Decreasing cytosolic translation is beneficial to yeast and human Tafazzin-deficient cells

Cardiolipin (CL) optimizes diverse mitochondrial processes, including oxidative phosphorylation (OXPHOS). To function properly, CL needs to be unsaturated, which requires the acyltransferase Tafazzin (TAZ). Loss-of-function mutations in the TAZ gene are responsible for the Barth syndrome (BTHS), a rare X-linked cardiomyopathy, presumably because of a diminished OXPHOS capacity. Herein we show that a partial inhibition of cytosolic protein synthesis, either chemically with the use of cycloheximide or by specific genetic mutations, fully restores biogenesis and the activity of the oxidative phosphorylation system in a yeast BTHS model (taz1Δ). Interestingly, the defaults in CL were not suppressed, indicating that they are not primarily responsible for the OXPHOS deficiency in taz1Δ yeast. Low concentrations of cycloheximide in the picomolar range were beneficial to TAZ-deficient HeLa cells, as evidenced by the recovery of a good proliferative capacity. These findings reveal that a diminished capacity of CL remodeling deficient cells to preserve protein homeostasis is likely an important factor contributing to the pathogenesis of BTHS. This in turn, identifies cytosolic translation as a potential therapeutic target for the treatment of this disease

Identification et caractérisation de quatre lysolipide acyltransférases de S. cerevisiae (études in silico, in vitro et in vivo)

BORDEAUX2-BU Santé (330632101) / SudocSudocFranceF

Les bioindicateurs pour la gestion des sites contaminés - Evaluation des risques de transfert dans les chaînes trophiques terrestres : résultats sur sites ateliers.

International audienceCette présentation synthétise les résultats obtenus avec des bio-indicateurs d'accumulation (plantes, escargots) et d'effet (teneurs des feuilles en acides gras) par plusieurs équipes dans le cadre du programme Bioindicateur conduit sur 13 sites en France. Il est également montré que la biodisponibilité (évaluée avec des méthodes biologiques) ne peut être estimée par l'évaluation de la disponibilité (évaluée avec des méthodes chimiques)

Microbial communities in As contaminated agricultural soils – How PK fertiliser can influence As speciation

International audienc

Communautés microbiennes dans les sols agricoles pollués par l'arsenic - comment les engrais KP peuvent influencer la spéciation de l'arsenic

International audienc

Influence of agricultural amendments on arsenic biogeochemistry and phytotoxicity in a soil polluted by the destruction of arsenic-containing shells

Agricultural soils can contain high arsenic (As) concentrations due to specific geological contexts or pollution. Agricultural practices, in particular fertilizer amendments, could influence As speciation and mobility, thus increasing its transfer to crops and its toxicity. In the present study, field-relevant amounts of fertilizers were applied to soils from a cultivated field that was a former ammunition-burning site. Potassium phosphate, ammonium sulfate and organic matter were applied to these soils in laboratory experiments to assess both their impact on As leaching and on As bioavailability to Lactuca sativa. Results indicate that none of the fertilizers significantly influences the speciation and quantity of mobile As, although trends showed an increase of mobility with KP and a decrease of mobility with ammonium sulfate. The most probable number of AsIII-oxidizing microbes and AsIII-oxidizing activity were strongly linked to As levels in water and soils. In the reference un-polluted soil, ammonium sulfate negatively affected AsIII-oxidizing activity. KP amendment induced a small increase of As content in plants, and the polluted soil amended with ammonium sulfate was significantly less phytotoxic than the un-amended soil. Results suggest that ammonium sulfate, the most frequently applied fertilizer on site, influences the interactions between As, microorganisms and plants.Evaluation et gestion des contaminations en arsenic dans les eaux et les sols agricole

The reductase activity of the Arabidopsis Caleosin RESPONSIVE TO DESSICATION20 mediates gibberellin-dependent flowering time, abscisic acid sensitivity, and tolerance to oxidative Stress

International audienceContrasting with the wealth of information available on the multiple roles of jasmonates in plant development and defense, knowledge about the functions and the biosynthesis of hydroxylated oxylipins remains scarce. By expressing the caleosin RESPONSIVE TO DESSICATION20 (RD20) in Saccharomyces cerevisiae, we show that the recombinant protein possesses an unusual peroxygenase activity with restricted specificity toward hydroperoxides of unsaturated fatty acid. Accordingly, Arabidopsis (Arabidopsis thaliana) plants overexpressing RD20 accumulate the product 13-hydroxy-9,11,15-octadecatrienoic acid, a linolenate-derived hydroxide. These plants exhibit elevated levels of reactive oxygen species (ROS) associated with early gibberellin-dependent flowering and abscisic acid hypersensitivity at seed germination. These phenotypes are dependent on the presence of active RD20, since they are abolished in the rd20 null mutant and in lines overexpressing RD20, in which peroxygenase was inactivated by a point mutation of a catalytic histidine residue. RD20 also confers tolerance against stress induced by Paraquat, Rose Bengal, heavy metal, and the synthetic auxins 1-naphthaleneacetic acid and 2,4-dichlorophenoxyacetic acid. Under oxidative stress, 13-hydroxy-9,11,15-octadecatrienoic acid still accumulates in RD20-overexpressing lines, but this lipid oxidation is associated with reduced ROS levels, minor cell death, and delayed floral transition. A model is discussed where the interplay between fatty acid hydroxides generated by RD20 and ROS is counteracted by ethylene during development in unstressed environments

Soil bioindicators: how soil properties influence their responses and how choose them in function of the site issues?

National audienc

Impact de trois pesticides sur les acides gras de Gomphonema gracile

International audienc

Lipids of plant membrane raftsLipids of plant membrane rafts

International audienceLipids tend to organize in mono or bilayer phases in a hydrophilic environment. While they have long been thought to be incapable of coherent lateral segregation, it is now clear that spontaneous assembly of these compounds can confer microdomain organization beyond spontaneous fluidity. Membrane raft microdomains have the ability to influence spatiotemporal organization of protein complexes, thereby allowing regulation of cellular processes. In this review, we aim at summarizing briefly: (i) the history of raft discovery in animals and plants, (ii) the main findings about structural and signalling plant lipids involved in raft segregation, (iii) imaging of plant membrane domains, and their biochemical purification through detergent-insoluble membranes, as well as the existing debate on the topic. We also discuss the potential involvement of rafts in the regulation of plant physiological processes, and further discuss the prospects of future research into plant membrane raft