Tor Sverre Solberg

Immunochemical detection of cytochrome P450IA1 induction in cod larvae and juveniles exposed to a water soluble fraction of North Sea crude oil

Abstract Using a flow-through biotest exposure system, cod eggs, larvae and juveniles were exposed to the water-soluble fraction (WSF) of North Sea (Statfjord B) crude oil at concentrations ranging from 40–300 μg l−1 (ppb) for 1–6 weeks. The WSF was analysed by GC/MS, and was shown to be dominated by low-aromatic compounds such as benzenes, toluene and xylenes (80–90%). Cytochrome P450IA1 levels were measured by immunochemical techniques in 10 000 × g supernatants of whole larvae or juvenile gill homogenates, and in juvenile liver microsomal fractions. With rabbit anti-cod P450IA1 IgG as primary antibody in an indirect ELISA, a clear induction response was observed in the exposed groups of both larvae and juveniles. The response was dose-dependent, and recovery in clean sea-water resulted in normalization of the induced P450IA1 levels. In larvae exposed during the egg stage, the induction process seemed restricted until the time of hatching. In juvenile cod, the response was observed in the gill in addition to the liver. The study demonstrates the usefulness of the cytochrome P450IA1 ELISA in detecting sublethal biological effects of pollutants in small sample sizes where enzyme activity is difficult to measure.

Sublethal effects of the water-soluble fraction of Ekofisk crude oil on the early larval stages of cod (Gadus morhua L.)

Abstract Low levels of dissolved oil hydrocarbons are demonstrated to produce sublethal effects on the early cod larval stages. These effects are discussed in relation to larval survival through the first critical stages. Continuous exposure of cod eggs and larvae to 0·05 and 0·25 ppm of the water-soluble fraction (WSF) of Ekofisk crude oil for 14 days caused significant reduction in growth and change in neutral buoyancy. The larvae exposed to 0·25 ppm showed malformation in the foremost part of the head and jaw, which reduced their ability to capture prey organisms at first feeding.

Variations in growth pattern among yolk-sac larvae of cod (Gadus morhua L.) due to differences in rearing temperature and light regime

Abstract Yolk-sac larvae of cod reared under continuous illumination obtained shorter maximum lengths than larvae reared in total darkness. The lengths, however, were uneffected by the rearing temperatures (3, 5, and 7° C). Exept for larvae reared in darkness at 7° C, which were heavier than the other ones, the larvae obtained the same maximum somatic tissue weights at yolk absorption irrespectable of light regime and temperature. Dark adapted larvae reared at 3° C grew faster than the corresponding light adapted ones when fed nauplii of Artemia salina during the first feeding stage. Deviations in lengths and weights under different light regimes are discussed in relation to effects of light on larval energy metabolism and utilization of yolk. Lengths and weights of yolk sac larvae from different groups, reared under identical light and temperature regimes, were compared. Large larvae grew faster and seemed to utilize their yolk supplies better for growth than smaller ones.

Cytochromes P-450 in fish larvae: Immunochemical detection of responses to oil pollution

Abstract Rabbit antiserum against the major β-naphthoflavone-inducible cytochrome P-450 isoenzyme purified from cod (Gadus morhua L.), liver were used as an immunochemical probe to detect responses of cod larvae to oil-exposure. Cod eggs were fertilized, reared and exposed in a system allowing full control of the concentration of water soluble compounds from crude North Sea oil. The immunochemical response in homogenates of whole larvae were shown to reflect the exposure in a dose-dependent manner. The study shows that cod larvae do respond to oil-exposure with induced cytochrome P-450 synthesis, and that immunochemical probes of cytochrome P-450 induction can be a valuable tool in monitoring marine pollution.

Response of cod (Gadus morhua) larvae and juveniles to oil exposure detected with anti-cod cytochrome P-450c IgG and anti-scup cytochrome P-450E MAb 1-12-3

Abstract Cytochrome P-450c (Mr = 58 000 D) is the major cytochrome P-450 isozyme inducible by β-naphthoflavone (BNF) in cod ( Gadus morhua ) liver. Polyclonal rabbit IgG against this form was used as an immunochemical probe to detect responses of cod larvae and juveniles to oil exposure. In addition, monoclonal mouse antibodies against the homologous isozyme in scup ( Stenotomus chrysops ), scup cytochrome P-450E, were employed. The eggs, larvae and juveniles were reared and exposed in a system allowing controlled dosage of the water-soluble compounds from crude North Sea oil. The immunochemical response, measured with Western blotting and ELISA, in the liver of juveniles and in homogenates of whole larvae, reflected the exposure in a dose-dependent way. Larvae and juveniles that were allowed to recover in clean sea water, showed a decline towards the control levels within a few days. In this study, it is shown that cod larvae do respond to oil exposure with induced synthesis of the cytochrome P-450c isozyme, and that immunochemical detection of this induction can be a convenient tool for monitoring the pollution of aquatic environments.

A flowthrough biotest system for continuous exposure of aquatic organisms to oil hydrocarbons

Abstract A biotest system for continuous exposure of aquatic organisms to the water soluble fraction of oil hydrocarbons is described. A stock solution was prepared in a separate tank, diluted with clean sea water to appropriate test concentrations, and continuously transferred to the exposure aquaria. The system was cleaned every week to avoid bacterial contamination. The hydrocarbon levels of aquaria and stock solution correlated with a coefficient of 0.96. Due evaporation, however, on the way from the stock solution tank to the aquaria, the oil concentration of the aquaria were 40–60 % lower than expected from the dilution ratios. The test solutions also contained traceable amounts of polar components which probably were oxidized compounds of oil hydrocarbon origin. These compounds could be of importance for the evaluation of eventual effects on test organisms.