Sex Steroids in Scleractinian Coral, Euphyllia ancora: Implication in Mass Spawning1

Abstract

The objectives of this study were to investigate the presence and annual cycle of sex steroids in scleractinian coral, Euphyllia ancora. The free and conjugated forms of sex steroids in coral and spawning seawater were investigated, and aromatase activity in the coral tissue was identified. Polyps collected from corals and seawater were extracted with diethyl ether, and purified by alumina column and reversed-phase HPLC; testosterone and estradiol-17beta (E2) was measured by a validated RIA. E2 and testosterone in their free and glucuronide forms were consistently detected in coral tissue throughout the year. Peak concentrations of free E2, E2 glucuronide, and testosterone glucuronide were obtained in the coral tissue just prior to spawning. The presence of specific aromatase activity was demonstrated in coral tissue. Free E2 and E2 glucuronide concentrations were higher than androgen (testosterone and testosterone glucuronide) in coral tissue and spawning seawater. Higher concentrations of free E2 than E2 glucuronide were detected in coral tissues throughout the year. In contrast, higher concentrations of E2 glucuronide than free E2 and testosterone glucuronide were found in seawater during mass coral spawning. No steroid sulfate could be detected in the coral tissue and seawater. We suggest that the release of E2 glucuronide may play an important role in coral mass spawning.

Presence of spawn-inducing pheromones in two brittle stars (Echinodermata: Ophiuroidea)

“…reef corals, dilution of sperm, as well as possible pheromones, may be a more severe problem. Large colony or aggregation sizes may be a solution for these immobile benthic organisms (Soong 1993), which may also evolve inductive spawning mechanisms (see Twan et al 2003). It remains to be tested whether individuals in large aggregations enjoy a disproportionately high fitness.…”

Independent elaboration of steroid hormone signaling pathways in metazoans

“…Our phylogenetic analyses are relevant to studies in the comparative endocrinology field, which discuss the presence of vertebrate-type steroids and steroidogenic activities in non-model species, especially in protostomes or cnidarians (33,36). In nonvertebrate species, the presence of steroids is usually monitored by radioimmunoassay (RIA) using antibodies generated against vertebrate hormones.…”

Gender expression and group size: a test in a hermaphroditic and a gonochoric congeneric species of Ophryotrocha (Polychaeta)

“…In aquatic (Stebbing et al, 2003) and the scale worm Harmothoe imbricata (Watson et al, 2000)], synchronizing release of gametes [e.g. in polychaetes (Hardege et al, 1998;Hardege and Bentley, 1997;Ram et al, 1999) and in corals (Twan et al, 2003)], and sperm activation and sperm attraction by eggs (Müller, 1976;Foltz, 1995). Hermaphroditic sea slugs of the genus Aplysia release a pheromone from their egg masses, which attracts potential mates and stimulates them to lay eggs on the same site (Painter et al, 2004).…”