Reprogramming of fatty acid and oxylipin synthesis in rhizobacteria-induced systemic resistance in tomato

The rhizobacterium Pseudomonas putida BTP1 stimulates induced systemic resistance (ISR) in tomato. A previous work showed that the resistance is associated in leaves with the induction of the first enzyme of the oxylipin pathway, the lipoxygenase (LOX), leading to a faster accumulation of its product, the free 13-hydroperoxy octadecatrienoic acid (13-HPOT), 2 days after Botrytis cinerea inoculation. In the present study, we further investigated the stimulation of the oxylipin pathway: metabolites and enzymes of the pathway were analyzed to understand the fate of the 13-HPOT in ISR. Actually the stimulation began upstream the LOX: free linolenic acid accumulated faster in P. putida BTP1-treated plants than in control. Downstream, the LOX products 13-fatty acid hydroperoxides esterified to galactolipids and phospholipids were more abundant in bacterized plants than in control before infection. These metabolites could constitute a pool that will be used after pathogen attack to produce free fungitoxic metabolites through the action of phospholipase A2, which is enhanced in bacterized plants upon infection. Enzymatic branches which can use as substrate the fatty acid hydroperoxides were differentially regulated in bacterized plants in comparison to control plants, so as to lead to the accumulation of the most fungitoxic compounds against B. cinerea. Our study, which is the first to demonstrate the accumulation of an esterified defense metabolite during rhizobacteria-mediated induced systemic resistance, showed that the oxylipin pathway is differentially regulated. It suggests that this allows the plant to prepare to a future infection, and to respond faster and in a more effective way to B. cinerea invasion.Peer reviewe

Noise Dressing of Financial Correlation Matrices

We show that results from the theory of random matrices are potentially of great interest to understand the statistical structure of the empirical correlation matrices appearing in the study of price fluctuations. The central result of the present study is the remarkable agreement between the theoretical prediction (based on the assumption that the correlation matrix is random) and empirical data concerning the density of eigenvalues associated to the time series of the different stocks of the S&P500 (or other major markets). In particular the present study raises serious doubts on the blind use of empirical correlation matrices for risk management.Comment: Latex (Revtex) 3 pp + 2 postscript figures (in-text

Non-Stationary Covariance Matrices And Noise

The exact meaning of the noise spectrum of eigenvalues of the covariance matrix is discussed. In order to better understand the possible phenomena behind the observed noise, the spectrum of eigenvalues of the covariance matrix is studied under a model where most of the true eigenvalues are zero and the parameters are non-stationary. The results are compared with real observation of Brazilian assets, suggesting that, although the non-stationarity seems to be an important aspect of the problem, partially explaining some of the eigenvalues as well as part of the kurtosis of the assets, it can not, by itself, provide all the corrections needed to make the proposed model fit the data perfectly.Comment: 11 pages, 3 figures, submitted to Physica

Large Scale Cross-Correlations in Internet Traffic

The Internet is a complex network of interconnected routers and the existence of collective behavior such as congestion suggests that the correlations between different connections play a crucial role. It is thus critical to measure and quantify these correlations. We use methods of random matrix theory (RMT) to analyze the cross-correlation matrix C of information flow changes of 650 connections between 26 routers of the French scientific network `Renater'. We find that C has the universal properties of the Gaussian orthogonal ensemble of random matrices: The distribution of eigenvalues--up to a rescaling which exhibits a typical correlation time of the order 10 minutes--and the spacing distribution follow the predictions of RMT. There are some deviations for large eigenvalues which contain network-specific information and which identify genuine correlations between connections. The study of the most correlated connections reveals the existence of `active centers' which are exchanging information with a large number of routers thereby inducing correlations between the corresponding connections. These strong correlations could be a reason for the observed self-similarity in the WWW traffic.Comment: 7 pages, 6 figures, final versio

Viral infection prevents diabetes by inducing regulatory T cells through NKT cell–plasmacytoid dendritic cell interplay

iNKT cell and pDC cross talk prevents type 1 diabetes by inducing T reg cells in the pancreatic lymph node during viral infection

Tye7 regulates yeast Ty1 retrotransposon sense and antisense transcription in response to adenylic nucleotides stress

Transposable elements play a fundamental role in genome evolution. It is proposed that their mobility, activated under stress, induces mutations that could confer advantages to the host organism. Transcription of the Ty1 LTR-retrotransposon of Saccharomyces cerevisiae is activated in response to a severe deficiency in adenylic nucleotides. Here, we show that Ty2 and Ty3 are also stimulated under these stress conditions, revealing the simultaneous activation of three active Ty retrotransposon families. We demonstrate that Ty1 activation in response to adenylic nucleotide depletion requires the DNA-binding transcription factor Tye7. Ty1 is transcribed in both sense and antisense directions. We identify three Tye7 potential binding sites in the region of Ty1 DNA sequence where antisense transcription starts. We show that Tye7 binds to Ty1 DNA and regulates Ty1 antisense transcription. Altogether, our data suggest that, in response to adenylic nucleotide reduction, TYE7 is induced and activates Ty1 mRNA transcription, possibly by controlling Ty1 antisense transcription. We also provide the first evidence that Ty1 antisense transcription can be regulated by environmental stress conditions, pointing to a new level of control of Ty1 activity by stress, as Ty1 antisense RNAs play an important role in regulating Ty1 mobility at both the transcriptional and post-transcriptional stages

La grossesse et l'accouchement chez la femme de plus de 40 ans, en fonction de la parité (étude sur 322 cas à l'hôpital Foch de Suresnes)

Les grossesses tardives sont devenues un sujet de préoccupation dans les pays occidentaux du fait de leur constante augmentation depuis plus de 20 ans, de leur réputation à haut risque et de leur proportion de primipares croissante (20% environ). Pour évaluer les risques que pouvait engendrer l âge maternel >= à 40 ans sur la grossesse, l accouchement et le nouveau-né, nous avons étudié les dossiers des 322 femmes ayant accouché après 40 ans, en les comparant à ceux des 7143 femmes de moins de 40 ans, entre 2004 et 2006 à la maternité de l hôpital Foch. Nous avons observé une augmentation significative mais faible de diabète gestationnel, d hypertension artérielle gravidique, de prééclampsie, et une augmentation plus nette de césarienne, sans explication médicale évidente. Ces césariennes arbitraires sont le reflet de l appréhension des médecins et des patientes face aux grossesses tardives, et remettent en cause le principe de précaution du fait du risque chirurgical pour la mère.ST QUENTIN EN YVELINES-BU (782972101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF