Role of StAR Gene in Sex Steroid Hormone Regulation and Gonadal Development in Ark Shell .

This study elucidates the role of the () in sex steroid hormone dynamics and the gonadal development of the commercially important marine bivalve ark shell . The sequence of the gene was obtained and verified from the transcriptome of ark shell, then the tissue localization and expression pattern during the gonad development of the gene were detected by in situ hybridization and quantitative real-time PCR, respectively. Additionally, the concentrations of three critical sex steroid hormones (progesterone, testosterone, and estradiol) were measured throughout gonadal development using enzyme-linked immunosorbent assay (ELISA). The results showed that the length of the coding region of was 1446 bp, encoding 481 amino acids. The results of qRT-PCR showed that the expression of the gene varied with gonadal development, increased from the early active stage to the development stage, and decreased from the mature stage to the spent stage. Notably, the expression level in ovaries was higher than that in testes, suggesting the potential involvement of in sex differentiation and gonadal development. Additionally, the results indicated that progesterone, testosterone, and estradiol accounted for 80%, 10%, and 10% of the total hormone content in the gonads, respectively. Correlation analysis revealed a highly significant strong positive correlation between progesterone/estradiol levels and gene expression, demonstrating that serves as a key regulator in sex steroid hormone biosynthesis. These findings provide crucial molecular evidence for -mediated steroidogenesis in bivalve reproduction, offering fundamental insights into invertebrate endocrinology.