On the nutrition and metabolism of zooplankton XIII. Further studies of steroids inCalanus

Abstract
The presence inCalanus finmarchicusof the sex hormone oestradiol-17β has been confirmed by gas chromatography-mass spectrometry (GC-MS) using the trimethylsilyl and heptafluorobutyrate derivatives.Levels of the sex hormone testosterone have been measured by radioimmunoassay inCalanus helgolandicuscollected from Plymouth Sound, and inC. finmarchicuscaptured off the Norwegian coast. Concentrations inC. helgolandicusvaried during the year from 150 to 626 fg/animal, accounting for 2.3 to 437 x 10-7% of the lipid content and 10.8 to 64.8 x 10-6%percnt; of the total sterol fraction. The mean level in Stage V C.finmarchicus,captured during spring, was 196 fg/animal.Testosterone was identified in C.finmarchicusby GC-MS of thetert-butyldimethylsilyl derivative.