Cloning and expression regulation of rhodopsin and long-wave sensitive opsin in Lutjanus erythropterus

【Objective】In order to provide a theoretical basis for exploring the process of snapper adaptation from surface plankton to bottom benthic light environment. Therhodopsin(RH1) gene and long-wave sensitive opsin(LWS) gene of Lutjanus erythropterus were cloned and their expression law were analyzed in different stages of early development and in different tissues of adult fish.【Method】The full-length cDNA of RH1 gene and LWS gene of L. erythropterus were cloned by RACE technology. Thesequence of the two genes and the encoded amino acid sequence were analyzed by bioinformatics software. Real-time fluorescence quantitative PCR(qRT-PCR) method was used to detect the embryonic development stages of L. erythropterus(1/2 epiboly stage,blastopore closure stage,optic capsule stage,eye lens formed stage,heart-beating stage,hatching stage) and larval developmental stages(1,3,10,15 and 20 d),as well as the expression patterns in different tissues of adult fish(brain,heart,liver,muscle,black skin,red skin,stomach and retina).【Result】The full-length c DNA of RH1 gene and LWS gene of L. erythropterus were 1723 bp and 1302 bp,respectively. The RH1 gene had 465 bp 3'-UTR and 196 bp 5'-UTR with 1062 bp open reading frame(ORF),encoding 353 amino acids;the LWS gene had 213 bp 3'-UTR and 15 bp 5'-UTR with 1074 bp ORF,encoding 357 amino acids. Phylogenetic analysis showed that the two opsin genes clustered first with Perciformes,and then clustered with Killiformes,Pleuronectiformes and Cypriniformes,and finally with terrestrial vertebrates. qRT-PCR detection results showed that the relative expression level of RH1 gene was significantly higher than other periods at 15 d and 20 d after hatching(P<0.05,the same below),and the relative expression level of LWS gene was significantly higher than other periods at 20 d. The expression patterns of the two opsin genes in different tissues of adult fish were similar,and the expression levels in the retina were significantly higher than those in other tissues.【Conclusion】The expression of RH1 and LWS genes are tissue-specific,and the expression levels in early developmental stage are related to the changes of living habits of L. erythropterus,indicating that the expression of RH1 and LWS opsin genes of L. erythropterus closely corresponds to the changes of their living light environment,and plays an important role in light regulation during early developmental metamorphosis and adaptation to dark environments.