Expression Of Sex Hormone Receptors(ERα, ERβ, AR) During Early Stage Of Acipenser Schrenckii Gonadal Differentiation

Amur sturgeon(Acipenser schrenckii), which is also called as living fossil, is one of the most primitive Actinopterygii species. Amur sturgeon is a riverine resident sturgeon species, distributed in the Amur River、Songhua River and Heilong River. It has been became one of the most popular sturgeon culture species in China for its considerable value in economy and ecology.The female sturgeons, which can produce eggs are desirable in the sturgeon aquaculture program. However, a dominant problem for aquaculture caviar producers is that 50% of the animals are profitless males which need to be discarded from production as quickly as possible, in order to minimise expenditure and maximise space. As a consequence, the reproductive and sexdifferentiation mechanism of A. schrenckii is urgent to research, in order to maintain its sustainable development. Therefore, the gonad, which is considered as reproductive center were researched by histology, endocrinology and molecular biology to explore the sturgeon sex differentiation features. Using real- time PCR to explore Kiss, ER and AR expression in sexual differentiation and research ER and AR regulation function by injecting a kiss peptide. Results and conclusions are as follows:1.Contents of soluble proteins, sexhormones, activity of immunological indicators during embryonic development of Acipenser schrenckii. The contents of soluble proteins, 17β-estradiol(E2) and testosterone(T) were examined by biochemical methods to understand the content of soluble protein and hormone level changes during embryonic development of Acipenser schrenckii. In addition, we examined the activity of acid phosphatase(ACP), alkaline phosphatase(AKP), catalase(CAT), superoxide dismutase(SOD) and content of reduced glutathione(GSH), malondialdehyde(MDA) to evaluate the non-specific immune responses. The results indicated that soluble protein content in optic vesicle stage reached maximum and significantly higher than other stages(P<0.05), while the levels of yolkplug and heartbeat soluble protein significantly lower than other periods(P<0.05); Testosterone(T) levels were significantly reduced(P<0.05), 17β-E2 levels were significantly higher in the hatching prophase, T and17β-E2 both have a peak value in this stage; ACP and GSH decreased first and then increased significantly(P <0.05), CAT activity was significantly increased(P <0.05), AKP activity changed little, MDA content remained at a low level and increased significantly after heartbeat(P <0.05), SOD activity was significantly reduced in the yolkplug(P<0.05) and then stabilized. Research shows: Acipenser schrenckii have a certain ability to synthetic sex hormone during embryonic development; Various immune enzymes play a different role in embryonic development, the high mortality in neurula stage related to oxidative damage.2. Expression analysis of sex hormone receptors(ERα, ERβ, AR) during critical period of Acipenser schrenckii gonadal differentiation and early growth stage. The level of estrogen receptor(ERα, ERβ) m RNA and androgen receptor(AR) m RNA in different time(Day150,160,170,180,190) were analyzed by Real-Time PCR, to explore the function of sex hormone receptors during critical period(150-190 day) of Amur sturgeon(Acipenser schrenckii) gonadal differentiation. The results showed that gonadal AR transcriptional levels higher than brain, gonad and brain were significantly higher than other organizations. Contrastingly, ERα expressions in brain were slightly higher than gonads, while ERβ have a higher expression in gonads, but low expression in brain and other tissues. In gonadal differentiation process, AR expression of brain and gonad decreased to the lowest value in the 170 d and then gradually increased; ERα expression in brain is similar to AR, and ERα expression in 160d-gonadal have a peak value; Gonads ERβ expression were significantly reduced with the development. Our results indicated that ERα, ERβ, AR were involved in the regulation of gonad differentiation, and play different role at different times.3. Expression analysis of sex hormone receptors(ERα, ERβ, AR) and sex homone level during gonadal differentiation of Acipenser schrenckii,which were injected by kiss-1/kiss-2. Estradiol levels of brain and the gonads that injected by kiss1 increased with the increasing of injections number, testosterone significantly reduced after three injections. AR expression levels of brain and the gonads that injected kiss1don’t have significant changes. ERα brain expression inhibited, ERα gonadal expression after the third injection forming small peak expression. gonads ERβ expression reach peak after the second injection.