排序方式: 共有153条查询结果,搜索用时 15 毫秒
21.
Bouraoui H Aissa MB Abbassi F Touzel JP O'donohue M Manai M 《Archives of microbiology》2012,194(5):315-322
An ultraviolet-radiation-resistant, Gram-positive, orange-pigmented, thermophilic and strictly aerobic cocci was isolated
from Saharan water hot spring in Tunisia. The newly isolated bacterium, designated HAN-23T, was identified based on polyphasic taxonomy including genotypic, phenotypic and chemotaxonomic characterization. Phylogenetic
analysis based on 16S rRNA gene sequences placed this strain within Deinococcus genus. However, strain HAN-23T is different from recognized species of the genus Deinococcus, showing less than 94.0% similarity values to its closest relatives. The predominant cellular fatty acids determined by gas
chromatography were iso-C15:0, iso-C17:0 and iso C17:1 ω9c. The major respiratory quinone was MK-8. The DNA G + C content was 66.9 mol%. DNA–DNA hybridization measurements revealed
low DNA relatedness (6%) between the novel isolate and its closest neighbor, the type strain Deinococcus geothermalis DSM 11300. On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain HAN-23T represents a novel species of the genus Deinococcus, for which the name Deinococcus sahariens sp. nov. is proposed, the type strain being HAN-23T (=DSM 18496T; LMG 23756T). 相似文献
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Abbassi F Oury B Blasco T Sereno D Bolbach G Nicolas P Hani K Amiche M Ladram A 《Peptides》2008,29(9):1526-1533
Temporins are small antimicrobial peptides isolated from North American and Eurasian ranid frogs that are particularly active against Gram-positive bacteria. To date, no temporins have been characterized from North African frog species. We isolated three novel members of the temporin family, named temporin-1Sa (FLSGIVGMLGKLF(amide)), -1Sb (FLPIVTNLLSGLL(amide)), and -1Sc (FLSHIAGFLSNLF(amide)), from the skin of the Sahara frog Pelophylax (Rana) saharica originating from Tunisia. These temporins were identified by a combined mass spectrometry/molecular cloning approach. Temporin-1Sa was found to be highly active against Gram-positive and Gram-negative bacteria, yeasts and fungi (MIC=2-30muM). To our knowledge, this is the first 13-residue member of the temporin family with a net charge of +2 that shows such broad-spectrum activity with particularly high potency on the clinically relevant Gram-negative strains, Escherichia coli (MIC=10muM) and Pseudomonas aeruginosa (MIC=31muM). Moreover, temporin-1Sa displays significant antiparasitic activity (IC(50) approximately 20muM) against the promastigote and amastigote stages of Leishmania infantum. 相似文献
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Isolation of soil Streptomyces strains capable of degrading humic acids and analysis of their peroxidase activity 总被引:8,自引:0,他引:8
Abstract Fifteen Streptomyces strains capable of decolorizing humic acids in presence of glucose were isolated from soil samples using the dilute suspension technique and spread on agar plates. Six strains, displaying a significant and stable activity, were selected for further characterization. Some features of these isolates (carbon source utilization, enzyme production, antibiotic resistance) were compared with those of the reference strain Streptomyces viridosporus ATCC 39115. Degradation properties studied in batch cultures at pH 7.0 showed that the catabolic activity on humic acids was generally stimulated by incubation with 100% oxygen and was cell surface-associated. Peroxidase activity from cell-free extracts was analysed by using the oxidation of N,N,N′,N′-tetramethyl-phenylene-diamine. PAGE analysis revealed the existence of two major types of peroxidases (molecular mass: about 39.2 and 61.6 kDa), dividing the strains into two groups. The role of cell surface-associated peroxidase activity in the breakdown of humic acids is discussed. 相似文献
24.
Qingqing Zhou Tristan A. Reekie Ramzi H. Abbassi Dinesh Indurthi Venkata Josep S. Font Renae M. Ryan Lenka Munoz Michael Kassiou 《Bioorganic & medicinal chemistry》2018,26(22):5852-5869
Dual-specificity tyrosine phosphorylation-related kinase 1A (DYRK1A) is a dual-specificity protein kinase that catalyses phosphorylation and autophosphorylation. Higher DYRK1A expression correlates with cancer, in particular glioblastoma present within the brain. We report here the synthesis and biological evaluation of new heterocyclic diphenolic derivatives designed as novel DYRK1A inhibitors. The generation of these heterocycles such as benzimidazole, imidazole, naphthyridine, pyrazole-pyridines, bipyridine, and triazolopyrazines was made based on the structural modification of the lead DANDY and tested for their ability to inhibit DYRK1A. None of these derivatives showed significant DYRK1A inhibition but provide valuable knowledge around the importance of the 7-azaindole moiety. These data will be of use for developing further structure-activity relationship studies to improve the selective inhibition of DYRK1A. 相似文献
25.
Patrizia Zamberletti Khadija Sabir Thomas Opitz Olivier Bonnefon Edith Gabriel Julien Papaïx 《PLoS computational biology》2021,17(11)
In agricultural landscapes, the amount and organization of crops and semi-natural habitats (SNH) have the potential to promote a bundle of ecosystem services due to their influence on ecological community at multiple spatio-temporal scales. SNH are relatively undisturbed and are often source of complementary resources and refuges, therefore supporting more diverse and abundant natural pest enemies. However, the nexus of SNH proportion and organization with pest suppression is not trivial. It is thus crucial to understand how the behavior of pest and natural enemy species, the underlying landscape structure, and their interaction, may influence conservation biological control (CBC). Here, we develop a generative stochastic landscape model to simulate realistic agricultural landscape compositions and configurations of fields and linear elements. Generated landscapes are used as spatial support over which we simulate a spatially explicit predator-prey dynamic model. We find that increased SNH presence boosts predator populations by sustaining high predator density that regulates and keeps pest density below the pesticide application threshold. However, predator presence over all the landscape helps to stabilize the pest population by keeping it under this threshold, which tends to increase pest density at the landscape scale. In addition, the joint effect of SNH presence and predator dispersal ability among hedge and field interface results in a stronger pest regulation, which also limits pest growth. Considering properties of both fields and linear elements, such as local structure and geometric features, provides deeper insights for pest regulation; for example, hedge presence at crop field boundaries clearly strengthens CBC. Our results highlight that the integration of species behaviors and traits with landscape structure at multiple scales is necessary to provide useful insights for CBC. 相似文献
26.
Maternal protein restriction during gestation and lactation in the rat results in increased brain levels of kynurenine and kynurenic acid in their adult offspring
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27.
Abel Garcia-Pino Sergio Martinez-Rodriguez Khadija Wahni Lode Wyns Remy Loris Joris Messens 《Journal of molecular biology》2009,385(5):1590-5783
The thioredoxin (Trx) fold is a small monomeric domain that is ubiquitous in redox-active enzymes. Trxs are characterized by a typical WCGPC active-site sequence motif. A single active-site mutation of the tryptophan to an alanine in Staphylococcus aureus Trx converts the oxidized protein into a biologically inactive domain-swapped dimer. While the monomeric protein unfolds reversibly in a two-state manner, the oxidized dimeric form is kinetically stable and converts to the monomeric form upon refolding. After reduction, the half-life of the dimer decreases many orders of magnitude to ∼ 4.3 h, indicating that the active-site disulfide between Cys29 and Cys32 is an important determinant for the kinetics of unfolding. We propose kinetic stability as a possible evolutionary strategy in the evolution of multimeric proteins from their monomeric ancestors by domain swapping, which, for this biologically inactive Trx mutant, turned out to be an evolutionary dead end. 相似文献
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Vasco Rodrigues Anabela Cordeiro-da-Silva Mireille Laforge Ali Ouaissi Khadija Akharid Ricardo Silvestre Jér?me Estaquier 《PLoS neglected tropical diseases》2014,8(2)
In mammals subverted as hosts by protozoan parasites, the latter and/or the agonists they release are detected and processed by sensors displayed by many distinct immune cell lineages, in a tissue(s)-dependent context. Focusing on the T lymphocyte lineage, we review our present understanding on its transient or durable functional impairment over the course of the developmental program of the intracellular parasites Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Trypanosoma cruzi in their mammalian hosts. Strategies employed by protozoa to down-regulate T lymphocyte function may act at the initial moment of naïve T cell priming, rendering T cells anergic or unresponsive throughout infection, or later, exhausting T cells due to antigen persistence. Furthermore, by exploiting host feedback mechanisms aimed at maintaining immune homeostasis, parasites can enhance T cell apoptosis. We will discuss how infections with prominent intracellular protozoan parasites lead to a general down-regulation of T cell function through T cell anergy and exhaustion, accompanied by apoptosis, and ultimately allowing pathogen persistence. 相似文献