Exploring endocrine regulation of sea urchin reproductive biology: effects of 17ß-oestradiol

Abstract

Although several authors have suggested a plausible involvement of steroids in the reproductive biology of echinoderms, their definitive role is still poorly understood. In this paper we focused on oestradiol (E2), whose presence and variations were previously revealed in different echinoderm tissues. The aim of this investigation was to provide further information on the scarcely known role of this hormone in the reproductive biology of sea urchins. We injected two different concentrations (5 ng ml−1and 50 ng ml−1) of 17ß-oestradiol into specimens of the commonParacentrotus lividusfor 10 weeks. The E2treatment did not influence the maturation stage of the gonads and the development of the gametes; it caused a slight decrease in the gonad index and an increase in lipid content. Our present results suggest that E2could have a function different from that reported for vertebrates and suggested for other echinoderms such as asteroids.