The use of microsomal in vitro assay to study phase I biotransformation of chlorobornanes (Toxaphene) in marine mammals and birds. Possible consequences of biotransformation for bioaccumulation and genotoxicity.

The factors determining the bioaccumulation of lipophilic compounds in wildlife are often poorly understood, partly because it is difficult to do in vivo experiments with animals such as marine mammals and birds. To evaluate the role of phase I biotransformation in the bioaccumulation process of chlorobornanes (toxaphene), this was studied in in vitro assays with hepatic microsomes of animals that could be sampled shortly after death. The capacity of microsomes to metabolise a technical toxaphene mixture decreased in the order Phoca vitulina (harbour seal) >> Lagenorhynchus albirostris (whitebeaked dolphin) approximately equal to Diomedea immutabilis (Laysan albatross) > Physeter macrocephalus (sperm whale).

Temporal induction pattern of hepatic cytochrome P450 1A in thermally acclimated dab (Limanda limanda) treated with 3,3',4,4'-tetrachlorobiphenyl (CB77).

Mature male dab (Limanda limanda) acclimated at 10 degrees and 16 degrees C were orally administered a single dose of 0.5 mg/kg 3,3',4,4'-tetrachlorobiphenyl (CB77). At both temperatures, levels of cytochrome P450 1A (CYP1A) protein and 7-ethoxyresorufin O-deethylase (EROD) activity showed a two to six fold induction 40 days after CB77 treatment compared to control groups.

Sensitivity of cytochrome P450 1A induction in dab (Limanda limanda) of different age and sex as a biomarker for environmental contaminants in the southern North Sea.

The sensitivity of cytochrome P450 1A (CYPIA) induction as a biomarker for environmental contaminants in the flatfish dab (Limanda limanda) was evaluated by studying fish of different age and sex from the southern North Sea. Mature and juvenile dab from both sexes were collected in autumn and winter during two surveys from four different stations with varying levels of polychlorinated biphenyls (PCBs) contamination in the southern North Sea. All groups of fish exhibited highest muscle PCB concentrations near the Dutch coast.

Molecular responses as indicators of marine pollution: DNA damage and enzyme induction in Limanda limanda and Asterias rubens.

During a survey from 26 August through 13 September 1991, specimens of the flatfish, Limanda limanda (dab), and the asteroid echinoderm Asterias rubens (seastar), were collected at sampling locations along transects radiating into the North Sea from the coastal zone of The Netherlands. In homogenates of liver tissue from male dab and the digestive gland (pyloric caeca) of female seastar, DNA damage (strand breaks) and induction of the cytochrome P450-dependent monooxygenase system (MO) were determined. Areas could be described with significantly increased percentages of strand breaks (lower integrity) both in dab and seastar.