Sustained increases in atmospheric oxygen and marine productivity in the Neoproterozoic and Palaeozoic eras

A geologically rapid Neoproterozoic oxygenation event is commonly linked to the appearance of marine animal groups in the fossil record. However, there is still debate about what evidence from the sedimentary geochemical record—if any—provides strong support for a persistent shift in surface oxygen immediately preceding the rise of animals. We present statistical learning analyses of a large dataset of geochemical data and associated geological context from the Neoproterozoic and Palaeozoic sedimentary record and then use Earth system modelling to link trends in redox-sensitive trace metal and organic carbon concentrations to the oxygenation of Earth’s oceans and atmosphere. We do not find evidence for the wholesale oxygenation of Earth’s oceans in the late Neoproterozoic era. We do, however, reconstruct a moderate long-term increase in atmospheric oxygen and marine productivity. These changes to the Earth system would have increased dissolved oxygen and food supply in shallow-water habitats during the broad interval of geologic time in which the major animal groups first radiated. This approach provides some of the most direct evidence for potential physiological drivers of the Cambrian radiation, while highlighting the importance of later Palaeozoic oxygenation in the evolution of the modern Earth system

Implication of vitamin A in neuroprotection of dopaminergic neurons in a rat model of Parkinson's disease

PosterParkinson's disease (PD) is caused by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNc), leading to strong motor impairments. Dopaminergic neurons from the SNc project to the striatum which allow the control of voluntary movements. Vitamin A, through the action of its active metabolite, retinoic acid (RA), is involved in the development, differentiation and neuroprotection of SNc dopaminergic neurons. Additionally, retinaldehyde dehydrogenase (RALDH), the synthesis enzyme of retinoic acid, is involved in cellular detoxification. However, the cerebral bioavailability of retinoic acid decreases with aging, which downregulates RALDH expression. This may precipitate neurodegenerative processes such as those observed in Parkinson's disease. Here we hypothesize that nutritional supplementation with vitamin A normalizes brain levels of retinoic acid and thus RALDH, which exhibit a neuroprotective effect on dopaminergic neurons, to delay the progression of the disease. To test our hypothesis, we modeled Parkinson's disease with unilateral injection of 6-hydroxydopamine (6-OHDA), a toxin that selectively destroys dopaminergic neurons, into rats' striatum. Rats were supplemented or not with dietary vitamin A (20 UI/g) for 5 weeks before the lesion. Motor impairments induced by 6-OHDA and protective effect of vitamin A were quantified with the step test, cylinder test and rotarod. Extend of dopaminergic neurons degeneration was assessed with stereological analysis of tyrosine hydroxylase, the production enzyme of dopamine, staining in the striatum. To evaluate the functionality of the dopaminergic system, levels of dopamine and its metabolites were measured in the striatum with HPLC. Finally, to precisely interrogate the impact of vitamin A supplementation on RALDH enzyme, its expression and localization will be assessed with immunostaining, western blot and RT-qPCR analyses. These experiments that are still in progress will allow a precise assessment of the neuroprotective effects of vitamin A supplementation on dopaminergic neurons in a rat model of Parkinson's disease. This work may open therapeutic strategies to prevent neurodegeneration

Implication of vitamin A in neuroprotection of dopaminergic neurons in a rat model of Parkinson's disease

PosterParkinson’s disease (PD) is a brain disease caused by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNc), leading to strong motor impairments. Vitamin A, through the action of its active metabolite retinoic acid (RA), is involved in the development, differentiation and protection of SNc dopaminergic neurons. However, the bioavailability of retinoic acid in the brain decreases with aging. Prior reports suggest that altered vitamin A signaling is implicated in the etiology of Parkinson’s disease, though the mechanisms are poorly understood. Here we hypothesize that nutritional supplementation with vitamin A may reduce dopaminergic cells loss by increasing RA levels in the brain, thus delaying the progression of the disease. We showed that rats deprived of vitamin A became progressively impaired in their motor functions and were unable to perform correctly the rotarod test after thirteen weeks of deprivation. However, locomotor functions were improved after just three weeks of vitamin A supplementation. To assess the effect of vitamin A supplementation, we modeled Parkinson’s disease in rat. Dopaminergic neurons were selectively deleted with unilateral injection of 6-hydroxydopamine (6-OHDA) toxin into rat’s striatum. Rats fed a vitamin A supplemented diet (20UI/g) for five weeks prior to the toxin injection exhibited an improvement in rotarod test compared to rats fed with control diet (5UI/g). Degeneration of dopaminergic terminals was assessed with stereological analysis of tyrosine hydroxylase staining in the striatum. Finally, dopamine levels in striatum were measured with HPLC. These preliminary data established the link between dietary vitamin A and dopaminergic system in PD. Future work will focus on establishing its underlying mechanisms and molecular basis

Implication of vitamin A in survival of dopaminergic neurons in a rat model of Parkinson's disease

Poste

Évolution cognitive des enfants et adolescents polyhandicapés

à veni

L'évaluation de la qualité de vie des personnes polyhandicapées : recension des écrits

International audience[No abstract

Nouvelles compilations et modélisations 2D des données gravimétriques et magnétiques autour de l'Archipel des Comores (projet ANR COYOTES)

International audienceLa crise sismo-volcanique de Mayotte en cours depuis Mai 2018 s’est matérialisé entre autre, par de nombreux séismes de magnitude supérieure à 5 et l’éruption à 50 km à l’Est de Mayotte d’un nouvel édifice volcanique sous-marin, Fani Maoré (plus de 800 m de haut et 5 km de large). Afin d’aider à la compréhension de cet évènement tellurique exceptionnel, l’une des thématiques du projet ANR COYOTES (COmoros & maYotte : vOlcanism, TEctonics and Seismicity) a pour objectif de mieux caractériser la structuration crustale du Canal Nord Mozambique autour de l’archipel des Comores et la répartition du volcanisme. A partir de nouvelles compilations des données de gravimétrie et de magnétisme terre-mer, acquises lors des différentes campagnes océanographiques de recherche (SISMAORE, 2020-2021-DOI: 10.17600/4200020 ; PTOLEMEE, 2014-DOI:10.17600/14000900; BATHYMAY, 2004-DOI: 10.17600/4200020 …) et de surveillance (MAYOBS, 2018-2023-DOI :10.18142/291), et lors de levé aéroporté sur Mayotte (GeoMayotte, 2012 @BRGM), nous présentons les cartes d’anomalies magnétique et gravimétrique. Nous présenterons aussi les résultats des modélisations gravimétriques et magnétiques 2D effectuées le long des profils de sismique réflexion multitrace SISMAORE interprété par Masquelet et al. (2022). Le croisement des modélisations permettront d’étendre les interprétations et de mieux contraindre la géométrie 3D des structures crustales et volcaniques observées. Ce résumé est une contribution des équipes de l’ANR COYOTES (ANR-19-CE31-0018, http://www.geocean.net/coyotes/doku.php?id=start). Ces travaux sont financés par l’ANR COYOTES et le BRGM. Nous remercions les équipes de REVOSIMA ainsi que de l’ANR COYOTES pour les fructueuses discussions

Volcanism and tectonics unveiled in the Comoros Archipelago between Africa and Madagascar

International audienceGeophysical and geological data acquired during the 2020–2021 SISMAORE oceanographic cruise reveal a corridor of recent volcanic and tectonic features 200 km wide and 600 km long within and north of Comoros Archipelago in the North Mozambique Channel. More than 2200 submarine volcanic edifices, comparable to the Fani Maoré volcano, have been identified. Most of them are distributed according to two large submarine tectonic-volcanic fields: the N’Drounde province oriented N160°E north of Grande-Comore Island, and the Mwezi province oriented N130°E north of Anjouan and Mayotte Islands. The presence of popping basaltic rocks sampled in the Mwezi suggests post-Pleistocene volcanic activity. The geometry and distribution of recent structures observed on the seafloor are consistent with a current regional dextral transtensional context. Their orientations change progressively from west to east (∼N160°E, ∼N130°E, ∼EW). In the western part, the volcanism could be influenced by the pre-existing structural fabric of the Mesozoic crust. The wide tectono-volcanic corridor underlines the incipient Somalia–Lwandle dextral lithospheric plate boundary between the East-African Rift System and Madagascar. For details see Thinon et al. (2022;  doi 10.5802/crgeos.159)

Impact of Non-alcoholic Fatty Liver Disease on long-term cardiovascular events and death in Chronic Obstructive Pulmonary Disease

Abstract Chronic Obstructive Pulmonary Disease (COPD) and Non-Alcoholic Fatty Liver Disease (NAFLD) both independently increase cardiovascular risk. We hypothesized that NAFLD might increase the incidence of cardiovascular disease and death in COPD patients. The relationship between NAFLD, incident cardiovascular events, and death was assessed in a prospective cohort of COPD patients with 5-year follow-up. Noninvasive algorithms combining biological parameters (FibroMax®) were used to evaluate steatosis, non-alcoholic steatohepatitis (NASH) and liver fibrosis. Univariate and multivariate Cox regression models were used to assess the hazard for composite outcome at the endpoint (death or cardiovascular event) for each liver pathology. In 111 COPD patients, 75% exhibited liver damage with a prevalence of steatosis, NASH and fibrosis of 41%, 37% and 61%, respectively. During 5-year follow-up, 31 experienced at least one cardiovascular event and 7 died. In univariate analysis, patients with liver fibrosis had more cardiovascular events and higher mortality (Hazard ratio [95% CI]: 2.75 [1.26; 6.03]) than those with no fibrosis; this remained significant in multivariate analysis (Hazard ratio [95% CI]: 2.94 [1.18; 7.33]). We also found that steatosis and NASH were not associated with increased cardiovascular events or mortality. To conclude, early assessment of liver damage might participate to improve cardiovascular outcomes in COPD patients

Coastal water vapor isotopic composition driven by katabatic wind variability in summer at Dumont 1 d'Urville, coastal East Antarctica

International audienc