Interaction of erythromycin ethylsuccinate and acetaminophen with protein fraction of extracellular polymeric substances (EPS) from various bacterial aggregates

Extracellular polymeric substances (EPS) are, along with microbial cells, the main components of the biological sludges used in wastewater treatment and natural biofilms. EPS play a major role in removing pollutants from water by means of sorption. The ability of soluble EPS (S-EPS) and bound EPS (B-EPS) derived from various bacterial aggregates (flocs, granules, biofilms) to bind at pH 7.0?±?0.1 to two pharmaceutical substances, acetaminophen (ACE) and erythromycin ethylsuccinate (ERY), has been investigated using the fluorescence quenching method. Two intense fluorescence peaks, A (Ex/Em range, 200–250/275–380 nm) and B (Ex/Em range, 260–320/275–360 nm), corresponding respectively to the aromatic protein region and soluble microbial by-product-like region, were identified in a three-dimensional excitation-emission matrix of EPS samples. The fluorescence peak, which corresponds to humic-like substances, was also identified though at low intensity. The ability of EPS to bind ACE was found to exceed that for ERY. The aromatic protein fraction of EPS displays a slightly higher affinity for drugs than that shown by the soluble microbial by-product-like fraction. The S-EPS and B-EPS present the same affinity for ACE and ERY. The effective quenching constants (log K) derived from the Stern–Volmer Equation equaled at peak A (with S-EPS): 3.7?±?0.2 to 4.0?±?0.1 for ACE and 2.1?±?0.3 to 2.7?±?0.1 for ERY. With B-EPS, these values were 3.9?±?0.1 to 4.0?±?0.1 for ACE and 2.0?±?0.2 to 2.6?±?0.1 for ERY. Our results suggest that the weaker EPS affinity for ERY than for ACE serves to partially explain why only about 50–80 % of ERY is removed from wastewater at the treatment plant. Moreover, this work demonstrates that EPS from natural river biofilms are able to bind drugs, which in turn may limit the mobility of drugs in natural waters.     

Oxidoreductases provide a more generic response to metallic stressors (Cu and Cd) than hydrolases in soil fungi: new ecotoxicological insights

The present study investigates the effect of metals on the secretion of enzymes from12 fungal strains maintained in liquid cultures. Hydrolases (acid phosphatase, β-glucosidase, β-galactosidase, and N-acetyl-β-glucosaminidase) and ligninolytic oxidoreductases (laccase, Mn, and lignin peroxidases) activities, as well as biomass production, were measured in culture fluids from fungi exposed to Cu or Cd. Our results showed that all fungi secreted most of the selected hydrolases and that about 50 % of them produced a partial oxidative system in the absence of metals. Then, exposure of fungi to metals led to the decrease in biomass production. At the enzymatic level, Cu and Cd modified the secretion profiles of soil fungi. The response of hydrolases to metals was contrasted and complex and depended on metal, enzyme, and fungal strain considered. By contrast, the metals always stimulated the activity of ligninolytic oxidoreductases in fungal strains. In some of them, oxidoreductases were specifically produced following metal exposure. Fungal oxidoreductases provide a more generic response than hydrolases, constituting thus a physiological basis for their use as biomarkers of metal exposure in soils.     

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.     

Degradation of Polyethylene Designed for Agricultural Purposes

For many years now, scientific articles have been published on the potential biodegradability of polyethylene. Polyethylene (PE) with peroxidant additives, in the form of agricultural films, is sold by various suppliers as biodegradable mulch. Even though, the photo-chemical and thermal degradation of these products under artificial laboratory conditions is highlighted, several extrapolation on the biodegradation and, moreover, on the neutral environmental impact of PE are made. In this study, three different commercial mulch films have been submitted to standardised biodegradation tests and the results are discussed. The first conclusions are that a very low degree of biodegradation of the commercial PE films is achieved from these tests and that crosslinked PE micro-fragments are found in soil after a very long period of time.     

Effect of the endectocide ivermectin on filamentous fungi

We investigated the effect of ivermectin, at environmental concentrations and above, on several strains of filamentous fungi. Ivermectin did not show significant short-term effect on biomass production and germination rate of the spores. By contrast, the spore production was stimulated twofold in Phanerochaete chrysosporium and Mucor racemosus cultures, whereas that endpoint was reduced in Fusarium cultures. A long-term exposure of F. oxysporum to ivermectin reduced both production and germination of fungal spores. Ivermectin was not an inducer of exocellular oxidases.     

Measurements of personal exposure to nitrogen dioxide in four Mexican cities in 1996

Nitrogen dioxide is a ubiquitous pollutant in urban areas. Indoor NO2 concentrations are influenced by penetration of outdoor concentrations and by indoor sources. The objectives of this study were to evaluate personal exposure to NO2, taking into account human time-activity patterns in four Mexican cities. Passive filter badges were used for indoor, outdoor, and personal NO2 measurements over 48 hr and indoor workplace measurements over 16 hr. Volunteers completed a questionnaire on exposure factors and a time-activity diary during the sample period. An unpaired t test, an analysis of variance (ANOVA), and a linear regression were performed to compare differences among cities and mean personal NO2 concentrations involving housing characteristics, as well as to determine which variables predicted the personal NO2 concentration. Sampling periods were in April, May, and June 1996 in Mexico City, Guadalajara, Cuernavaca, and Monterrey. All 122 volunteers in the study were working adults, with a mean age of 34 (SD +/- 7.38); 64% were female, and the majority worked in public offices and universities. The highest NO2 concentrations were found in Mexico City (36 ppb for outdoor, 57 ppb for indoor, and 39 ppb for personal concentration) and the lowest in Monterrey (19 ppb for outdoor, 24 ppb for indoor, and 24 ppb for personal concentration). Significant differences in NO2 concentrations were found among the cities in different microenvironments. During the sampling period, volunteers spent 85% of their time indoors. The highest personal NO2 concentration was found when volunteers kept their windows closed (p = 0.03). In the regression model adjusted by city and gender, the best predictors of personal NO2 concentration were outdoor levels and time spent outdoors (R2 = 0.68). These findings suggest that outdoor NO2 concentrations were an important influence on the personal exposure to NO2, due to the specific characteristics and personal behavior of the people in these Mexican cities.     

Tibial hemimelia syndrome: Prenatal diagnosis by real-time ultrasound

The tibial hemimelia syndrome is a rare autosomal dominant condition associated with limb deficiencies. We recently diagnosed this condition in a pregnancy at 16·5 weeks' gestation by ultrasound and a positive family history. To our knowledge, this represents the first case to be detected prenatally.