A field study on EROD activity and quantitative hepatocytological changes in an immature demersal fish

Screening toxicological effects of different contaminants using hepatic homogenates-based ethoxyresorufin-O-deethylase in vitro

In this paper, we demonstrated the potential of an in vitro method of liver homogenate-based ethoxyresorufin-O-deethylase (EROD) to determine the toxicological effects of multiple kinds of contaminants. We evaluated the in vitro impact of nine pharmaceutically active compounds (PhACs), 13 polycyclic aromatic hydrocarbons (PAHs), and three polychlorinated biphenyls (PCBs). There were different responses of EROD to these contaminants. The response of EROD to PhACs was quite complex, exhibiting both induction and inhibition effects. PAHs and PCBs elicited a strong inhibitory response on EROD activity at high concentrations in a dose-dependent manner. PAHs showed more inhibitory effects as the number of benzene rings increased. Our in vitro bioassay seems to be a potential method for toxicological screening of multiple types of contaminants.

In vitro effects of brominated flame retardants, selected metals and their mixtures on ethoxyresorufin-O-deethylase activity in Mossambica tilapia liver

The in vitro effects of individual brominated flame retardants (BFRs), selected metals, and their binary mixtures on ethoxyresorufin-O-deethylase (EROD) activity were evaluated using a plate-reader method. The BFRs, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), decabromodiphenyl oxide (BDE-209), hexabromocyclododecane (HBCD), and tetrabromobisphenol A (TBBPA), were tested at doses ranging from 0.1 ng/L to 100 µg/L. Selected metals (Cu²⁺, Cd²⁺, Hg²⁺, and Zn²⁺) were screened at doses of 0.1 mg/L to 50 mg/L. The activity of EROD was significantly induced by TBBPA, BDE-209, and Zn²⁺, while HBCD, Cu²⁺, Cd²⁺, and Hg²⁺ decreased EROD activity. Moreover, following exposure to binary mixtures of metals and BFRs, the EROD activity dose-response curves were similar to those of the metals alone, indicating that EROD activity was governed by the metals.

Assessment of biological effects of environmental pollution in Mersin Bay (Turkey, northeastern Mediterranean Sea) using Mullus barbatus and Liza ramada as target organisms

The increasing emphasis on the assessment and monitoring of marine ecosystems has revealed the need to use appropriate biological indicators for these areas. Enzyme activities and histopathology are increasingly being used as indicators of environmental stress since they provide a definite biological end-point of pollutant exposure. As part of an ecotoxicological assessment of Mersin Bay, EROD enzyme activity and histopathological response in selected organs and tissues of two species of fish, Mullus barbatus (red mullet) and Liza ramada (thinlip grey mullet), captured from area were examined. Pollutant (Organochlorines (OC), alkylphenols (APs) and BPA) levels and biomarker responses in tissue samples were evaluated together for their potential to alter the metabolism and cellular aspects in liver and gonad. Elevated induction of EROD activity and histopathological alterations in contaminated samples from Mersin Bay was observed compared to reference site indicating the exposure to potential pollutants.

Ethoxyresorufin-O-deethylase enzyme activities and accumulation of secondary/tertiary lysosomes in rabbitfish Siganus oramin as biomarkers for xenobiotic exposures

The sensitivities of using hepatic and intestinal ethoxyresorufin-O-deethylase (EROD) activities and hepatic accumulation of secondary/tertiary (2 degrees/3 degrees) lysosomes to detect xenobiotic exposures were assessed in the rabbitfish Siganus oramin in a metropolitan harbour, subtropical Hong Kong, over a complete seasonal cycle of one year. Additional information on the body-burden pollutants and physiological indices in S. oramin, and seasonal variables in seawater quality, were extracted from published data and re-analyzed. Under the influences of pollutant cocktail and seasonal factors, neither the hepatic nor intestinal EROD activity was indicative of total polycyclic aromatic hydrocarbons (Sigma PAH), total polychlorinated biphenyls, condition factor and hepatosomatic index (HSI) in S. oramin. However, the relative ratio of hepatic to intestinal EROD activities provided an indication to differentiate the xenobiotic intake route in the fish through diffusion via gills/skin or consumption of contaminated food. In addition, the elevated hepatic accumulation of 2 degrees/3 degrees lysosomes was closely associated with the dominant temporal trends of zinc and Sigma PAH, as well as reduced HSI, in S. oramin. Being minimally influenced by any investigated seasonal factors, the hepatic 2 degrees/3 degrees lysosomes in S. oramin was recommended as an effective biomarker of xenobiotic exposures and toxic effects for use in coastal pollution monitoring programmes.

Chemical and biochemical tools to assess pollution exposure in cultured fish

There is little information regarding pollutant levels in farmed fish, and the risks associated to consumption. This study was designed to assess levels of exposure to metals, organochlorinated compounds, polycyclic aromatic hydrocarbons (PAHs) and alkylphenols (APEs) in farmed sea bass Dicentrarchus labrax from five aquacultures located in Southern Europe. Additionally, several biochemical responses (metallothionein, 7-ethoxyresorufin O-deethylase, vitellogenin) were determined as complementary tools. The obtained data indicate that pollutants exposure in farmed fish is similar to the levels reported in wild specimens from the area. Nonetheless, some biochemical responses were observed in the studied organisms, viz. metallothionein induction in Cu exposed organisms, and 7-ethoxyresorufin O-deethylase (EROD) and vitellogenin induction in PAHs and APEs exposed ones. The study further supports the usefulness of the biomarker approach as a first screening method to discriminate between basal and high levels of exposure in cultured fish.

Chemical residues and biochemical responses in wild and cultured European sea bass (Dicentrarchus labrax L.)

Cultured and wild sea bass (Dicentrarchus labrax) from the Arade Estuary were sampled in summer and winter and the degree of exposure to metals and polycyclic aromatic hydrocarbons (PAHs) assessed, together with some biochemical responses against those and other pollutants. The highest levels of copper (up to 997 microg g-1 dry weight) and cadmium (up to 4.22 microg g-1 dry weight) were detected in the liver and kidney of cultured specimens, whereas the highest exposure to PAHs was observed in wild fish. Significant alterations in some biochemical markers were detected and associated to pollutant exposure. Thus, metallothionein concentrations were higher in the tissues of cultured fish and positively correlated with metal residues. The activity 7-ethoxyresorufin O-deethylase ranged from 28 pmol/min/mg protein in cultured fish to 83 pmol/min/mg protein in wild fish collected near a marina area. Cultured fish and wild fish from the marina area had depressed acetylcholinesterase in muscle tissue and a parasitic infection in the gonads. The obtained results support the usefulness of the combined use of chemical and biochemical markers to assess the impact of anthropogenic pollutants in both wild and cultured fish.

Significance of cytochrome P450 system responses and levels of bile fluorescent aromatic compounds in marine wildlife following oil spills

The relationships among cytochrome P450 induction in marine wildlife species, levels of fluorescent aromatic compounds (FAC) in their bile, the chemical composition of the inducing compounds, the significance of the exposure pathway, and any resulting injury, as a consequence of exposure to crude oil following a spill, are reviewed. Fish collected after oil spills often show increases in cytochrome P450 system activity, cytochrome P4501A (CYP1A) and bile fluorescent aromatic compounds (FAC), that are correlated with exposure to polycyclic aromatic hydrocarbons (PAH) in the oil. There is also some evidence for increases in bile FAC and induction of cytochrome P450 in marine birds and mammals after oil spills. However, when observed, increases in these exposure indicators are transitory and generally decrease to background levels within one year after the exposure. Laboratory studies have shown induction of cytochrome P450 systems occurs after exposure of fish to crude oil in water, sediment or food. Most of the PAH found in crude oil (dominantly 2- and 3-ring PAH) are not strong inducers of cytochrome P450. Exposure to the 4-ring chrysenes or the photooxidized products of the PAH may account for the cytochrome P450 responses in fish collected from oil-spill sites. The contribution of non-spill background PAH, particularly combustion-derived (pyrogenic) PAH, to bile FAC and cytochrome P450 system responses can be confounding and needs to be considered when evaluating oil spill effects. The ubiquity of pyrogenic PAH makes it important to fully characterize all sources of PAH, including PAH from natural resources, e.g. retene, in oil spill studies. In addition, such parameters as species, sex, age, ambient temperature and season need to be taken into account. While increases in fish bile FAC and cytochrome P450 system responses, can together, be sensitive general indicators of PAH exposure after an oil spill, there is little unequivocal evidence to suggest a linkage to higher order biological effects, e.g. toxicity, lesions, reproductive failure.

The application of histo-cytopathological biomarkers in marine pollution monitoring: a review

During the past two decades, a variety of histopathological alterations in fish and bivalves have been developed and used as biomarkers in pollution monitoring. Some of these have been successfully adopted in major national monitoring programmes, while others, although show promise, are still in the experimental stage. This paper critically reviews the scientific basis, cause and effect relationship, reliability, advantages and limitations of 14 histo-cytopathological biomarkers. The usefulness and practical application of each biomarker have been evaluated against a number of objective criteria including: ecological relevance, sensitivity, specificity, dose-response relationship, confounding factors, technical difficulties and cost-effectiveness.