Affiliation: | a Department of Anatomy, Kochi Medical School, Nankoku 783-8505, Japan b Primate Research Institute, Kyoto University, Inuyama 484-8506, Japan c Department of Biology, Mahidol University, Bangkok 10400, Thailand d Department of Environmental Health Science, Kochi Medical School, Nankoku 783-8505, Japan |
Abstract: | Chromosome analyses were performed on three races (alpha, beta, gamma) of Neotricula aperta which were previously reported to show variation in the chromosome number and pairing in meiosis. We used an air-drying method, which was more reliable for chromosome preparations from fresh animal tissues than a squash method. Each of the races had the same number of chromosomes, 2n=33 for males, and 2n=34 for females. The sex determination system was XO type (male: 32+X, female: 32+XX). The sex chromosome of each race was distinct in its morphology, but not in its length. Karyotyping revealed that the X-chromosome of the alpha race was metacentric (M), whereas it was acrocentric (A) in the beta and the gamma races. An association between the X-chromosome and a small autosome in meiosis suggested that a neo-Y chromosome probably lies in the terminal region of the small autosome. |