Steroidogenesis in vitro in the harp seal (Pagophilus groenlandicus) without and with methyl mercury treatment in vivo.

Tissue from a harp seal given methyl mercury at a concentration of 0.25 mg/kg in its diet for 61 days, was highly contaminated with mercury. Over 70% of the mercury in the seal's liver (64.0 p.p.m.) was in the inorganic form indicating a demethylating system in this organ. Most of the mercury in the liver, spleen and kidney of an untreated seal was also in the inorganic form. In contrast, over 75% of the mercury in the adrenals and gonads (14.2 and 13.0 p.p.m., respectively) of the treated seal was methyl mercury. Mercury was not detectable in the gonads and not analyzed in the adrenals of the untreated seal. Biosynthesized (in vitro) cortisol, corticosterone, cortisone, and 11-ketotestosterone were isolated and identified from the adrenal incubations, and delta4-androstene-3,17-dione and testosterone were isolated and identified from ovarian incubations from both untreated and methyl mercury (in vivo) treated seals. The ovaries and adrenals from both seals appeared to be normal under the light microscope. The ovaries from both seals were in the same follicular phase, but in vitro incubations of tissue from these organs indicated that the methyl mercury and treatment caused a marked alteration of steroid biosynthesis in tissue from the treated seal. The altered pattern of steroid biosynthesis was also demonstrated by autoradiography, and it is suggested that this technique could be used as an indicator of incipient contamination by a pollutant.