Université de Sherbrooke

About: Université de Sherbrooke is a education organization based out in Sherbrooke, Quebec, Canada. It is known for research contribution in the topics: Population & Receptor. The organization has 14922 authors who have published 28783 publications receiving 792511 citations. The organization is also known as: Universite de Sherbrooke & Sherbrooke University.

The σ factors of Mycobacterium tuberculosis

Abstract: Mycobacterium tuberculosis is a remarkable pathogen capable of adapting and surviving in various harsh conditions. Correct gene expression regulation is essential for the success of this process. The reversible association of different σ factors is a common mechanism for reprogramming bacterial RNA polymerase and modulating the transcription of numerous genes. Thirteen putative σ factors are encoded in the M. tuberculosis genome, several being important for virulence. Here, we analyse the latest information available on mycobacterial σ factors and discuss their roles in the physiology and virulence of M. tuberculosis.

Some relevant parameters affecting the glass transition of supported ultra-thin polymer films

Abstract: We have measured, the thickness dependence of the glass transition temperature T g(h), using ellipsometry at variable temperature, for poly(methyl-methacrylate) (PMMA) of various tacticity in confined geometry. We report that several factors significantly affect T g(h): i) polymer microstructure (stereoregularity of PMMA) related to local dynamics; ii) interfacial interactions; iii) conformation of the polymer chains. These results raise many fundamental questions on the origin of the thickness-dependent glass transition. Why and how do the interactions with the substrate significantly affect T g(h)? Does T g(h) depend on the modifications of conformational parameters of the chains (their entropy)? What is the correlation between local dynamics and T g(h) in thin films? The aim of this paper is to summarise these open questions, which should stimulate further investigations in the thin polymer film scientific community.

Small RNA-induced differential degradation of the polycistronic mRNA iscRSUA

Abstract: Most polycistronic genes are expressed in a single transcript, in which each cistron produces a fixed amount of protein. In this report, we show the first example of differential degradation of a polycistronic gene induced by a small regulatory RNA (sRNA). Our data show that the iron-responsive sRNA, RyhB, binds to the second cistron of the polycistronic mRNA, iscRSUA, which encodes the necessary machinery for biosynthesis of Fe–S clusters, and promotes the cleavage of the downstream iscSUA transcript. This cleavage gives rise to the remaining 5′-section of the transcript encoding IscR, a transcriptional regulator responsible for activation and repression of several genes depending on the cellular Fe–S level. Our data indicate that the iscR transcript is stable and that translation is active. The stability of the iscR transcript depends on a 111-nucleotide long non-translated RNA section located between iscR and iscS, which forms a strong repetitive extragenic palindromic secondary structure and may protect against ribonucleases degradation. This novel regulation shows how sRNAs and mRNA structures can work together to modulate the transcriptional response to a specific stress.

The emerging landscape of small nucleolar RNAs in cell biology.

Abstract: Small nucleolar RNAs (snoRNAs) are a large class of small noncoding RNAs present in all eukaryotes sequenced thus far. As a family, they have been well characterized as playing a central role in ribosome biogenesis, guiding either the sequence-specific chemical modification of pre-rRNA (ribosomal RNA) or its processing. However, in higher eukaryotes, numerous orphan snoRNAs were described over a decade ago, with no known target or ascribed function, suggesting the possibility of alternative cellular functionality. In recent years, thanks in great part to advances in sequencing methodologies, we have seen many examples of the diversity that exists in the snoRNA family on multiple levels. In this review, we discuss the identification of novel snoRNA members, of unexpected binding partners, as well as the clarification and extension of the snoRNA target space and the characterization of diverse new noncanonical functions, painting a new and extended picture of the snoRNA landscape. Under the deluge of novel features and functions that have recently come to light, snoRNAs emerge as a central, dynamic, and highly versatile group of small regulatory RNAs.