The First Report of NORs and Chromosome Analysis of Tripletail Wrasse, Cheilinus trilobatus (Perciformes: Labridae)

Abstract

SummaryWe report the first chromosome analysis and chromosomal characteristics of nucleolar organizer regions/NORs in the tripletail wrasse (Cheilinus trilobatus) from the Andaman Sea, Southern Thailand. Kidney cell samples were taken from three male and three female fishes. The mitotic chromosome preparation was prepared directly from kidney cells. Conventional staining and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of C. trilobatus was 2n=38, the fundamental number (NF) was 54 in both males and females. The types of chromosomes were 6 large metacentric, 4 medium metacentric, 2 medium submetacentric, 4 medium telocentric, 4 small submetacentric, and 18 small telocentric chromosomes. The region adjacent to the short arms near the telomeres of submetacentric chromosome pair 7 showed clearly observable NORs. There was no observation of irregularly sized chromosomes related to sex. The karyotype formula for C. trilobatus could be deduced as:2n (