Occurrence and hormonal action of ecdysone on gametogenesis and energy utilization in the leech Nephelopsis obscura (Erpobdellidae)

Abstract The present study provides novel information on the presence of compounds with ecdysone‐like activity and its involvement in the control of gonadal development in a leech. The presence of ecdysone was demonstrated in leech ( Nephelopsis obscura ) extract by means of high‐performance liquid chromatography (HPLC) in combination with radioimmunoassy. Leech extract was found to bind specifically to an anti‐ecdysone antiserum in a similar manner as standard ecdysone. Further HPLC purification demonstrated the presence of an immunoreactive fraction coeluting exactly with the standard ecdysone, strongly suggesting the presence of ecdysone in N. obscura . Addition of ecdysone to the ambient medium not only advanced leech gametogenesis but also influenced energy utilization. Both low (60 μg·L −1 ) and high (600 m̈g·L −1 concentrations of ecdysone increased testisac number, spermatogonia, 4th stage spermatogonia, ovisac size, and 2nd stage oogonia within 14 days compared to 35 days in the controls. Ecdysone also caused significant decreases in glycogen, total lipid, and triacylglycerols correlated with the energetic demands of gametogenesis. The findings provide support for the hypothesis that endogenous ecdysone is involved in the regulation of reproduction in N. obscura . © 1995 Wiley‐Liss, Inc.