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41.
42.
Cyrille Gavazzi Catherine Isel Emilie Fournier Vincent Moules Annie Cavalier Daniel Thomas Bruno Lina Roland Marquet 《Nucleic acids research》2013,41(2):1241-1254
The genome of influenza A viruses (IAV) is split into eight viral RNAs (vRNAs) that are encapsidated as viral ribonucleoproteins. The existence of a segment-specific packaging mechanism is well established, but the molecular basis of this mechanism remains to be deciphered. Selective packaging could be mediated by direct interaction between the vRNA packaging regions, but such interactions have never been demonstrated in virions. Recently, we showed that the eight vRNAs of a human H3N2 IAV form a single interaction network in vitro that involves regions of the vRNAs known to contain packaging signals in the case of H1N1 IAV strains. Here, we show that the eight vRNAs of an avian H5N2 IAV also form a single network of interactions in vitro, but, interestingly, the interactions and the regions of the vRNAs they involve differ from those described for the human H3N2 virus. We identified the vRNA sequences involved in five of these interactions at the nucleotide level, and in two cases, we validated the existence of the interaction using compensatory mutations in the interacting sequences. Electron tomography also revealed significant differences in the interactions taking place between viral ribonucleoproteins in H5N2 and H3N2 virions, despite their canonical ‘7 + 1’ arrangement. 相似文献
43.
Emilie Bilodeau Jean-Christophe Simon Jean-Frédéric Guay Julie Turgeon Conrad Cloutier 《Evolutionary ecology》2013,27(1):165-184
The host-associated differentiation (HAD) hypothesis states that higher trophic levels in parasitic associations should exhibit similar divergence in case of host sympatric speciation. We tested HAD on populations of Aphidius ervi the main parasitoid of the pea aphid Acyrthosiphon pisum, emerging from host populations specialized on either alfalfa or red clover. Host and parasitoid populations were assessed for genetic variation and structure, while considering geography, host plant and host aphid protective symbionts Regiella insecticola and Hamiltonella defensa as potential covariables. Cluster and hierarchical analyses were used to assess the contribution of these variables to population structure, based on genotyping pea aphids and associated A. ervi with microsatellites, and host aphid facultative symbionts with 16S rDNA markers. Pea aphid genotypes were clearly distributed in two groups closely corresponding with their plant origins, confirming strong plant associated differentiation of this aphid in North America. Overall parasitism by A. ervi averaged 21.5 % across samples, and many parasitized aphids producing a wasp hosted defensive bacteria, indicating partial or ineffective protective efficacy of these symbionts in the field. The A. ervi population genetic data failed to support differentiation according to the host plant association of their pea aphid host. Potential for parasitoid specialization was also explored in experiments where wasps from alfalfa and clover aphids were reciprocally transplanted on alternate hosts, the hypothesis being that wasp behaviour and parasitic stages should be most adapted to their host of origin. Results revealed higher probability of oviposition on the alfalfa aphids, but higher adult emergence success on red clover aphids, with no interaction as expected under HAD. We conclude that our study provides no support for the HAD in this system. We discuss factors that might impair A. ervi specialization on its divergent aphid hosts on alfalfa and clover. 相似文献
44.
Jiřina Vávrová Lenka Zárybnická Emilie Lukášová Martina Řezáčová Eva Novotná Zuzana Šinkorová Aleš Tichý Jaroslav Pejchal Kamila Ďurišová 《Radiation and environmental biophysics》2013,52(4):471-479
We compared the effects of inhibitors of kinases ATM (KU55933) and ATR (VE-821) (incubated for 30 min before irradiation) on the radiosensitization of human promyelocyte leukaemia cells (HL-60), lacking functional protein p53. VE-821 reduces phosphorylation of check-point kinase 1 at serine 345, and KU55933 reduces phosphorylation of check-point kinase 2 on threonine 68 as assayed 4 h after irradiation by the dose of 6 Gy. Within 24 h after gamma-irradiation with a dose of 3 Gy, the cells accumulated in the G2 phase (67 %) and the number of cells in S phase decreased. KU55933 (10 μM) did not affect the accumulation of cells in G2 phase and did not affect the decrease in the number of cells in S phase after irradiation. VE-821 (2 and 10 μM) reduced the number of irradiated cells in the G2 phase to the level of non-irradiated cells and increased the number of irradiated cells in S phase, compared to irradiated cells not treated with inhibitors. In the 144 h interval after irradiation with 3 Gy, there was a considerable induction of apoptosis in the VE-821 group (10 μM). The repair of the radiation damage, as observed 72 h after irradiation, was more rapid in the group exposed solely to irradiation and in the group treated with KU55933 (80 and 77 % of cells, respectively, were free of DSBs), whereas in the group incubated with 10 μM VE-821, there were only 61 % of cells free of DSBs. The inhibition of kinase ATR with its specific inhibitor VE-821 resulted in a more pronounced radiosensitizing effect in HL-60 cells as compared to the inhibition of kinase ATM with the inhibitor KU55933. In contrast to KU55933, the VE-821 treatment prevented HL-60 cells from undergoing G2 cell cycle arrest. Taken together, we conclude that the ATR kinase inhibition offers a new possibility of radiosensitization of tumour cells lacking functional protein p53. 相似文献
45.
Marianne Rooman Emilie Cauët Jacques Liévin René Wintjens 《Journal of biomolecular structure & dynamics》2013,31(6):949-954
Abstract Electron holes are known to migrate along the DNA or RNA duplexes and to localize preferentially on successive guanines. The stationary point conformations of Gua pairs that can trap or let pass these holes have been characterized by quantum chemistry calculations. Here we show their recurrent occurrence in DNA and RNA X-ray structures, often in quadruplex conformations or in interaction with proteins, ligands or metal ions. These findings give support to the biological, possibly regulatory, roles of charge migration in cell functioning. 相似文献
46.
Emilie Widemann Laurence Miesch Rapha?l Lugan Emilie Holder Clément Heinrich Yann Aubert Michel Miesch Franck Pinot Thierry Heitz 《The Journal of biological chemistry》2013,288(44):31701-31714
Jasmonates (JAs) are a class of signaling compounds that mediate complex developmental and adaptative responses in plants. JAs derive from jasmonic acid (JA) through various enzymatic modifications, including conjugation to amino acids or oxidation, yielding an array of derivatives. The main hormonal signal, jasmonoyl-l-isoleucine (JA-Ile), has been found recently to undergo catabolic inactivation by cytochrome P450-mediated oxidation. We characterize here two amidohydrolases, IAR3 and ILL6, that define a second pathway for JA-Ile turnover during the wound response in Arabidopsis leaves. Biochemical and genetic evidence indicates that these two enzymes cleave the JA-Ile signal, but act also on the 12OH-JA-Ile conjugate. We also show that unexpectedly, the abundant accumulation of tuberonic acid (12OH-JA) after wounding originates partly through a sequential pathway involving (i) conjugation of JA to Ile, (ii) oxidation of the JA-Ile conjugate, and (iii) cleavage under the action of the amidohydrolases. The coordinated actions of oxidative and hydrolytic branches in the jasmonate pathway highlight novel mechanisms of JA-Ile hormone turnover and redefine the dynamic metabolic grid of jasmonate conversion in the wound response. 相似文献
47.
48.
Pascal Hingamp Nigel Grimsley Silvia G Acinas Camille Clerissi Lucie Subirana Julie Poulain Isabel Ferrera Hugo Sarmento Emilie Villar Gipsi Lima-Mendez Karoline Faust Shinichi Sunagawa Jean-Michel Claverie Hervé Moreau Yves Desdevises Peer Bork Jeroen Raes Colomban de Vargas Eric Karsenti Stefanie Kandels-Lewis Olivier Jaillon Fabrice Not Stéphane Pesant Patrick Wincker Hiroyuki Ogata 《The ISME journal》2013,7(9):1678-1695
Nucleo-cytoplasmic large DNA viruses (NCLDVs) constitute a group of eukaryotic viruses that can have crucial ecological roles in the sea by accelerating the turnover of their unicellular hosts or by causing diseases in animals. To better characterize the diversity, abundance and biogeography of marine NCLDVs, we analyzed 17 metagenomes derived from microbial samples (0.2–1.6 μm size range) collected during the Tara Oceans Expedition. The sample set includes ecosystems under-represented in previous studies, such as the Arabian Sea oxygen minimum zone (OMZ) and Indian Ocean lagoons. By combining computationally derived relative abundance and direct prokaryote cell counts, the abundance of NCLDVs was found to be in the order of 104–105 genomes ml−1 for the samples from the photic zone and 102–103 genomes ml−1 for the OMZ. The Megaviridae and Phycodnaviridae dominated the NCLDV populations in the metagenomes, although most of the reads classified in these families showed large divergence from known viral genomes. Our taxon co-occurrence analysis revealed a potential association between viruses of the Megaviridae family and eukaryotes related to oomycetes. In support of this predicted association, we identified six cases of lateral gene transfer between Megaviridae and oomycetes. Our results suggest that marine NCLDVs probably outnumber eukaryotic organisms in the photic layer (per given water mass) and that metagenomic sequence analyses promise to shed new light on the biodiversity of marine viruses and their interactions with potential hosts. 相似文献
49.
Charlotte Gineste Yann Le Fur Christophe Vilmen Arnaud Le Troter Emilie Pecchi Patrick J. Cozzone Edna C. Hardeman David Bendahan Julien Gondin 《PloS one》2013,8(4)
Nemaline myopathy (NM) is the most common disease entity among non-dystrophic skeletal muscle congenital diseases. Mutations in the skeletal muscle α-actin gene (ACTA1) account for ∼25% of all NM cases and are the most frequent cause of severe forms of NM. So far, the mechanisms underlying muscle weakness in NM patients remain unclear. Additionally, recent Magnetic Resonance Imaging (MRI) studies reported a progressive fatty infiltration of skeletal muscle with a specific muscle involvement in patients with ACTA1 mutations. We investigated strictly noninvasively the gastrocnemius muscle function of a mouse model carrying a mutation in the ACTA1 gene (H40Y). Skeletal muscle anatomy (hindlimb muscles and fat volumes) and energy metabolism were studied using MRI and 31Phosphorus magnetic resonance spectroscopy. Skeletal muscle contractile performance was investigated while applying a force-frequency protocol (from 1–150 Hz) and a fatigue protocol (80 stimuli at 40 Hz). H40Y mice showed a reduction of both absolute (−40%) and specific (−25%) maximal force production as compared to controls. Interestingly, muscle weakness was associated with an improved resistance to fatigue (+40%) and an increased energy cost. On the contrary, the force frequency relationship was not modified in H40Y mice and the extent of fatty infiltration was minor and not different from the WT group. We concluded that the H40Y mouse model does not reproduce human MRI findings but shows a severe muscle weakness which might be related to an alteration of intrinsic muscular properties. The increased energy cost in H40Y mice might be related to either an impaired mitochondrial function or an alteration at the cross-bridges level. Overall, we provided a unique set of anatomic, metabolic and functional biomarkers that might be relevant for monitoring the progression of NM disease but also for assessing the efficacy of potential therapeutic interventions at a preclinical level. 相似文献
50.
Emilie Vessières Anne-Laure Guihot Bertrand Toutain Maud Maquigneau Céline Fassot Laurent Loufrani Daniel Henrion 《PloS one》2013,8(7)
Endothelial dysfunction in resistance arteries alters end organ perfusion in type 2 diabetes. Superoxides and cyclooxygenase-2 (COX-2) derivatives have been shown separately to alter endothelium-mediated relaxation in aging and diabetes but their role in the alteration of vascular tone in old diabetic subjects is not clear, especially in resistance arteries. Consequently, we investigated the role of superoxide and COX-2-derivatives on endothelium-dependent relaxation in 3 and 12 month-old Zucker diabetic fatty (ZDF) and lean (LZ) rats. Mesenteric resistance arteries were isolated and vascular tone was investigated using wire-myography. Endothelium (acetylcholine)-dependent relaxation was lower in ZDF than in LZ rats (60 versus 84% maximal relaxation in young rats and 41 versus 69% in old rats). Blocking NO production with L-NAME was less efficient in old than in young rats. L-NAME had no effect in old ZDF rats although eNOS expression level in old ZDF rats was similar to that in old LZ rats. Superoxide level and NADPH-oxidase subunits (p67phox and gp91phox) expression level were greater in ZDF than in LZ rats and were further increased by aging in ZDF rats. In young ZDF rats reducing superoxide level with tempol restored acetylcholine-dependent relaxation to the level of LZ rats. In old ZDF rats tempol improved acetylcholine-dependent relaxation without increasing it to the level of LZ rats. COX-2 (immunolabelling and Western-blot) was present in arteries of ZDF rats and absent in LZ rats. In old ZDF rats arterial COX-2 level was higher than in young ZDF rats. COX-2 blockade with NS398 restored in part acetylcholine-dependent relaxation in arteries of old ZDF rats and the combination of tempol and NS398 fully restored relaxation in control (LZ rats) level. Accordingly, superoxide production and COX-2 derivatives together reduced endothelium-dependent relaxation in old ZDF rats whereas superoxides alone attenuated relaxation in young ZDF or old LZ rats. 相似文献