OCCURRENCE AND HORMONAL ACTION OF ECDYSONE ON GAMETOGENESIS AND ENERGY-UTILIZATION IN THE LEECH NEPHELOPSIS-OBSCURA (ERPOBDELLIDAE)

The present study provides novel information on the presence of compou nds with ecdysone-like activity and its involvement in the control of gonadal development in a leech. The presence of ecdysone was demonstra ted in leech (Nephelopsis obscura) extract by means of highperformance liquid chromatography (HPLC) in combination with radioimmunoassay. Le ech extract was found to bind specifically to an anti-ecdysone antiser um in a similar manner as standard ecdysone. Further HPLC purification demonstrated the presence of an immunoreactive fraction coeluting exa ctly with the standard ecdysone, strongly suggesting the presence of e cdysone in N. obscura. Addition of ecdysone to the ambient medium not only advanced leech gametogenesis but also influenced energy utilizati on. Both low (60 mu g . L(-1)) and high (600 mu g . L(-1)) concentrati ons of ecdysone increased testisac number, spermatogonia, 4th stage sp ermatogonia, ovisac size, and 2nd stage oogonia within 14 days compare d to 35 days in the controls. Ecdysone also caused significant decreas es in glycogen, total lipid, and triacylglycerols correlated with the energetic demands of gametogenesis. The findings provide support for t he hypothesis that endogenous ecdysone is involved in the regulation o f reproduction in N. obscura. (C) 1995 Wiley-Liss, Inc.