Unveiling the Chromosomal Blueprint of the Pearl Oyster (Pintada maxima): A First Comprehensive Karyotype Analysis in Indonesia

The pearl oyster (Pinctada maxima) is a high-value commodity in the pearl aquaculture industry. However, aquaculture development in Indonesia is hindered by the lack of genetic information, particularly on its chromosomal characteristics. This study aimed to characterize the chromosomes and analyze the karyotype of P. maxima for the first time in Indonesia. Chromosome preparations were made from gill tissues of pearl oyster juveniles using a modified solid tissue technique. Karyotype analysis was performed by observing and measuring chromosomes at the mitotic metaphase stage. P. maxima has 28 diploid chromosomes (2n) with sizes ranging from 0.419 to 2.077 microns. The karyotype consists of two pairs of metacentric, three pairs of submetacentric, five pairs of subtelocentric, and four pairs of telocentric chromosomes, with the chromosomal formula 2m + 3sm + 5st + 4t. No physical chromosomal abnormalities were found. This study provides valuable information on the genome organization of P. maxima, which can be used as a basis for comparative studies, development of breeding strategies, and aquaculture management programs.