Differential responses of biomarkers in tissues of a freshwater mussel, Dreissena polymorpha, to the exposure of sediment extracts with different levels of contamination.

In this study, zebra mussels, D. polymorpha, were exposed to extracts of sediments obtained from two sites, a contaminated lake (Ketelmeer, Km) and a relatively clean lake (Drontenmeer, Dm). The main objective of this work was to investigate whether six selected biomarkers could discriminate between the two sediments. The selected biomarkers included phase I enzymes such as DT-diaphorase, NADPH-cytochrome c reductase, NADH-cytochrome c reductase, a phase II enzyme (glutathione S-transferase, GST), an antioxidant enzyme, catalase, and the total glutathione, reduced (GSH) and oxidized (GSSG). After a short (24 h) and a long-term (7 days) exposure, the levels of these biomarkers were measured in gills and the rest of soft mussel tissues (soft mussel tissue minus gills) and compared with control values. A decrease of GST level by 20% (P = 0.004) and a 4-fold decrease of total glutathione concentration relative to the control, were observed in the gills of mussels exposed to the more contaminated Km extract. No significant differences in the GST activities were observed in the gills of control and Dm extract-treated mussels (P = 0.23). Although the levels of catalase and NADH-cytochrome c reductase were, in the short-term exposure, unaffected, both activities were, in the long-term exposure, reduced in the gills of the mussels exposed to the contaminated Km extract, compared with control values, by 43% and 20%, respectively. The activities of DT-diaphorase and NADPH-cytochrome c reductase remained unaffected in all exposure conditions. However, the level of NADPH-cytochrome c reductase was found higher in gills than in the rest of soft mussel tissues. This difference in the ratio of the two reductases between the two tissues could account for the observed differential responses of the biomarkers.

Osman AM ，van den Heuvel H ，van Noort PC 《JOURNAL OF APPLIED TOXICOLOGY》

Comparison of key enzymes in the zebra mussel, Dreissena polymorpha, the earthworm Allolobophora chlorotica and Chironomus riparius larvae.

Osman AM ，van Noort PC 《ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY》

In vivo exposure of Dreissena polymorpha mussels to the quinones menadione and lawsone: menadione is more toxic to mussels than lawsone.

The principal aim of this study was to assess whether the two quinones, menadione (2-methyl-1,4-naphthoquinone) and lawsone (2-hydroxy-1,4-naphthoquinone), elicit differential toxicity in mussels as has been reported for higher organisms. Therefore, the effects of short-term (48 h) and long-term (20 days) exposure of the two quinones at concentrations of 0.56 and 1 mg l(-1) to zebra mussels, Dreissena polymorpha, under laboratory conditions were studied. After the short-term exposure, the specific activities of the two-electron quinone oxidoreductase (DT-diaphorase) and the one-electron catalysing quinone reductases NADPH-cytochrome c reductase and NADH-cytochrome c reductase were determined in the gills and the rest of the soft tissues (soft mussel tissues minus the gills) of both treated and control mussels. At the higher concentrations of menadione and lawsone used, a significant reduction of the activity of NADPH-cytochrome c reductase in the gills and in the rest of the soft mussel tissues (by 33-34% and 31-43%, respectively) was observed. The activities of DT-diaphorase and NADH-cytochrome c reductase were not significantly affected. Interestingly, DT-diaphorase was observed in the gills, an organ requiring protection against antioxidants. Furthermore, a single-cell electrophoretic assay (comet assay) performed with gill cells to assess DNA damage by the quinones did not show any significant difference between the treated and the control organisms. This indicates that the formation of reactive species by the quinone metabolism in vivo in the mussels was possibly suppressed through the concerted action of DT-diaphorase and antioxidant enzymes. The results of in vitro experiments with gill extracts confirmed the protective role of DT-diaphorase. The rate of the two-electron quinone reduction was found to be five times that of the one-electron quinone reduction. The results of the long-term exposure unambiguously demonstrated that in mussels menadione, unlike in higher organisms, is more toxic than lawsone. The lack of detectability of xanthine oxidase in the mussel tissues could explain the comparatively lower toxicity of lawsone in the invertebtrate, lending support to a previous suggestion that xanthine oxidase might be responsible for the mechanism of toxicity of lawsone in higher organisms in vivo.

Osman AM ，Rotteveel S ，den Besten PJ ，van Noort PC ... -  《JOURNAL OF APPLIED TOXICOLOGY》

Biotransformation and antioxidant enzymes of Dreissena polymorpha for detection of site impact in watercourses of Berlin.

Contardo-Jara V ，Krueger A ，Exner HJ ，Wiegand C ... -  《-》

Comparison of bioaccumulation and biomarker responses in Dreissena polymorpha and D. bugensis after exposure to resuspended sediments.

Schäfer S ，Hamer B ，Treursić B ，Möhlenkamp C ，Spira D ，Korlević M ，Reifferscheid G ，Claus E ... -  《-》