Detection of vertebrate-type steroid hormones and their converting activities in the neogastropod Thais clavigera (Küster, 1858)

Abstract

Knowledge of the regulation of molluscan reproductive systems is limited. Many studies have described how the development and maturation of molluscan gonads are regulated by oestrogen. Vertebrate-type oestrogen, 17β-oestradiol, has been detected in molluscs and its concentration in the gonads has been suggested to change in conjunction with reproductive cycles. However, it is unclear if molluscan gonadal tissues are relatively high in aromatase activities. Thais clavigera has been shown to possess a preferential expression of the oestrogen receptor gene in the ovary and ganglia, suggesting an association with gonadal maturation and expression of the oestrogen receptor gene. Therefore, it is interesting to explore the existence of vertebrate-type sex steroid hormones and aromatase activity in T. clavigera. We applied gas chromatography-mass spectrometry techniques to detect steroids in the gonadal tissues of T. clavigera and identified testosterone, androstenedione, 17β-oestradiol and oestrone. The aromatase activities converting androstenedione and testosterone into oestrone and 17β-oestradiol were much higher in gonads than in digestive glands. These data provide insights into the endocrinological system of neogastropods, prompting molecular evidence for the aromatase gene. © 2012 The Author.