L. Lari

Serum esterase inhibition in birds: A nondestructive biomarker to assess organophosphorus and carbamate contamination

With the aim of proposing a nondestructive biomarker for monitoring the toxicological risk to birds of exposure to the organophosphorus insecticide azamethiphos and the carbamate insecticide methomyl, laboratory studies were performed on serum “B” esterases in Japanese quail (Coturnix coturnix japonica). The birds received two single dose treatments of each compound (azamethiphos and methomyl), i.e., 50 mg/kg and 250 mg/kg respectively. In the first treatment, serum butyrylcholinesterase (BChE) and carboxylesterase (CbE) were drastically inhibited in the azamethiphos-treated group, 24 h after the dose. No inhibition was detected for BChE and CbE activities in the methomyl-treated group, 24 h after the dose. In the second treatment, the birds died or were sacrified 3 h after the dose. Serum BChE and brain acetylcholinesterase (AChE) were strongly inhibited after treatment with both insecticides. Serum CbE, hepatic microsomal CbE and 7-ethoxyresorufin dealkylation activities were also inhibited. A statistically significant correlation between serum BChE and brain AChE was found at lethal and sublethal doses of these xenobiotics. The experimental results indicate that the nondestructive biomarker BChE can give an early qualitative and semi-quantitative warning of the toxic effects of organophosphate and carbamate insecticides in birds.

Induction of MFO activity in the antarctic fish Pagothenia bernacchii: Preliminary results

Abstract The aim of this study was to determine the detoxication capacity and the sensitivity to pollutants of fish living in a pristine environment such as the Antarctic Ocean. Forty specimens of Pagothenia bernacchii collected during the Antarctic summer of 1991–1992 were divided into three groups, and were treated with 10 mg/kg of B(α)P, 50 mg/kg of PCBs and corn oil and sacrificed after 2, 4 and 10 days. The mixed function oxidase activity measured in these fish through the test of BPMO, EROD and BROD activities revealed that both B(α)P and PCBs are effective in inducing this enzyme system. Owing to the slow metabolic rate of this species, related to the low ambient temperature of its natural habitat, the highest level of induction was monitored after 10 days i.e. much later than in fish of temperate seas.

Interspecies variation of B esterases in birds : The influence of size and feeding habits

Interspecies differences in “B” esterases were evaluated in seven species of wild birds in order to investigate their different susceptibilities to organophosphorus (OP) insecticides. The relationship between “B” esterases and body size and the influence of feeding habits in the evolution of esterase activities were explored. An in vitro inhibition test was carried out with paraoxon and azinphos methyl oxon in order to investigate the role of equilibrium binding parameters (acetylcholinesterase/organophosphorus compounds affinity) in determining susceptibility of the different species to parathion and azinphos methyl. Esterase activities were different in all species. The smallest bird studied (the sparrow) had the highest brain acetylcholinesterase (AChE) and plasma carboxylesterase (CbE) activities. The largest bird (the cormorant) had the lowest level of both activities. For microsomal CbE, the coot had the highest activity. An inverse correlation was found between brain AChE and plasma CbE activity in relation to body size. Omnivorous species showed the highest brain AChE and plasma CbE activities which were low in species with a specialised diet. The in vitro inhibition test demonstrated the active involvement of equilibrium binding parameters in determining different susceptibilities to these contaminants in birds.

Biochemical and genotoxic biomarkers in the Mediterranean crab Carcinus aestuarii experimentally exposed to polychlorobiphenyls, benzopyrene and methyl-mercury

The aim of this study was to test a multi-trial biomarker approach for evaluating toxicological risk due to the main contaminants in the Mediterranean, using the Mediterranean crab Carcinus aestuarii as bioindicator organism. Forty crabs were injected with different doses of the following contaminants: benzopyrene, polychlorobiphenyls and methyl-mercury. Several molecular, biochemical and genotoxic biomarkers were tested in different tissues and excreta. The main conclusions of this preliminary study can be summarized as follows: (1) midgut-gland, haemolymph and excreta seem to be useful for biomarker studies in this species; (2) several biochemical, molecular and genotoxic biomarkers were found suitable for testing in certain tissues; and (3) several biomarkers were found suitable for evaluating chemical stress due to Mediterranean contaminants.

Mixed function oxidase activity and chlorinated hydrocarbon residues in antarctic sea birds: South polar skua (Catharacta maccormicki) and adélie penguin (Pygoscelis adeliae)

Abstract Mixed function oxidase activity (MFO) and chlorinated hydrocarbon residues were studied in the Antarctic Adelie penguin and south polar skua, collected on Ross Island (Antarctica). The results show striking differences in MFO activities and organochlorines in the two species. Aldrin epoxidase. 7-ethoxyresorufin- O -deethylase (EROD) and cytochrome e reductase activities were very low in penguins, whereas skuas showed activities similar to those reported for certain northern hemisphere larids. Organochlorine residue analysis showed polychlorinated biphenyl (PCB) concentrations in liver about five times higher in skuas than in penguins.

Evaluation of toxic effects of the organophosphorus insecticide azinphos-methyl in experimentally and naturally exposed birds

Laboratory and field studies were conducted to evaluate the effects of the organophosphorus insecticide, azinphosmethyl, on bird populations and into the possibility of assessing toxic hazard by a non-destructive biomarker such as BChE inhibition. Japanese quail were treated with increasing doses of azinphos-methyl (0.5, 5, and 50 mg/kg) and sacrificed 7 and 24 h later. Serum BChE and CbE, brain AChE, and liver microsomal CbE activities showed different patterns of inhibition. The maximum inhibition of BChE and CbE usually occurred 7 h after treatment, whereas the effect on AChE was greater at 24 h. A positive correlation was found between BChE and AChE, 7 and 24 h after treatment. This correlation could serve as the foundation for a theoretical model for assessing toxic hazard through non-destructive biomarkers. The only effect on brain AChE was detected in the group treated with the highest concentrations of azinphos-methyl (50 mg/kg). Fugacity model calculations showed that such massive concentrations are very unlikely to occur under natural conditions after agricultural use of the compound.The non-destructive biomarker was used to test a population of tree sparrows living in a cherry orchard sprayed once with azinphos-methyl. No inhibition of BChE activity was found 24 h after application, and it was therefore concluded that the concentration of the insecticide used did not constitute a hazard for the birds.

Interspecific differences in mixed function oxidase activity in birds: a tool to identify ‘species at risk’

Abstract The aim of this study was to explore the influence of diet on the development of interspecific differences in the detoxication capacity of the mixed function oxidase (MFO) system (monooxygenase) among birds. The role of MFO activity in the detoxication/bioaccumulation of organochlorines (e.g., PCBs) was also investigated. Seven different species of birds were analysed: the yellow-legged herring gull ( Larus cachinnans ), black-headed gull ( Larus ridibundus ), jackdaw ( Corvus monedula ), magpie ( Pica pica ), cormorant, ( Phalacrocorax carbo ), coot ( Fulica atra ) and sparrow ( Passer italiae ). These species have different feeding habits ranging from omnivorous species like the yellow-legged herring gull to specialist and stenophagic species like the cormorant. This preliminary study confirms the relationship between feeding habits and evolutionary interspecific diffences in MFO activity.

INFLUENCE OF CADMIUM ON POLYCHLOROBIPHENYL UPTAKE, MFO ACTIVITY, AND SERUM-LIPID LEVELS IN JAPANESE-QUAIL

The effect of cadmium on the metabolism of polychlorobiphenyls (PCBs) (Aroclor® 1260) was investigated in quails fed diets containing 100 ppm Cd, 100 ppm PCBs (Aroclor® 1260) and 100 ppm Cd + 100 ppm PCBs for a period of 45 days. The presence of Cd in the diet did not interfere with MFO activity (EROD and ALDE) and cytochrome P-450 enzymes. Quails fed simultaneously with Cd and PCBs, accumulated PCBs in muscle five times greater than quails fed PCBs only. Quails fed with Cd-containing diet showed a slight increase of cholesterol and triglycerides. These data suggested that a combined chronic exposure to Cd and PCBs could modify PCBs metabolism. The interaction seems due not to inhibition of drug-metabolizing enzymes but to the increase of circulating lipids that favor the accumulation of lipophilic compounds.

Induction of a putative monooxygenase of crabs (Carcinus spp.) by polycyclic aromatic hydrocarbons.

As part of a programme to develop biomarker assays for polycyclic aromatic hydrocarbons (PAHs) in marine invertebrates, two species of crabs, Carcinus maenas and Carcinus aestuarii were exposed to benzo(a)pyrene (B(a)P) or crude oil. Microsomes were prepared from the midgut gland (hepatopancreas), examined by gel electrophoresis and Western blotting and assayed for B(a)P monooxygenase activity. In early experiments there was evidence of protein degradation and results were inconsistent and inconclusive. However, when steps were taken to minimize this in subsequent experiments, including the inclusion of four protease inhibitors in the homogenization buffer, there was consistent evidence for an increase of proteins of estimated molecular weight 45-60 kDa, and particularly of a distinct band at c. 48 kDa, following exposure to PAH at levels down to 0.1 ppm in ambient water. In C. aestuarii the increase in this band was found to coincide with an 8-12-fold increaseof B(a)P monooxygenase activity in midgut gland microsomes. These results suggest that one or more forms of cytochrome P450 may be induced by PAHs in these species. However, Western blotting using antibodies raised to vertebrate P450s, and representing four different gene families, failed to recognize any proteins in either the PAH-treated samples or in the controls. The isolation and characterization of induced protein, and the production of antibodies may provide the basis for a biomarker assay to measure a response to environmental PAHs in crabs.

Multiresponse biomarker evaluation of interactions between methylmercury and Arochlor 1260 in quail

The single and combined effects of methylmercury and Arochlor 1260 were investigated in experimental quail treated chronically with the two compounds at low and high doses. A series of metabolic and biochemical biomarkers were evaluated together with mercury and PCB accumulation to pinpoint the effects of treatment with one or both chemicals. Methylmercury alone was associated with a decrease in serum cholesterol. Less PCBs were accumulated in tissues when Arochlor 1260 was combined with methylmercury than when the former was administered alone. Liver monooxygenase (MFO) activity was depressed 50% more in the presence of methylmercury than with Arochlor 1260 alone. Single or combined treatment with high doses of the two compounds resulted in similar degrees of DNA damage. This approach was found to provide a good picture of the interaction between environmental contaminants.