Richard F. Addison

Bioaccumulation of polychlorinated biphenyls (PCBs) in the marine pelagic food web, based on a seasonal study in the southern Gulf of St. Lawrence, 1976−1977

Copyright (c) 1996 Elsevier Science B.V. All rights reserved. Polychlorinated biphenyls (PCBsr were quantified in bulk seawater (3.1p1.0 ng l −1 , N=3r in 1976, in plankton (2.9p3.3 ng g −1 wet weight, N=176r in 1976 and 1977 and in fish (155p194 ng g −1 wet weight, N=135r in 1977 collected from St. Georges Bay in the southern Gulf of St. Lawrence. PCB concentrations in the plankton of the entire water column varied seasonally by ten times, with the highest values occurring in spring, lowest during summer and variable levels in late fall. The lower PCB levels in the total summer community coincide with a reduced biomass in certain size fractions in the Bay rather than a decrease in PCB concentration of the plankton. PCBs were concentrated in the middle-sized fractions of the planktonic community and this is attributed to the greater biomass present in these categories. PCB concentrations in plankton were most highly correlated with their lipid content at the time of sampling. Seasonal reductions of lipid in the plankton per m 3 resulted in a higher concentration of PCB per unit lipid in the remaining community. Planktonic PCB concentrations, expressed on a lipid basis, are found to be correlated with cumulative rainfall 21 d before sampling for both years combined. Adult fish were more contaminated by PCBs than either their egg or juvenile stages. Mature gaspereau, herring and smelt had higher concentrations of PCB contamination than mackerel, capelin, white hake and silversides. No difference was found between PCB contamination of the sexes of fish species analyzed. PCBs were transferred from mother to offspring in fish, but at lower levels than the level present in the parent; and the maximum accumulation from the environment occurred between immature and adult fish. The best predictors of PCB contamination in fish in St. Georges Bay are lipid content followed by size and age. PCB concentrations in plankton, normalized to lipid content, did not increase with size or trophic level. PCB concentrations in fish increased with size and on average were ten times the levels found in plankton. Marine mammals collected by other researchers in the region during the 1970s had accumulated up to several orders-of-magnitude higher concentrations than those found in fish, with a more gradual increase with size of organism. Lipid content and age or exposure period appear to be the main factors which determine PCB concentrations in the marine food chain in the southern Gulf of St. Lawrence.

Liver microsomal mono-oxygenase induction in winter flounder (Pseudopleuronectes americanus) from a gradient of sediment PAH concentrations at Sydney Harbour, Nova Scotia

Abstract Winter flounder (Pseudopleuronectes americanus) were sampled in summer 1989 and 1990 in Sydney Harbour, Nova Scotia, along a gradient of sediment polynuclear aromatic hydrocarbon (PAH) concentrations arising from industrial contamination; an uncontaminated bay nearby was used as a reference site. Hepatic mono-oxygenase activity, estimated by measurements of catalytic activity and by immunochemical analysis of cytochrome P-450 1A, increased with sediment PAH concentrations; the extent of induction between the reference and the most contaminated sites ranged up to 50-fold. Cyanoethoxycoumarin O-de-ethylase activity was at least as sensitive an indicator of mono-oxygenase induction as ethoxyresorufin O-de-ethylase or benzo(a)pyrene hydroxylase, and all three enzyme activities were well correlated with cytochrome P-450 1A concentrations and with sediment PAH concentrations.

Seasonal variation of hepatic mixed function oxidases in winter flounder (Pseudopleuronectes americanus)

Abstract Indices of hepatic mixed function oxidase (MFO) activity in winter flounder ( Pseudopleuronectes americanus ) were measured at approximately monthly intervals from November 1983 to October 1985. Benzo[a]pyrene hydroxylase and ethoxyresorufin O -deethylase activities and cytochromes P450 and b 5 were generally, but not significantly, higher in males than in females. The MFO activity varied seasonally, reaching a maximum during or shortly after spawning. Variation in MFO enzyme activity between sexes was never greater than 2-fold at any time, and within sex, no greater than 6-fold during the seasonal cycle. This variability is less than that caused by exposure to environmentally realistic levels of some pollutants; measurements of MFO activity in this species might therefore be used to indicate environmental contamination.

Experimental and environmental induction of cytochrome P450E in fish from Bermuda waters

Abstract The chemical induction of liver microsomal cytochrome P450 in fish from Bermuda was evaluated by examining the rates of ethoxyresorufin O -deethylase (EROD) activity and the levels of protein recognized in Western blot by monoclonal antibody 1-12-3 to scup cytochrome P450E (P450E). Scup P450E is the EROD catalyst and a teleost representative of the hydrocarbon-inducible P4501A gene family in vertebrates. Treatment of blue-striped grunt Haemulon sciurus with β-naphthoflavone (BNF), an aromatic hydrocarbon-type inducer of P450E, resulted in a strong induction of total P450, EROD activity and the immunodetected P450E homologue, at doses > 1 mg·kg −1 . The induction peaked at ≈ days, declining progressively after that. A P450E counterpart was also induced by BNF in squirrelfish Holocentrus rufus . Analysis of freshly caught blue-striped grunt, squirrelfish and four additional fish species from sites in Hamilton Harbour, Castle Harbour and Ferry Reach, Bermuda, revealed appreciable levels of EROD activity and P450E in most of these fish. Two species, squirrelfish and tomtate Haemulon aurolineatum , had unusually high levels of total microsomal P450 (up to 1.5 nmol·mg −1 ), the majority of which was not P450E. The levels of both EROD activity and P450E homologue in some species, notably blue-striped grunt, French grunt Haemulon flavolineatum and sergeant major Abudefduf saxatilis , were significantly higher in fish taken at sites characterized by higher levels of sedimentary hydrocarbons and/or polychlorinated biphenyls. Association of EROD or P450E content with contaminant residues was strongest when comparison was with the PCB content in the bivalve Arca zebra from the sampling sites, one measure of bioavailable PCB content in the environment. The results indicate that induction of specific P450E by environmental chemicals is occurring in many fish in Bermuda waters; the origin of these chemicals is not known. The results further support the utility of P450 induction as an indicator of chemical contamination in aquatic systems.

Mixed function oxidase activity in the harbour seal (Phoca vitulina) from sable is., N.S.

One adult male, eight pups (including two full term foetuses) and nine adult female harbour seals (Phoca vitulina) were analysed for indices of mixed function oxidase (MFO) activity. MFO activity was present in liver samples, but was at or below detection limits in samples of kidney, lung and pancreas. Hepatic ethoxyresorufin O-de-ethylase and benzo[a]pyrene hydroxylase activities were similar to those reported in other seals and in other mammals. Cytochromes P-450 and b5 concentrations were slightly lower than those observed in other mammals. MFO activities in newborn pups and foetuses were significantly lower than those in adult females. No qualitative differences in cytochrome P-450 isozyme distribution between foetal and adult samples could be discerned by electrophoresis.

The IOC/GEEP Bermuda Workshop

Abstract A 3-wk practical workshop on the biological effects of pollutants was held in Bermuda, September 1988, under the auspices of the Intergovernmental Oceanographic Commissions Group of Experts on the Effects of Pollutants (GEEP). Field and laboratory studies examined the applicability, to subtropical ecosystems, of several techniques for measuring biological effects whose utility had previously been established mainly for temperate zones. The Workshop results, covering chemical, biochemical, physiological and community data, are reported in the nine papers of this JEMBE Special Issue. This introduction describes the background to the Workshop and gives details of the integrated sampling programme carried out in two Bermudan harbours.

Effects of Ugilec-141®, a PCB substitute based on tetrachlorobenzyltoluenes, on hepatic mono-oxygenase induction in estuarine fish

Abstract Ugilec-141® is a PCB substitute based on chlorinated benzyltoluenes which has been reported as an environmental contaminant in some German rivers. It is structurally similar to some phenylxylylethanes which induce hepatic microsomal mono-oxygenases in fish. When injected i.p. into dab ( Limanda limanda ) or flounder ( Platichthys flesus ) Ugilec-141 did not consistently induce hepatic microsomal ethoxyresorufin O -de-ethylase (EROD), ethoxycoumarin O -de-ethylase (ECOD) or pentoxyresorufin O -de-alkylase (PROD). When injected into winter flounder ( Pseudopleuronectes americanus ) to yield tissue concentrations in the 2–40 μg/g range, Ugilec-141 slightly (but significantly) induced EROD (2·4-fold), ECOD (2·5-fold) and 3-cyano-7-ethoxycoumarin O -de-ethylase (4·4-fold). The classic inducer, β-naphthoflavone, consistently induced all these indices of mono-oxygenase activity in all species. Components of Ugilec-141 therefore appear to be only mild inducers of fish hepatic microsomal mono-oxygenase systems.

THE UTILIZATION OF CYTOCHROME P4501A MRNA IN LIMANDA LIMANDA (DAB) AS A MONITOR OF CHEMICAL EXPOSURE IN THE NORTH SEA

Abstract Various components of the mixed function oxidase system in the livers of Limanda limanda (Dab) were utilized to monitor the extent of pollution in the German Bight area of the North Sea. The elevation of ethoxyresorufin-O-deethylase and cyano-ethoxycoumarin dealkylase activities in hepatic microsomes in samples taken from sites close to shore indicate significant pollution by chemicals capable of inducing cytochrome P4501A in the liver. Cytochrome P4501A mRNA was also elevated in the livers of fish taken at inshore sites. The measurement of mRNA for this form of cytochrome P450 can therefore be utilized as a biochemical monitor of chemical pollution. The same biochemical markers were utilized to assess hydrocarbon pollution in the area of an abandoned oil rig site, and the results indicated that contamination with inducing compounds was negligible. These results indicate that the measurement of cytochrome P4501A in a number of ways, including the assessment of its mRNA level, is a valid indicator of the exposure of fish to certain environmental pollutants.

A spectrophotometric assay of trout (Salvelinus fontinalis) liver diphenyl ether hydroxylase activity

Abstract Subcellular fractions of trout ( Salvelinus fontinalis ) liver homogenate metabolized diphenyl ether mainly to the 4-hydroxy derivative, but with traces of other compounds, including the 3-hydroxy derivative and possibly the 4,4-dihydroxy derivative. An ultraviolet spectrophotometric method for the determination of 4-hydroxydiphenyl ether is described.

Turnover of hepatic hemoproteins in rainbow trout

Abstract The hepatic mixed function oxidase system in the fish differs from that in mammals in its responses to the two classic mammalian inducers. The cytochrome P-448-type inducers (polycyclic aromatic hydrocarbons) stimulate monooxygenase activity, but phenobarbital, a P-450-type inducer, does not.1 We have compared the effects of phenobarbital (PB) and polychlorinated biphenyls (PCB) on the turnover of hepatic microsomal hemoproteins in trout (PCBs are P-448- and P-450-type inducers in mammals, which in fish induce only cytochrome P-448). We show here that neither PCB nor PB treatment changed the turnover rate. However, both the rates of synthesis and degradation were much slower than in the rat.