Detection of unconjugated and conjugated steroids in the ovary, eggs, and haemolymph of the decapod crustacean Nephrops norvegicus

Abstract

Gas chromatography/mass spectrometry with selected ion monitoring has been employed to examine extracts from the ovary, eggs, and haemolymph of the marine prawn, Nephrops nnorvegicus, to demonstrate the presence of steroids. Both free and conjugated steroids were isolated by solvent partitioning and chromatography (lipophilic Sephadex, reversed-phase Sep Pak, and normal phase medium-pressure liquid chromatography) and steroidal conjugates were cleaved enzymatically. Steroids were determined as their methyloxime derivatives, trimethylsilyl (TMS) ethers or methyloxime-TMS ethers. All assignments were based on the detection of characteristic ions and cochromatography with the authentic steroid derivatives. 5α-Dihydrotestosterone, testosterone, pregnenolone, and 20α-hydroxypregn-4-en-3-one were detected in unconjugated form in the ovary. The eggs and haemolymph were found to contain unconjugated 17β-estradiol. Conjugated 5α-dihydrotestosterone was detected in both the ovary and haemolymph, but no conjugated steroids were found in the eggs.