| The sex selection is first major problems in the origin and evolution after having an initial cell morphology. The genetic approach has become the main line of gender evolution from the development of biological system,,however, a few species chose Environment-dependent sex determination (ESD) as a model of sex determination. The function of genetic factors is an attractive biological problem in its sex determination mechanisms. Gender selection method has shown some certain characteristics on the gene level, the physiological level and apparent level, they have a uniform type in most cases, but, the separation occurs between the three levels in some certain conditionsThe sex determination mechanism of Trionyx sinensis is temperature-dependent sex determination. The apparent gender identity is studied in this experiment, and its formation and development were observed. The gender identity and sexual selection direction are impacted by treating for hormone in embryo and larvae stage. The determination function of sex is explored in developmental stage, hormones and temperature. The biological material is provided for further study on sex determination mechanism of the soft-shelled turtle.In the first 15 days of incubation, the sex differentiation of the embryos is in critical period and the incubation temperature at 32 ℃. we use 17a-Methyl te stosterone(17a-MT) and Estradiol (E2) for the treatment of embryos, observing th e incubation period, hatching rate and differences in external morphology of expe rimental group and the control group. The finding indicate that different group h as different incubation time, E2 group’s incubation time is 38 d,17a-MT group’s incubation time is 43.5 d, and the control group’s incubation time is 44 d. This result shows that Estradiol ahead the incubation time nearly 10 days and signifi cantly shorten the incubation period, moreover 17a-MT has no significant effect on the incubation time. In the hatching rate, E2 group’s hatching rate is 66.7%, 17a-MT group is 53.3% and the control group’s hatching rate is 86.7%. The res ult shows that exogenous hormones slightly decrease the embryos’hatching rate. In the sex ratio of female and male, experimental group is different from the co ntrol group. The control group’s sex ratio is 3:11,17a-MT group is 0:4 and the E2 group is 8:0. All of the results indicate that exogenous hormones affect the gender identity.The concentrations of 17a-MT and E2 are 25,50 mg/kg and 100 mg/kg, mixed with the basic feed to treatment the young turtle, meanwhile observing the changes of their gender characteristics. At different points in time, the gender characteristics of the experimental group and the control group changed with the time. In the 17a-MT group, the gender characteristics tend to be female at the beginning.10 days later, the turtle’s tail become longer and closer to skirts, the gender characteristics change from female to male. After 20 days, the tail beyond the skirt and the gender characteristics almost can be identified as male. In 30 days, the group of 17a-MT’s gender identity is male. In the E2 group, most of the gender characteristics tend to be male in first 10 days.20 days later, the tail beyond skirts, gender characteristics almost can be identified as male. In 30 days, the gender identity can be determined as male. |
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