斜带石斑鱼(Epinephelus coioides)两种催乳素受体基因的 cDNA 克隆和 mRNA 表达分析

采用RT-PCR方法克隆了斜带石斑鱼两种催乳素受体(Prolactin receptor,PRLR)的cDNA序列,序列分析表明:PRLR1开放阅读框为1947bp,共编码649个氨基酸,PRLR2开放阅读框为1749bp,共编码487个氨基酸,PRLR1与PRLR2的氨基酸同源性为40.4%。用Real-time RT-PCR方法研究了PRLR1和PRLR2在各组织和早期发育不同阶段的表达情况,结果表明:PRLR1和PRLR2在所检测的12种组织中均有表达,其中以鳃、肾、肠表达量较高;PRLR1在受精期表达最高,PRLR2在视囊形成期表达最高,而且除受精卵期外PRLR2在各时期的表达量均高于PRLR1。

cDNAs CLONING AND mRNA EXPRESSION OF TWO PROLACTIN RECEPTORS IN ORANGE-SPOTTED GROUPER EPINEPHELUS COIOIDES

Prolactin (PRL) has many important physiological roles in the control of growth, osmoregulation and reproduction, which is mediated by prolactin receptor (PRLR). In this study, two cDNAs encoding PRLR were isolated from the gill of orange-spotted grouper Epinephelus coioides. The two cDNAs, one consisting of 1947bp and the other of 1749bp, encoding for putative 649- and 487-amino acid PRLR (designated PRLR1 and PRLR2, respectively), shared 40.4% identity in deduced amino acid sequence. PRLR1 and PRLR2 showed the conserved structural characteristics of PRLR family, including the WS motif, the box1 region, extracellular cysteine residues and intracellular tyrosine residues. However, there were differences of structural features between the two receptors as well. PRLR1 has 13 intracellular tyrosine residues while PRLR2 only has 8. The structural discrepancies thus undoubtedly indicated the distinct biological functions of PRLR1 and PRLR2. Real-time RT-PCR analysis showed that both PRLR1 and PRLR2 mRNAs were presented in all tissues tested and expressed extremely highly in gill, kidney and intestine, lowly in pituitary and hypothalamus. The expressions of PRLR1 and PRLR2 in different embryo developmental stages were also detected by real-time PCR. The strongest signal was detected in the fertilized egg stage for PRLR1, while in the stage of optic vesicle and smoite formation for PRLR2. The expression level of PRLR2 is much higher than PRLR1 in all stages examined except in the fertilized egg stage. The expression distinction of PRLR1 and PRLR2 suggested that they may play different roles during early development of orange-spotted grouper.