Traitement médical et chirurgical de la pathologie ombilicale chez le veau

Les affections ombilicales représentent la troisième cause de mortalité en élevage après les atteintes digestives et respiratoires, avec 8% des veaux qui ne survivent pas en l'absence de traitement. Ces affections s'accompagnent donc de pertes économiques importantes pour les éleveurs. Ces derniers mettent en place de nombreuses mesures de prévention (hygiène au vêlage, colostrum, soins du cordon ombilical...) afin de diminuer l'incidence de ces atteintes dans leur élevage.Cependant, ces mesures ne sont pas toujours suffisantes et le vétérinaire est souvent appelé pour des veaux présentant un "gros nombril". La prise en charge se fait alors au travers d'un diagnostic clinique et échographique précis afin de proposer à l'éleveur le meilleur traitement possible. Celui-ci peut être médical au travers d'antibiotiques ciblés et d'anti-inflammatoires, ou bien chirurgical,par le biais d'une anesthésie adaptée et de différentes techniques choisies selon la nature de l'atteinte ombilicale

Modulation of TCR signalling components occurs prior to positive selection and lineage commitment in iNKT cells

iNKT cells play a critical role in controlling the strength and character of adaptive and innate immune responses. Their unique functional characteristics are induced by a transcriptional program initiated by positive selection mediated by CD1d expressed by CD4+CD8+ (double positive, DP) thymocytes. Here, using a novel Vα14 TCR transgenic strain bearing greatly expanded numbers of CD24hiCD44loNKT cells, we examined transcriptional events in four immature thymic iNKT cell subsets. A transcriptional regulatory network approach identified transcriptional changes in proximal components of the TCR signalling cascade in DP NKT cells. Subsequently, positive and negative selection, and lineage commitment, occurred at the transition from DP NKT to CD4 NKT. Thus, this study introduces previously unrecognised steps in early NKT cell development, and separates the events associated with modulation of the T cell signalling cascade prior to changes associated with positive selection and lineage commitment. © 2021, The Author(s). **Please note that there are multiple authors for this article therefore only the name of the first 5 including Federation University Australia affiliate “Stuart Berzins” is provided in this record*

Selective protein unfolding: a universal mechanism of action for the development of irreversible inhibitors

High-throughput differential scanning fluorimetry of GFP-tagged proteins (HT-DSF-GTP) was applied for the identification of novel enzyme inhibitors acting by a mechanism termed: selective protein unfolding (SPU). Four different protein targets were interrogated with the same library to identify target-selective hits. Several hits selectively destabilized bacterial biotin protein ligase. Structure–activity relationship data confirmed a structure-dependent mechanism of protein unfolding. Simvastatin and altenusin were confirmed to irreversibly inactivate biotin protein ligase. The principle of SPU combined with HT-DSF-GTP affords an invaluable and innovative workflow for the identification of new inhibitors with potential applications as antimicrobials and other biocides

Delineation of the ancestral tus-dependent replication fork trap

In Escherichia coli, DNA replication termination is orchestrated by two clusters of Ter sites forming a DNA replication fork trap when bound by Tus proteins. The formation of a ‘locked’ Tus– Ter complex is essential for halting incoming DNA replication forks. However, the absence of replication fork arrest at some Ter sites raised questions about their significance. In this study, we examined the genome-wide distribution of Tus and found that only the six innermost Ter sites (TerA–E and G) were significantly bound by Tus. We also found that a single ectopic insertion of TerB in its non-permissive orientation could not be achieved, advocating against a need for ‘back-up’ Ter sites. Finally, examination of the genomes of a variety of Enterobacterales revealed a new replication fork trap architecture mostly found outside the Enterobacteriaceae family. Taken together, our data enabled the delineation of a narrow ancestral Tus-dependent DNA replication fork trap consisting of only two Ter sites

Modulation of TCR signalling components occurs prior to positive selection and lineage commitment in iNKT cells

iNKT cells play a critical role in controlling the strength and character of adaptive and innate immune responses. Their unique functional characteristics are induced by a transcriptional program initiated by positive selection mediated by CD1d expressed by CD4+CD8+ (double positive, DP) thymocytes. Here, using a novel Vα14 TCR transgenic strain bearing greatly expanded numbers of CD24hiCD44loNKT cells, we examined transcriptional events in four immature thymic iNKT cell subsets. A transcriptional regulatory network approach identified transcriptional changes in proximal components of the TCR signalling cascade in DP NKT cells. Subsequently, positive and negative selection, and lineage commitment, occurred at the transition from DP NKT to CD4 NKT. Thus, this study introduces previously unrecognised steps in early NKT cell development and separates, the events associated with modulation of the T cell signalling cascade prior to changes associated with positive selection and lineage commitment

Revisiting and exploring Middle-Late Triassic vertebrate tracksites in Ardèche (southern France)

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DNA replication in Escherichia coli: a comprehensive study of the Tus-Ter complex

The circular chromosome of bacteria is replicated by two replisomes assembled at the unique origin and moving in opposite direction until they meet at specific termination sites. The process of DNA replication termination is the stage of replication that is the least understood, both in prokaryotes and eukaryotes. In E. coli, the termination protein Tus binds to 14 termination sites (TerA-J, TerK, L, TerY, Z) spread throughout the genome. The intriguing organization and symmetry of Ter sites has puzzled scientists for decades. The Tus-Ter complex is polar and blocks replication forks approaching from one direction but not from the other. Most Ter sites are oriented to form a fork trap so that convergent forks can enter and merge in the terminus region but not exit. However, the significance of having maintained such a wide fork trap remains unclear. The mechanism responsible for the polarity of the Tus-Ter complex is still being debated. A protein-protein interaction between the DnaB helicase at the forefront of the replisome and Tus bound to Ter has been proposed (Bastia et al., 2008, Mulugu et al., 2001). The alternative mechanism involves the formation of the Tus-Ter-lock (TT-lock) where Tus captures the cytosine at position 6 in the Ter core sequence upon duplex unwinding by DnaB and becomes locked on Ter thereby preventing DnaB translocation (Mulcair et al., 2006). Since the discovery of the TT-lock, there has been no further investigation on its formation in the remaining Tus-Ter complexes. However, the proportion of fork pausing at each Ter sites has previously been determined in vivo and was detected at seven Ter sites (TerA-D, TerG, TerH and TerI). The remaining Ter sites were classified as pseudo-Ter (Duggin and Bell, 2009). Nevertheless, all Ter were able to arrest forks in an artificial context, yet with varying efficiencies (Duggin and Bell, 2009). This prompted the question of whether or not the outer Ter sites maintained their biological function. This work provides the first comparative study of the ten primary Ter sites (TerA-J) in terms of their affinity and specificity for Tus and whether they are all able to form a TT-lock. The variation in affinity and TT-lock forming ability of Ter sites was compared to their intrinsic efficiency in arresting a replisome and to the in vivo distribution of Tus on Ter sites. Finally, ectopic Ter sites were inserted into the E. coli genome to determine the effect of TT-lock formation on cell growth. Several new methods were developed during this thesis for the characterization of Tus-Ter and Tus-Terlock complexes in a time and cost-effective manner.\ud \ud The Ter sites were shown to be different both in terms of their affinity for Tus and in their ability to form a TT-lock. Six strong Tus binding sites (TerA-E and TerG) were identified and the outermost TerH, TerI and TerJ were classified as moderate binders. The binding of Tus to TerF was only marginally stronger than a non-specific DNA region of the oriC. The strong binders were all able to form a strong TT-lock whereas moderate binders varied in their TTlock forming efficiencies. TerF and TerH were unable to form significant locks. The affinity and TT-lock forming efficiencies of the Ter sites correlated well with their intrinsic pausing efficiency determined by Duggin and Bell (2009). In the cell, Tus was distributed onto Ter sites according to their intrinsic affinity. It was demonstrated that only the strong Ter sites are able to cause significant fork arrest suggesting that replication forks are unlikely to break through the innermost Ter sites and that the outer Ter sites may be used to prevent non-oriC initiated forks to travel towards the origin. A new paradigm is being proposed to explain the multiplicity of Ter sites and the advantage in maintaining such a wide fork trap. Finally, the three new assays developed in this study, GFP-Basta, DSF-GTP and the qPCR-based DNA binding assay, proved to be invaluable tools for the detailed characterization of protein-DNA complexes. These news techniques have considerable applications in both genomic and proteomic programs

Manifestations cutanées au cours du syndrome de SMITH-MAGENIS chez l'enfant et l'adulte jeune

ANGERS-BU Médecine-Pharmacie (490072105) / SudocSudocFranceF

Differential Tus–Ter binding and lock formation: implications for DNA replication termination in Escherichia coli

In E. coli, DNA replication termination occurs at Ter sites and is mediated by Tus. Two clusters of five Ter sites are located on each side of the terminus region and constrain replication forks in a polar manner. The polarity is due to the formation of the Tus–Ter-lock intermediate. Recently, it has been shown that DnaB helicase which unwinds DNA at the replication fork is preferentially stopped at the non-permissive face of a Tus–Ter complex without formation of the Tus–Ter-lock and that fork pausing efficiency is sequence dependent, raising two essential questions: Does the affinity of Tus for the different Ter sites correlate with fork pausing efficiency? Is formation of the Tus–Ter-lock the key factor in fork pausing? The combined use of surface plasmon resonance and GFP-Basta showed that Tus binds strongly to TerA–E and G, moderately to TerH–J and weakly to TerF. Out of these ten Ter sites only two, TerF and H, were not able to form significant Tus–Ter-locks. Finally, Tus's resistance to dissociation from Ter sites and the strength of the Tus–Ter-locks correlate with the differences in fork pausing efficiency observed for the different Ter sites by Duggin and Bell (2009)

A polyplex qPCR-based binding assay for protein–DNA interactions

The measurement of protein–DNA interactions is difficult and often involves radioisotope-labelled DNA to obtain the desired assay sensitivity. More recently, high-throughput proteomic approaches were developed but they generally lack sensitivity. For these methods, the level of technical difficulties involved is high due to the need for specialised facilities or equipment and training. The new qPCR-based DNA-binding assay involves immunoprecipitation of a GFP-tagged DNA-binding protein in complex with various DNA targets (Ter sites) followed by qPCR quantification, affording a very sensitive and quantitative method that can be performed in polyplex. Using a single binding reaction, the binding specificity of the DNA replication terminator protein Tus for ten termination sites TerA–J could be obtained for the first time in just a few hours. This new qPCR DNA-binding assay can easily be adapted to determine the binding specificity of virtually any soluble and functional epitope-tagged DNA-binding protein