MOLECULAR CLONING OF GONADOTROPIN HORMONES I (GtH-I) AND II (GtH-II) GENES IN THE HARD-LIPPED BARB (Osteochillus hasseltii) AND THE EFFECT OF PHOTOPERIODS ON THE GENES EXPRESSION

摘要

Photoperiods is one of the factors that influence regulation on endocrine gland in producing hormones necessary for gonadal growth and development, gametogenesis and reproductive cycles in fish reproduction. This study clones the gonadotropin hormones I (GtH-I) and II (GtH-II) genes in hard-lipped bard, and investigates the effect of photoperiod on the genes expression. Experiment was designed using three treatments; 14L: 10D (control), 8L: 16D (short photoperiods), and 18L: 6D (long photoperiods). Four aquariums with nine fish/tank were used, serving as replicates. Fish were kept under this photoperiods treatment for eight weeks. ?Pituitary activities were observed by GtH genes expression measurement. ?The length of cDNA GtH-I was 222 bp, and the cDNA GtH-II was 354 bp. The GtH-I precursors encoded by cDNA consisted of 67 amino acids, including mature peptide. The level of GtH gene expression was significantly increased as longer photoperiods given (P<0.05). The results indicated that hard-lipped barb reproductive performance is affected by photoperiods treatment.