Bioaccumulation and biomarkers in the sea star Asterias rubens (Echinodermata: Asteroidea): a North Sea field study.

During two North Sea field trips in March 1995 and September 1996 sea stars, Asterias rubens, were collected at various stations along pollution gradients in order to study the relation between biochemical markers and levels of accumulated contaminants. Biomarkers measured were: cytochrome P450 level, benzo[a]pyrene hydroxylase (BPH) activity, acetylcholinesterase (AChE) activity and DNA integrity. Accumulation levels of heavy metals, polychlorinated biphenyls, organochlorine pesticides and polycyclic aromatic hydrocarbons (PAHs) in the pyloric caeca of sea stars indicate different pollution gradients, influenced by rivers in The Netherlands, UK and Germany. For some contaminants, especially PAHs, relatively high levels were found in the central part of the North Sea (Dogger Bank). On the basis of multivariate statistics, stations near the mouth of the Elbe and the Rhine/Meuse were shown to have different patterns of biomarker responses. Sea stars from stations in coastal zones showed relatively high levels of cytochrome P450 and 'P418', another haemoprotein that is present in most marine invertebrates. The station nearest to the Elbe Estuary showed the lowest BPH and AChE activity. DNA integrity was lower especially in stations near the Dutch coast and in a station near the Tees/Tyne estuaries. Using these biomarkers as early warning signals of exposure and/or adverse effects, this type of monitoring can be used also in the future to study the spatial and temporal trends in the quality of coastal waters.

Dose- and time-dependent formation of biliary benzo[a]pyrene metabolites in the marine flatfish dab (Limanda limanda).

Polycyclic aromatic hydrocarbons (PAHs) are abundant pollutants, and many PAHs are carcinogenic, but only after metabolic activation. Benzo[a]pyrene (BaP) is among the most carcinogenic PAHs. The dose and time response of two enzymes involved in BaP metabolism and the amounts of BaP metabolites excreted into the bile were evaluated in an experiment with dab (Limanda limanda). Ninety dab were exposed orally to one of five doses of BaP (0, 0.08, 0.4, 2, or 10 mg/kg) and sampled at 3, 6, or 12 d after exposure. None of the doses studied caused significant induction of either microsomal ethoxyresorufin-O-deethylase (EROD). which reflects cytochrome P450 1A (CYP1A) activity, or cytosolic glutathione-S-transferase activity (GST). Concentrations of biliary BaP metabolites significantly increased with dose and significantly decreased with time after exposure. It is concluded that biliary BaP metabolites provide a much more sensitive method than EROD (CYP1A) or GST activity to monitor recent exposure to PAHs in dab.

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. However, enhanced DNA strand breaks did not correspond with contamination gradients, expressed as concentrations of polychlorinated biphenyls (PCBs) or polyaromatic hydrocarbons. MO enzyme induction in the hepatic 13,000g fraction of male dab, measured as 7-ethoxyresorufin-O-deethylase activity, was significantly enhanced in response to low ambient temperatures. Some evidence was found for the facilitation of benzo[a]pyrene hydroxylase activity expressing the enzyme induction in the microsomal fraction of pyloric caeca of seastars, at increasing PCB concentrations. DNA integrity and enzyme induction elucidate the physiologic status and might be indicative for ambient impairment within restricted areas, and not necessarily related to the presence of anthropogenic or xenobiotic substances.

Changes in levels of hepatic biotransformation enzymes and haemoglobin levels in female plaice (Pleuronectes platessa) after oral administration of a technical polychlorinated biphenyl mixture (Clophen A40).

Female plaice (Pleuronectes platessa) were orally dosed with a gelatin capsule containing a solution of the technical PCB mixture Clophen A40 in sunflower oil. They were compared to plaice injected with a gelatin capsule containing only the sunflower oil at 10 and 16 days after injection. Even at 16 days after injection, the increase in concentrations of individual CB congeners in muscle was proportional to their contribution in Clophen A40. Biochemical effects are related to increases in concentrations of well-separable CB congeners in muscle, which increased by factors between 1.6 and 64 compared to the reference group of fish. Of both sampling points, total cytochrome P-450 levels were higher than the control groups, but surprisingly ethoxyresorufin-O-deethylase (EROD) activities did not differ between the groups. Enzyme-linked immunosorbent assay (ELISA) showed increased concentrations of the inducible cytochrome P-450IA1 in PCB-treated fish. The apparent lack of EROD induction may be due to competitive substrate inhibition by certain CB congeners present in the sample. The activity of glutathione-S-transferase (GST) (with CDNB as model substrate) was significantly elevated by PCB-treatment at day 16, but not at day 10. A longer time interval between injection with PCBs and induction of GST compared to P-450 monooxygenase activities has been reported earlier and may indicate that in fish both groups of enzymes are regulated individually and not as an [Arylhydrocarbon] gene battery as appears to be the case in mammals. Haemoglobin concentrations and MCHC were decreased in fish treated with Clophen A40. Haematocrit values did not differ between groups of fish.

Residues of chlorinated biphenyl congeners and pesticides in brain and liver of the oystercatcher (Haematopus ostralegis) in relation to age, sex and biotransformation capacity.

Polychlorinated biphenyl concentrations in brain and liver oystercatchers, Haematopus ostralegis, increased similarly in males and females until sexual maturation. The concentrations were higher in adult males than in subadults, but for females the concentrations were lower in adults than in subadults. Absolute PCB, dieldrin and DDE concentrations were higher in liver than in brain. Compared with these compounds, alpha-HCH was relatively enriched in brain. No significant relation between pesticide concentrations and age or sex could be established. Despite differences in absolute PCB concentrations, the PCB patterns were very similar between all categories of birds and between brain and liver of the same animals. Only in the brain of juvenile males were some congeners present in relatively higher concentrations than in the brain of subadults and adults. Oystercatchers are able to metabolize CB congeners with vicinal H-atoms in the meta and para positions irrespective of the number of ortho-chlorines present. However, their ability to metabolize congeners with vicinal H-atoms in the ortho and meta positions is limited.

Is monitoring of respiratory properties of the haemoglobin of the Lugworm Arenicola marina meaningfull?

Haemoglobin in Arenicola has a high oxygen affinity, with a half saturation oxygen pressure of about 180 Pa at pH 7.4 and 15°C. The oxygen affinity decreases with increasing copper concentration in the blood to about 300 Pa at pH 7.4, 15°C. at a copper concentration of 35 µg ml(-1). Copper exerts only a slight influence on the subunit cooperativity in oxygen binding. The oxygen affinity, subunit cooperativity and the Bohr effect are pH dependent. Copper affects the functioning of the blood by inhibiting oxygen binding to the haemoglobin in the respiratory area and oxygen delivery in the tissues.