ECDYSTEROIDS IN NEMERTEANS - FURTHER CHARACTERIZATION AND IDENTIFICATION

Ecdysteroids are a class of steroidal hormones that are important in m olting and reproduction in arthropods. These hormones have been recent ly detected in non-arthropodan groups, such as soft-bodied worms. To c ontinue our efforts to determine the presence of ecdysteroids in nemer teans, this study further documents the identification of 20-hydroxyec dysone (20E), in Paranemertes peregrina, by gas chromatography/mass sp ectrometry (GC/MS). After C-18 Sep-Pak extraction, radioimmunoassay of the 40% and 80% methanolic fractions from an extract of 1000 worms in dicated 98 and 156 ng of ecdysteroids, respectively. Ecdysteroids of t hese two samples, as well as the 20E and ecdysone standards, were N-tr imethylsilyimidazole (TMSI)-derivatized before GC/MS analysis. The met hanolic samples contained a large number of compounds but only small, insignificant peaks in the area where ecdysteroid standards eluted. Ho wever, the reconstruction ion current (RIC) chromatograms for m/z 561 indicated the presence of 20E at the correct retention time of 12.48 m in in the 40% methanolic fraction. Reanalysis of the samples under sel ected ion monitoring mode demonstrated the presence of 20E in both the 40% and 80% fractions. These results demonstrate conclusively the pre sence of an active ecdysteroid in the phylum Nemertea.