Molecular cloning of vitellogenin gene in the hard-lipped barb (Osteochillus hasseltii C.V) and the effect of photoperiods on gene expression

Abstract

Fish reproduction is influenced by photoperiods through regulation on endocrine gland activities in producing hormones needed for gonadal growth and development, gametogenesis and reproductive cycles. This study was conducted to find out the effect of photoperiod on hard-lipped barb reproductive performance by manipulating photoperiod. Experiments were designed with three photoperiod treatments, namely 14L:10D (control), 8L:16D (short photoperiods) and 18L:6D (long photoperiods). Four aquaria consisting of nine fishes each were served as replicates. Fishes were kept under these photoperiods for 8 weeks. The observed variable was the liver activities evaluated by measuring gene expression of Vitellogenin. The normalized data were subjected to ANOVA followed by Tukey's multiple-comparison tests. The length of cDNA Vitellogenin was 1136 bp. The vitellogenin precursors encoded cDNA consisted of 378 amino acids. The average of vitellogenin gene in each experimental group significantly increased according to longer photoperiods (P < 0.05), and the highest vitelogenin gene expression was in Long Photoperiods (LP, 18Light: 6 dark). These results indicated that photoperiods had a stimulatory effect in improving hard-lipped barb reproductive performance.