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91.
Deraët M Rihakova L Boucard A Pèrodin J Sauvé S Mathieu AP Guillemette G Leduc R Lavigne P Escher E 《Canadian journal of physiology and pharmacology》2002,80(5):418-425
We have applied photoaffinity labelling methods combined with site-directed mutagenesis towards the two principal angiotensin II (AnglI) receptors AT1 and AT2 in order to determine contact points between AngII and the two receptors. We have first identified the receptor contact points between an N- and a C-terminal residue of the AngII molecule and the AT1 receptor and constructed with this stereochemical restriction a molecular model of AT1. A similar approach with a modified procedure of photoaffinity labelling has allowed us now to determine contact points also in the AT2 receptor. Molecular modelling of AT2 on the rhodopsin scaffold and energy minimisation of AngII binding into this AT2 model produced a model strikingly similar to the AT11 structure. Superposition of the experimentally obtained contact points of AngII with AT2 upon this model revealed excellent congruence between the experimental and modelling results. Conclusions: (i) athough AT1 and AT2 have quite low sequence homology, they both bind AngII with similar affinity and in an almost identical fashion, as if the ligand dictates the way it has to be bound, and (ii) in its bound form, AngII adopts an extended conformation in both AT1 and AT2, contrary to all previous predictions. 相似文献
92.
Emilie Lecomte Sylvie Saleun Mathieu Bolteau Aurélien Guy-Duché Oumeya Adjali Véronique Blouin Magalie Penaud-Budloo Eduard Ayuso 《Biotechnology journal》2021,16(1):2000016
Adeno-associated viral vectors (AAV) are efficient engineered tools for delivering genetic material into host cells. The commercialization of AAV-based drugs must be accompanied by the development of appropriate quality control (QC) assays. Given the potential risk of co-transfer of oncogenic or immunogenic sequences with therapeutic vectors, accurate methods to assess the level of residual DNA in AAV vector stocks are particularly important. An assay based on high-throughput sequencing (HTS) to identify and quantify DNA species in recombinant AAV batches is developed. Here, it is shown that PCR amplification of regions that have a local GC content >90% and include successive mononucleotide stretches, such as the CAG promoter, can introduce bias during DNA library preparation, leading to drops in sequencing coverage. To circumvent this problem, SSV-Seq 2.0, a PCR-free protocol for sequencing AAV vector genomes containing such sequences, is developed. The PCR-free protocol improves the evenness of the rAAV genome coverage and consequently leads to a more accurate relative quantification of residual DNA. HTS-based assays provide a more comprehensive assessment of DNA impurities and AAV vector genome integrity than conventional QC tests based on real-time PCR and are useful methods to improve the safety and efficacy of these viral vectors. 相似文献
93.
James G. Ogilvie Steven Van Belleghem Ryan Range Riccardo Papa Owen W. McMillan Mathieu Chouteau Brian A. Counterman 《Ecology and evolution》2021,11(24):18319
The evolution of mimicry in similarly defended prey is well described by the Müllerian mimicry theory, which predicts the convergence of warning patterns in order to gain the most protection from predators. However, despite this prediction, we can find great diversity of color patterns among Müllerian mimics such as Heliconius butterflies in the neotropics. Furthermore, some species have evolved the ability to maintain multiple distinct warning patterns in single populations, a phenomenon known as polymorphic mimicry. The adaptive benefit of these polymorphisms is questionable since variation from the most common warning patterns is expected to be disadvantageous as novel signals are punished by predators naive to them. In this study, we use artificial butterfly models throughout Central and South America to characterize the selective pressures maintaining polymorphic mimicry in Heliconius doris. Our results highlight the complexity of positive frequency‐dependent selection, the principal selective pressure driving convergence among Müllerian mimics, and its impacts on interspecific variation of mimetic warning coloration. We further show how this selection regime can both limit and facilitate the diversification of mimetic traits. 相似文献
94.
Didjour Albert Kambir Jean Brice Boti Thierry Acafou Yapi Zana Adama Ouattara Mathieu Paoli Ange Bighelli Flix Tomi Joseph Casanova 《化学与生物多样性》2020,17(1)
The chemical composition of 44 leaf oil samples of Laggera pterodonta (DC.) Sch.Bip. ex Oliv. (Asteraceae) from Côte d'Ivoire was investigated, using combination of chromatographic (GC‐FID) and spectroscopic (GC/MS, 13C‐NMR) techniques. Two oil samples chosen according to their chromatographic profiles were submitted to column chromatography and all fractions of CC were analyzed by GC‐FID, GC/MS and 13C‐NMR. In total, 83 components accounting for 96.5 to 99.4 % of the whole chemical composition were identified. Significant variations were observed within terpene classes: monoterpene hydrocarbons (0.4–22.7 %), oxygenated monoterpenes (32.9–54.9 %), sesquiterpene hydrocarbons (18.6–38.3 %) and oxygenated sesquiterpenes (3.5–38.4 %). Thus, the 44 compositions were subjected to hierarchical cluster analysis (HCA) and principal component analysis (PCA). Two groups were differentiated according to their composition. All the samples contained 2,5‐dimethoxy‐p‐cymene, α‐humulene and (E)‐β‐caryophyllene among the main components. Other components were present at appreciable contents and allowed differentiation of two groups: sabinene and germacrene D for Group I; 10‐epi‐γ‐eudesmol and eudesm‐7(11)‐en‐4α‐ol for Group II. All the samples collected in Eastern Côte d'Ivoire constituted Group I, while samples collected in the Central area of the country constituted Group II. 相似文献
95.
Agns Attard Mathieu Gourgues Eric Galiana Franck Panabires Michel Ponchet Harald Keller 《Journal of plant physiology》2008,165(1):83
Oomycetes from the genus Phytophthora are fungus-like plant pathogens that are devastating for agriculture and natural ecosystems. Due to their particular physiological characteristics, no efficient treatments against diseases caused by these microorganisms are presently available. To develop such treatments, it appears essential to dissect the molecular mechanisms that determine the interaction between Phytophthora species and host plants. Available data are scarce, and genomic approaches were mainly developed for the two species, Phytophthora infestans and Phytophthora sojae. However, these two species are exceptions from, rather than representative species for, the genus. P. infestans is a foliar pathogen, and P. sojae infects a narrow range of host plants, while the majority of Phytophthora species are quite unselective, root-infecting pathogens. To represent this majority, Phytophthora parasitica emerges as a model for the genus, and genomic resources for analyzing its interaction with plants are developing. The aim of this review is to assemble current knowledge on cytological and molecular processes that are underlying plant–pathogen interactions involving Phytophthora species and in particular P. parasitica, and to place them into the context of a hypothetical scheme of co-evolution between the pathogen and the host. 相似文献
96.
Servettaz A Guilpain P Camoin L Mayeux P Broussard C Tamby MC Tamas N Kaveri SV Guillevin L Mouthon L 《Proteomics》2008,8(5):1000-1008
In order to identify target antigens of anti-endothelial cell (anti-EC) antibodies (AECA) in healthy individuals, we have used a proteomic approach combining 2-DE and immunoblotting. Whole cell protein extracts obtained from human umbilical vein EC (HUVEC) cultures were used as a source of antigens. Serum IgG from 12 healthy blood donors were tested at a concentration of 200 microg/mL. Targeted spots were identified by MS. The HUVEC proteome was composed of 884 protein spots. Among these, 61 +/- 25.8 (mean +/- SD) spots were recognized by serum IgG from healthy individuals, with marked differences from one individual to another. Among these spots, 11 were recognized by serum IgG from all healthy individuals tested. These spots corresponded to six different proteins with several spots corresponding to different isoforms of the same protein. Target antigens were: cytoskeletal proteins (beta-actin, alpha-tubulin, and vimentin); glycolytic enzymes (glucose-3-phosphate-deshydrogenase and alpha-enolase); and prolyl-4-hydroxylase beta subunit, a member of the disulfide isomerase family. This study shows that the repertoire of IgG AECA is heterogeneous among healthy individuals. IgG from all of the healthy individuals tested recognized a restricted set of highly conserved ubiquitous proteins playing key roles in cell biology and maintenance of homeostasis. 相似文献
97.
Kyoko E. Yuki Megan M. Eva Etienne Richer Dudley Chung Marilène Paquet Mathieu Cellier Fran?ois Canonne-Hergaux Sophie Vaulont Silvia M. Vidal Danielle Malo 《PloS one》2013,8(2)
Salmonella, a ubiquitous Gram-negative intracellular bacterium, is a food borne pathogen that infects a broad range of hosts. Infection with Salmonella Typhimurium in mice is a broadly recognized experimental model resembling typhoid fever in humans. Using a N-ethyl-N-nitrosurea (ENU) mutagenesis recessive screen, we report the identification of Ity16 (Immunity to Typhimurium locus 16), a locus responsible for increased susceptibility to infection. The position of Ity16 was refined on chromosome 8 and a nonsense mutation was identified in the ankyrin 1 (Ank1) gene. ANK1 plays an important role in the formation and stabilization of the red cell cytoskeleton. The Ank1Ity16/Ity16 mutation causes severe hemolytic anemia in uninfected mice resulting in splenomegaly, hyperbilirubinemia, jaundice, extramedullary erythropoiesis and iron overload in liver and kidneys. Ank1Ity16/Ity16 mutant mice demonstrated low levels of hepcidin (Hamp) expression and significant increases in the expression of the growth differentiation factor 15 (Gdf15), erythropoietin (Epo) and heme oxygenase 1 (Hmox1) exacerbating extramedullary erythropoiesis, tissue iron deposition and splenomegaly. As the infection progresses in Ank1Ity16/Ity16, the anemia worsens and bacterial load were high in liver and kidneys compared to wild type mice. Heterozygous Ank1+/Ity16 mice were also more susceptible to Salmonella infection although to a lesser extent than Ank1Ity16/Ity16 and they did not inherently present anemia and splenomegaly. During infection, iron accumulated in the kidneys of Ank1+/Ity16 mice where bacterial loads were high compared to littermate controls. The critical role of HAMP in the host response to Salmonella infection was validated by showing increased susceptibility to infection in Hamp-deficient mice and significant survival benefits in Ank1
+/Ity16 heterozygous mice treated with HAMP peptide. This study illustrates that the regulation of Hamp and iron balance are crucial in the host response to Salmonella infection in Ank1 mutants. 相似文献
98.
Adam K. A. Wright Mathieu Bangert Jenna F. Gritzfeld Daniela M. Ferreira Kondwani C. Jambo Angela D. Wright Andrea M. Collins Stephen B. Gordon 《PLoS pathogens》2013,9(3)
Pneumococcal carriage is both immunising and a pre-requisite for mucosal and systemic disease. Murine models of pneumococcal colonisation show that IL-17A-secreting CD4+ T-cells (Th-17 cells) are essential for clearance of pneumococci from the nasopharynx. Pneumococcal-responding IL-17A-secreting CD4+ T-cells have not been described in the adult human lung and it is unknown whether they can be elicited by carriage and protect the lung from pneumococcal infection. We investigated the direct effect of experimental human pneumococcal nasal carriage (EHPC) on the frequency and phenotype of cognate CD4+ T-cells in broncho-alveolar lavage and blood using multi-parameter flow cytometry. We then examined whether they could augment ex vivo alveolar macrophage killing of pneumococci using an in vitro assay. We showed that human pneumococcal carriage leads to a 17.4-fold (p = 0.007) and 8-fold (p = 0.003) increase in the frequency of cognate IL-17A+ CD4+ T-cells in BAL and blood, respectively. The phenotype with the largest proportion were TNF+/IL-17A+ co-producing CD4+ memory T-cells (p<0.01); IFNγ+ CD4+ memory T-cells were not significantly increased following carriage. Pneumococci could stimulate large amounts of IL-17A protein from BAL cells in the absence of carriage but in the presence of cognate CD4+ memory T-cells, IL-17A protein levels were increased by a further 50%. Further to this we then show that alveolar macrophages, which express IL-17A receptors A and C, showed enhanced killing of opsonised pneumococci when stimulated with rhIL-17A (p = 0.013). Killing negatively correlated with RC (r = −0.9, p = 0.017) but not RA expression. We conclude that human pneumococcal carriage can increase the proportion of lung IL-17A-secreting CD4+ memory T-cells that may enhance innate cellular immunity against pathogenic challenge. These pathways may be utilised to enhance vaccine efficacy to protect the lung against pneumonia. 相似文献
99.
100.
Human cytomegalovirus US3 chimeras containing US2 cytosolic residues acquire major histocompatibility class I and II protein degradation properties 下载免费PDF全文
Human cytomegalovirus (HCMV) glycoprotein US2 increases the proteasome-mediated degradation of major histocompatibility complex (MHC) class I heavy chain (HC), class II DR-alpha and DM-alpha proteins, and HFE, a nonclassical MHC protein. US2-initiated degradation of MHC proteins apparently involves the recruitment of cellular proteins that participate in a process known as endoplasmic reticulum (ER)-associated degradation. ER-associated degradation is a normal process by which misfolded proteins are recognized and translocated into the cytoplasm for degradation by proteasomes. It has been demonstrated that truncated forms of US2, especially those lacking the cytoplasmic domain (CT), can bind MHC proteins but do not cause their degradation. To further assess how the US2 CT domain interacts with the cellular components of the ER-associated degradation pathway, we constructed chimeric proteins in which the US2 CT domain or the CT and transmembrane (TM) domains replaced those of the HCMV glycoprotein US3. US3 also binds both class I and II proteins but does not cause their degradation. Remarkably, chimeras containing the US2 CT domain caused the degradation of both MHC class I and II proteins although this degradation was less than that by wild-type US2. Therefore, the US2 CT and TM domains can confer on US3 the capacity to degrade MHC proteins. We also analyzed complexes containing MHC proteins and US2, US3, US11, or US3/US2 chimeras for the presence of cdc48/p97 ATPase, a protein that binds polyubiquitinated proteins and likely functions in the extraction of substrates from the ER membrane before the substrates meet proteasomes. p97 ATPase was present in immunoprecipitates containing US2, US11, and two chimeras that included the US2 CT domain, but not in US3 complexes. Therefore, it appears that the CT domain of US2 participates in recruiting p97 ATPase into ER-associated degradation complexes. 相似文献