Channidae)

Abstract

A first chromosomal characterization of the nucleolar organizer regions (NORs) of the splendid snakehead fish, Channa lucius (Cuvier 1831) from the Bung Klua reservoir in the Roi-Et Province of northeastern Thailand was conducted. Blood samples were taken from four male and four female fish. After standard whole blood lymphocytes had been cultured at 27°C for 96 h in the presence of colchicine, the metaphase spreads were performed on a microscopic slide and air-dried. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of C. lucius was 2n = 48, and the fundamental number (NF) was 54 in both males and females. The types of autosomes were 2 large metacentric, 2 large acrocentric, 22 large telocentric, 2 medium acrocentric, 18 medium telocentric and 2 small telocentric chromosomes. There was no observation of strange-sized chromosomes related to sex. The region adjacent to the telomere of the short arm of chromosome pair 2 showed clearly observable secondary constriction (NORs). The karyotype formula for C. lucius is as follows:
2n (diploid) 48 = L^m₂+L^a₂+L^t₂₂+M^a₂+M^t₁₈+S^t₂