177 research outputs found
Étude des interactions entre Streptococcus suis et des neutrophiles porcins
Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal
Dehydrated pork manure by-product: effect of a chitosan amendment on bacterial community and common scab incidence
Chitosan amendment modified the composition of a microbial community associated with dehydrated pork manure by-product. The amended product (biosolid PC) contained a lower number of anaerobic bacteria than the non-amended product (biosolid P). Chitosan also significantly reduced the fungal population. A 16S rRNA gene bank constructed from DNA extracted from the bacterial community associated with both P and PC biosolids revealed that bacterial orders Xanthomonodales, Pseudomonadales, Enterobacteriales, Burkholderiales, Actinomycetales, Bacillales, Clostridiales and Lactobacillales were found in both biosolids. Bacteria from the Stenotrophomonas genus were abundant in both biosolids. However, the addition of chitosan appeared to induce changes in the population of some bacterial genera. For example, clones carrying a 16S rRNA gene corresponding to the Bacillus genus were doubled in biosolid PC. In field trials carried out to test their effect on common scab incidence, biosolids P and PC were applied as potato seed treatment. Biosolid P increased disease incidence by a factor of 1.33 and 2.85 in two independent experiments. However, when chitosan was added to the seed treatment, the stimulating effect of biosolid P on common scab was cancelled out.Un amendement en chitosane a modifié la composition de la communauté microbienne associée à un sous-produit déshydraté de fumier de porc. Le produit amendé (biosolide PC) contenait un nombre de bactéries anaérobies inférieur à celui du produit non amendé (biosolide P). Le chitosane a aussi réduit de façon significative la population fongique. Une banque de gènes de l’ARNr 16S construite à partir de l’ADN extrait de la communauté bactérienne associée aux biosolides P et PC a révélé que les ordres bactériens Xanthomonodales, Pseudomonadales, Enterobacteriales, Burkholderiales, Actinomycetales, Bacillales, Clostridiales et Lactobacillales se trouvaient dans les deux types de biosolides. Les bactéries du genre Stenotrophomonas étaient les plus abondantes dans les deux types de biosolides. L’addition de chitosane a toutefois induit des changements dans la population de quelques genres de bactéries. Par exemple, les clones transportant un gène d’ARNr 16S correspondant au genre Bacillus doublaient dans le biosolide PC. Dans des essais en champs entrepris dans le but de tester leur effet sur l’incidence de la gale commune, les biosolides P et PC ont été appliqués comme traitement des semences de pomme de terre. Le biosolide P a augmenté l’incidence de la maladie par un facteur de 1,33 et de 2,85 dans deux expériences indépendantes. Toutefois, quand le chitosane était ajouté au traitement de semences, l’effet stimulant du biosolide P sur la gale commune était aboli
Conditioned spin and charge dynamics of a single electron quantum dot
In this article we describe the incoherent and coherent spin and charge
dynamics of a single electron quantum dot. We use a stochastic master equation
to model the state of the system, as inferred by an observer with access to
only the measurement signal. Measurements obtained during an interval of time
contribute, by a past quantum state analysis, to our knowledge about the system
at any time within that interval. Such analysis permits precise estimation
of physical parameters, and we propose and test a modification of the classical
Baum-Welch parameter re-estimation method to systems driven by both coherent
and incoherent processes.Comment: 9 pages, 9 figure
Acute invariant NKT cell activation triggers an immune response that drives prominent changes in iron homeostasis
Iron homeostasis is an essential biological process that ensures the tissue distribution of iron for
various cellular processes. As the major producer of hepcidin, the liver is central to the regulation of
iron metabolism. The liver is also home to many immune cells, which upon activation may greatly
impact iron metabolism. Here, we focus on the role of invariant natural killer T (iNKT) cells, a subset
of T lymphocytes that, in mice, is most abundant in the liver. Activation of iNKT cells with the
prototypical glycosphingolipid antigen, α-galactosylceramide, resulted in immune cell proliferation
and biphasic changes in iron metabolism. This involved an early phase characterized by hypoferremia,
hepcidin induction and ferroportin suppression, and a second phase associated with strong
suppression of hepcidin despite elevated levels of circulating and tissue iron. We further show that
these changes in iron metabolism are fully dependent on iNKT cell activation. Finally, we demonstrate
that the biphasic regulation of hepcidin is independent of NK and Kupfer cells, and is initially driven
by the STAT3 infammatory pathway, whereas the second phase is regulated by repression of the
BMP/SMAD signaling pathway. These fndings indicate that iNKT activation and the resulting cell
proliferation infuence iron homeostasis
Acute invariant NKT cell activation triggers an immune response that drives prominent changes in iron homeostasis
© The Author(s) 2020. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licen ses/by/4.0/.Iron homeostasis is an essential biological process that ensures the tissue distribution of iron for various cellular processes. As the major producer of hepcidin, the liver is central to the regulation of iron metabolism. The liver is also home to many immune cells, which upon activation may greatly impact iron metabolism. Here, we focus on the role of invariant natural killer T (iNKT) cells, a subset of T lymphocytes that, in mice, is most abundant in the liver. Activation of iNKT cells with the prototypical glycosphingolipid antigen, α-galactosylceramide, resulted in immune cell proliferation and biphasic changes in iron metabolism. This involved an early phase characterized by hypoferremia, hepcidin induction and ferroportin suppression, and a second phase associated with strong suppression of hepcidin despite elevated levels of circulating and tissue iron. We further show that these changes in iron metabolism are fully dependent on iNKT cell activation. Finally, we demonstrate that the biphasic regulation of hepcidin is independent of NK and Kupffer cells, and is initially driven by the STAT3 inflammatory pathway, whereas the second phase is regulated by repression of the BMP/SMAD signaling pathway. These findings indicate that iNKT activation and the resulting cell proliferation influence iron homeostasis.This work was supported by grants from the Canadian Institutes of Health Research (CIHR, Grant no. PJT-159775) and Natural Sciences and Engineering Research Council of Canada (NSERC, Grant RGPIN-2018-06442) to MMS. HH received a PhD scholarship from the NSERC. SL is a Research Scholars Emeritus awardee from the FRQS.info:eu-repo/semantics/publishedVersio
High-throughput refractive index-based microphotonic sensor for enhanced cellular discrimination
This paper presents a novel microphotonic sensor based on silicon technologies for high-throughput single cell measurements. It employs a highly sensitive Fabry-PĂ©rot resonant cavity to extract cellular refractive index information. The integrated large cross-section rib waveguides provide a single-mode like behavior important for resonant cell sensing. Differentiated myeloid cells derived from a promyelocytic leukemia cell line were injected in a microchannel, sheathlessly focused using inertial forces and analyzed while flowing through the resonant cavity volume. Results were compared against a commercial flow cytometer and showed a substantial improvement on cellular discrimination. Thus, this sensor has the ability to discriminate cell populations, usually identified using fluorescent parameters, without any dyes and can reach measurement rate as high as 2000 cells per second. By harnessing the cell's effective volume refractive index, our device offers complementary measurements readily improving actual technologies and thus providing crucial information for research and clinical professionals
Immature and mature bone marrow-derived dendritic cells exhibit distinct intracellular mechanical properties
ABSTRACT: Dendritic cells (DCs) patrol the organism at an immature stage to detect the presence of pathogens. Once activated, these mature DCs reach the lymph nodes to activate antigen-specific T lymphocytes and thus initiate an adaptative immune response to control the pathogen. The migration of both immature and mature DCs is a key process for their optimal function. DC migration requires transit through narrow constrictions that is allowed by their high local and global deformation capabilities. In addition to cytoplasmic changes, the nucleus mechanical properties also have a major impact for cellular migration and motility. Yet, nucleus intracellular mobility of dendritic cells or its variation upon maturation have not been investigated. Our study defines the biophysical phenotypic variations of dendritic cells upon maturation using interferometric deformability cytometry. This method characterizes different cellular mechanical properties, such as elongation and nucleus offset, by assessing the refractive index spatial distribution of shear-induced deformed cells. By using these parameters, our data suggest that in vitro bone marrow derived dendritic cell (BMDC) maturation induces cell stiffening and reduces nucleus mobility, allowing to distinguish immature and mature dendritic cells. Overall, our method provides insights on intracellular mechanical properties of two dendritic cell states
Nearby Construction Impedes the Progression to Overt Autoimmune Diabetes in NOD Mice
Construction nearby animal houses has sporadically been reported to affect various aspects of animal health. Most of the reports have focussed on the impact on stress hormone levels and the hypersensitivity of animals relative to humans. There has also been an anecdotal report on the impact of construction on autoimmune diabetes in NOD mice. Here, we describe that nearby construction significantly impedes the progression to overt diabetes in female NOD mice offspring. We demonstrate that this was not due to a genetic drift or to particularities associated with our specific mouse colony. Interestingly, although the glycemia levels remained low in mice born from mothers subject to construction stress during gestation, we detected an active autoimmune reaction towards pancreatic islet cells, as measured by both the degree of insulitis and the presence of insulin autoantibody levels in the serum. These results suggest that the external stress imposed during embryonic development does not prevent but significantly delays the autoimmune process. Together, our findings emphasize the impact of surrounding factors during in vivo studies and are in agreement with the hypothesis that both environmental and genetic cues contribute to autoimmune diabetes development
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