The Zebra Mussel (Dreissena polymorpha) as a Model Organism for Ecotoxicological Studies: A Prior 1H NMR Spectrum Interpretation of a Whole Body Extract for Metabolism Monitoring

International audienceThe zebra mussel (Dreissena polymorpha) represents a useful reference organism for the ecotoxicological study of inland waters, especially for the characterization of the disturbances induced by human activities. A nuclear magnetic resonance (NMR)-based metabolomic approach was developed on this species. The investigation of its informative potential required the prior interpretation of a reference 1 H NMR spectrum of a lipid-free zebra mussel extract. After the extraction of polar metabolites from a pool of whole-body D. polymorpha powder, the resulting highly complex 1D 1 H NMR spectrum was interpreted and annotated through the analysis of the corresponding 2D homonuclear and heteronuclear NMR spectra. The spectrum interpretation was completed and validated by means of sample spiking with 24 commercial compounds. Among the 238 detected 1 H signals, 53% were assigned, resulting in the identification of 37 metabolites with certainty or high confidence, while 5 metabolites were only putatively identified. The description of such a reference spectrum and its annotation are expected to speed up future analyses and interpretations of NMR-based metabolomic studies on D. polymorpha and to facilitate further explorations of the impact of environmental changes on its physiological state, more particularly in the context of large-scale ecological and ecotoxicological studies

Multiscale Approach to Deciphering the Molecular Mechanisms Involved in the Direct and Intergenerational Effect of Ibuprofen on Mosquito <i>Aedes aegypti</i>

The anti-inflammatory ibuprofen is a ubiquitous surface water contaminant. However, the chronic impact of this pharmaceutical on aquatic invertebrate populations remains poorly understood. In model insect <i>Aedes aegypti</i>, we investigated the intergenerational consequences of parental chronic exposure to an environmentally relevant concentration of ibuprofen. While exposed individuals did not show any phenotypic changes, their progeny showed accelerated development and an increased tolerance to starvation. In order to understand the mechanistic processes underpinning the direct and intergenerational impacts of ibuprofen, we combined transcriptomic, metabolomics, and hormone kinetics studies at several life stages in exposed individuals and their progeny. This integrative approach revealed moderate transcriptional changes in exposed larvae consistent with the pharmacological mode of action of ibuprofen. Parental exposure led to lower levels of several polar metabolites in progeny eggs and to major transcriptional changes in the following larval stage. These transcriptional changes, most likely driven by changes in the expression of numerous transcription factors and epigenetic regulators, led to ecdysone signaling and stress response potentiation. Overall, the present study illustrates the complexity of the molecular basis of the intergenerational pollutant response in insects and the importance of considering the entire life cycle of exposed organisms and of their progeny in order to fully understand the mode of action of pollutants and their impact on ecosystems

Contrasting patterns of tolerance between chemical and biological insecticides in mosquitoes exposed to UV-A

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UV light and urban pollution: Bad cocktail for mosquitoes?

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Estrogen-related receptor γ is an in vivo receptor of bisphenol A

Bisphenol A (BPA) is an endocrine disruptor that displays estrogenic activity. Several reports suggest that BPA may have estrogen receptor-independent effects. In zebrafish, 50 &mu;M BPA exposure induces otic vesicle abnormalities, including otolith aggregation. The purpose of this study was to test if BPA action was mediated in vivo during zebrafish development by the orphan nuclear estrogen related receptor (ERR) &gamma;. Combining pharmacological and functional approaches, we demonstrate that the zebrafish ERR&gamma; mediates BPA-induced malformations in otoliths. Using different bisphenol derivatives, we show that different compounds can induce a similar otolith phenotype than BPA and that the binding affinity of these derivatives to the zebrafish ERR&gamma; correlates with their ability to induce otolith malformations. Morpholino knockdown of ERR&gamma; function suppresses the BPA effect on otoliths whereas overexpression of ERR&gamma; led to a BPA-like otolith phenotype. Moreover, a subphenotypical dose of BPA (1 &mu;M) combined with ERR&gamma; overexpression led to a full-dose (50 &mu;M) BPA otolith phenotype. We therefore conclude that ERR&gamma; mediates the otic vesicle phenotype generated by BPA. Our results suggest that the range of pathways perturbed by this compound and its potential harmful effect are larger than expected.&mdash;Tohm&eacute;, M., Prud&rsquo;homme, S. M., Boulahtouf, A., Samarut, E., Brunet, F., Bernard, L., Bourguet, W., Gibert, Y., Balaguer, P., Laudet, V. Estrogen-related receptor &gamma; is an in vivo receptor of bisphenol A

1H-NMR metabolomics profiling of zebra mussel (Dreissena polymorpha): A field-scale monitoring tool in ecotoxicological studies

International audienceBiomonitoring of aquatic environments requires new tools to characterize the effects of pollutants on living organisms. Zebra mussels (Dreissena polymorpha) from the same site in north-eastern France were caged for two months, upstream and downstream of three wastewater treatment plants (WWTPs) in the international watershed of the Meuse (Charleville-Mézières “CM” in France, Namur “Nam” and Charleroi “Cr” in Belgium). The aim was to test 1H-NMR metabolomics for the assessment of water bodies’ quality. The metabolomic approach was combined with a more “classical” one, i.e., the measurement of a range of energy biomarkers: lactate dehydrogenase (LDH), lipase, acid phosphatase (ACP) and amylase activities, condition index (CI), total reserves, electron transport system (ETS) activity and cellular energy allocation (CEA). Five of the eight energy biomarkers were significantly impacted (LDH, ACP, lipase, total reserves and ETS), without a clear pattern between sites (Up and Down) and stations (CM, Nam and Cr). The metabolomic approach revealed variations among the three stations, and also between the upstream and downstream of Nam and CM WWTPs. A total of 28 known metabolites was detected, among which four (lactate, glycine, maltose and glutamate) explained the observed metabolome variations between sites and stations, in accordance with chemical exposure levels. Metabolome changes suggest that zebra mussel exposure to field contamination could alter their osmoregulation and anaerobic metabolism capacities. This study reveals that lactate is a potential biomarker of interest, and 1H-NMR metabolomics can be an efficient approach to assess the health status of zebra mussels in the biomonitoring of aquatic environments

Sweet specificities of the root extracellular trap of perennial ryegrass (Lolium perenne), a fructan accumulating plant

International audiencePerennial ryegrass (Lolium perenne) is a fructan-accumulating plant constituting one of the most important grassland species with high herbage production, nutritive value and digestibility for grazing cattle. Although fructans were reported to be involved in plant defense acting as antioxidants or stress signals, their contribution in root protection is still to be explored. In roots, atypical defense is provided by the “Root Extracellular Trap” or “RET” at the root-soil interface. The molecular composition and structural organization of the RET are essential to provide root defense against pathogen attacks and abiotic stresses. The RET was reported to be mainly composed of polysaccharides (homogalacturonan, xylogalacturonan, xyloglucan) and proteoglycans such as arabinogalactan proteins (AGPs). Our aim is to characterize the RET composition of L. perenne using cell imaging techniques and a wide range of monoclonal antibodies directed against epitopes from cell wall glycomolecules and to investigate the potential presence of fructans. Interestingly, we found that both mucilage and cell wall surface of border cells were enriched in AGP epitopes. An increased amount of the AGP-containing mucilage was produced by L. perenne root tip in response to both elicitor and osmotic stress. Fructan epitopes were also detected in root cap cells and appeared to be released in the RET under stress conditions. Taken together our findings suggest that AGPs together with fructans are involved in root response of L. perenne to environmental stresses

Prenatal Ultrasound Suspicion of Cystic Fibrosis in a Multiethnic Population: Is Extensive CFTR Genotyping Needed?

International audienceIn families without a Cystic Fibrosis (CF) history, fetal ultrasound bowel abnormalities can unexpectedly reveal the disease. Isolated or in association, the signs can be fetal bowel hyperechogenicity, intestinal loop dilatation and non-visualization of fetal gallbladder. In these cases, search for CF transmembrane conductance regulator (CFTR) gene mutations is part of the recommended diagnostic practices, with a search for frequent mutations according to ethnicity, and, in case of the triad of signs, with an exhaustive study of the gene. However, the molecular diagnosis remains a challenge in populations without well-known frequent pathogenic variants. We present a multiethnic cohort of 108 pregnancies with fetal bowel abnormalities in which the parents benefited from an exhaustive study of the CFTR gene. We describe the new homozygous p.Cys1410* mutation in a fetus of African origin. We did not observe the most frequent p.Phe508del mutation in our cohort but evidenced variants undetected by our frequent mutations kit. Thanks to the progress of sequencing techniques and despite the difficulties of interpretation occasionally encountered, we discuss the need to carry out a comprehensive CFTR study in all patients in case of fetal bowel abnormalities

Évaluer le potentiel de soins linguistiquement concordants pour les francophones de l’Ontario : une étude populationnelle transversale

Cette étude a utilisé les données sur les médecins, la facturation et le recensement de 2016 dont dispose l’ICES pour examiner l’accès potentiel à des médecins de famille francophones pour les francophones résidant dans 1 643 aires de diffusion agrégées (ADA) de l’Ontario. L’Ontario compte 550 280 francophones, soit 4,1 % de sa population. Nous avons identifié 8 199 médecins de famille, parmi lesquels 1 169 se sont autodéclarés francophones. Le ratio provincial global pour les francophones était de 2,12 médecins par 1 000 résidentes et résidents, comparativement à un ratio de 0,66 pour les anglophones. Dans les ADA où les francophones étaient majoritaires, le ratio pour les francophones était inférieur au ratio pour les anglophones (0,63 vs 2,02), alors que dans toutes les autres ADA, le ratio francophone était plus élevé (3,46 vs 0,62 dans les 83,4 % des ADA où les francophones représentaient >0 % à 0% to <5% of the population). Eight ADAs in northeastern and eastern Ontario had a large relative deficit in French-speaking family physicians compared to the provincial ratio. These findings offer insights about areas that could benefit from strategies addressing linguistic barriers