Mapping risks associated with soil copper contamination using availability and bio-availability proxies at the European scale

Environmental Science and Pollution Research - Soil contamination by trace elements like copper (Cu) can affect soil functioning. Environmental policies with guidelines and soil survey measurements...     

Detection of trisomy 21 by quantitative fluorescent–polymerase chain reaction in uncultured amniocytes

Prenatal diagnosis of fetal trisomy 21 is usually performed by cytogenetic analysis. This requires lengthy laboratory procedures, high costs and is unsuitable for large-scale screening of pregnant women. Today, trisomy 21 can be rapidly diagnosed within 24 h by molecular analysis of uncultured fetal cells using the semi-quantification of fluorescent PCR products from short tandem repeat (STR) polymorphic markers. The aim of our study was to test a chromosome quantification method on the basis of the analysis of fluorescent PCR products derived from non-polymorphic target genes. Co-amplification of a portion of DSCR1 (Down syndrome Critical Region 1) and the reference gene, CFTR (cystic fibrosis transmembrane regulator) enabled molecular detection of trisomy 21. Our method was successfully tested on a total of 154 amniotic fluids in a blind prospective study. Calculation of the DSCR1/CFTR ratio allowed us to distinguish between 152 normal amniotic fluids (mean ratio 0.99) and 2 amniotic fluids presenting a trisomy 21 status (DSCR1/CFTR ratio of 1.53 and 1.61, respectively). The results obtained by conventional cytogenetic analysis and our quantitative PCR method were concordant in every case. Our gene-based fluorescent PCR approach represents an alternative molecular method for rapid and reliable detection of trisomy 21, which can be helpful in the prenatal diagnosis of women at high risk of fetal trisomy 21. Copyright © 2003 John Wiley & Sons, Ltd.     

Natural formation and degradation of chloroacetic acids and volatile organochlorines in forest soil--challenges to understanding

- DOI: http:/dx.doi.org/10.1065/espr2005.06.262 Goal, Scope and Background The anthropogenic environmental emissions of chloroacetic acids and volatile organochlorines have been under scrutiny in recent years because the two compound groups are suspected to contribute to forest dieback and stratospheric ozone destruction, respectively. The two organochlorine groups are linked because the atmospheric photochemical oxidation of some volatile organochlorine compounds is one source of phytotoxic chloroacetic acids in the environment. Moreover, both groups are produced in higher amounts by natural chlorination of organic matter, e.g. by soil microorganisms, marine macroalgae and salt lake bacteria, and show similar metabolism pathways. Elucidating the origin and fate of these organohalogens is necessary to implement actions to counteract environmental problems caused by these compounds. Main Features While the anthropogenic sources of chloroacetic acids and volatile organochlorines are relatively well-known and within human control, knowledge of relevant natural processes is scarce and fragmented. This article reviews current knowledge on natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soils, with particular emphasis on processes in the rhizosphere, and discusses future studies necessary to understand the role of forest soils in the formation and degradation of these compounds. Results and Discussion Reviewing the present knowledge of the natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soil has revealed gaps in knowledge regarding the actual mechanisms behind these processes. In particular, there remains insufficient quantification of reliable budgets and rates of formation and degradation of chloroacetic acids and volatile organochlorines in forest soil (both biotic and abiotic processes) to evaluate the strength of forest ecosystems regarding the emission and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale. Conclusion It is concluded that the overall role of forest soil as a source and/or sink for chloroacetic acids and volatile organochlorines is still unclear; the available laboratory and field data reveal only bits of the puzzle. Detailed knowledge of the natural degradation and formation processes in forest soil is important to evaluate the strength of forest ecosystems for the emission and uptake of chloroacetic acids and volatile organochlorines, both on a regional scale and on a global scale. Recommendation and Perspective As the natural formation and degradation processes of chloroacetic acids and volatile organochlorines in forest soil can be influenced by human activities, evaluation of the extent of this influence will help to identify what future actions are needed to reduce human influences and thus prevent further damage to the environment and to human health caused by these compounds.     

Primary co-culture as a complementary approach to explore the diversity of bacterial associations in marine invertebrates: the example of <Emphasis Type="Italic">Nautilus macromphalus</Emphasis> (Cephalopoda: Nautiloidea)

The recent application of molecular tools to address associations between bacteria and marine invertebrates has provided access to an immense diversity of unidentified microbes resistant to cultivation. However, the role of bacteria as partners in animal physiology remains unclear and in most cases difficult to investigate in the absence of adequate condition of cell growth and proliferation. In this work, we studied the reservoir of microbes associated with the excretory organs of Nautilus macromphalus as a model. Using the bacterial 16S RNA gene as a marker, we compared three complementary approaches for bacterial detection: bacterial DNA extraction from N. macromphalus tissues (“molecular approach”), strain isolation to provide a bacterial culture collection (“microbiological approach”) and finally, maintenance of N. macromphalus excretory organ cells with associated bacteria (“cellular approach”). Our results stress the potential of the “cellular approach” as a promising new tool as it promotes the detection of as yet uncultured β-proteobacteria and spirochaetes associated with N. macromphalus, and serves as a foundation for future studies describing potential roles that these bacteria may play in Nautilus.     

Disposition and metabolic profiling of [14C]-decabromodiphenyl ether in pregnant Wistar rats

Fully brominated diphenyl ether, decabromodiphenyl ether (DBDE), is one of the most widely used brominated flame retardants worldwide. Little data is available about the metabolic fate of DBDE in animal models and nothing at all about the extent of foetal exposure. In this work, pregnant Wistar rats were force-fed with 99.8% pure [14C]-DBDE over 96 h at a late stage of gestation (days 16 to 19). More than 19% of the administered dose was recovered in tissues and carcasses, demonstrating efficient absorption of DBDE despite its high molecular weight and low solubility. The highest concentrations of DBDE residues were found in endocrine glands (adrenals, ovaries) and in the liver, with lower values recorded for fat. In all tissue extracts, most of the radioactivity was associated with unchanged DBDE. The use of high-grade purity [14C]-DBDE allowed quantification of several metabolites present both in maternal tissues and in foetuses. These biotransformation products accounted for 9-27% of the extractable radioactivity in tissues and 14% of that in foetuses. Three nona-BDEs and one octa-BDE were identified by LC-APPI/MS. The unequivocal characterisation of a hydroxylated octa-BDE isolated from liver was confirmed by NMR. In rat, the main metabolic pathways of DBDE are debromination and oxidation. DBDE, and very likely most of its metabolites, are able to cross the placental barrier in rat. Metabolic profiles, obtained in vivo for the first time, demonstrated the presence of DBDE and major biotransformation products in endocrine glands as well as in foetuses. The biological activity of these metabolites still needs to be assessed in order to better understand the potential toxicity of DBDE.     

Dietary intake of hexabromocyclododecane diastereoisomers (α-, β-, and γ-HBCD) in the Belgian adult population

A study was performed to assess exposure of the Belgian population to HBCD diastereoisomers. Measurements of HBCD were performed by UPLC-MS/MS, on 45 composite samples from 5 major food groups: dairy (products), meat (products), eggs, fish (products) and a group of “other” products. The medium bound estimated average daily intake (EDI) of ΣHBCD in the Belgian population was 0.99 ng kg⁻¹ bw d⁻¹. The diastereoisomer contribution to the mean EDI showed a predominance of γ-HBCD at 67%, followed by α-HBCD at 25% and 8% for β-HBCD. These results are consistent with the pattern found in the two food groups contributing the most to the EDI: meat (products) and the group of “other” products. Anyway, it has to be noted that diastereomeric distribution of HBCD can change due to bioisomerisation in biological material. Levels of HBCD diastereoisomers found in Belgian food samples of animal origin were low in comparison with those found in other EU countries and the resulting EDI was substantially below the proposed thresholds.     

Secretion profiles of fungi as potential tools for metal ecotoxicity assessment: a study of enzymatic system in Trametes versicolor

The relationship between the expression of extracellular enzymatic system and a metal stress is scarce in fungi, hence limiting the possible use of secretion profiles as tools for metal ecotoxicity assessment. In the present study, we investigated the effect of Zn, Cu, Pb and Cd, tested alone or in equimolar cocktail, on the secretion profiles at enzymatic and protein levels in Trametesversicolor. For that purpose, extracellular hydrolases (acid phosphatase, β-glucosidase, β-galactosidase and N-acetyl-β-glucosaminidase) and ligninolytic oxidases (laccase, Mn-peroxidase) were monitored in liquid cultures. Fungal secretome was analyzed by electrophoresis and laccase secretion was characterized by western-blot and mass spectrometry analyses. Our results showed that all hydrolase activities were inhibited by the metals tested alone or in cocktail, whereas oxidase activities were specifically stimulated by Cu, Cd and metal cocktail. At protein level, metal exposure modified the electrophoretic profiles of fungal secretome and affected the diversity of secreted proteins. Two laccase isoenzymes, LacA and LacB, identified by mass spectrometry were differentially glycosylated according to the metal exposure. The amount of secreted LacA and LacB was strongly correlated with the stimulation of laccase activity by Cu, Cd and metal cocktail. These modifications of extracellular enzymatic system suggest that fungal oxidases could be used as biomarkers of metal exposure.