Total RNA was isolated from pituitary of grouper (Epinephelus coioides), and SMART cDNA was synthesized from 50 ng RNA. Two genes in the growth hormone/prolactin family were cloned from SMART cDNAs plasmid library. The growth hormone (GH) cDNA contains 938 by and encodes 204 amino acids (aa). The prolactin (PRL) cDNA contains 1 429 by and encodes 212 art. The deduced as sequences of grouper GH, PRL and SL were compared with those of other eight species. Average genetic distances and a dendrogram showing the hierarchical structure of affinity among different nine fishes were implemented in Mega 2 and CLUSTAL W1.64b. Branch and bound strap analysis (1000 replicates) were performed and the degree of support for particular nodes were produced. The three phylogenetic trees drawn from the whole as sequence of GH, PRL and SL were almost identical, Epinephelus coioides, Perca flavescens, Spares aurata and Paralichthys olivaceus were clustered into one group, Oncorhynchus keta and Oncorhynchus mykiss were clustered into one group, Carassius auras and Ictalurus punctatus were clustered into one group, while Anguilla japonica alone was clustered into another group. Alignment of the deduced as sequence and the phylogenetic tree based on GH/PRL/SL showed the same clustering as the present hierarchy of fish and a higher conservation of SL than GH and PRL among various fish species is suggested in this text. Although there is only 24% - 31% identity between the three hormones overall, the C-terminal region shows a higher identity. Grouper SL appears to be more closely related to GH (30.8%) than to PRL (25.6%), which is slightly more than the identity of GH to PRL (24.1%).
Jia Hai-Bo; Zhou Li; Shi Yao-Hua; Gui Jian-Fang (email@example.com).Molecular cloning and evolutionary implications of growth hormone/prolactin family gene cDNAs in grouper Epinephelus coioides,Zoological Research,2004,25(3):242-248