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Ecological assessment of groundwater ecosystems disturbed by recharge systems using organic matter quality, biofilm characteristics and bacterial diversity
No full textInternational audienceRecharge of aquifers by urban stormwater may trigger significant ecological changes that can be detrimental to the biodiversity and functioning of groundwater ecosystems. Here, the effects of aquifer recharge (AR) on three levels of parameters were investigated: dissolved organic carbon (DOC) quantity and quality, global biofilm characteristics, and diversity changes of bacterial communities. As DOC enrichment by AR can be mitigated by vadose zone (VZ) thickness, three AR sites with thin VZ ( 10 m) were selected. For each AR site, clay beads were incubated over a 10-day-long rainy period through wells in recharged and non-recharged groundwaters. Total proteins, dehydrogenase, and hydrolytic activities were monitored from clay beads to assess biofilm development. Bacterial richness on beads was estimated by 16S rRNA-based metabarcoding. AR was found to significantly increase DOC and biodegradable DOC (BDOC) concentrations, biofilm development, and bacterial richness especially in sites with thin VZ. VZ thickness was inversely related to microbial growth indicators and bacterial richness in groundwater, through a control of DOC availability. The proportion of Bacteroidetes 16S rRNA gene reads was higher in recharged groundwater than in non-recharged groundwater, suggesting that this phylum could be used as an indicator of DOC enrichment associated with AR. Quantitative PCR assays for Bacteroides DNA confirmed these trends and showed an enrichment of this bacterial group in DOC-rich aquifer waters. The positive linear relationships between BDOC concentrations and biofilm variables highlighted a strong C-limitation of groundwater impacting bacterial species sorting and activity
Life-long Dietary Pesticides Cocktail Induces Astrogliosis Along with Behavioral Adaptations and Activates p450 Metabolic Pathways
No full textInternational audienceExposure to environmental contaminants is a public health concern. However, pre-clinical studies examining the impact of pesticides at low-dose and their long-term consequences are uncommon. Here, C57BL6/j male and female mice were daily fed from weaning and up to 12 months, corresponding to early-childhood into middle-age in humans, using chow pellets containing a cocktail of pesticides and exposing them to the tolerable daily intake level for each pesticide. We found that 12 months of dietary exposure to pesticides was associated with a moderate astrogliosis in the hippocampus. The expression of platelet-derived growth factor receptor beta (PDGFRβ), an indicator of pro-fibrotic tissue changes, was modified at the perivascular level. Examination of Iba1+ microglial cells did not reveal sizeable changes. Concomitantly to astrogliosis, spontaneous spatial memory and sociability were impaired in males at 12 months of dietary exposure to pesticides. Telemetry electrocorticograhic explorations ruled out the presence of epileptiform activity or theta-gamma wave modifications in these conditions. Long-term pesticides impacted the periphery where the hepatic P450 metabolic cytochromes Cyp4a14 and Cyp4a10 were significantly upregulated in male and female mice during the 12 months of exposure. The expression of β-oxidation genes, such as Acox1, Cpt1a and Eci, was also significantly increased in male and female mice in response to pesticides. Collectively, our results indicate that long-term exposure to pesticides cocktail elicits spatio-temporally restricted brain modifications and significant activation of P450 pathways in the periphery. These brain-peripheral adjustments are discussed as time-dependent vulnerability elements
Ecological association between residential natural background radiation exposure and the incidence rate of childhood central nervous system tumors in France, 2000–2012
No full textInternational audienceBackground: High-dose ionizing radiation is an established risk factor for childhood central nervous system tumors (CNST) but the role of low doses remains debated. In particular, there are few studies of natural background radiation (NBR, gamma radiation and radon) and childhood CNST, and their results are inconclusive.Objectives: This study aimed to investigate the ecological association between NBR exposure and childhood CNST incidence in France, considering childhood CNST overall and by subgroups.Methods: Incidence data were provided by the French national registry of childhood cancers, which has high completeness. We included 5471 childhood CNST cases registered over the period 2000-2012, and their municipality of residence at diagnosis was recorded. Municipality NBR exposures were estimated by cokriging models, using NBR measurements and additional geographic data. The incidence rate ratio (IRR) per unitvariation of exposure was estimated with Poisson regression models. NBR exposures were considered at the time of diagnosis, and cumulatively from birth to diagnosis. In an exploratory analysis, the total brain dose due to NBR was used.Results: Overall, there was no association between NBR exposure and childhood CNST incidence (IRR = 1.03(0.98,1.09) per 50 nSv/h for gamma radiation, and IRR = 1.02 (0,96,1.07) per 100 Bq/m3 for radon). An association was suggested between pilocytic astrocytomas and gamma radiation (IRR = 1.12 (1.00,1.24) per 50nSv/h) but not with radon (IRR = 1.07 (0.95,1.20) per 100 Bq/m3). Upward trends for this CNST subtype were also suggested with the cumulative exposures to gamma radiation and the total brain dose. NBR exposure was not associated with other CNST subgroups (ependymomas, embryonal tumors, and gliomas other than pilocytic astrocytomas). Adjustment for socio-demographic factors did not change the findings.Conclusions: Our study was based on high quality incidence data, large numbers of CNST cases, and validated models of NBR exposure assessment. Results suggest an association between gamma radiation, as a component of NBR, and pilocytic astrocytomas incidence in France
A multi-band body-worn distributed exposure meter for personal radio-frequency dosimetry in diffuse indoor environments
No full textInternational audienceA multi-band body-worn distributed exposure meter (BWDM) is designed and calibrated for diffuse fields in a reverberation chamber (RC) for personal exposure assessment in indoor environments. The BWDM uses 22 nodes distributed over the torso and measures the incident power density (Sinc) on body for 11 telecommunication bands in the frequency range 790-5513 MHz. In order to calibrate the measurement device in diffuse fields, a protocol is proposed for on-body calibration of the BWDM. This protocol is applicable to wearable personal exposure meters in general. The BWDM and the proposed calibration protocol are validated in five indoor locations and five frequency bands (the downlink bands at 800, 900, 1800 and 2100 MHz and WiFi 2 GHz) using a tri-axial broadband antenna and a spectrum analyzer (SA). The calibration shows that the BWDM has a relatively low measurement uncertainty with a 68% confidence interval on its antenna apertures, in the range 3.4-5.5 dB. A maximum difference of 0.9 dB is obtained for the total exposure in the test areas between the measurements of the BWDM and SA, which is an excellent agreement
Contributions of participatory ergonomics to the involvement of workers in chemical risk prevention projects
No full textInternational audienceIn a context where preventive measures are developed via a functionalist and technological approach, the aim of this work is to set out general principles and methods for new preventive solutions that will enrich these existing measures. We propose an approach centered on the involvement of workers at all hierarchical levels around "intermediary objects" of prevention in order to foster a collective debate. This might provide empowered workers to be actors into their own prevention of risk faced. Observational data was coupled with chemical and physiological measurements. We developed, reworked and enriched the notion of risk representation, which promotes the visibility and recognition of the knowledge built, developed and held by workers on their activities and on ways to protect themselves from dangers or hazards. Implementation of the method generates detailed knowledge of chemical risks, knowledge that is constructed by the workers. This knowledge is made possible by the experience of the body and senses, and becomes accessible via references to the domestic and professional sphere in reflexive activities. The actors get involved and make use of their individual, collective and organizational resources to propose prevention solutions. Use of intermediate prevention objects in an "intermediate space for dialogue" allows dialogues to be produced and fostered. Ultimately, these spaces are circulating entities for the co-production of knowledge for action: to generate knowledge and innovative prevention solutions collectively
Dissemination of CTX-M-producing Escherichia coli in freshwater fishes from a french watershed (Burgundy)
No full textInternational audienceThe burden of extended-spectrum beta-lactamases producing Escherichia coli (ESBL-Ec), has increased over several decades. Freshwater ecosystems are suspected to play an important ecological and evolutionary role in driving the dissemination of antimicrobial resistance. The aim of our study was to decipher the occurrence of ESBL-Ec in a small watershed (Ouche river, Burgundy, France), targeting environmental matrices and fishes. Among cefotaxime resistant E. coli (ctxR Ec) isolates, we detected and characterized 36 ESBL-Ec from water, biofilm and fish guts. ctxR Ec and ESBL-Ec were found in samples from sites near the first small town, located downstream from the watershed which was studied. Treatment of urban wastewater by waste water treatment plants (WWTP), might therefore be a major potential source of ctxR Ec and thus of ESBL-Ec. Prevalence of total E. coli and ctxR Ec in fish guts ranged between 0 to 92% and 0 to 85%; respectively, depending on the sampling site and the fish species. The diet of fish (predator or omnivore) seems to strongly influence the prevalence of total E. coli and ESBL-Ec. Extended spectrum beta-lactamases produced by the isolates from this study belonged to the CTX-M family (CTX-M group 1 and 9). Moreover, some environmental ESBL-Ec proved to share genotypic features (MLST types) with isolates which originated from 8 WWTP effluents discharged in the Ouche river and with the sequence type ST131, which is widely described in clinical isolates. Ninety-seven % (97%) of ESBL-Ec from the study harbored additional antibiotic resistances and can thus be considered as multi drug resistant (MDR) bacteria. Finally, 53% of the ESBL-Ec strains harbored class 1 integron-integrase (intl1). These results are discussed with the perspective of defining indicators of antibiotic resistance contamination in freshwater ecosystems
Identification of human skin bacteria attractive to the Asian Tiger mosquito
No full textInternational audienceAedes albopictus is a vector of arboviruses and filarial nematodes. Originating from Asia, this mosquito has rapidly expanded its geographical distribution and colonized areas across both temperate and tropical regions. Due to the increase in insecticide resistance, the use of environmentally friendly vector control methods is encouraged worldwide. Using methods based on semiochemicals in baited traps are promising for management of mosquito populations. Interestingly, human skin microbiota was shown to generate volatile compounds that attract the mosquito species Anopheles gambiae and Aedes aegypti. Here, we investigated the composition of skin bacteria from different volunteers and the attractive potential of individual isolates to nulliparous Ae. albopictus females. We showed that three out of 16 tested isolates were more attractive and two were more repulsive. We identified dodecenol as being preferentially produced by attractive isolates and 2-methyl-1-butanol (and to a lesser extent 3-methyl-1-butanol) as being overproduced by these isolates compared with the other ones. Those bacterial volatile organic compounds represent promising candidates but further studies are needed to evaluate their potential application for baited traps improvement
Effects of combined exposure of adult male mice to di-(2-ethylexyl)phthalate and nonylphenol on behavioral and neuroendocrine responses
No full textInternational audienceThe present study evaluates the effects of adult exposure to low doses of a mixture of di-(2-ethylexyl)phthalate (DEHP) and nonylphenol (NP) on reproductive neuroendocrine function and behavior. The neural circuitry that processes male sexual behavior is tightly regulated by testosterone and its neural metabolite estradiol. In previous studies, we showed that adult exposure of mice to low doses of each of these widespread environmental contaminants resulted in altered sexual behavior, without any effect on the regulation of the gonadotropic axis. Here, adult C57BL/6J male mice were exposed to DEHP/NP (0.5 or 5 μg/kg body weight/day) for 4 weeks before starting the analyses. Mice treated with DEHP/NP at 0.5 μg/kg/day show altered olfactory preference, and fewer of them emit ultrasonic vocalization compared to the other treatment groups. These mice also exhibit a lower number of mounts and thrusts, increased locomotor activity and unaffected anxiety-state level, along with unaltered testosterone levels and kisspeptin system, a key regulator of the gonadotropic axis. Analysis of the neural circuitry that underlies sexual behavior showed that the number of cells expressing androgen and estrogen receptors is comparable between control and DEHP/NP-exposed males. The comparison of these data with those obtained in males exposed to each molecule separately highlights synergistic effects at the lower dose of contaminants of 0.5 μg/kg/day. In contrast, the effects previously observed for each molecule at 5 μg/kg/day were not detected. A detailed comparison of the effects triggered by separate or combined exposure to DEHP and NP is discussed
Lysosome mediates toxicological effects of polyethyleneimine-based cationic carbon dots
No full textCationic carbon dots (CDs) have been recently described as nucleic acid carriers with high in vitro and in vivo transfection efficiency and imaging properties. However, developing nanoparticles (NPs) for bio-medical applications requires assessing their safety. In the present study, we characterized the cell uptake and trafficking, as well as the cell viability loss, oxidative stress, inflammation, and mitochondrial and lysosomal perturbations evoked by cationic CDs prepared by microwave-assisted pyrolysis of citric acid and high molecular weight branched polyethyleneimine (bPEI25k), using THP-1-derived macrophages. CDs were rapidly internalized by cells and addressed to the lysosomes after their cell entry. The NPs induced a dose-and time-dependent loss in cell viability that was associated with oxidative stress and IL-8 release. The CDs triggered also a dose-dependent loss in lysosome integrity , mitochondrial dysfunction, and NLRP3 inflammasome activation. Inhibition of the lysosomal protease cathepsin B significantly reduced CD-induced mitochondrial dysfunction and NLRP3 inflammasome activation, suggesting a pivotal role of the lysosome in the toxicological effects of the NPs. Our study provides for the first time a mechanistic pathway for the toxicological effects of bPEI25k-based cationic CDs