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21.
Four genes, fagA, B, C and D, encoding products with 32-47% identity to proteins involved in bacterial iron uptake systems, were identified immediately downstream of the Corynebacterium pseudotuberculosis phospholipase D gene. beta-Galactosidase assays on a C. pseudotuberculosis strain carrying a fagA-lacZ fusion indicated that the putative fagABC operon was poorly expressed in iron-rich media. However, similar experiments in iron-limited media resulted in an approximately three-fold increase in beta-galactosidase activity, suggesting that this operon is regulated by iron in vitro. Although no defect in iron utilization could be determined for a C. pseudotuberculosis fagB(C) mutant in vitro, this mutant showed reduced virulence compared to wild-type in a goat model of caseous lymphadenitis. Thus, expression of the fag genes in the host appears to contribute to virulence.  相似文献   
22.
Despite the long history of forestry activity in Brazil and its importance to the national economy, there is still much disorder in the information regarding pests of forestry species. Considering the importance of the entomological knowledge for the viability of silvicultural management, this work aimed to gather information on the species of Lepidoptera associated with forestry crops within Brazil using a historical approach. Through a literature review, all registered species of Lepidoptera related to forestry crops in Brazil from 1896 to 2010 were identified. The historical evaluation was based on the comparison of the number of published articles, species richness, and community similarities of the Lepidoptera and their associated forest crops, grouped in 10-year samples. A total of 417 occurrences of Lepidoptera associated with forestry species were recorded, from which 84 species are related with 40 different forestry crops. The nocturnal Lepidoptera were dominant on the records, with Eacles imperialis magnifica Walker as the most frequent pest species cited. Myrtaceae was the most frequent plant family, with Cedrela fissilis as the most cited forestry crop species. A successional change in both Lepidoptera species and their host plants was observed over the decades. The richness of lepidopteran pest species increased over the years, unlike the richness of forestry crop species. This increase could be related to the inefficient enforcement of sanitary barriers, to the increase of monoculture areas, and to the adaptability of native pests to exotic forestry species used in monoculture stands.  相似文献   
23.
The pharmacological activity of 2NTX-99 ([4-methoxy-N1-(4-trans-nitrooxycyclohexyl)-N3-(3-pyridinylmethyl)-1,3-benzenedicarboxamide]) was investigated in vitro in the intact, rat pulmonary vasculature and in guinea pig airways. Rat lungs were perfused at constant flow and changes in vascular tone recorded. Challenge with the TXA? analogue 9,11-dideoxy-9α11α-methanoepoxy ProstaglandinF? (U46619, 0.5 μM) increased vessel tone (32.48±1.5 vs 13.13±0.56 mmHg; n=12). 2NTX-99 (0.1-100 μM; n=5), caused a concentration-dependent relaxation, prevented by 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ, 10 μM, n=4), an inhibitor of soluble guanylate cyclase. Acetylcholine (0.1-10 μM; n=3) and a reference NO-donor, isosorbide-5-mononitrate (5-100 μM; n=4), were ineffective. Intraluminal perfusion of washed human platelets (2 × 10? cells/ml) increased intravascular pressure after challenge with arachidonic acid (AA, 2 μM; n=5), an increase abolished by acetylsalicylic acid and significantly reduced by 2NTX-99 (40 μM; n=5). TXB? in the lung perfusate was detected after platelet activation, 2NTX-99 inhibited TXA? synthesis (6.45±0.6 and 1.10±0.2 ng/ml, respectively). 2NTX-99 did not alter central or peripheral airway responsiveness to Histamine (0.001-300 μM; n=6), U46619 (0.001-3 μM, n=3) or LTD? (1 pM-1 μM; n=6). 2NTX-99 vasodilates the pulmonary vasculature via the release of nitric oxide (NO) and reduces intraluminal, AA-induced, TXA? formation. The combined activity of 2NTX-99 as an NO-donor and a TXA?-synthesis inhibitor provides strong support for its potential therapeutic use in pathologies of the pulmonary vascular bed (e.g. pulmonary hypertension).  相似文献   
24.
Data from both toxin-based and gene-based models suggest that dysfunction of the microtubule system contributes to the pathogenesis of Parkinson's disease, even if, at present, no evidence of alterations of microtubules in vivo or in patients is available. Here we analyze cytoskeleton organization in primary fibroblasts deriving from patients with idiopathic or genetic Parkinson's disease, focusing on mutations in parkin and leucine-rich repeat kinase 2. Our analyses reveal that genetic and likely idiopathic pathology affects cytoskeletal organization and stability, without any activation of autophagy or apoptosis. All parkinsonian fibroblasts have a reduced microtubule mass, represented by a higher fraction of unpolymerized tubulin in respect to control cells, and display significant changes in microtubule stability-related signaling pathways. Furthermore, we show that the reduction of microtubule mass is so closely related to the alteration of cell morphology and behavior that both pharmacological treatment with microtubule-targeted drugs, and genetic approaches, by transfecting the wild type parkin or leucine-rich repeat kinase 2, restore the proper microtubule stability and are able to rescue cell architecture. Taken together, our results suggest that microtubule destabilization is a point of convergence of genetic and idiopathic forms of parkinsonism and highlight, for the first time, that microtubule dysfunction occurs in patients and not only in experimental models of Parkinson's disease. Therefore, these data contribute to the knowledge on molecular and cellular events underlying Parkinson's disease and, revealing that correction of microtubule defects restores control phenotype, may offer a new therapeutic target for the management of the disease.  相似文献   
25.
Anthropogenic impacts are an increasing threat to the diversity of fishes, especially in areas around large urban centres, and many effective conservation actions depend on accurate species identification. Considering the utility of DNA barcoding as a global system for species identification and discovery, this study aims to assemble a DNA barcode reference sequence library for marine fishes from the coastal region of São Paulo State, Brazil. The standard 652 bp ‘barcode’ fragment of the cytochrome c oxidase subunit I (COI) gene was PCR amplified and bidirectionally sequenced from 678 individuals belonging to 135 species. A neighbour‐joining analysis revealed that this approach can unambiguously discriminate 97% of the species surveyed. Most species exhibited low intraspecific genetic distances (0.31%), about 43‐fold less than the distance among species within a genus. Four species showed higher intraspecific divergences ranging from 2.2% to 7.6%, suggesting overlooked diversity. Notably, just one species‐pair exhibited barcode divergences of <1%. This library is a first step to better know the molecular diversity of marine fish species from São Paulo, providing a basis for further studies of this fauna – extending the ability to identify these species from all life stages and even fragmentary remains, setting the stage for a better understanding of interactions among species, calibrating the estimations about species composition and richness in an ecosystem, and providing tools for authenticating bioproducts and monitoring illegal species exploitation.  相似文献   
26.
The genome of Escherichia coli contains four genes assigned to the peptide transporter (PTR) family. Of these, only tppB (ydgR) has been characterized, and named tripeptide permease, whereas protein functions encoded by the yhiP, ybgH and yjdL genes have remained unknown. Here we describe the overexpression of yhiP as a His-tagged fusion protein in E. coli and show saturable transport of glycyl-sarcosine (Gly-Sar) with an apparent affinity constant of 6.5 mm. Overexpression of the gene also increased the susceptibility of cells to the toxic dipeptide alafosfalin. Transport was strongly decreased in the presence of a protonophore but unaffected by sodium depletion, suggesting H(+)-dependence. This was confirmed by purification of YhiP and TppB by nickel affinity chromatography and reconstitution into liposomes. Both transporters showed Gly-Sar influx in the presence of an artificial proton gradient and generated transport currents on a chip-based sensor. Competition experiments established that YhiP transported dipeptides and tripeptides. Western blot analysis revealed an apparent mass of YhiP of 40 kDa. Taken together, these findings show that yhiP encodes a protein that mediates proton-dependent electrogenic transport of dipeptides and tripeptides with similarities to mammalian PEPT1. On the basis of our results, we propose to rename YhiP as DtpB (dipeptide and tripeptide permease B), by analogy with the nomenclature in other bacteria. We also propose to rename TppB as DtpA, to better describe its function as the first protein of the PTR family characterized in E. coli.  相似文献   
27.
The L-arginine/agmatine antiporter AdiC is a key component of the arginine-dependent extreme acid resistance system of Escherichia coli. Phylogenetic analysis indicated that AdiC belongs to the amino acid/polyamine/organocation (APC) transporter superfamily having sequence identities of 15-17% to eukaryotic and human APC transporters. For functional and structural characterization, we cloned, overexpressed, and purified wild-type AdiC and the point mutant AdiC-W293L, which is unable to bind and consequently transport L-arginine. Purified detergent-solubilized AdiC particles were dimeric. Reconstitution experiments yielded two-dimensional crystals of AdiC-W293L diffracting beyond 6 angstroms resolution from which we determined the projection structure at 6.5 angstroms resolution. The projection map showed 10-12 density peaks per monomer and suggested mainly tilted helices with the exception of one distinct perpendicular membrane spanning alpha-helix. Comparison of AdiC-W293L with the projection map of the oxalate/formate antiporter from Oxalobacter formigenes, a member from the major facilitator superfamily, indicated different structures. Thus, two-dimensional crystals of AdiC-W293L yielded the first detailed view of a transport protein from the APC superfamily at sub-nanometer resolution.  相似文献   
28.
Summary Telomeric fingerprinting was found to be highly differentiating for Paecilomyces fumosoroseus and Paecilomyces lilacinus isolates in comparison to intron splice site PCR and is therefore a good method for quality control of future products based on these fungi. Although the telomeric restriction length polymorphisms correctly divided the isolates into their appropriate species, further correlation with host range or geographical origin of the isolates was not found. In this respect, intron splice site PCR was more informative taxonomically. The chromosome numbers inferred from telomeric fingerprints were seven chromosomes for P. lilacinus and between six and nine chromosomes for P. fumosoroseus.  相似文献   
29.
30.
G Casagrande  F Michot 《Blut》1989,59(3):231-236
The investigation described in this paper has confirmed the existence of alcohol-induced bone marrow damage as a nosological entity in alcohol-dependent individuals. In our patients total abstinence from alcohol without disulfiram or similar drugs led to reversal of the pathological findings in peripheral blood and in bone marrow. In patients undergoing detoxification while taking disulfiram, on the other hand, the pathological bone marrow findings, especially erythropoiesis associated with impaired iron utilization, persisted. The metabolic pathway of disulfiram is discussed. It is probably justifiable to assume that the toxin responsible for alcohol-induced bone marrow damage is the ethanol metabolite acetaldehyde. The persistence of erythropoiesis with impaired iron utilization during abstinence from alcohol and treatment with disulfiram is also of importance in differential diagnosis from the myelodysplastic syndrome (MDS), and especially from refractory anaemia with ring sideroblasts (RARS). For this reason, where the situation is unclear, it is essential that a diagnosis of MDS be supported by specific investigations such as cell cultures, cytogenetic analyses, etc. It is the first time that the toxic, alcohol-like-effect of disulfiram on haematopoiesis is discussed.  相似文献   
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