The First Karyological Analysis and Chromosomal Characteristics of NORs of the Cloudy Grouper, Epinephelus erythrurus (Perciformes, Epinephelinae) in Thailand

Abstract

This study examines for the first time the karyological and chromosomal characteristics of nucleolar organizer regions (NORs) of the cloudy grouper, Epinephelus erythrurus (Valenciennes 1828) from Phuket and Phang Nga Provinces, Andaman Sea, Thailand (two localities). Kidney cell samples were taken from six fish and mitotic chromosome preparations were prepared directly from kidney cells. Conventional and Ag-NOR banding techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of E. erythrurus was 2n=48 and the fundamental number (NF, number of chromosome arms) was 52. The karyotype comprised 26 large telocentric, 4 medium acrocentric, and 18 medium telocentric chromosomes. The region adjacent to the telomeres of the short arms of acrocentric chromosome pair No. 18 showed clearly observable NORs (telomeric NORs). The karyotype formula was deduced as:
2n(diploid)48=L₂₆^t + M₄^a + M₁₈^t