罗非鱼催乳素Ⅰ基因的组织分布及盐胁迫对其表达的影响

Effect of salinity stress on expression of PRLⅠgenes from tilapia and their distribution in different tissues

采用同源克隆方法从橙色莫桑比克罗非鱼(Oreochromis mossambicus)、荷那龙罗非鱼(O.hornorum)及其正反交子代垂体中克隆了催乳素Ⅰ基因(PRLⅠ),并对其核苷酸序列和推导的氨基酸序列进行了比对分析。结果显示,4种罗非鱼的PRLⅠ基因序列长度均为798 bp,ORF长639 bp,共编码212个氨基酸;橙色莫桑比克罗非鱼和荷那龙罗非鱼仅在31号位点存在一个氨基酸残基差异。用q PCR方法分析橙色莫桑比克罗非鱼和荷那龙罗非鱼PRLⅠ基因在不同组织或器官中的表达,结果表明罗非鱼PRLⅠ基因在垂体中的表达量最高,在其他组织中的表达量较低;盐胁迫后4种罗非鱼垂体中的PRLⅠmRNA水平均显著降低,而在其他组织中的表达变化不大。由此可知PRLⅠ基因主要在垂体表达,参与罗非鱼的渗透压调节。

The prolactinⅠ（ PRLⅠ） genes were cloned from pituitary glands of Oreochromis mossambicus,O. hornorum and their hybrids by homology cloning approach. The c DNA sequences and amino acid sequences deduced from them were analyzed through alignment. The results show that PRL Ⅰ genes from the four different species of tilapia consisted of 798 bp including open reading frame（ ORF） of 639 bp,and encoded a putative protein of 212 amino acids. There was only amino acid residue difference between O. mossambicus and O. hormorum at the 31 stsite. The expression of PRLⅠ genes in different tissues and organs of O. mossambicus and O. hornorum as well as the relative expression of PRLⅠ genes of the four species of tilapia under salt stress were analyzed by real time quantitative PCR（ q PCR）. The results reveal that PRLⅠ transcript was detected at high level in pituitary and low level in other tissues and organs. The expression of PRLⅠ decreased significantly after exposure to salt stress in pituitary. These results suggest that PRLⅠ genes play an important role in the osmoregulation of tilapia.