Chromosomal characteristics of the tropical oyster, Crassostrea belcheri Sowerby, 1871 (Ostreoida, Ostreidae) by conventional and Ag-NOR banding techniques

Abstract

Chromosome preparation from gill tissue of the tropical oyster (Crassostera belcheri Sowerby, 1871) collected from an oyster farm in Kantang District, Trang Province, southern Thailand was studied by conventional staining and Ag-NOR baining techniques. The result revealed that the diploid chromosome number is 2n=20 and the fundamental number (NF) is 40. The karyotype has revealed 10 large metacentric and 10 medium metacentric chromosomes. One pair of nucleolar organizer regions (NORs) was apparent on the short arm telomeric region of chromosome pair 10. Basic information on the cytogenetics of the C. belcheri may be useful for future studies on interspecific hybridization and polyploidy. The karyotype formula of C. belcheri is as follows: 2n (diploid) 20=Lm10+Mm10