Brain Vitamin E Deficiency During Development Is Associated With Increased Glutamate Levels and Anxiety in Adult Mice

Vitamin E, the most important lipophilic radical scavenging antioxidant in vivo, has a pivotal role in brain. In an earlier study, we observed that adult mice with a defect in the gene encoding plasma phospholipid transfer protein (PLTP) display a moderate reduction in cerebral vitamin E levels, and exacerbated anxiety despite normal locomotion and memory functions. Here we sought to determine whether dietary vitamin E supplementation can modulate neurotransmitter levels and alleviate the increased anxiety phenotype of PLTP-deficient (PLTP−/−) mice. To address this question, a vitamin E-enriched diet was used, and two complementary approches were implemented: (i) “early supplementation”: neurotransmitter levels and anxiety were assessed in 6 months old PLTP−/− mice born from vitamin E-supplemented parents; and (ii) “late supplementation”: neurotransmitter levels and anxiety were assessed in 6 months old PLTP−/− mice fed a vitamin E-enriched diet from weaning. Our results show for the first time that an inadequate supply of vitamin E during development, due to moderate maternal vitamin E deficiency, is associated with reduced brain vitamin E levels at birth and irreversible alterations in brain glutamate levels. They also suggest this deficiency is associated with increased anxiety at adulthood. Thus, the present study leads to conclude on the importance of the micronutrient vitamin E during pregnancy

Studies of the population structure of the arbuscular mycorrhiza fungus Rhizophagus irregularis

National audienceThe aim of this project is to better understand biodiversity of arbuscular mycorrhiza (AM) fungi at the community and population levels. Populations of AM fungi are studied in different habitats at several scales under the impact of disturbance and fertilization (phosphorus or/and nitrogen). The influence of these factors was addressed in a field experiment. This study focuses on Rhizophagus irregularis, the widespread model species, previously named Glomus intraradices. Competition between strains of this species was assessed under controlled conditions in a growth chamber experiment using mitochondrial large subunit of ribosomal DNA as a specific marker for Real Time PCR

Structuration et diversité des communautés et populations de champignons mycorhizogènes à arbuscules (Glomeromycota) à différentes échelles

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Elucidating the population structure of the ubiquitous arbuscular mycorrhizal fungal species Rhizophagus irregularis: implications for fungal community assembly

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Non-Innocent Ligands: New Opportunities in Iron Catalysis

International audienceIntroduced in the late sixties, non-innocent (or redox) ligands have been extensively studied for their unusual and intriguing chemical behavior. Their ability to delocalize and/or provide electrons to the metal center of organometallic complexes confers them undisputable chemical interest and has proved valuable in the development of novel synthetic methodologies. This review will focus on the chemistry and applications of low-valent iron complexes bearing potentially non-innocent ligands. Because of the elusive nature of these ligands, and whenever possible, theoretical calculations and analysis of spectroscopic data will be presented in an effort to provide insights into the catalytic activity of the complexes

Brain Vitamin E Deficiency During Development Is Associated With Increased Glutamate Levels and Anxiety in Adult Mice

International audienceVitamin E, the most important lipophilic radical scavenging antioxidant in vivo, has a pivotal role in brain. In an earlier study, we observed that adult mice with a defect in the gene encoding plasma phospholipid transfer protein (PLTP) display a moderate reduction in cerebral vitamin E levels, and exacerbated anxiety despite normal locomotion and memory functions. Here we sought to determine whether dietary vitamin E supplementation can modulate neurotransmitter levels and alleviate the increased anxiety phenotype of PLTP-deficient (PLTP -/-) mice. To address this question, a vitamin E-enriched diet was used, and two complementary approches were implemented: (i) "early supplementation": neurotransmitter levels and anxiety were assessed in 6 months old PLTP -/- mice born from vitamin E-supplemented parents; and (ii) "late supplementation": neurotransmitter levels and anxiety were assessed in 6 months old PLTP -/- mice fed a vitamin E-enriched diet from weaning. Our results show for the first time that an inadequate supply of vitamin E during development, due to moderate maternal vitamin E deficiency, is associated with reduced brain vitamin E levels at birth and irreversible alterations in brain glutamate levels. They also suggest this deficiency is associated with increased anxiety at adulthood. Thus, the present study leads to conclude on the importance of the micronutrient vitamin E during pregnancy

Influence of SARS-CoV-2 Variant B.1.1.7, Vaccination, and Public Health Measures on the Spread of SARS-CoV-2

International audienceThe spread of SARS-CoV-2 and the resulting disease COVID-19 has killed over 2.6 million people as of 18 March 2021. We have used a modified susceptible, infected, recovered (SIR) epidemiological model to predict how the spread of the virus in regions of France will vary depending on the proportions of variants and on the public health strategies adopted, including anti-COVID-19 vaccination. The proportion of SARS-CoV-2 variant B.1.1.7, which was not detected in early January, increased to become 60% of the forms of SARS-CoV-2 circulating in the Toulouse urban area at the beginning of February 2021, but there was no increase in positive nucleic acid tests. Our prediction model indicates that maintaining public health measures and accelerating vaccination are efficient strategies for the sustained control of SARS-CoV-2

Deletion of plasma Phospholipid Transfer Protein (PLTP) increases microglial phagocytosis and reduces cerebral amyloid-β deposition in the J20 mouse model of Alzheimer's disease

International audiencePlasma phospholipid transfer protein (PLTP) binds and transfers a number of amphipathic compounds, including phospholipids, cholesterol, diacylglycerides, tocopherols and lipopolysaccharides. PLTP functions are relevant for many pathophysiological alterations involved in neurodegenerative disorders (especially lipid metabolism, redox status, and immune reactions), and a significant increase in brain PLTP levels was observed in patients with Alzheimer's disease (AD) compared to controls. To date, it has not been reported whether PLTP can modulate the formation of amyloid plaques, i.e. one of the major histopathological hallmarks of AD. We thus assessed the role of PLTP in the AD context by breeding PLTP-deficient mice with an established model of AD, the J20 mice. A phenotypic characterization of the amyloid pathology was conducted in J20 mice expressing or not PLTP. We showed that PLTP deletion is associated with a significant reduction of cerebral Aβ deposits and astrogliosis, which can be explained at least in part by a rise of Aβ clearance through an increase in the microglial phagocytic activity and the expression of the Aβ-degrading enzyme neprilysin. PLTP arises as a negative determinant of plaque clearance and over the lifespan, elevated PLTP activity could lead to a higher Aβ load in the brain

Fungicide Residues Exposure and β-amyloid Aggregation in a Mouse Model of Alzheimer’s Disease

International audienceBACKGROUND:Pesticide residues have contaminated our environment and nutrition over the last century. Although these compounds are present at very low concentrations, their long-term effects on human health is of concern. The link between pesticide residues and Alzheimer's disease is not clear and difficult to establish. To date, no in vivo experiments have yet modeled the impact of this chronic contamination on neurodegenerative disorders.OBJECTIVES:We investigated the impact of fungicide residues on the pathological markers of Alzheimer's disease in a transgenic mouse model.METHODS:Transgenic (J20, hAPPSw/Ind) mice were chronically exposed to a cocktail of residues of cyprodinil, mepanipyrim, and pyrimethanil at 0.1μg/L in their drinking water for 9 months. We assessed the effects of fungicide residues on the pathological markers of the disease including Aβ aggregates, neuroinflammation, and neuronal loss. Then, we studied the dynamics of Aβ aggregation in vivo via a longitudinal study using two-photon microscopy. Finally, we investigated the molecular mechanisms involved in the production and clearance of Aβ peptides.RESULTS:We found that a chronic exposure to three fungicide residues exacerbated aggregation, microgliosis, and neuronal loss. These fungicides also increased vascular amyloid aggregates reminiscent of cerebral amyloid angiopathy between 6 and 9 months of treatment. The mechanism of action revealed that fungicides promoted Aβ peptide fibril formation in vitro and involved an in vivo overexpression of the levels of the β-secretase-cleaving enzyme (BACE1) combined with impairment of Aβ clearance through neprylisin (NEP).CONCLUSIONS:Chronic exposure of the J20 mouse model of Alzheimer's disease to a cocktail of fungicides, at the regulatory concentration allowed in tap water (0.1μg/L), strengthened the preexisting pathological markers: neuroinflammation, Aβ aggregation, and APP β-processing. We hypothesize prevention strategies toward pesticide long-term exposure may be an alternative to counterbalance the lack of treatment and to slow down the worldwide Alzheimer's epidemic. https://doi-org.proxy.insermbiblio.inist.fr/10.1289/EHP5550

Répétabilité et reproductibilité des analyses de la composition chimique de la matière organique naturelle par thermochimiolyse GC-MS : exercice d'intercomparaison au sein du réseau GEOF

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