Recherches sur la résistance des sols aux maladies. X. - Comparaison de la mycoflore colonisant les racines de melons cultivés dans un sol résistant ou dans un sol sensible aux fusarioses vasculaires

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Murine model for Fusarium oxysporum invasive fusariosis reveals organ-specific structures for dissemination and long-term persistence

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Complete Genome and Phylogeny of Puumala Hantavirus Isolates Circulating in France

Puumala virus (PUUV) is the agent of nephropathia epidemica (NE), a mild form of hemorrhagic fever with renal syndrome (HFRS) in Europe. NE incidence presents a high spatial variation throughout France, while the geographical distribution of the wild reservoir of PUUV, the bank vole, is rather continuous. A missing piece of the puzzle is the current distribution and the genetic variation of PUUV in France, which has been overlooked until now and remains poorly understood. During a population survey, from 2008 to 2011, bank voles were trapped in eight different forests of France located in areas known to be endemic for NE or in area from where no NE case has been reported until now. Bank voles were tested for immunoglobulin (Ig)G ELISA serology and two seropositive animals for each of three different areas (Ardennes, Jura and Orleans) were then subjected to laboratory analyses in order to sequence the whole S, M and L segments of PUUV. Phylogenetic analyses revealed that French PUUV isolates globally belong to the central European (CE) lineage although isolates from Ardennes are clearly distinct from those in Jura and Orleans, suggesting a different evolutionary history and origin of PUUV introduction in France. Sequence analyses revealed specific amino acid signatures along the N protein, including in PUUV from the Orleans region from where NE in humans has never been reported. The relevance of these mutations in term of pathophysiology is discussed.Peer reviewe

Functional analysis of a novel Cys2/His2-type zinc finger protein involved in salt tolerance in rice

The Cys2/His2-type zinc finger proteins have been implicated in different cellular processes involved in plant development and stress responses. Through microarray analysis, a salt-responsive zinc finger protein gene ZFP179 was identified and subsequently cloned from rice seedlings. ZFP179 encodes a 17.95 kDa protein with two C2H2-type zinc finger motifs having transcriptional activation activity. The real-time RT-PCR analysis showed that ZFP179 was highly expressed in immature spikes, and markedly induced in the seedlings by NaCl, PEG 6000, and ABA treatments. Overexpression of ZFP179 in rice increased salt tolerance and the transgenic seedlings showed hypersensitivity to exogenous ABA. The increased levels of free proline and soluble sugars were observed in transgenic plants compared to wild-type plants under salt stress. The ZFP179 transgenic rice exhibited significantly increased tolerance to oxidative stress, the reactive oxygen species (ROS)-scavenging ability, and expression levels of a number of stress-related genes, including OsDREB2A, OsP5CS OsProT, and OsLea3 under salt stress. Our studies suggest that ZFP179 plays a crucial role in the plant response to salt stress, and is useful in developing transgenic crops with enhanced tolerance to salt stress

Atrophy of primary lymphoid organs induced by Marek's disease virus during early infection is associated with increased apoptosis, inhibition of cell proliferation and a severe B-lymphopenia

Marek's disease is a multi-faceted highly contagious disease affecting chickens caused by the Marek's disease alphaherpesvirus (MDV). MDV early infection induces a transient immunosuppression, which is associated with thymus and bursa of Fabricius atrophy. Little is known about the cellular processes involved in primary lymphoid organ atrophy. Here, by in situ TUNEL assay, we demonstrate that MDV infection results in a high level of apoptosis in the thymus and bursa of Fabricius, which is concomitant to the MDV lytic cycle. Interestingly, we observed that in the thymus most of the MDV infected cells at 6 days post-infection (dpi) were apoptotic, whereas in the bursa of Fabricius most of the apoptotic cells were uninfected suggesting that MDV triggers apoptosis by two different modes in these two primary lymphoid organs. In addition, a high decrease of cell proliferation was observed from 6 to 14 dpi in the bursa of Fabricius follicles, and not in the thymus. Finally, with an adapted absolute blood lymphocyte count, we demonstrate a major B-lymphopenia during the two 1st weeks of infection, and propose this method as a potent non-invasive tool to diagnose MDV bursa of Fabricius infection and atrophy. Our results demonstrate that the thymus and bursa of Fabricius atrophies are related to different cell mechanisms, with different temporalities, that affect infected and uninfected cells

Replication, dissemination and morphogenesis of Marek's disease virus in differentiated cells of the dermo-epidermal lineage

Le virus de la maladie de Marek (MDV) est un alpha-herpesvirus responsable de lymphomes T mortels chez la poule. La peau et en particulier le follicule plumeux est considéré comme le seul site de production de particules virales extracellulaires et est à l'origine de la dissémination horizontale du virus et de la contamination de l'environnement. Cependant, aucun système cellulaire ne permet de reproduire ce qui se passe dans ce tissu. Le but de ma thèse a donc été de développer de nouveaux systèmes de culture permettant de reproduire la réplication, la morphogenèse et l’excrétion décrites in vivo. Pour cela, j’ai développé deux systèmes, des explants de peau d’embryons de poulet cultivés ex vivo et des kératinocytes obtenus par différenciation de cellules souches embryonnaires de poule. J’ai également montré la permissivité au MDV de ces deux modèles de peau puis y ai étudié la réplication et la morphogénèse virale. Ces modèles permettront la recherche des déterminants viraux et cellulaires impliqués dans la production de virions extracellulaires et leur dissémination.Marek's disease (MD) is a highly contagious virus-induced lymphoma in chicken, caused by an alphaherpesvirus named Marek’s disease virus (MDV). The skin and especially, the feather follicle is the only tissue known to produce infectious cell-free virions and is responsible for the shedding of MDV into the environment and transmission between birds. However, no cell culture system actually reproduces this process ex vivo. Herein my thesis aim was to develop new culture systems to reproduce the efficient MDV replication, morphogenesis and shedding from the feather follicle. For that, I developed two systems, skin explants derived from embryos cultivated ex vivo and keratinocytes obtained by differentiation of chicken embryonic stem cells. I also showed that these two models were permissive to MDV infection and I studied in each one MDV replication and morphogenesis. These models will allow the search of viral and cellular determinants involved in the production of extracellular virions and shedding

Réplication, dissémination et morphogenèse du virus de la maladie de Marek en cellules différenciées vers le lignage peau

Le virus de la maladie de Marek (MDV) est un alpha-herpesvirus responsable de lymphomes T mortels chez la poule. La peau et en particulier le follicule plumeux est considéré comme le seul site de production de particules virales extracellulaires et est à l'origine de la dissémination horizontale du virus et de la contamination de l'environnement. Cependant, aucun système cellulaire ne permet de reproduire ce qui se passe dans ce tissu. Le but de ma thèse a donc ét de développer de nouveaux systèmes de culture permettant de reproduire la réplication, la morphogenèse et !'excrétion décrites in vivo. Pour cela, j'ai développé deux systèmes, des explants de peau d'embryons de poulet cultivés ex vivo et des kératinocytes obtenus par différenciation de cellules souches embryonnaires de poule. J'ai également montré la permissivité au MDV de ces deux modèles de peau puis y ai étudié la réplication et la morphogenèse virale. Ces modèles permettront la recherche des déterminants viraux et cellulaires impliqués dans la production de virions extracellulaires et leur dissémination