作　　者： ; ; ; ;

机构地区： 中山大学生命科学学院水生经济动物繁殖营养和病害控制国家重点学科专业实验室

出　　处： 《中国水产科学》 2009年第1期1-7,共7页

摘　　要： 选取同一批30日龄的尼罗罗非鱼(Oreochromis niloticus)鱼苗置于水泥池中自然饲养,分别于30、60、80、110、140日龄取样测定不同发育阶段雄鱼的特定生长率。用实时荧光定量PCR方法检测雄鱼肝脏中两种生长激素受体(GHR1和GHR2)的mRNA丰度。结果表明,30～110日龄,雄鱼特定生长率呈不断上升趋势,至80～110日龄达到最高,之后开始下降;雄鱼肝脏中2种GHR基因表达的发育性变化趋势不相同,30～110日龄,GHR1mRNA表达逐渐上升,110日龄达到最高,随后开始下降,其发育性变化与特定生长率显著正相关(R=0.96,P<0.01);GHR2mRNA表达在60日龄达到最高,80日龄急剧下降,之后又缓慢上升,其发育性变化与特定生长率无相关性。提示尼罗罗非鱼生长激素可能主要通过与肝脏中GHR1受体的结合启动其促生长机制,肝脏中GHR1mRNA表达具有显著的年龄依赖性,其表达对尼罗罗非鱼的生长有重要影响。 Growth hormone （GH） plays a central role as a pluripotent endocrine regulator of physiological functions in fish and higher vertebrates, working through specific growth hormone receptors （GHR） that trigger a phosphorylation cascade for signaling and gene expression events. Two genomic contigs of putative growth hormone receptors （GHRs） were identified in fugu and zebrafish genomes by in silico analysis, suggesting the presence of two GHR subtypes in a single teleost species. We have tested this hypothesis by cloning The full-length cDNA sequences of both GHR subtypes from Nile tilapia, Oreochromis niloticus, were cloned in present study. Phylogenetic analysis of known GHR sequences from various vertebrates revealed that fish GHRs cluster into two distinct clades, viz. GHRl and GHR2. One clade （GHR1）, containing 6 to 7 extracellular cysteine residues, was structurally more akin to non-teleost GHRs. The other clade （GHR2）, containing only 4 to 5 extracellular cysteine residues, was unique to teleosts and was structurally more divergent from the non-teleost GHRs. To accurately analyze the roles of two growth hormone receptors of GHR1 and GHR2 during development of Nile tilapia Oreochromis niloticus, methods of real-time quantitative PCR were established to examine GHR gene expression. Total RNA was extracted from male Nile tilapia liver tissue and the fragments of target gene were amplified by RT- PCR with special primers. PCR product was cloned via pGEM-T Easy vector and extracted plasmid. The success of recombinant plasmid was identified by PCR amplified and restriction enzyme analysis. Variation of mRNA levels of GHR1 and GHR2 during development of male Nile tilapia was studied with real-time quantitative PCR. Male Nile tilapias from 30-day to 140-day old were used in the study to investigate the developmental changes of two GHRs mRNA expressions in liver. Male Nile tilapias were sampled at days 30,60,80, 110 andl40 respectively. The body lengths and body weights were recorded to calculate spe

关 键 词： 尼罗罗非鱼 生长激素受体 基因表达 实时定量 发育性变化

领　　域： [农业科学]