Further characterization and determination of the single amino acid change in the tsI138 reovirus thermosensitive mutant

Many temperature-sensitive mutants have been isolated in early studies of mammalian reovirus. However, the bio- logical properties and nature of the genetic alterations remain incompletely explored for most of these mutants. The mutation harbored by the tsI138 mutant was already assigned to the L3 gene encoding the l1 protein. In the present study, this mu- tant was further studied as a possible tool to establish the role of the putative l1 enzymatic activities in viral multiplication. It was observed that synthesis of viral proteins is only marginally reduced, while it was difficult to recover viral particles at the nonpermissive temperature. A single nucleotide substitution resulting in an amino acid change was found; the position of this amino acid is consistent with a probable defect in assembly of the inner capsid at the nonpermissive temperature.Plusieurs mutants thermosensibles ont été rapidement isolés dès le début de l’étude du réovirus de mammifères. Cependant, les propriétés biologiques et la nature des changements génétiques demeurent peu connues pour la plupart de ces mutants. La mutation au sein du mutant tsI138 a déjà été localisée comme étant présente sur le gène L3 codant pour la protéine l1. Dans la présente étude, ce mutant a été étudié davantage comme outil possible pour établir le rôle des poten- tielles activités enzymatiques de l1 dans la multiplication virale. Il a été observé que la synthèse des protéines virales est peu affectée alors qu’il est difficile de récupérer des particules virales à température non permissive. La substitution d’un seul nucléotide, entraînant le changement d’un acide aminé, a été retrouvée; la position de cet acide aminé est compatible avec un défaut probable d’assemblage de la capside interne à la température non permissive.Conseil de recherches en sciences naturelles et en génie du Canad

Reovirus μ2 protein modulates host cell alternative splicing by reducing protein levels of U5 snRNP core components

Abstract : Mammalian orthoreovirus (MRV) is a doublestranded RNA virus from the Reoviridae family presenting a promising activity as an oncolytic virus. Recent studies have underlined MRV’s ability to alter cellular alternative splicing (AS) during infection, with a limited understanding of the mechanisms at play. In this study, we investigated how MRV modulates AS. Using a combination of cell biology and reverse genetics experiments, we demonstrated that theM1 gene segment, encoding the μ2 protein, is the primary determinant of MRV’s ability to alter AS, and that the amino acid at position 208 in μ2 is critical to induce these changes. Moreover, we showed that the expression of μ2 by itself is sufficient to trigger AS changes, and its ability to enter the nucleus is not required for all these changes. Moreover, we identified core components of the U5 snRNP (i.e. EFTUD2, PRPF8, and SNRNP200) as interactors of μ2 that are required for MRV modulation of AS. Finally, these U5 snRNP components are reduced at the protein level by both MRV infection and μ2 expression. Our findings identify the reduction of U5 snRNP components levels as a new mechanism by which viruses alter cellular AS

La gestion des biosolides de papetières au Québec : quelle serait la meilleure option pour réduire les émissions de gaz à effet de serre? (Pulp and paper mill sludge management in Quebec: what should be the best option to reduce greenhouse gas emissions?)

Les biosolides de papetières (BP) sont des matières organiques résiduelles provenant du processus d’épuration des effluents de l’industrie des pâtes et papiers. Le gouvernement québécois vise à réduire de 20 % les émissions de gaz à effet de serre (GES) par rapport au niveau de 1990 et à bannir la matière organique des lieux d’élimination d’ici 2020, ce qui affectera probablement la gestion des BP. Cette étude vise à quantifier les émissions de GES provenant des trois principales filières de gestion des BP : l’enfouissement, l’épandage sur sol agricole et la combustion avec récupération de chaleur. Les émissions de GES de l’enfouissement ont été mesurées à l’échelle pilote et celles de l’épandage, l’ont été pour des doses respectant les recommandations agronomiques. Les émissions de la combustion ont été mesurées à la cheminée de chaudières à biomasse utilisant entre 10 et 40 % de BP mélangés aux combustibles. L’enfouissement était la filière la plus émettrice de GES (0,90 t éq. CO2 t-1 BP secs), alors que les émissions étaient inférieures pour l’épandage (0,12 t éq. CO2 t-1 BP secs) et la combustion (0,00057-0,13 t éq. CO2 t-1 BP secs). L’épandage agricole et la combustion seraient de bonnes alternatives à l’enfouissement pour atténuer les émissions de GES. Toutefois, il serait nécessaire de multiplier les mesures d’émissions pour en augmenter la précision et assurer des scénarios robustes si l’on vise à initier l’élaboration d’un nouveau protocole d’obtention de crédits compensatoires pour le système de plafonnement et d’échange de droits d’émission de GES au Québec. Pulp and paper mill sludge (PPMS) is an organic residual generated from the paper mill wastewater treatments. The Quebec’s government policies aim to reduce the greenhouse gas emissions (GHG) by 20% below the level of 1990 and to ban disposal (landfilling and incineration without energy recovery) of organic material by 2020, which will likely affect PPMS management. This study aims at quantifying GHG emissions from the three main practices currently used to manage PPMS: landfilling, land application in agriculture and combustion for energy recovery. GHG emissions from landfilling were measured at the pilot-scale and those from land were measured following PPMS application at rates based on local agronomic recommendations. GHG emissions from combustion were measured at the chimney of biomass boilers using 10 to 40% PPMS in the fuel. Landfilling had the highest GHG emissions (0.90 t CO2e t-1 dry PPMS) whereas those from land application (0.12 t CO2e t-1 dry PPMS) and combustion (0.00057-0.13 t CO2e t-1 dry PPMS) were lower. Application of PPMS to agricultural land and combustion would therefore be good alternatives to landfilling to abate GHG emissions. However, more measurements would be required to increase the accuracy on the emission quantifications and start building a new offset credit protocol to be used in the Quebec cap-and-trade system for GHG emission allowances applied bylaw

Non-invasive pulmonary artery pressure estimation by electrical impedance tomography in a controlled hypoxemia study in healthy subjects.

Pulmonary hypertension is a hemodynamic disorder defined by an abnormal elevation of pulmonary artery pressure (PAP). Current options for measuring PAP are limited in clinical practice. The aim of this study was to evaluate if electrical impedance tomography (EIT), a radiation-free and non-invasive monitoring technique, can be used for the continuous, unsupervised and safe monitoring of PAP. In 30 healthy volunteers we induced gradual increases in systolic PAP (SPAP) by exposure to normobaric hypoxemia. At various stages of the protocol, the SPAP of the subjects was estimated by transthoracic echocardiography. In parallel, in the pulmonary vasculature, pulse wave velocity was estimated by EIT and calibrated to pressure units. Within-cohort agreement between both methods on SPAP estimation was assessed through Bland-Altman analysis and at subject level, with Pearson's correlation coefficient. There was good agreement between the two methods (inter-method difference not significant (P > 0.05), bias ± standard deviation of - 0.1 ± 4.5 mmHg) independently of the degree of PAP, from baseline oxygen saturation levels to profound hypoxemia. At subject level, the median per-subject agreement was 0.7 ± 3.8 mmHg and Pearson's correlation coefficient 0.87 (P < 0.05). Our results demonstrate the feasibility of accurately assessing changes in SPAP by EIT in healthy volunteers. If confirmed in a patient population, the non-invasive and unsupervised day-to-day monitoring of SPAP could facilitate the clinical management of patients with pulmonary hypertension

A Dual Platform Approach to Transcript Discovery for the Planarian Schmidtea Mediterranea to Establish RNAseq for Stem Cell and Regeneration Biology

The use of planarians as a model system is expanding and the mechanisms that control planarian regeneration are being elucidated. The planarian Schmidtea mediterranea in particular has become a species of choice. Currently the planarian research community has access to this whole genome sequencing project and over 70,000 expressed sequence tags. However, the establishment of massively parallel sequencing technologies has provided the opportunity to define genetic content, and in particular transcriptomes, in unprecedented detail. Here we apply this approach to the planarian model system. We have sequenced, mapped and assembled 581,365 long and 507,719,814 short reads from RNA of intact and mixed stages of the first 7 days of planarian regeneration. We used an iterative mapping approach to identify and define de novo splice sites with short reads and increase confidence in our transcript predictions. We more than double the number of transcripts currently defined by publicly available ESTs, resulting in a collection of 25,053 transcripts described by combining platforms. We also demonstrate the utility of this collection for an RNAseq approach to identify potential transcripts that are enriched in neoblast stem cells and their progeny by comparing transcriptome wide expression levels between irradiated and intact planarians. Our experiments have defined an extensive planarian transcriptome that can be used as a template for RNAseq and can also help to annotate the S. mediterranea genome. We anticipate that suites of other 'omic approaches will also be facilitated by building on this comprehensive data set including RNAseq across many planarian regenerative stages, scenarios, tissues and phenotypes generated by RNAi

Defects, order, and hysteresis in driven charge-density waves

We model driven two-dimensional charge-density waves in random media via a modified Swift-Hohenberg equation, which includes both amplitude and phase fluctuations of the condensate. As the driving force is increased, we find that the defect density first increases and then decreases. Furthermore, we find switching phenomena, due to the formation of channels of dislocations. These results are in qualitative accord with recent dynamical x-ray scattering experiments by Ringlandet al. and transport experiments by Lemay et al.Comment: Accepted to Phys. Rev. Lett. Click here for "http://www-theory.mpip-mainz.mpg.de/~karttune/CDW/", movies of driven CDW