Novel Insights on the Toxicity of Phycotoxins on the Gut through the Targeting of Enteric Glial Cells

International audienceIn vitro and in vivo studies have shown that phycotoxins can impact intestinal epithelial cells and can cross the intestinal barrier to some extent. Therefore, phycotoxins can reach cells underlying the epithelium, such as enteric glial cells (EGCs), which are involved in gut homeostasis, motility, and barrier integrity. This study compared the toxicological effects of pectenotoxin-2 (PTX2), yessotoxin (YTX), okadaic acid (OA), azaspiracid-1 (AZA1), 13-desmethyl-spirolide C (SPX), and palytoxin (PlTX) on the rat EGC cell line CRL2690. Cell viability, morphology, oxidative stress, inflammation, cell cycle, and specific glial markers were evaluated using RT-qPCR and high content analysis (HCA) approaches. PTX2, YTX, OA, AZA1, and PlTX induced neurite alterations, oxidative stress, cell cycle disturbance, and increase of specific EGC markers. An inflammatory response for YTX, OA, and AZA1 was suggested by the nuclear translocation of NF-κB. Caspase-3-dependent apoptosis and induction of DNA double strand breaks (γH2AX) were also observed with PTX2, YTX, OA, and AZA1. These findings suggest that PTX2, YTX, OA, AZA1, and PlTX may affect intestinal barrier integrity through alterations of the human enteric glial system. Our results provide novel insight into the toxicological effects of phycotoxins on the gut

Differences in regulation of the first two M-phases in Xenopus laevis embryo cell-free extracts

AbstractThe first embryonic M-phase is special, being the time when paternal and maternal chromosomes mix together for the first time. Reports from a variety of species suggest that the regulation of first M-phase has many particularities; however, no systematic comparative study of the biochemical aspects of first and the following M-phases has been previously undertaken. Here, we ask whether the regulation of the first embryonic M-phase is modified, using Xenopus cell-free extracts. We developed new types of extract specific for the first and the second M-phase obtained either from parthenogenetic or from in vitro fertilized embryos. Analyses of these extracts confirmed that the amplitude of histone H1 kinase activity reflecting CDK1/cyclin B (or MPF for M-phase Promoting Factor) activity is higher and persists longer than during the second M-phase, and that levels of cyclins B1 and B2 are correspondingly higher during the first than the second embryonic M-phase. Inhibition of protein synthesis shortly before M-phase entry reduced mitotic histone H1 kinase amplitude, shortened the period of mitotic phosphorylation of chosen marker proteins, and reduced cyclin B1 and B2 levels, suggesting a role of B-type cyclins in regulating the duration of mitotic events. Moreover, addition of exogenous cyclin B to the extract prior the second mitosis brought forward the activation of mitotic histone H1 kinase but prolonged the duration of this activity. We also confirmed that the inhibitory phosphorylation of CDK1 on tyrosine 15 oscillates between the first two embryonic M-phases, but is clearly more pronounced before the first than the second mitosis, while the MAP kinase ERK2 tended to show greater activation during the first embryonic M-phase but with a similar duration of activation. We conclude that discrete differences exist between the first two M-phases in Xenopus embryo and that higher CDK1/cyclin B activity and B-type cyclin levels could account for the different characteristics of these M-phases

Polyhexamethylene biguanide promotes adaptive cross-resistance to gentamicin in Escherichia coli biofilms

Antimicrobial resistance is a critical public health issue that requires a thorough understanding of the factors that influence the selection and spread of antibiotic-resistant bacteria. Biocides, which are widely used in cleaning and disinfection procedures in a variety of settings, may contribute to this resistance by inducing similar defense mechanisms in bacteria against both biocides and antibiotics. However, the strategies used by bacteria to adapt and develop cross-resistance remain poorly understood, particularly within biofilms –a widespread bacterial habitat that significantly influences bacterial tolerance and adaptive strategies. Using a combination of adaptive laboratory evolution experiments, genomic and RT-qPCR analyses, and biofilm structural characterization using confocal microscopy, we investigated in this study how Escherichia coli biofilms adapted after 28 days of exposure to three biocidal active substances and the effects on cross-resistance to antibiotics. Interestingly, polyhexamethylene biguanide (PHMB) exposure led to an increase of gentamicin resistance (GenR) phenotypes in biofilms formed by most of the seven E. coli strains tested. Nevertheless, most variants that emerged under biocidal conditions did not retain the GenR phenotype after removal of antimicrobial stress, suggesting a transient adaptation (adaptive resistance). The whole genome sequencing of variants with stable GenR phenotypes revealed recurrent mutations in genes associated with cellular respiration, including cytochrome oxidase (cydA, cyoC) and ATP synthase (atpG). RT-qPCR analysis revealed an induction of gene expression associated with biofilm matrix production (especially curli synthesis), stress responses, active and passive transport and cell respiration during PHMB exposure, providing insight into potential physiological responses associated with adaptive crossresistance. In addition, confocal laser scanning microscopy (CLSM) observations demonstrated a global effect of PHMB on biofilm architectures and compositions formed by most E. coli strains, with the appearance of dense cellular clusters after a 24h-exposure. In conclusion, our results showed that the PHMB exposure stimulated the emergence of an adaptive cross-resistance to gentamicin in biofilms, likely induced through the activation of physiological responses and biofilm structural modulations altering gradients and microenvironmental conditions in the biological edifice

Genome wide analysis of gene dosage in 24,092 individuals estimates that 10,000 genes modulate cognitive ability

International audienceGenomic copy number variants (CNVs) are routinely identified and reported back to patients with neuropsychiatric disorders, but their quantitative effects on essential traits such as cognitive ability are poorly documented. We have recently shown that the effect size of deletions on cognitive ability can be statistically predicted using measures of intolerance to haploinsufficiency. However, the effect sizes of duplications remain unknown. It is also unknown if the effect of multigenic CNVs are driven by a few genes intolerant to haploinsufficiency or distributed across tolerant genes as well. Here, we identified all CNVs > 50 kilobases in 24,092 individuals from unselected and autism cohorts with assessments of general intelligence. Statistical models used measures of intolerance to haploinsufficiency of genes included in CNVs to predict their effect size on intelligence. Intolerant genes decrease general intelligence by 0.8 and 2.6 points of intelligence quotient when duplicated or deleted, respectively. Effect sizes showed no heterogeneity across cohorts. Validation analyses demonstrated that models could predict CNV effect sizes with 78% accuracy. Data on the inheritance of 27,766 CNVs showed that deletions and duplications with the same effect size on intelligence occur de novo at the same frequency. We estimated that around 10,000 intolerant and tolerant genes negatively affect intelligence when deleted, and less than 2% have large effect sizes. Genes encompassed in CNVs were not enriched in any GOterms but gene regulation and brain expression were GOterms overrepresented in the intolerant subgroup. Such pervasive effects on cognition may be related to emergent properties of the genome not restricted to a limited number of biological pathways

Eutrophication and acidification: Do they induce changes in the dissolvedorganic matter dynamics in the coastal Mediterranean Sea?

Original research paperTwo mesocosms experiments were conducted in winter 2010 and summer 2011 to examine how increased pCO2and/or nutrient concentrations potentially perturbate dissolved organic matter dynamics in natural microbialassemblages. Thefluorescence signals of protein- and humic-like compounds were used as a proxy for labileand non-labile material, respectively, while the evolution of bacterial populations, chlorophylla(Chla) anddissolved organic carbon (DOC) concentrations were used as a proxy for biological activity. For both seasons,the presence of elevated pCO2did not cause any significant change in the DOC dynamics (p-valueb0.05). Theconditions that showed the greatest changes in prokaryote abundances and Chlacontent were those amendedwith nutrients, regardless of the change in pH. The temporal evolution offluorophores and optical indices re-vealed that the degree of humification of the organic molecules and their molecular weight changed significantlyin the nutrient-amended treatment. The generation of protein-like compounds was paired to increases in theprokaryote abundance, being higher in the nutrient-amended tanks than in the control. Different patterns inthe magnitude and direction of the generation of humic-like molecules suggested that these changes dependedon initial microbial populations and the availability of extra nutrient inputs. Based on our results, it is expected that in the future projected coastal scenarios the eutrophication processes will favor the transformations of labile and recalcitrant carbon regardless of changes in pCO2.MINECO, European Union, Generalitat de Catalunya, CSICVersión del editor3,25

Nouvelles données sur l’agglomération antique d’<i>Epomanduodurum</i> (Mandeure et Mathay, Doubs)

International audienceDem antiken Mandeure-Mathay (Epomanduodurum), dem aufgrund seiner Größe und seiner bedeutenden Monumentalbauten im Sequanerland der zweite Platz nach dem Civitas-Hauptort Besançon zukommt, ist seit 2001 ein pluridisziplinäres Forschungsprojekt gewidmet. Im Anschluß an einen im Jahrgang 2007 dieser Zeitschrift vorgelegten Beitrag berichtet das vorliegende Dossier über die Forschungen der Jahre 2005 bis 2011. Parallel zur Weiterführung und Vertiefung der im Bereich der Kult- und Monumentalbauten begonnenen Arbeiten, trieb das Forschungsteam während dieses zweiten Projektabschnittes verschiedene Studien zur gesamten antiken Stadtanlage und der sie umgebenden Mikroregion voran. Diese Untersuchungen liefern neue Einsichten zur Entstehung, Entwicklung und zum Niedergang von Epomanduodurum und tragen zu einem vertieften Verständnis der Gestalt dieser Stadt und ihrer religiösen, ökonomischen und sozialen Organisation im Zeitraum vom Ende der Eisenzeit bis zum Frühmittelalter bei.A collective research program is studying since 2001 the ancient agglomeration of Mandeure-Mathay (Epomanduodurum), considered as second one after the chief town Besançon, in the Sequani territory, by its size and its impressive monumental buildings. This article, following a previous paper published in Gallia in 2007, draws up a report of the researches completed between 2005 and 2011. In this second stage, alongside the ongoing in-depth investigations on cult and monumental area, the PCR (Collective Program Research) team intensified its different studies and researches on the ancient agglomeration and its microregional environment. These studies lead to a better understanding of the appearance, development and decline of Epomanduodurum ; a better knowledge of its morphology, and its religious, economic and social organization between the end of the Iron Age and the Early Middle Ages.L’agglomération antique de Mandeure-Mathay (Epomanduodurum), considérée comme la seconde du pays séquane par ses dimensions et l’ampleur de sa parure monumentale, derrière la capitale de cité, Besançon, fait l’objet d’un programme collectif de recherche (PCR), pluridisciplinaire, depuis 2001. Le présent dossier, qui fait suite à un précédent article paru dans Gallia en 2007, dresse un bilan des recherches réalisées entre 2005 et 2011. Dans cette seconde étape, parallèlement à la poursuite et à l’approfondissement des actions engagées sur le secteur cultuel et monumental, l’équipe du PCR a accentué les études et investigations de diverses natures portant sur l’ensemble de l’agglomération antique et sur l’espace microrégional dans lequel celle-ci s’insère. Ces recherches aboutissent à une meilleure compréhension des modalités d’émergence, de développement et de déclin de la ville d’Epomanduodurum, et à une connaissance plus approfondie de sa morphologie et de son organisation religieuse, économique et sociale, entre la fin de l’âge du Fer et le haut Moyen Âge

To meat or not to meat? New perspectives on Neanderthal ecology.

Neanderthals have been commonly depicted as top predators who met their nutritional needs by focusing entirely on meat. This information mostly derives from faunal assemblage analyses and stable isotope studies: methods that tend to underestimate plant consumption and overestimate the intake of animal proteins. Several studies in fact demonstrate that there is a physiological limit to the amount of animal proteins that can be consumed: exceeding these values causes protein toxicity that can be particularly dangerous to pregnant women and newborns. Consequently, to avoid food poisoning from meat-based diets, Neanderthals must have incorporated alternative food sources in their daily diets, including plant materials as well

CHANTIER « Collecte » DCSMM. Diagnostic jeux de données Stratégie de collecte et propositions pour la gestion de données en lien avec l’évaluation 2018 de la DCSMM

Le MTES a confié à l'Ifremer en 2016 le chantier  de collecte des données pour permetre de produire les indicateurs des onze descripteurs du bon  état  écologique  (BEE),  ainsi  que  l’analyse  économique  et  sociale  (AES)  et  l’analyse  des  impacts cumulés (Carpe Diem) de la DCSMM. Le chantier a  permis  d'organiser la collecte des données d'entrée pour le 2e cycle de la DCSMM.   Ce document est une mise à jour de la version envoyée début 2017 au MTES et qui faisait le point sur l’avancement du chantier « collecte ». Le chantier a montré que l'évaluation s’appuie   sur des systèmes très hétérogènes, avec des niveaux de technicité et d’administration différents. Ces systèmes ne sont pas interopérables et la mise à disposition des données est extrêmement variable avec de nombreux freins pour des jeux de données essentiels à l’évaluation. Le scénario d’avoir une gestion centralisée de l’essentiel des données « transversales » et des appels à données pour les jeux problématiques a été retenu

Utilisation des données satellite pour la surveillance marine dans les Antilles

Le traitement des données satellite permet d’établir des climatologies très longues souvent sur plusieurs dizaines d’années. Ces traitements fournissent des produits utilisables notamment dans le cadre de la réponse à la Directive Cadre sur l’Eau sur plusieurs indicateurs : transparence, température et biomasse. Leur utilisation a été largement étudiée en métropole et a donné des résultats intéressants. L’idée de les reprendre pour les DOMs semble encore plus pertinente du fait des séries temporelles in situ plus limitées. L’apport du satellite devrait donc permettre d’avoir des séries plus longues et d’apporter une vision globale à la surveillance de l’environnement côtier. Ce document, à destination de l'OFB, présente dans un premier temps les traitements effectués et la constitution des climatologies nécessaires aux analyses des données. Il compare plusieurs capteurs et évalue leur pertinence. Dans un second temps, une comparaison est effectuée entre les résultats obtenus par une évaluation DCE basée sur des données issues du satellite et une évaluation DCE basée sur les données in situ. Enfin, les séries temporelles issues des climatologies satellite seront comparées aux séries temporelles issues des données in-situ

Differences in Toxic Response Induced by Three Variants of the Diarrheic Shellfish Poisoning Phycotoxins in Human Intestinal Epithelial Caco-2 Cells

Diarrheic shellfish poisoning (DSP) is caused by the consumption of shellfish contaminated with a group of phycotoxins that includes okadaic acid (OA), dinophysistoxin-1 (DTX-1), and dinophysistoxin-2 (DTX-2). These toxins are inhibitors of serine/threonine protein phosphatases 1 (PP1) and 2A (PP2A), but show distinct levels of toxicity. Aside from a difference in protein phosphatases (PP) inhibition potency that would explain these differences in toxicity, others mechanisms of action are thought to be involved. Therefore, we investigated and compared which mechanisms are involved in the toxicity of these three analogues. As the intestine is one of the target organs, we studied the transcriptomic profiles of human intestinal epithelial Caco-2 cells exposed to OA, DTX-1, and DTX-2. The pathways specifically affected by each toxin treatment were further confirmed through the expression of key genes and markers of toxicity. Our results did not identify any distinct biological mechanism for OA and DTX-2. However, only DTX-1 induced up-regulation of the MAPK transduction signalling pathway, and down-regulation of gene products involved in the regulation of DNA repair. As a consequence, based on transcriptomic results, we demonstrated that the higher toxicity of DTX-1 compared to OA and DTX-2 was consistent with certain specific pathways involved in intestinal cell response