The Effects Of Implanted Estradiol On Serum Physiological Indices And Ovarian Development In Female Chinese Sturgeon (Acipenser Sinensis) Juvenile

The endengered species,Chinese sturgeon（Acipenser sinensis）, is an anadromousfish and spawns mainly in the Yangtze River. The age of maturity is14-26years old inthe females. The aquaculture on large scale began in late1990’s.In2009，the culturedindividuals have been successed in producing F2generation. However, thephysiology and endocrinology of Chinese sturgeon are not clear. And it’s a good ideato accelerate the gonadual development by some methods. Physiological indices,sexhormone in serum and ovarian development were studied after E2was implanted infemale juvenile Chinese sturgeon，as well as the seasonal differences in biochemicalindices.1、Estradiol（E2） at dose of30mg/kg was implanted in back muscle of culturedfemale Chinese sturgeon （Acipenser sinensis）（age:11years old; average bodyweight:46kg）. Serum was sampled from the tail of fish before implantation and30days,120days and200days after implantation. The serum concentration of totalprotein （TP）, albumin （ALB）, globulin （GLB）, triglyceides （TG）, total cholesterol（TCH）, glucose （GLU）, vitellogenin （VTG） were measured. The results showed thatthe concentration of TP, ALB, GLB, TG, TCH, VTG, except for GLU, in serum in thetreated group were significantly higher than that in control group. The results couldoffer us the initial dada to search for the exogenous substance to accelerate ovariandevelopment of Chinese sturgeon.2、In order to study the effects of17-estradiol on overian development ofChinese sturgeon, juvenile Chinese sturgeon were implanted E2on30mg/kg. The effects of E2on serum T and E2were determined. Serum T levels were significantlylower than that of control group （P<0.05）. Serum E2level was increasing incontinuously during0to30d, and then decreased from30d to200d,.These resultsindicated that exogenous estradiol can increase the level of estradiol in serum,decrease the level of T in serum, and might accelerate the ovarian development.3、Estradiol（E2） at dose of30mg/kg was implanted in back muscle of culturedfemale Chinese sturgeon（age:11years old; average body weight:46kg）for stimulationof ovarian development. Before implantion and120d after implantion, gonadal tissuesof each individual were collected by biopsies, fixed with Bouin fluid, andembedded in paraffin. Serial sections of5um thickness were prepared and stainedwith haematoxylin and eosin.The diameters of oocyte were recorded under a lightmicroscope.There are no difference in the oocyte diameters between E2group andcontrol group at the beginning. However, the oocyte diameters in E2group weresignificant bigger than those in control group at120d after implantion.The resultsshowed that exogenous E2could stimulate the ovarian development.4Estradiol（E2） at dose of20mg/kg was implanted in back muscle of culturedfemale Chinese sturgeon（age:4years old; average body weight:15.00kg）. Livertissues were sampled in30days after implantation. Using degenerate primers，reversetranscription–polymerase chain reaction （RT-PCR） were established and used to studythe VTG and β-actin gene expression in the liver of juvenile Chinese sturgeon. Thesignifcant induction of VTG gene expression was detected in both treated groups, andno VTG mRNA was detected in the control group in male group.5、Serum was sampled from the tail of each individual every season. The serumconcentration of total protein （TP）, albumin （ALB）, globulin （GLB）, triglyceides （TG）,total cholesterol （TCH）, glucose （GLU） and vitellogenin （VTG） were measured.Theresults showed that the levels of serum TP,ALB,GLB,TCH,TG and VTG displayedseasonal significant variation．The main value of TP,ALB and GLB went up to peak inspring. Then it began to drop from spring to autumn to minimum point. Two peaks inTCH and TG contents were found in spring and autumn.There was no significant difference in GLU content among different seasons. The content of VTG in serumincreased to its highest level in autumn.6、The growth characteristics of the Chinese sturgeon juveniles at age of1-7years, cultured in cages at Three Gorges reservoir,were analysised using statisticalmethods. In cultured conditions, the fish showed continuous growth. The average totallength and body weight at age of1year were91.36cm and3.94kg respectively, andadded up to173.63cm,36.61kg at age of7years. There was a linear relationshipbetween total length（L） and age（t） in form of L=13.549t+89.041（n=7,R²=0.9532）,and there was a power function relationship between body weight and age in form ofW=3.833e^0.3595t（n=7,R²=0.9292）,. The relationship between total length and bodyweight was W=1.6×10^-6L^3.2722（R²=0.9033,n=840）.