Genome-Wide Identification of 5-HT Receptor Gene Family in Razor Clam and Their Circadian Rhythm Expression Analysis.

Serotonin (5-HT) is primarily distributed in the gastrointestinal and central nervous systems, where it plays a crucial role in regulating various physiological functions such as digestion, reproduction and establishing animal emotions. 5-HT is an effective oxytocin widely used in molluscan aquaculture, and its physiological functions are performed by binding to corresponding 5-HT receptors (5-HTRs). In this study, seven genes of () were identified and analyzed, and they were designated as , , , , , and . Phylogenetic analysis showed that the seven were conserved among mollusks, and the Sc5-HTRs were all transmembrane proteins. The seven genes were distributed on chromosome 1, 2, 13 and 14. After injecting 5-HT, there was a significant increase in mRNA expression levels of ( < 0.05) and ( < 0.01), while decreased significantly ( < 0.01) compared to control groups which might be effective 5-HT receptors. Furthermore, two of the receptors ( and ) were expressed in the circadian rhythm patterns, indicating their potential influence on the nocturnal spawning of . Overall, these findings provide a theoretical basis for understanding the structures and functions of gene family members, and may facilitate the artificial propagation of mollusks.