Estrone and estradiol-17 beta concentration in tissue of the scleractiniancoral, Montipora verrucosa

Spawnings of scleractinian corals are affected by light, temperature, and o ther environmental cues, but no studies elucidate physiological mechanisms that regulate coral gametogenesis. We hypothesized that estrogens may act a s bioregulators of coral reproduction. Estrone (E-1) and estradiol-17 beta (E-2) concentrations were measured in homogenates of tissue and skeleton fr om M. verrucosa. Tissue samples were collected monthly throughout the year, and more frequently in July and August around spawning. Steroids were extr acted with diethyl ether, purified via celite chromatography and assayed wi th radioimmunoassay. Non-specific binding in coral tissue varied with sampl e weight and was elevated relative to standards. Monthly mean E-1 ranged fr om 20-70 ng E-1 g ash-free dry weight (AFDW)(-1), with highest values in Ap ril. Smaller asynchronous peaks occurred in early July, prior to spawning. Monthly mean E-2 ranged from 8-25 ng E-2 g AFDW(-1), with highest values in February and March. Peaks in E-2 preceded peaks in E-1, indicating metabol ism of a pool of estrogen. E-1 was positively correlated with protein conce ntration, which is consistent with a bioregulatory role of estrogens. Estro gen peaks in spring and prior to the July spawn corroborate our hypothesis that estrogens regulate coral gametogenesis and spawning. (C) 1999 Elsevier Science Inc. All rights reserved.