Study On Apoptosis And Related Gene Expression Changes In Gonad Of Female Nile Tilapia Induce By High Temperature

Gender determination is of great significance to biology and is one of the research hotspots.In vertebrates,there are approximately three gender-determining mechanisms: Genetic sex determination(GSD),Environment-dependent Sex Determination(ESD),and Genetic sex determination.+Temperature Effect,GSD+TE).Nile tilapia grows rapidly,males grow much larger than females,have early sexual maturity,have strong fertility,and have high nutritional value.Nile tilapia was found to be a genetic-temperature type of sex determination as early as 1995.GSD+TE)fish(Baroiller et al,1995).In the critical period of gonad differentiation in Nile tilapia,10 to 20 days after fertilization,high temperature induction can reverse female sex to male fish.So what is the theoretical mechanism of high temperature-induced sexual reversal in females of Nile tilapia? In the process of sexual reversal of Nile tilapia females,how do specific female gonadal cells change and whether female reproductive and somatic cells are present? Apoptosis,if apoptotic,will be at what stage of apoptosis and what changes will occur in specific gonadal cells.These issues are not yet clear.In order to understand the continuing effects of high temperature on the development of gonads in Nile tilapia,and to analyze the presence of gonadal apoptosis in the gonadal process during hyperthermia induced sexual reversal,the control XX group and the high temperature induction group(high temperature XX group)and The gonads of the control male fish group(XY group)were stained at 17,21,25,and 35 days after hatching.On 17 dah,there was no difference in the size of gonadal development between the control XX group,the high temperature XX group,and the XY group.Germ cells were observed in the high temperature XX group of the control XX group.It is noteworthy that round cavities appeared in the gonadal tissues of the high temperature XX group,and The number of gonadal cells was less than that of the control XX group.In 21 dah,25dah,and 35 dah,gonadal development showed differences between individuals.The primary oocytes were observed in the control XX group.Larger oocytes were observed in the hyperthermia-reversed individuals in the XX group,andhyperthermia induction was observed.The number of post oocytes was more than that of the control group.However,only germ cells were observed in individuals with no reversal in the high temperature group.Compared with the XY group,the number of cells in the testis in the XY gland tissue was relatively small.The results showed that during these periods,Nile tilapia that did not have a sexual reversal in the high-temperature-induced group developed faster than the females in the control group,but the high temperature had an inhibitory effect on the development of sexually reversing genetic female Nile tilapia reproduction cells.This inhibition slows down the development of germ cells.In addition,in order to analyze the effects of high temperature induction on the development of Nile tilapia,the measured body length and full length of Nile tilapia in control XX and high temperature XX groups were not significantly different,indicating that the effect of high temperature on the growth of Nile tilapia is not significant.obvious.In this study,three female parents were constructed by pairing Nile tilapia pseudo-male(XX male)and normal XX females.The rate of males in the three families was 73.3%,71%,and 90%.Using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay(TUNEL technique),it was detected that the apoptotic signal was detected in the high temperature XX group 17 days after hatching,indicating that the hyperthermia induction was the occurrence of gonadal cells during this period.Apoptosis.Through technical validation,it was found that the pro-apoptotic gene Caspase 3 and Bax gene were up-regulated after high temperature induction,and the apoptosis-inhibiting gene bcl-2 was down-regulated in the high temperature XX group.Although this down-regulation was not obvious,the induction of apoptosis was down-regulated by high temperature induction.The level of expression of the deceased gene,and this down-regulation is continuous,consistent with the observation of the tissue section at the same time(35dah).In conclusion,the results of this study preliminarily demonstrated that high temperature induces sexual gonadal development in individuals who do not have sexual reversal of Nile tilapia and that sexual hyperplasia induces apoptosis in individual gonadal cells,and the associated apoptotic genes also change.It is expected to initially explore the changes of female sex gonadal cells induced by high temperature and the expression of related apoptotic genes,enrich and improve the theory of fish sex differentiation,and provide theoretical and technical support for the establishment of new fish sex control techniques.