Temperature-dependent Index of Mitotic Interval (τ0) for Chromosome Manipulation in Korean Bullhead, Pseudobagrus fulvidraco

Korean bullhead (Pseudobagrus fulvidraco) was collected from the Kum River areas of Kangkyung-eup, Nonsan city, Chungcheongnam-do, Korea, from April to June, 2012 and was fertilized in order to observe egg development and temperature-related cleavage rates and mitotic intervals (τ0). The fertilized eggs were separative, demersal and light yellowish with 1.5±0.06 mm in diameter, and did not contain oil globules. The first cleavage stages were 90 min, 80 min, 60 min and 50 min at 21°C , 24°C , 27°C and 30°C , respectively. At higher temperatures, eggs developed faster and underwent further identical development. For Korean bullhead, τ0 were 33.4±2.08 min at 21°C, 31.5±3.06 min at 24°C, 28.1±2.11 min at 27°C and 26.4±3.35 min at 30°C . There were strong negative correlations between the τ0 and water temperatures at all points studied (Y= 1.13X+58.15, R (2)=0.98, n=30, where Y is τ0 and X is temperature). The results obtained in this work will be helpful for chromosome manipulation by use of cleavage frequency data and τ0 data in Korean bullhead.