The full length cDNA cloning and expression analysis of RXR from the Chinese mitten crab(Eriocheir sinensis)

Retinoid X receptor( RXR) is a member of the second subfamily of nuclear receptor superfamily. In the insect and the crustacean,RXR is an important signaling protein w ith varied roles in regulating aspects of reproductive maturation,molting and embryo development. In this study,w e cloned RXR gene from Eriocheir sinensis using reverse transcriptase polymerase chain reaction( RT-PCR) and rapid-amplification of cDNA ends( RACE),and primers w ere designed according to the conserved sequence of RXR from G ecarcinus lateralis. The full-length cDNA sequence of RXR is 1 517 bp and codes a protein of about 433 amino acids. The amino acid sequence comparison results show ed that the RXR gene of Eriocheir sinensis shared 96% identity w ith G ecarcinus lateralis,using BLASTn and BLASTx softw are. Phylogenetic tree of RXR gene generated by Neighbor Joining method suggested that RXR is clustered closely w ith that of G ecarcinus lateralis. The expression of the gene in different tissues and molting stages of E. sinensis w as analyzed by real-time fluorescent quantitative PCR. The result show ed the RXR mRNA w as expressed in all tissues examined and highly in Y-organ,w ith small amount in hepatopancreas,gill and muscle,trace in heart, stomach,intestine,thoracic ganglion and brain ganglion. RXR mRNA w as detected w ith high volume in Yorgan compared to hepatopancreas,muscles and gill at the same molting stages of the crab. RXR mRNA of Y-organ in stage D w as significantly( P 0. 05) higher than that of stage AB and stage C. It also had significant difference( P 0. 05) betw een muscles at stage AB and stage E,and there w as no significant difference expression in hepatopancreas and gill tissues in different molting stages.