Purification Of Gonadotropin And Identification Of A Novel Splice Variant Of GtH Alpha Subunit In The Common Carp

Gonadotropin (GtH) is a pituitary glycoprotein hormone that regulates gonaddevelopment and sex maturation in vertebrates. In teleost fish, as in other vertebrates,there are two forms of GtHs, traditionally referred to as GtH-I and GtH-II, which arebelieved to be FSH-like and LH-like, respectively. GtHs are dimeric glycoproteinhormones composed of a common alpha subunit and a hormone-specificβsubunit,which confers its biological specificity. The hormonal activity is expressed only aftera non-covalent association between these two subunits. Though many factors affectthereproductionanddevelopmentofteleostfish,GtHsecretedbythepituitaryplaysacrucial role in regulating gonad development and controlling the final sex maturationaswellasendocrineregulation.Common carp (Cyprinus carpio), a familiar economic freshwater fish in China,isusedasthemodel organism ofendocrineregulationresearchoffreshwaterfish.Butthe molecular mechanism of regulating gonad development and reproduction ofcommon carp hasn't been clearly elucidated. Since 1980s, transgenic carp has beenbred in our laboratory. Up to now fast-growing autotransgenic fish by transferringgrowth hormone gene into fish genome have been successfully obtained. The GHtransgenic carp has the feature of accelerated growth rate and shorten the time whichis required to reach the marketable size. However, Hormone regulation is a complexnetwork system, and the change of one hormone certainly will lead to the change ofanother one. Moreover, the sexural maturity of fast-growth GH transgenic commoncarp is highly delayed compared to the control ones (unpublished data). Therefore, inaddition to the desired traits for aquaculture, growth hormone transgenic commoncarp might become a special model which will play a role in the endocrinologystudyof fish. The present study focused on the GtH, the key signal molecular in theHypothalamic-Pituitary-Gonad (HPG) axis, which primarily stimulated gonaddevelopment.Themainresultsarepresentedasfollows:...