Impacts of 17beta-estradiol, including environmentally relevant concentrations, on reproduction after exposure during embryo-larval-, juvenile- and adult-life stages in zebrafish (Danio rerio).

Zebrafish (Danio rerio) were exposed for 3 weeks to low concentrations of estradiol including environmentally relevant concentrations (5, 25 and 100 ng/l), encompassing either their embryo-larvae (from fertilization to 21 day post-fertilization (dpf)), juvenile (from 21 to 42 dpf) or adult life stages (>200 dpf) with a view to investigating the most sensitive life stage of the zebrafish to 17beta-estradiol (E2). At all sampling points, whole-body vitellogenin concentrations and gonadal development were analyzed in order to investigate the effects of estrogen exposure on these endpoint in the zebrafish. In the adult stage, additional endpoints were measured including secondary sexual characteristics (manifestation of the uro-genital papillae (UGP) in males), gonadal growth (the gonado-somatic index (GSI)) and sex ratio.

Do migratory or demographic disruptions rule the population impact of pollution in spatial networks?

Ecotoxicology supplies environmental quality criteria mainly based on the potential effects of contaminants on demographic rates of natural populations. Possible impacts through pollutant-induced disruptions of spatial behaviors are totally neglected. Should it be significant to take into account this "second way"? We developed the example of a hypothetical brown trout population living in a river network.

A model to understand the confounding effects of natural sediments in toxicity tests with Chironomus riparius.

Recently, we built a model to link feeding input with growth, emergence, and reproduction of the midge Chironomus riparius exposed to an artificial sandy sediment. This model is based on assumptions about both feeding behavior and use of energy. Here, we show how it can be used for toxicity tests with natural sediments to understand and model the influence of sediment characteristics.

Ecotoxicology and spatial modeling in population dynamics: an illustration with brown trout.

We developed a multiregion matrix population model to explore how the demography of a hypothetical brown trout population living in a river network varies in response to different spatial scenarios of cadmium contamination. Age structure, spatial distribution, and demographic and migration processes are taken into account in the model. Chronic or acute cadmium concentrations affect the demographic parameters at the scale of the river range.

The measurement of cholinesterase activities as a biomarker in chub (Leuciscus cephalus): the fish length should not be ignored.

Biomarkers are early warning systems of the exposure of aquatic organisms to pollutants. Among them, the measurement of the cholinesterase (ChE) activities in fish muscle is a biomarker of the exposure to organophosphosphates and carbamates pesticides. As such it has been used in numerous field studies both in marine and continental waters.

A modeling approach to link food availability, growth, emergence, and reproduction for the midge Chironomus riparius.

We present models to link feeding with growth, emergence, and reproduction of the midge Chironomus riparius. These models are based on assumptions about the biology of this species and distinguish between males and females. The assumptions are the isomorphism of the chironomidae, the fact that much more energy is used for growth than for maintenance, and the existence of a maximum length for male and female larvae that does not depend on food availability.

Multibiomarker responses in fish from the Moselle River (France).

The response of wild fish to pollutants was studied using two biomarkers in chub (Leuciscus cephalus) at five stations in the Moselle River (France) in 1998 and in 1999. The induction of cytochrome P450 1A was quantified by the ethoxyresorufin O-deethylase (EROD) activity in the liver and the level of DNA single-strand breaks was determined in erythrocytes using the comet assay. EROD activity was observed to be up to 10-fold induced in both males and females from the downstream stations in comparison to the fish from the upstream station.

Using a biology-based model (DEBtox) to analyze bioassays in ecotoxicology: opportunities and recommendations.

The conventional analysis of bioassays does not account for biological significance. However, mathematical models do exist that are realistic from a biological point of view and describe toxicokinetics and effects on test organisms of chemical compounds. Here we studied a biology-based model (DEBtox) that provides an estimate of a no-effect concentration, and we demonstrated the ability of such a model to adapt to different situations.

Statistical analysis of regulatory ecotoxicity tests.

ANOVA-type data analysis, i.e..

Responses of chub (Leuciscus cephalus) populations to chemical stress, assessed by genetic markers, DNA damage and cytochrome P4501A induction.

Indicators of effects at the population level (genetic variation using allozymes) and early indicators of pollution (EROD activity and DNA strand break formation) were analysed in chub (Leuciscus cephalus) living in weakly and heavily contaminated stations of the Rhône River watershed. The genetic erosion was mainly detected in a fish population living in a contaminated small river system, through modifications in allelic and genotypic frequencies for PGM-2 locus and could be linked to a genetic bottleneck and to the reduced gene flow from upstream unable to maintain or restore the genetic diversity. In a contaminated large river system, the genetic diversity for PGM-2 and other loci was maintained and was probably the consequence of a high gene flow from upstream, linked to a sustained drift of larvae and juveniles in the system.

Two-step purification method of vitellogenin from three teleost fish species: rainbow trout (Oncorhynchus mykiss), gudgeon (Gobio gobio) and chub (Leuciscus cephalus).

A two-step purification protocol was developed to purify rainbow trout (Oncorhynchus mykiss) vitellogenin (Vtg) and was successfully applied to Vtg of chub (Leuciscus cephalus) and gudgeon (Gobio gobio). Capture and intermediate purification were performed by anion-exchange chromatography on a Resource Q column and a polishing step was performed by gel permeation chromatography on Superdex 200 column. This method is a rapid two-step purification procedure that gave a pure solution of Vtg as assessed by silver staining electrophoresis and immunochemical characterisation.

An index of effluent aquatic toxicity designed by partial least squares regression, using acute and chronic tests and expert judgements.

The evaluation of the ecotoxicity of effluents requires a battery of biological tests on several species. In order to derive a summary parameter from such a battery, a single endpoint was calculated for all the tests: the EC10, obtained by nonlinear regression, with bootstrap evaluation of the confidence intervals. Principal component analysis was used to characterize and visualize the correlation between the tests.

Cytochrome P450 1A induction in gudgeon Gobio gobio : Laboratory and Field Studies.

The induction of cytochrome P450 1A was studied in gudgeon (Gobio gobio), a common European cyprinid, using both farm-raised and field-caught fish. The effects of sex, reproductive status and past exposure to xenobiotics were assessed. When exposed to beta-naphthoflavone (bNF), reared gudgeon showed a dose-dependent increase of EROD activity with a plateau observed at doses from 20 mg kg-1 (females) and 5 mg kg-1 (males).

Impact assessment of a wastewater treatment plant effluent using the fish biomarker ethoxyresorufin-O-deethylase: field and on-site experiments.

The impact of a wastewater treatment plant (WWTP) effluent was assessed with the fish biomarker ethoxyresorufin-O-deethylase (EROD) using field and on-site laboratory experiments. EROD activity was measured in chub (Leuciscus cephalus) and stone loach (Noemacheilus barbatulus) caught at three sites of the Chalaronne River (southeast France). Liver somatic index (LSI) and organochloride bioaccumulation in muscle were estimated for chub only.

Statistical analysis of cyprinid ethoxyresorufin-O-deethylase data in a large French watershed.

A comparison of ethoxyresorufin-O-deethylase (EROD) data collected in 1995 in various sites in the Rhône watershed (France) was carried out to quantify the influence of factors such as contamination and biological parameters on EROD levels and within-group variabilities. Three species of cyprinids were collected and fish chemical contamination was measured. A log transformation of EROD data provided both normalization and homogeneity of variances.