tailieunhanh - ẢNH HƯỞNG CỦA NHIỆT ĐỘ LÊN GIỚI TÍNH VÀ SỰ PHÁT TRIỂNTUYẾN SINH DỤC CỦA CÁ XƯƠNG

ẢNH HƯỞNG CỦA NHIỆT ĐỘ LÊN GIỚI TÍNH VÀ SỰ PHÁT TRIỂN TUYẾN SINH DỤC CỦA CÁ XƯƠNG | ẢNH HƯỞNG CỦA NHIỆT ĐỘ LÊN GIỚI TÍNH VÀ Sự PHÁT TRIỂNTUYẾN SINH DỤC CỦA CÁ XƯƠNG TEMPERATURE INFLUENCES ON TELEOST SEX AND GONADOGENESIS Phan Khắc Vĩnh Nguyễn Tường Anh ĐH Khoa học Tự nhiên Email tuonganh5183@gmail. com ABSTRACT Most of teleost species have the sex chromosomes and genetic sex determination GSD . Their sex determining gene may be Dmy dmrtl which for the first time was discovered in medaka Oryzias latipes. Sex of more than 60 different teleost species is in under influence of environmental factors. Approximately 75 of experimental cases indicates that fish sex formation depends on only the extreme temperature fluctuations outside their optimal limits of normal ontogenesis. High temperature during embryogenesis corresponding to GSD and juvenile period of life corresponding temperature-depending sex differentiation TSD is able to masculinize Nile tilapia Oreochromis niloticus. This phenomenon may be involved in aromatization where the testosterone is converted to the estradiol - the crutial reaction in sex differentiation. High temperature may also activate some so-called unlinked sex reversal genes located even on somatic chromosomes. These genes could drive the gonads toward both directions genetic females to phenotypic males and vice versa though in lower levels . Consequently it s immposible to reach 100 of males by high temperature treatment and selection for the trait of a surplus of males in temperature treatment was recommended. Like almost of biological process the rate of fish gonadogenesis vitellogenesis and maturation is correlated with water temperature on principle of temperature coefficient Q10 Q10 Ki K2 10 ti- t2 2 Which means the temperature increase in 10oC K evokes the double increase in reaction rate. The sum of heat during conditioning equal average temperature multiplified the number of days of conditioning brootstock of a fish species is stable. The latency the time duration from resolving injection until total maturation and .

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• ẢNH HƯỞNG CỦA NHIỆT ĐỘ LÊN GIỚI TÍNH VÀ SỰ PHÁT TRIỂNTUYẾN SINH DỤC CỦA CÁ XƯƠNG