Molecular Cloning, Characterization And Expression Of Gonadotropin And Their Receptors From Grass Carp (Ctenopharyngodon Idellus)

GTH(Gonadotropin Hormone) and GTHR(Gonadotropin receptor) play a central role in reproduction in fish gonad development and ovulation.The three GTH subunits and two partial GTHR cDNA were cloned and characterized from grass carp.RT-PCR was employed to check tissue distribution of FSH and LH.Real-time PCR showed the expression pattern of GTH in different period of ovary.This study showed some results of GTH and GTHR gene cloning and characterization.1.Full length cDNA of GTHα,FSHβand LHβcDNA was 844bp, 739bp and 576bp,with open reading frame encoding proteins of 118,130 and 146 amino acids,respectively.2.Partial cDNA of FSHR and LHR were cloned.FHSR was 509bp encoding 169 amino acids.LHR obtained two partial fragments.LHR1 was 869bp encoding 289 amino acids,and LHR2 was 1204bp encoding 253 amino acids.3.Phylogenetic analysis of the proteins of GTH showed a high homology with other fishes.Homology analysis also indicated that GTHαhas the highest conservation.The Phylogenetic tree was identical with morphologic.4.RT-PCR analysis indicated that GTH were only expressed in the pituitary. 5.Real-time quantitative PCR protocols were employed to measure FSHβand LHβmRNAs during ovarian development.The FSHβand LHβmRNA level was very low in the pituitaries of early-pubertal fish and significantly increased during ovulation period.These results suggested that in grass carp the gonadotropins synthesized synchronously in order for asynchronous oogenesis to take place.