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Pau, France

Yao Y.,Yeshiva University | Tsuchiyama S.,Buck Institute | Yang C.,Yeshiva University | Bulteau A.L.,LCABIE UMR5254 | And 10 more authors.
PLoS Genetics

Elevated proteasome activity extends lifespan in model organisms such as yeast, worms and flies. This pro-longevity effect might be mediated by improved protein homeostasis, as this protease is an integral module of the protein homeostasis network. Proteasomes also regulate cellular processes through temporal and spatial degradation of signaling pathway components. Here we demonstrate that the regulatory function of the proteasome plays an essential role in aging cells and that the beneficial impact of elevated proteasome capacity on lifespan partially originates from deregulation of the AMPK signaling pathway. Proteasome-mediated lifespan extension activity was carbon-source dependent and cells with enhancement proteasome function exhibited increased respiratory activity and oxidative stress response. These findings suggested that the pro-aging impact of proteasome upregulation might be related to changes in the metabolic state through a premature induction of respiration. Deletion of yeast AMPK, SNF1, or its activator SNF4 abrogated proteasome-mediated lifespan extension, supporting this hypothesis as the AMPK pathway regulates metabolism. We found that the premature induction of respiration in cells with increased proteasome activity originates from enhanced turnover of Mig1, an AMPK/Snf1 regulated transcriptional repressor that prevents the induction of genes required for respiration. Increasing proteasome activity also resulted in partial relocation of Mig1 from the nucleus to the mitochondria. Collectively, the results argue for a model in which elevated proteasome activity leads to the uncoupling of Snf1-mediated Mig1 regulation, resulting in a premature activation of respiration and thus the induction of a mitohormetic response, beneficial to lifespan. In addition, we observed incorrect Mig1 localization in two other long-lived yeast aging models: cells that overexpress SIR2 or deleted for the Mig1-regulator HXK2. Finally, compromised proteasome function blocks lifespan extension in both strains. Thus, our findings suggest that proteasomes, Sir2, Snf1 and Hxk2 form an interconnected aging network that controls metabolism through coordinated regulation of Mig1. © 2015 Yao et al. Source

Vacchina V.,UT2A | Oguey S.,Pancosma | Ionescu C.,Pancosma | Bravo D.,Pancosma | Lobinski R.,LCABIE UMR5254
Analytical and Bioanalytical Chemistry

A method was developed for the determination of metal complexes with glycine (glycinates, [M(Gly)x(H2O)y(SO 4)z]n, where M denotes Zn, Cu, Mn and Fe) in premix samples used for the preparation of animal feeds enriched in essential trace elements. The method was based on the extraction of the glycinates with 10 mM ammonium acetate (pH 7.4) followed by their determination using capillary electrophoresis with ICP MS detection. The stability of the glycinates in solution was verified by electrospray TOF-MS. Each supplement was shown to be a mixture of complexes, with polymerization degrees ranging from n∈=∈1 to n∈=∈4 (depending on the metal), that were fully or partially dehydrated. The metal glycine complex moiety was found to be preserved during capillary electrophoresis. The detection limits, calculated as three times the standard deviation of the blank plus the blank, were between 0.05 and 0.2 μg mL-1 (as the metal), and the calibration curves were linear, allowing the analysis of premix samples. Repeatability for glycinate standards was below 12%, and analytical precision was typically within 15%. © 2010 Springer-Verlag. Source

Tenorio-Daussat C.L.,Pontifical Catholic University of Rio de Janeiro | Resende M.C.M.,Pontifical Catholic University of Rio de Janeiro | Ziolli R.L.,Rio de Janeiro State Federal University | Hauser-Davis R.A.,Pontifical Catholic University of Rio de Janeiro | And 2 more authors.

Fish bile metallothioneins (MT) have been recently reported as biomarkers for environmental metal contamination; however, no studies regarding standardizations for their purification are available. Therefore, different procedures (varying centrifugation times and heat-treatment temperatures) and reducing agents (DTT, β-mercaptoethanol and TCEP) were applied to purify MT isolated from fish (Oreochromis niloticus) bile and liver. Liver was also analyzed, since these two organs are intrinsically connected and show the same trend regarding MT expression. Spectrophotometrical analyses were used to quantify the resulting MT samples, and SDS-PAGE gels were used to qualitatively assess the different procedure results. Each procedure was then statistically evaluated and a multivariate statistical analysis was then applied. A response surface methodology was also applied for bile samples, in order to further evaluate the responses for this matrix. Heat treatment effectively removes most undesired proteins from the samples, however results indicate that temperatures above 70 C are not efficient since they also remove MTs from both bile and liver samples. Our results also indicate that the centrifugation times described in the literature can be decreased in order to analyze more samples in the same timeframe, of importance in environmental monitoring contexts where samples are usually numerous. In an environmental context, biliary MT was lower than liver MT, as expected, since liver accumulates MT with slower detoxification rates than bile, which is released from the gallbladder during feeding, and then diluted by water. Therefore, bile MT seems to be more adequate in environmental monitoring scopes regarding recent exposure to xenobiotics that may affect the proteomic and metalloproteomic expression of this biological matrix. © 2013 Elsevier B.V. Source

Martin L.,Bordeaux Montaigne University | Mercier N.,Bordeaux Montaigne University | Incerti S.,Bordeaux Gradignan Center of Nuclear Studies | Lefrais Y.,Bordeaux Montaigne University | And 9 more authors.
Radiation Measurements

The effects of sediment heterogeneity on beta dose rate have been investigated by simulation with the DosiVox software. Basic sediment cases, as well as a model of a micro-stratified sediment from the Mas d'Azil cave have been modeled at a few centimeters scale. The results of the simulations have highlighted different factors having a significant impact on the beta dose rate dispersion, among which the heterogeneity of the radioactive elements, the distribution of grains in the matrix and their proportion in the sample. These factors contribute to enlarge beta dose distributions and even create complex ones, and inevitably induce errors in the dating process. These effects are discussed, as well as the potential of the simulation to calculate beta dose rates in sediment samples and the necessity of using sampling protocols adapted to sediment complexity. © 2015 Elsevier Ltd. Source

Fontagne-Dicharry S.,French National Institute for Agricultural Research | Godin S.,LCABIE UMR5254 | Liu H.,French National Institute for Agricultural Research | Liu H.,CAS Wuhan Institute of Hydrobiology | And 6 more authors.
British Journal of Nutrition

Se is an essential micronutrient required for normal growth, development and antioxidant defence. The objective of the present study was to assess the impact of dietary Se sources and levels on the antioxidant status of rainbow trout (Oncorhynchus mykiss) fry. First-feeding fry (initial body weight: 91 mg) were fed either a plant- or fishmeal-based diet containing 0·5 or 1·2 mg Se/kg diet supplemented or not with 0·3 mg Se/kg diet supplied as Se-enriched yeast or sodium selenite for 12 weeks at 17°C. Growth and survival of rainbow trout fry were not significantly affected by dietary Se sources and levels. Whole-body Se was raised by both Se sources and to a greater extent by Se-yeast. The reduced:oxidised glutathione ratio was raised by Se-yeast, whereas other lipid peroxidation markers were not affected by dietary Se. Whole-body Se-dependent glutathione peroxidase (GPX) activity was enhanced in fish fed Se-yeast compared to fish fed sodium selenite or non-supplemented diets. Activity and gene expression of this enzyme as well as gene expression of selenoprotein P (SelP) were reduced in fish fed the non-supplemented plant-based diet. Catalase, glutamate-cysteine ligase and nuclear factor-erythroid 2-related factor 2 (Nrf2) gene expressions were reduced by Se-yeast. These results suggest the necessity to supplement plant-based diets with Se for rainbow trout fry, and highlight the superiority of organic form of Se to fulfil the dietary Se requirement and sustain the antioxidant status of fish. GPX and SelP expression proved to be good markers of Se status in fish. Copyright © The Authors 2015. Source

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