Molecular cloning, characterization, and expression of two 5-HTRs from the pearl oyster Pinctada fucata martensii

The receptors of serotonin, also known as 5-hydroxytryptamine receptor (5-HTR) can mediate regulatory metamorphosis processes in a variety of mollusks. Studying the mechanisms of metamorphosis of the pearl oyster is significant to elucidate breeding, resource recovery and marine pearl production. In this study, two 5-HTR genes from Pinctada fucata martensii (Pm5-HTR2 and Pm5-HTR4) were cloned. A total of 1623 bp open reading frame was identified in Pm5-HTR2, and a 1185 bp open reading frame was detected in Pm5-HTR4; these open reading frames encoded a 540-residue polypeptide and a 394-residue polypeptide, respectively. We also conducted a domain analysis, which indicated that Pm5-HTR2 and Pm5-HTR4 contained a seven-transmembrane domain and revealed that the receptors had high similarity to Crassostrea gigas 5-HTR2 (54.62%) and 5-HTR4 (66.23%). Sequence analysis demonstrated conserved advanced structure and motifs (the DRY/ERY and NPXXY motifs). The expression pattern analysis revealed high expression levels of Pm5-HTR2 and Pm5-HTR4 during the developmental stages. ISH analysis showed that Pm5-HTR2 was primarily expressed in the FE, B, T, EU, and EL stages and Pm5-HTR4 was mainly expressed in the FE, B, T, D, EU, and EL stages. These results suggest that 5-HTRs may play key roles in P. f. martensii larval metamorphosis.

Automated summary

In this study, two 5-HTR genes were cloned from Pinctada fucata martensii, and their expression patterns and tissue localization were analyzed. The results indicate that these genes may play important roles in the metamorphosis of the pearl oyster.