Preliminary study of responses in mussel (Mytilus edilus) exposed to bisphenol A, diallyl phthalate and tetrabromodiphenyl ether.

Environmental pollutants with hormonal activity including bisphenol, diallyl phtalate and tetrabromodiphenyl ether, have the potential to alter gonadal development and reproduction in aquatic wildlife. Little is known about the biological impact of environmentally relevant concentrations in mussels. To investigate some aspects of their potential estrogenic action, mussels were continuously exposed during 3 weeks. Gonadal development and vitellogenin like protein levels were examined. Bisphenol (50 microg/l) induced the expression of phospho-proteins in females and spawning in both sexes. Diallyl phthalate and tetrabromodiphenyl ether decreased phospho-protein levels in both sexes and induced spawning in males. Moreover, severe damaging effects on ovarian follicles and ovocytes were observed in both bisphenol A- and tetrabromodiphenyl ether-exposed female mussels.

In vitro dose-response study of the effect of cadmium on eel (Anguilla anguilla) gill Na+/K(+)-ATPase activities.

The effect of cadmium exposure was studied in vitro on the ATPase activities of gill membrane microsomes from seawater- and freshwater-adapted eel (Anguilla anguilla) using a microassay technique. The basal activity (Mg(2+)-ATPase) was decreased by 40 and 25%, respectively, in seawater and freshwater preparations for the highest concentrations tested (respectively, 4 and 2 microM). The Na+/K(+)-ATPase activity was estimated either by potassium stimulation or by ouabain inhibition. This enzyme activity was inhibited by cadmium in a dose-dependent manner with a I50 of 146 +/- 9.3 nM. Neither the technique used to measure the enzyme nor the adaptative environment significantly changed the I50. The results are compared to results obtained in other groups and to the effects of cadmium on metal ion exchanges in fish.

The uptake, metabolism, and biological half-life of benzo[a]pyrene administered by force-feeding in sea bass (Dicentrarchus labrax).

The kinetics of uptake and metabolism of benzo[a]pyrene (BaP) were studied in various tissues of a marine fish, the sea bass (Dicentrarchus labrax), after intragastric administration of pellets containing a 14C-labeled compound. Only 25% of injected radioactivity was detected and it was found only in intestine, gallbladder, liver, and kidney. The major part of radioactivity was found in gallbladder (85% of the whole body radioactivity). The calculated half-lives determined after the decrease in radioactivity measured in these tissues were 8.2, 3.5, 3.3, and 0.8 days for liver, gallbladder, intestine, and kidney, respectively. The kinetics of distribution of radioactivity between alkali and hexane tissue extracts showed the high metabolization potential of intestine which represents the main site of BaP uptake by this route of exposure. The other organs received mainly metabolites brought by general blood circulation. Intragastric administration as an experimental exposure route compared to other exposure patterns and particularly intraperitoneal injection, which has been used previously in the same species and under the same experimental conditions for the same kind of study, is discussed.

Ultrastructural changes induced by benzo[a]pyrene in sea bass (Dicentrarchus labrax) liver and intestine: importance of the intoxication route.

The ultrastructural effects of benzo[a]pyrene (BaP) on sea bass (Dicentrarchus labrax) liver and intestine were studied after experimental intoxication by two different routes: intraperitoneal injection and force-feeding. In both hepatocytes and enterocytes, the main structural perturbations concerned a large development of both rough and smooth endoplasmic reticulum and a great increase in the number of vacuoles and lysosomes in BaP-treated fish. After 17 days of contamination, some nuclear changes were observed, indicating the high reactivity of BaP metabolites which form covalent adducts with DNA and the long-term toxicity of this compound. However, in the intestine, after force-feeding intoxication, more perturbations were seen, particularly concerning the mitochondria. Both organs were altered in a different way with respect to the intoxication route. In BaP intraperitoneal injected fish, the liver was the first injured organ and presented heavier injuries than intestine. In force-feeding treated fish, the intestinal epithelium was the first concerned tissue and it was highly modified after BaP intoxication. The importance of the intoxication pathway in the effects of BaP on liver and intestine was discussed with special reference to their role in BaP uptake, metabolism, and distribution in the organism.