Study On Gynogenesis And Early Embryonic Development In Zebrafish(Danio Rerio)

Studies on artificially induced gynogenesis in zebrafish (Danio rerio) were conducted. Effects of ultraviolet irradiation on genetic inactivation of sperm of zebrafish and early stages of embryonic development of gynogenetic haploids and diploids were also studied. The result was shown as follows:1. The genetic inactivation of sperm was the key stage of artificial indution of gynogenesis in fish. In order to determine the optimal condition of UV irradiation for the inactivation of sperm of zebrafish, the sperm were irradiated by UV with five difference solutions:pure water(A), Cortland solution(B), medium M199(C), Hank's solution(D) and Ringer's solution(E). And then, we mixed the irradiated sperm and the normal eggs in relevant solution, and counted the fertilization rate, incubation rate and abnormality rate. The results showed that all of the five groups obtained abnormal fry, and the phenomenon of "haploid syndrome" were validated. The average of fertilization rate in the Cortland solution was better than that of the rest four groups. Compared fertilization rate with abnormality rate,35 seconds of irradiation time can inactive fully.2.The other key stage of gynogenesis was inducing gynogenesis diploid. In order to find the right time to double genome, the fertilization eggs which were activated by the right UV irradiation applied 2 min of heat shock at 41.5±0.5℃. Two high yields of genogenesis diploid occurred at 15 min and 27 min respectively after fertilization, and the former with 66.67% yield was better than the latter.3.Zebrafish embryonic development of normal diploid, gynogenetic haploid and gynogenetic diploid was compared with photomicrography. The results showed:Three type embryo were obvious different in developing speed. Before middle gastrulae stage, normal diploid>gynogenetic haploid>gynogenetic diploid, but after middle gastrulae stage, the developing speed had difference, normal diploid>gynogenetic diploid>gynogenetic haploid. And three type embryo had obvious difference in morphologic. Gynogenetic diploid embryo was similar to normal diploid embryo, but gynogenetic diploid embryo showed weak activity and hatching difficulty. Gynogenetic haploid embryo character as small brain, shorter body axes, weak activity, and hatching difficultly, being as same as "haploid syndrome". Haploid genome was the main reason for embryo abnormal, UV irradiation and heat shock could effect the embryo development too.4.The electrophoretograms of EST, LDH, SOD, MDH isozymes were studied in several tissues of zebrafish by polyacrylamide gel electrophoresis(PAGE) and the specific histochemical staining. The experimental results showed that there existed no differences between the gynogenetic zebrafish and female parent, but they had obvious differences compared with male parent, not only in the activities of the isozymes, but also the belts' number and mobility. Otherwise these had different exhibitions in different tissues, in parts of tissues had no difference with the gynogenetic zebrafish and female parent.5. The hacthing gynogenetic zebrafish fry were under to normal at body weight, but it is not significance difference between 30 days and 90 days, it is significance difference after 90 days.27 zebrafishes were female and 2 were difficult to find out their sex kind in all gynogenetic zebrafish.