Adapting SimpleTreat for simulating behaviour of chemical substances during industrial sewage treatment.

The multimedia model SimpleTreat, evaluates the distribution and elimination of chemicals by municipal sewage treatment plants (STP). It is applied in the framework of REACH (Registration, Evaluation, Authorization and Restriction of Chemicals). This article describes an adaptation of this model for application to industrial sewage treatment plants (I-STP). The intended use of this re-parametrized model is focused on risk assessment during manufacture and subsequent uses of chemicals, also in the framework of REACH. The results of an inquiry on the operational characteristics of industrial sewage treatment installations were used to re-parameterize the model. It appeared that one property of industrial sewage, i.e. Biological Oxygen Demand (BOD) in combination with one parameter of the activated sludge process, the hydraulic retention time (HRT) is satisfactory to define treatment of industrial wastewater by means of the activated sludge process. The adapted model was compared to the original municipal version, SimpleTreat 4.0, by means of a sensitivity analysis. The consistency of the model output was assessed by computing the emission to water from an I-STP of a set of fictitious chemicals. This set of chemicals exhibit a range of physico-chemical and biodegradability properties occurring in industrial wastewater. Predicted removal rates of a chemical from raw sewage are higher in industrial than in municipal STPs. The latter have typically shorter hydraulic retention times with diminished opportunity for elimination of the chemical due to volatilization and biodegradation.

Molecular and cellular changes in skin and muscle during metamorphosis of Atlantic halibut (Hippoglossus hippoglossus) are accompanied by changes in deiodinases expression.

Flatfish metamorphosis is the most dramatic post-natal developmental event in teleosts. Thyroid hormones (TH), thyroxine (T4) and 3,3'-5'-triiodothyronine (T3) are the necessary and sufficient factors that induce and regulate flatfish metamorphosis. Most of the cellular and molecular action of TH is directed through the binding of T3 to thyroid nuclear receptors bound to promoters with consequent changes in the expression of target genes. The conversion of T4 to T3 and nuclear availability of T3 depends on the expression and activity of a family of 3 selenocysteine deiodinases that activate T4 into T3 or degrade T4 and T3. We have investigated the role of deiodinases in skin and muscle metamorphic changes in halibut. We show that, both at the whole body level and at the cellular level in muscle and skin of the Atlantic halibut (Hippoglossus hippoglossus) during metamorphosis, the coordination between activating (D2) and deactivating (D3) deiodinases expression is strongly correlated with the developmental TH-driven changes. The expression pattern of D2 and D3 in cells of both skin and muscle indicate that TH are necessary for the maintenance of larval metamorphic development and juvenile cell types in these tissues. No break in symmetry occurs in the expression of deiodinases and in metamorphic developmental changes occurring both in trunk skin and muscle. The findings that two of the major tissues in both larvae and juveniles maintain their symmetry throughout metamorphosis suggest that the asymmetric changes occurring during flatfish metamorphosis are restricted to the eye and head region.

Identification of estrogen-responsive genes in the testis of sea bream (Sparus auratus) using suppression subtractive hybridization.

There is growing evidence that estrogens play important roles in both normal and xenoestrogen disrupted testis physiology. However, the mechanisms and signaling pathways involved, in particular in fish, are largely unknown. We have used suppression subtractive hybridization to isolate 152 candidate estrogen-responsive genes in the testis of male estradiol (E2)-treated sea bream (Sparus aurata). The E2 up-regulation of some of the genes (e.g., choriogenin L and H, vitellogenin I and II, apolipoprotein A-I, fibrinogen beta and gamma, and thyroid receptor interacting protein 4) was confirmed by reverse transcriptase polymerase chain reaction in fish treated with 0.1-10 mg/kg E2. Many of these genes are typical E2-induced genes in liver, and this is the first report of its up regulation with E2 in testis. Moreover, low levels of expression were also found for nontreated fish. Hepatic differential expression for these genes was also confirmed, although, contrary to testis, fibrinogen beta, and gamma were downregulated. The possible significance of these findings in normal testis physiology and in endocrine disruption is discussed.

Developing a new method for soil pollution monitoring using molecular genetic biomarkers.

Physiological responses to environmental stressors may induce changes in gene expression as part of an organism's homeostatic mechanisms. Thus molecular genetic biomarkers have the potential to be used for monitoring sublethal chemical exposure in ecosystems. This paper describes a methodological assessment of the suitability of a protocol to monitor selected biomarkers. The TaqMan real-time quantitative polymerase chain reaction was used to measure gene transcription in earthworms (Lumbricus rubellus) maintained on control or cadmium- or copper-spiked soil. Changes in the expression of two target genes, that encoding metallothionein isoform 2 (MT-2) and that encoding the mitochondrial large ribosomal subunit (MLRS), were quantified against the internal control gene beta-actin. The protocol used produced reliable and reproducible results. Transcript levels displayed qualitative and quantitative differences in the responses to the two metal ions. MLRS gene levels were unaffected by exposure to cadmium but displayed a response to high levels of copper. Conversely, cadmium greatly induced MT-2 gene expression, but copper only altered transcription of this gene at high exposure concentrations. This study demonstrates that it is now technically feasible to use gene expression as an index of pollution exposure in environmentally relevant organisms.