AUTHOR=Zhu Shaojie , He Yubo , Xu Qiongyu , Zhang Jiabin , Yang Chuangye , Hao Ruijuan , Li Junhui , Deng Yuewen 

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

JOURNAL=Frontiers in Marine Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2022.1011420

DOI=10.3389/fmars.2022.1011420

ISSN=2296-7745

ABSTRACT=<p>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 <italic>5-HTR</italic> genes from <italic>Pinctada fucata martensii</italic> (<italic>Pm5-HTR2</italic> and <italic>Pm5-HTR4</italic>) were cloned. A total of 1623 bp open reading frame was identified in <italic>Pm5-HTR2</italic>, and a 1185 bp open reading frame was detected in <italic>Pm5-HTR4</italic>; 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 <italic>Crassostrea gigas</italic> 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 <italic>Pm5-HTR2</italic> and <italic>Pm5-HTR4</italic> during the developmental stages. ISH analysis showed that <italic>Pm5-HTR2</italic> was primarily expressed in the FE, B, T, EU, and EL stages and <italic>Pm5-HTR4</italic> was mainly expressed in the FE, B, T, D, EU, and EL stages. These results suggest that 5-HTRs may play key roles in <italic>P. f. martensii</italic> larval metamorphosis.</p>