Gas chromatographic-mass spectrometric analysis of steroids and steroid glucuronides in the seminal vesicle fluid of the African catfish, Clarias gariepinus.

Gas chromatographic-mass spectrometric analysis was carried out to identify steroids and steroid glucuronides in the seminal vesicle fluid of African catfish, Clarias gariepinus, collected in the Hula nature reserve (Israel) during the breeding season. Full mass spectra of 5 beta-pregnane-3 alpha, 17 alpha-diol-20-one and cholesterol were obtained. After treatment with beta-glucuronidase the following steroid glucuronides were determined by full mass spectra of the corresponding free steroids: etiocholanolone, 5 beta-androstane-3 alpha, 17 beta-diol-11-one, 5 beta-pregnane-3 alpha, 17 alpha-diol-20-one, and cholesterol. Furthermore, after selected ion monitoring the following steroids and steroid glucuronides could be detected by the presence of at least two characteristic ions at the expected retention time: 5 beta-androstane-3 beta, 17 beta-diol, 5 beta-androstane-3 alpha, 17 beta-diol, etiocholanolone, 5 beta-androstane-3 alpha, 17 beta-diol-11-one, testosterone, 5 beta-androstane-3 alpha, 17 beta-diol-glucuronide, and testosterone-glucuronide. These results agree with the hypothesis that steroid glucuronides, synthesized by the seminal vesicles, are excreted with the seminal vesicle fluid into the external environment, where they might function as sex pheromones.