Abstract:

Dopamine receptor is an important neurotransmitter receptor, playing a key role in organism growth, development, metabolism, and other physiological processes. In this study, we obtained a fragment of dopamine receptor gene from transcriptome library of razor clam (Sinonovacula constricta), and cloned the full-length cDNA of dopamine receptor gene using RACE (rapid-amplification of cDNA ends) and Touchdown PCR (polymerase chain reaction). The full-length cDNA sequence contains two isoforms of alternative polyadenylation (APA), named as ScDopR2a and ScDopR2b, with a length of 1824 bp and 2758 bp, respectively. Both isoforms contain a 24 bp 5′untranslated region (UTR), and a 1440 bp open reading frame encoding 479 amino acid residues. However, the 3′UTR length is 360 bp and 1294 bp for ScDopR2a and ScDopR2b, respectively, with an insertion of 936 bp in front of the polyA tail for ScDopR2b. Primers were designed in open reading frame (ORF)to detect the expression level of dopamine receptor gene (ScDopR2) by quantitative real-time PCR. The results revealed the expression in waterpipe, gill and foot were higher than that in the other tissues. Then, primers were designed in 3′UTR to detect the expression level of ScDopR2b, showing similar expression pattern with ORF region. In the tissue damage experiment, the samples were selected at 4, 8, 12, 24, 48, 60, and 72 h after injuring waterpipe. The fluorescence quantitative results showed that a significant increase in 12 and 48 h, and a significant decrease in 8, 24 and 72 h. The trend of ScDopR2b gene’s expression level was similar to that of ORF. The results suggested that dopamine receptors are involved in the damage-healing process, and the expression pattern may be due to a role of dopamine as compensatory neurotransmitters.

Key words: Sinonovacula constricta, dopamine receptor, alternative polyadenylation (APA), damage healing