Karyotype analysis of the East Asian common octopus, Octopus sinensis

Abstract:

Comparative studies of the karyotypes of closely related species may aid our understanding of the mechanisms of chromosomal evolution relevant to speciation. It may also help to clarify phylogenetic relationships. In the present study, we analyzed the karyotypes of ten wild immature East Asian common octopus (Octopus sinensis; 5 male and 5 female) from the coastal regions of the East China Sea. O. sinensis were held in seawater containing 0.005% colchicine for 2 h, and then the gill and kidney were collected for chromosome sample preparation via the hot-dropping method. The results showed that the diploid chromosomal number of O. sinensis is 60, and the karyotype formula is 2n = 14m + 26sm + 12st + 8t, NF = 100. No satellite, secondary constriction, or heteromorphic chromosomes of sex were observed. Therefore, we speculate that the sex determination mechanism of O. sinensis is autosomal. This study provides basic data for cytogenetic studies of Octopus and serves as a valuable reference for O. sinensis germplasm identification and conservation.