Sylvie Biagianti-Risbourg

Biochemical and (ultra)structural hepatic perturbations of Brachydanio rerio (Teleostei, Cyprinidae) exposed to two sublethal concentrations of copper sulfate.

The aim of this study was to compare biochemical and (ultra)structural perturbations induced by Cu in the liver of Brachydanio rerio exposed for 14 days to sublethal concentrations of copper and then replaced for 14 days to clean water. Toxicity of Cu was clearly demonstrated: simultaneously to Cu accumulation, the liver developed large lysed areas and hepatocytic alterations. However, the majority of the parenchyma was composed of functional dark hepatocytes displaying typical feature of increased metabolism: development of rough reticulum, increase in size of nucleus and nucleolus, glycogenic depletion. Increase in hepatic protein content and of anti-oxidative defences (glutathione content, catalase and glutathione-S-transferase (GST) activities) indicated that the overall response of the liver was adaptative. In all hepatocytes a cord-like structure of the nucleoli was suspected to be associated to metal deposition. After 14 days depuration, the liver still contained high Cu concentrations and the hepatic alterations were not reversed. Such complementary studies are necessary for a better understanding of the deleterious effects of pollutants and for the development of biomarkers for metal toxicity.

Effects of metals on feeding rate and digestive enzymes in Gammarus fossarum: An in situ experiment

The feeding activity and afterward the assimilation of the products resulting of the food digestion, allow organisms to obtain energy useful for growth, maintenance and reproduction. These biological parameters may be studied to assess the impact of contaminants on the energy metabolism of organisms, which could induce potential effects at an individual level. The studied species was an amphipod Gammarus fossarum, which has a high ecological relevance since it is widespread in European streams and plays a major role in the breakdown of leaf litter. Thus some G. fossarum were transplanted in four sites of a river characterized by metal contamination (Amous River, France). The following parameters were studied: digestive enzymes activities (esterase, beta-glucosidase, beta-galactosidase, amylase and endoglucanase), feeding rate, metal bioaccumulation and survival. Results showed a strong relationship between digestive enzymes activities, feeding rate and metal contents.

An original decontamination process developed by the aquatic oligochaete Tubifex tubifex exposed to copper and lead

The aquatic oligochaete Tubifex tubifex is known to be very resistant to pollution, however, the way this organism has adapted is poorly understood. T. tubifex was present in our study-site (Reuil sur Marne, Marne, France), a retention basin that receives contaminated runoff water from a vineyard. Field observations showed that a large proportion of the worms had abnormal caudal regions (completely missing or regenerating). After experimental contamination with subacute concentrations of copper and lead, two metals that cause problems in the vineyards, the animals lost their tails. Metal determinations in the anterior and posterior parts of whole T. tubifex from the polluted site and experimentally contaminated worms revealed a higher concentration of metals in the posterior part. These results indicated that T. tubifex may protect itself against the increase of internal concentrations of toxic metals (Cu and Pb) by the autotomy of the caudal region in which the metals had accumulated. The capacity of the worms to regenerate was not impaired, even in contaminated medium. The possibility to use the loss of tail as a biomarker of contamination is discussed.

Subcellular compartmentalization of cadmium, nickel, and lead in Gammarus fossarum: Comparison of methods

Knowledge of the subcellular behavior of toxicants, mainly metals, in living organisms is fundamental for understanding their toxicological consequences at individual and trans-generation levels and throughout the food web. However, different partitioning methodologies are available in the literature, particularly concerning the cytosolic fraction. Different cytosolic compounds, metallothionein-like proteins (MTLPs), and non-metallothionein-like proteins (non-MTLPs) could be separated by size exclusion chromatography or by heat treatment and centrifugation. Our results show changes of metal partitioning in the cytosolic fraction according to the methodologies used. After heat treatment, the majority of cytosolic cadmium (Cd) was found with MTLPs compounds and the opposite results were observed with size exclusion chromatography. Metal partitioning could also play an important role in the metal trophic transfer. Therefore, metal partitioning in Gammarus fossarum, an ecologically relevant species and good metal bioaccumulator, defining the trophically available metal fraction, is also discussed.

Effects of 4-Nonylphenol on Sex Differentiation and Puberty in Mosquitofish (Gambusia holbrooki)

Three days post-parturition mosquitofish were exposed to different concentrations of 4-NP following a semi-static protocol. Exposure lasted up to the development of male anal fin in male individuals of the control group. Exposure to 50 μg/L 4-NP resulted in 100% females considering secondary sexual characters, while external sex-ratio did not statistically differed from unity in control group. In group exposed to 0.5 and 5.0 μg/L sex-ratio did not differ from unity but incompletely developed gonopodium was observed in several individuals. Individuals exposed to 50 μg/L 4-NP exhibited female or undeveloped gonads, while gonadal sex-ratio did not statistically differ from unity in control group. Percentage of undeveloped gonads increased with 4-NP concentration. Additional observations demonstrated hepatic histopathology in fish exposed to the highest concentration and growth reduction dependent on 4-NP concentration. In a complementary experiment, extensive metabolism of [3H]4-n-NP was characterized following in vivo exposure of juvenile mosquitofish suggesting that metabolism could modulate 4-NP toxicity. This study suggests susceptibility of early life stages of mosquitofish to endocrine modulators with regard to development of reproductive capabilities.

Effects of platinum (Pt4+) on Lumbriculus variegatus müller (annelida, oligochaetae): Acute toxicity and bioaccumulation

The acute toxicity and bioaccumulation (rates, kinetic) of tetravalent platinum in Lumbriculus variegatus under different physicochemical conditions (temperature and total water hardness) were investigated. Increased Pt4+ concentration (from 0.05 to 50 mg/L), exposure (up to 30 days), temperature (from 4 to 20°C) and decreasing water hardness (from 300 to 0 mg/L CaCO3) increased Pt toxicity. The metal accumulated at a constant rate that was concentration, temperature and time dependent. The median lethal concentration (96h LC50) varied greatly from 0.397 mg/L in distilled water to 30 mg/L in the hard water from Champagne. Thus, L. var. can tolerate high levels of Pt. As a result, L. var. can be used in the laboratory to analyze mechanisms of adaptation to the induced stress and in the field as an indicator of Pt pollution.

One-year monitoring of core biomarker and digestive enzyme responses in transplanted zebra mussels (Dreissena polymorpha)

A 12-month active biomonitoring study was performed in 2008–2009 on the Vesle river basin (Champagne-Ardenne, France) using the freshwater mussel Dreissena polymorpha as a sentinel species; allochthonous mussels originating from a reference site (Commercy) were exposed at four sites (Bouy, Sept-Saulx, Fismes, Ardre) within the Vesle river basin. Selected core biomarkers (acetylcholinesterase (AChE) activity, glutathione-S transferase (GST) activity, metallothionein concentration), along with digestive enzyme activities (amylase, endocellulase) and energy reserve concentrations (glycogen, lipids), were monitored throughout the study in exposed mussels. At the Fismes and Ardre sites (downstream basin), metallic and organic contamination levels were low but still high enough to elicit AChE and GST activity induction in exposed mussels (chemical stress); besides, chemical pollutants had no apparent deleterious effects on mussel condition. At the Bouy and Sept-Saulx sites (upstream basin), mussels obviously suffered from adverse food conditions which seriously impaired individual physiological state and survival (nutritional stress); food scarcity had however no apparent effects on core biomarker responses. Digestive enzyme activities responded to both chemical and nutritional stresses, the increase in energy outputs (general adaptation syndrome—downstream sites) or the decrease in energy inputs (food scarcity—upstream sites) leading to mid- or long-term induction of digestive carbohydrase activities in exposed mussels (energy optimizing strategy). Complex regulation patterns of these activities require nevertheless the use of a multi-marker approach to allow data interpretation. Besides, their sensitivity to natural confounding environmental factors remains to be precised.

Toxic effects and bioaccumulation of the herbicide isoproturon in Tubifex tubifex (Oligocheate, Tubificidae): a study of significance of autotomy and its utility as a biomarker.

Tubifex is the only animal reported to respond with autotomy to contamination. This response of contaminated worm is understood as a mode of metal excretion. Few data concern the potential of organic compounds to induce tubifex autotomy. The objective of this study was to investigate if autotomy can be induced by a herbicide isoproturon (IP) and be related to the way of excretion. Isoproturon accumulation in worm tissues and its effect on tubifex mortality, autotomy and regeneration rates were analysed after 4 and 7 days of exposure to the herbicide and also when worms were replaced for 10 days in clean water. IP accumulated in the same way in all parts of the worm body but IP metabolite rates were significantly higher in the posterior part of the worm. Thus the loss of the posterior part allows the worm to eliminate an important amount of pesticide. Autotomy has a population importance and is related to the degree of worm contamination so it may become an interesting biomarker.

One-year monitoring of reproductive and energy reserve cycles in transplanted zebra mussels (Dreissena polymorpha)

A 12-month active biomonitoring study was performed in 2008-2009 on a northern French river system using the freshwater mussel Dreissena polymorpha as a sentinel species. Allochtonous mussels originating from a reference site (Commercy) were caged at four sites (Bouy, Sept-Saulx, Fismes, Ardre) within the Vesle River basin. The main objective of the study was to characterize the influence of biotic (sex, food availability) and abiotic (temperature, chemicals) factors on the reproductive and energy reserve (glycogen, lipids) cycles of exposed mussels. Both cycles were markedly disturbed at the Bouy and Sept-Saulx sites where the lowest chlorophyll a levels were recorded during the study. At these sites, mussels obviously faced a negative energy balance, as confirmed by the impairment of their physiological state and byssal attachment. At other exposure sites, reproductive and energy reserves cycles were less impacted but were still dependent on the nutritional state of mussels. The latter appeared as a significant natural confounding factor in ecotoxicological survey performed in low polluted areas.

Multi-Biomarkers Approach in Different Organs of Anodonta cygnea from the Dnister Basin (Ukraine)

The aim of this study was to compare environmental quality in two sites in western Ukraine—rural (R) and urbanized (U)—with the usage of the resident bivalve mollusk Anodonta cygnea. The study was realized during three seasons. The metal uptake and a set of biochemical markers were determined. For each season, Cd and metallothioneins (MTs) contents in the digestive gland and gills of the mollusc were higher at the U site, reflecting its chronic pollution. The oxidative stress in the mollusk was observed at the U site during spring and at the R site during summer and autumn according to the differences in Mn–superoxide dismutase and catalase activities, O2•− production, lipid peroxidation, and glutathione levels. The elevated vitellogenin-like protein levels in the hemolymph and the ethoxyresorufin-O-deethylase activity in the digestive gland in summer–autumn suggested pollutions by organic substances at the R site. The acetylcholinesterase activity was similar in both groups. The centroid grouping analysis of biomarkers and morphological and water indexes demonstrated the clear differentiation of general response in each group in spring and, at the R site, in summer and autumn but its similarity at the U site in summer and autumn.