Jan Erik Solbakken

Initial characterization of the hepatic microsomal cytochrome P-450-system of the piked whale (Minke) Balaenoptera acutorostrata

Abstract Components of the microsomal cytochrome P -450- system were measured in liver samples from several female, one male and two foetal piked whales. In the same samples, four eytochrome P -450- dependent monooxygenase activities were assayed, protein pattern was determined by SDS-polyacrylamide gel e electrophoresis and the regiospecificity of phenanthrene metabolism in vitro was determined by gas chromatography/mass spectrometry. Foetal samples contained cytochrome P -450, cytochrome b 5 and NADPH-cytochrome P -450,reductase, but at lower levels than adults. Of the monooxygenase activities, only the O -deethylation reactions (7-EROD ∗ and 7-ECOD) could be detected in the foetuses. The turnover of 7-ethoxyresorufin was even higher than in most ofthe adult samples. In the adult samples, apparent differences could be observed in the parameters investigated between immature specimens of different sex and between immature and mature female whales. In vitro metabolism of phenanthrene showed a clear preference for attack at the 9,10-position by adult liver microsomes, where 10–35% appeared as the 1,2-dihydrodiol, with large individual variations. When metabolized by foetal liver microsomes, only 25–35% of total phenanthrene metabolites appeared as the 9,10-dihydrodiol, whereas 38–50% were the 1,2-dihydrodiol. Between 16 and 32% of the metabolites in all samples were phenols.

Distribution and elimination of [14C]-hexachlorobenzene after single oral exposure in cod (Gadus morhua) and flounder (Platichthys flesus).

Distribution and elimination of hexachlorobenzene (HCB) after administration to COD (Gadus morhua) of a single oral dose of 5 microCi [14C]HCB/100 g body weight were studied by whole-body autoradiography and liquid scintillation counting. To obtain some information on the physicochemical properties of the radiolabeled compounds, whole-body autoradiography was performed exposing parallel sagittal sections, treated at -20 degrees C, evaporated at 50 degrees C, and extracted separately with polar and nonpolar solvents. The highest concentration of radioactivity was found in the liver, the bile, and the central nervous system (CNS). Radioactivity in the liver and CNS, which was completely evaporable, was considered to represent the highly volatile HCB itself, and/or metabolites with high vapor pressure. No part of radioactivity in bile was evaporable, but it was completely extractable with water. Radioactivity in the intestinal content, the skin, and the uveal tract of the eye was partly evaporable. No radioactivity remained in any tissue after extraction with polar and nonpolar solvents. The rate of elimination was slow, and substantial amounts remained in the body 60 d after administration. In addition to bile excretion of nonevaporable, water-soluble radioactivity, a possible excretion through the intestinal mucosa was suggested. Whole-body autoradiography of female flounders (Platichthys flesus) revealed a high content of radioactivity in the developing eggs.

Accumulation and elimination of [9-14C]phenanthrene in the calico clam (Macrocallista maculata)

The accumulation and elimination of radoactivity is studied after exposure of (9-/sup 14/C) phenanthrene in various tissues in the calico clam (Macrocallista maculata). Results show that accumulation is highest in the lipid-rich hepatopancreas, and the elimination is very efficient compared to the horse mussel. The calico clam, which is a sand-dwelling organism, can easily come in contact with hydrocarbon contaminated sedments and might accumulate the hydrocarbons at different extents in various tissues. The efficient elimination, however, will prevent a lasting accumulation. (JMT)

Uptake and elimination of [9-14C]phenanthrene in the turkey wing mussel (Arca zebra)

Turkey wing mussels of both sexes were collected from Harrington Sound, Bermuda and dosed after a week-long acclimation period with (9-/sup 14/C)phenanthrene (714 MBq/mmol). They were transferred into 8 liters of seawater containing 8 ..mu..g of labelled phenanthrene. Results show that the accumulation of labelled phenanthrene in the turkey wing mussel was very low compared to that found in other species. In the hepatopancreas, the uptake of phenanthrene based on the water concentration was only 4% of the corresponding value found in the calico clam (Macrocallista maculata) inhabiting the same area. In comparison, the uptake of phenanthrene in a temperate mollusc such as the horse mussel (Modiola modiolus) was also considerably higher than in the turkey wing (approx. 4 times). It therefore seems likely that these are due to species variations rather than environmental variations between subtropical and temperate areas. (JMT)