A baseline study of metals in cod (Gadus morhua) from the North Sea and coastal Norwegian waters, with focus on mercury, arsenic, cadmium and lead.

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and livers of 516 cod caught at 22 positions in the North Sea were analysed. An additional 687 cod were caught from 13 fjords and coastal areas along the coast of Norway. Three out of 1203 samples of muscle exceeded the maximum limit of 0.5 mg Hg kg(-1) wet weight set by the EU for foodstuffs. The mercury concentration in cod muscle was higher and the cadmium concentration in the liver was lower in the North Sea and coastal areas in the southern part of Norway than in the Barents Sea and coastal areas in the northern part of Norway. These differences are perhaps caused by differences in the cod diet.

A baseline study of levels of mercury, arsenic, cadmium and lead in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea.

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and liver of more than 800 Northeast Arctic cod caught at 32 sites in the Barents Sea are reported. The highest concentration of both mercury in the muscle and cadmium in the liver was found in cod caught in the western part of the Barents Sea, while the highest concentration of total arsenic was found in cod from the eastern part. The arsenic concentrations varied greatly among individual fish, ranging from 0.3 to 170 mg kg(-1) wet weight in the muscle. Such high levels of total arsenic have never previously been reported in any fish, and the primary factor for these high concentrations is likely to be the shrimp in the cod diet.

Development and validation of an enzyme-linked immunosorbent assay to measure vitellogenin in the zebrafish (Danio rerio).

In this study, an enzyme-linked immunosorbent assay (ELISA) was developed to quantify vitellogenin (Vtg) in zebrafish (Danio rerio). Zebrafish Vtg (zf-Vtg) was purified from whole-body homogenates of estradiol-exposed zebrafish, and polyclonal antibodies against zf-Vtg were raised. Using purified zf-Vtg as a standard and anti-zf-Vtg antibodies (DR-264), a competitive ELISA method was set up and validated. The working range of the assay is from 1 to 30 ng/ml (20-80% binding), and the detection limit is 0.4 ng/ml for purified zf-Vtg. In whole-body homogenates samples, the practical detection limit is higher than that for purified Vtg (40 ng/ml) due to matrix effect. The intra- and interassay variations were 4.7% and 14%, respectively, at 50% binding (n = 36). Its usefulness to detect changes in Vtg concentration in other cyprinid fish was also tested. In addition, the assay was used to assess Vtg induction in male zebrafish exposed to 17beta-estradiol (E2). Exposure of male zebrafish to 0.1, 1, 10, and 100 microg/L of E2 for 7 d led to a Vtg induction from the lowest concentration. The results show the suitability of the developed ELISA to quantify Vtg inductions in zebrafish, the cross-reactivity of DR264 antibodies with commonly used cyprinids, and the potential of zf-Vtg induction as a sensitive biochemical endpoint that could be used to detect estrogenic properties of chemical substances.

Monoclonal antibody enzyme-linked immunosorbent assay to quantify vitellogenin for studies on environmental estrogens in the rainbow trout (Oncorhynchus mykiss).

Vitellogenin (VTG) induction has proved to be a valuable biomarker for assessing exposure to environmental estrogens in fish. The widespread use of VTG in this regard has lead to the need for standardized assays to quantify VTG, and monoclonal antibodies have the potential to help accomplish this. A VTG enzyme-linked immunosorbent assay (ELISA) was developed using a monoclonal antibody prepared against Atlantic salmon (Salmo salar) VTG (MAb BN-5) and its ability to quantify VTG in the rainbow trout (Oncorhynchus mykiss) compared with a rainbow trout vitellogenin (rt-VTG) ELISA that employed homologous polyclonal antibodies (PAb). In routine protocols, the working range of the homologous rt-PAb VTG ELISA was between 9 ng/ml and 70 ng/ml (80- 20% relative maximum binding [B/Bo]) with a 50% B/Bo of 25+/-0.9 ng/ml and inter- and intraassay variations at 50% B/Bo of 7% (n = 7) and 8% (n = 15), respectively. The working range of the MAb BN-5 VTG ELISA was between 60 ng/ml and 850 ng/ml (80-20% B/Bo) with a 50% B/Bo of 227+/-22 ng/ml and inter- and intraassay variations at 50% B/Bo of 5% (n = 10) and 9% (n = 12), respectively. In the routine protocols, detection limits for measurement of plasma VTG in rainbow trout (at 80% B/Bo; and given the requirement to dilute plasma to a minimum of 1:10 for the assays) were 90 ng/ml for the polyclonal rt-VTG assay and approximately 600 ng/ml in the monoclonal antibody assay. In juvenile female rainbow trout exposed to a series of doses of estradiol-17beta (E2) and 4-tert nonylphenol (4-NP), there were no differences in the vitellogenic responses measured in the PAb and MAb BN-5 VTG ELISAs. The monoclonal MAb BN-5 VTG ELISA is likely to be of considerable value for studies on environmental estrogens in juvenile female rainbow trout in standardized tests.