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排序方式: 共有455条查询结果,搜索用时 265 毫秒
21.
Maxime Leroux Zoulikha Rezoug George Szatmari 《Molecular genetics and genomics : MGG》2013,288(10):495-502
Chromosome dimers, which form during the bacterial life cycle, represent a problem that must be solved by the bacterial cell machinery so that chromosome segregation can occur effectively. The Xer/dif site-specific recombination system, utilized by most bacteria, resolves chromosome dimers into monomers using two tyrosine recombinases, XerC and XerD, to perform the recombination reaction at the dif site which consists of 28–30 bp. However, single Xer recombinase systems have been recently discovered in several bacterial species. In Streptococci and Lactococci a single recombinase, XerS, is capable of completing the monomerisation reaction by acting at an atypical dif site called dif SL (31 bp). It was recently shown that a subgroup of ε-proteobacteria including Campylobacter spp. and Helicobacter spp. had a phylogenetically distinct Xer/dif recombination system with only one recombinase (XerH) and an atypical dif motif (difH). In order to biochemically characterize this system in greater detail, Campylobacter jejuni XerH was purified and its DNA-binding activity was characterized. The protein showed specific binding to the complete difH site and to both halves separately. It was also shown to form covalent complexes with difH suicide substrates. In addition, XerH was able to catalyse recombination between two difH sites located on a plasmid in Escherichia coli in vivo. This indicates that this XerH protein performs a similar function as the related XerS protein, but shows significantly different binding characteristics. 相似文献
22.
Leroux Nicole Nouhin Janin Prak Sophearot Roth Bunthoeun Rouet François Dussart Philippe Marx Nick 《International journal of primatology》2020,41(4):634-653
International Journal of Primatology - The risk of transmitting novel pathogens from released animals to wild conspecifics is an important consideration for reintroduction initiatives. Apart from... 相似文献
23.
Darryl Leroux 《Ethnic and racial studies》2013,36(5):718-733
Genealogy, or the study of one's ancestral patri-lineage, has a long and esteemed pedigree in French Canadian and Québécois history. From Cyprien Tanguay's late-nineteenth-century encyclopedias to René Jetté's updated versions more than a century later, genealogy has been an important component of French Canadian nationalisms. Tracing one's ancestry back to the early St. Lawrence settlement in the seventeenth century has provided Québécois subjects with opportune political and social capital with which to make territorial and national claims legitimate. Through a case study approach, I explain how genealogy provides the grounds upon which Québécois and French subjects remember a shared past. Specifically, I examine a variety of sites of memory in the French countryside, including a museum that relies on ‘genealogics’ to call the French Canadian Québécois back to its roots. As such, I demonstrate how the biological, read as a contemporary articulation of Balibar's notion of the racial supplément necessary to nation building, travels across the Atlantic. 相似文献
24.
Stefanie Zimmermann Mouhssin Oufir Alejandro Leroux R. Luise Krauth-Siegel Katja Becker Marcel Kaiser Reto Brun Matthias Hamburger Michael Adams 《Bioorganic & medicinal chemistry》2013,21(22):7202-7209
In mice cynaropicrin (CYN) potently inhibits the proliferation of Trypanosoma brucei—the causative agent of Human African Trypanosomiasis—by a so far unknown mechanism. We hypothesized that CYNs α,β-unsaturated methylene moieties act as Michael acceptors for glutathione (GSH) and trypanothione (T(SH)2), the main low molecular mass thiols essential for unique redox metabolism of these parasites. The analysis of this putative mechanism and the effects of CYN on enzymes of the T(SH)2 redox metabolism including trypanothione reductase, trypanothione synthetase, glutathione-S-transferase, and ornithine decarboxylase are shown. A two step extraction protocol with subsequent UPLC–MS/MS analysis was established to quantify intra-cellular CYN, T(SH)2, GSH, as well as GS-CYN and T(S-CYN)2 adducts in intact T. b. rhodesiense cells. Within minutes of exposure to CYN, the cellular GSH and T(SH)2 pools were entirely depleted, and the parasites entered an apoptotic stage and died. CYN also showed inhibition of the ornithine decarboxylase similar to the positive control eflornithine. Significant interactions with the other enzymes involved in the T(SH)2 redox metabolism were not observed. Alongside many other biological activities sesquiterpene lactones including CYN have shown antitrypanosomal effects, which have been postulated to be linked to formation of Michael adducts with cellular nucleophiles. Here the interaction of CYN with biological thiols in a cellular system in general, and with trypanosomal T(SH)2 redox metabolism in particular, thus offering a molecular explanation for the antitrypanosomal activity is demonstrated. At the same time, the study provides a novel extraction and analysis protocol for components of the trypanosomal thiol metabolism. 相似文献
25.
Laurent Montagano Shawn J. Leroux Marie‐Andre Giroux Nicolas Lecomte 《Ecology letters》2019,22(2):265-274
Material and energy flows among ecosystems can directly and indirectly drive ecosystem functions. Yet, how populations of consumers respond to allochthonous inputs at a macroecological scale is still unclear. Using a meta‐analysis spanning several biomes, we show that the abundance of recipient populations is 36–57% larger with increased allochthonous inputs. The strength of direct effects on the recipients of these inputs as well as the indirect effects on the consumers of these recipients (i.e. ascending indirect effects) are constant across a latitudinal gradient spanning subtropical, arid, temperate, boreal and arctic ecosystems. However, indirect effect on the in situ resources of the input recipient (i.e. descending indirect effects) decreases with latitude. Our results suggest that the influence of allochthonous inputs can vary across large‐scale gradients of ecosystem productivity and may be driven by the types of trophic interactions within recipient food webs. 相似文献
26.
Background
The anterior cruciate ligament rupture is a common injury which mainly affects young and active population. Faced to this problem, the development of synthetic structures for ligament reconstruction is increasing. The most recent researches focused on the development of biodegradable structures that could be functionalized to enhance host integration. This work describes the elaboration of different poly(ε-caprolactone) prototypes for the rat anterior cruciate ligament replacement in order to found the best design for further in vivo assays.Methods
According to the literature, it was decided to elaborate two different poly(ε-caprolactone) prototypes: a braided one and a free-fibers one. A chemical grafting of a bioactive polymer–poly(sodium styrene sulfonate) – was performed on both prototypes and mechanical and biological testing were assessed. Based on these results, one rat was implanted with the best prototype.Results
The mechanical and biological results demonstrated that the best prototype to implant was the poly(sodium styrene sulfonate)-grafted braided prototype. After one-month implantation, no inflammation was observable around the scar. The rat demonstrated good flexion and extension of the lower limb without any anterior drawer. The prototype was highly anchored to the bone. ESEM images of the explanted prototype showed the presence of cells and tissue ingrowth along and around the fibers.Conclusion
This work demonstrates the feasibility to implant a bioactive and biodegradable synthetic ligament in the rat model without any inflammation and with a good tissue anchoring at a short-term time. This will lead to an extensive in vivo assay. 相似文献27.
Veron W Lesouhaitier O Pennanec X Rehel K Leroux P Orange N Feuilloley MG 《The FEBS journal》2007,274(22):5852-5864
Natriuretic peptides of various forms are present in animals and plants, and display structural similarities to cyclic antibacterial peptides. Pretreatment of Pseudomonas aeruginosa PAO1 with brain natriuretic peptide (BNP) or C-type natriuretic peptide (CNP) increases bacterium-induced glial cell necrosis. In eukaryotes, natriuretic peptides act through receptors coupled to cyclases. We observed that stable analogs of cAMP (dibutyryl cAMP) and cGMP (8-bromo-cGMP) mimicked the effect of brain natriuretic peptide and CNP on bacteria. Further evidence for the involvement of bacterial cyclases in the regulation of P. aeruginosa PAO1 cytotoxicity by natriuretic peptides is provided by the observed doubling of intrabacterial cAMP concentration after exposure to CNP. Lipopolysaccharide (LPS) extracted from P. aeruginosa PAO1 treated with both dibutyryl cAMP and 8-bromo-cGMP induces higher levels of necrosis than LPS extracted from untreated bacteria. Capillary electrophoresis and MALDI-TOF MS analysis have shown that differences in LPS toxicity are due to specific differences in the structure of the macromolecule. Using a strain deleted in the vfr gene, we showed that the Vfr protein is essential for the effect of natriuretic peptides on P. aeruginosa PAO1 virulence. These data support the hypothesis that P. aeruginosa has a cyclic nucleotide-dependent natriuretic peptide sensor system that may affect virulence by activating the expression of Vfr and LPS biosynthesis. 相似文献
28.
29.
Mireille?MorissonEmail author Carine?Jiguet–Jiglaire Sophie?Leroux Thomas?Faraut Suzanne?Bardes Katia?Feve Carine?Genet Frédérique?Pitel Denis?Milan Alain?Vignal 《Mammalian genome》2004,15(9):732-739
To validate the ChickRH6 whole-genome radiation hybrid (WGRH) panel, we constructed a map of chicken Chromosome 7 based on 19 microsatellite markers from the genetic map and 76 ESTs (expressed sequence tags), whose efficient targeted development was made possible by using the ICCARE software. This high-density radiation hybrid (RH) map of a chicken macrochromosome gives us indications on characteristics of ChickRH6. The potential resolution of the panel is 325 kb and the practical resolution of our framework map is 1.3 Mb. Based on these results, a complete framework map of the chicken genome would comprise 1000 markers. The marker order is in good agreement with the genetic map and comparison with the human and mouse sequence maps revealed a number of internal rearrangements. 相似文献
30.
Comparative genomics identifies a flagellar and basal body proteome that includes the BBS5 human disease gene 总被引:31,自引:0,他引:31
Li JB Gerdes JM Haycraft CJ Fan Y Teslovich TM May-Simera H Li H Blacque OE Li L Leitch CC Lewis RA Green JS Parfrey PS Leroux MR Davidson WS Beales PL Guay-Woodford LM Yoder BK Stormo GD Katsanis N Dutcher SK 《Cell》2004,117(4):541-552
Cilia and flagella are microtubule-based structures nucleated by modified centrioles termed basal bodies. These biochemically complex organelles have more than 250 and 150 polypeptides, respectively. To identify the proteins involved in ciliary and basal body biogenesis and function, we undertook a comparative genomics approach that subtracted the nonflagellated proteome of Arabidopsis from the shared proteome of the ciliated/flagellated organisms Chlamydomonas and human. We identified 688 genes that are present exclusively in organisms with flagella and basal bodies and validated these data through a series of in silico, in vitro, and in vivo studies. We then applied this resource to the study of human ciliation disorders and have identified BBS5, a novel gene for Bardet-Biedl syndrome. We show that this novel protein localizes to basal bodies in mouse and C. elegans, is under the regulatory control of daf-19, and is necessary for the generation of both cilia and flagella. 相似文献