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141.
Anja Reinstädler Judith Müller Jerzy H Czembor Pietro Piffanelli Ralph Panstruga 《BMC plant biology》2010,10(1):31
Background
Recessively inherited natural and induced mutations in the barley Mlo gene confer durable broad-spectrum resistance against the powdery mildew pathogen, Blumeria graminis f.sp. hordei. Mlo codes for a member of a plant-specific family of polytopic integral membrane proteins with unknown biochemical activity. Resistant barley mlo mutant alleles identify amino acid residues that are critical for Mlo function in the context of powdery mildew susceptibility. 相似文献142.
Reduction of 17-ketosteroids is a biocatalytic process of economic significance for the production of steroid drugs. This reaction can be catalyzed by different microbial 17beta-hydroxysteroid dehydrogenases (17beta-HSD), like the 17beta-HSD activity of Saccharomyces cerevisiae, Pichia faranosa and Mycobacterium sp., and by purified 3beta,17beta-HSD from Pseudomonas testosteroni. In addition to the bacterial 3beta,17beta-HSD the 17beta-HSD of the filamentous fungus Cochliobolus lunatus is the only microbial 17beta-HSD that has been expressed as a recombinant protein and fully characterized. On the basis of its modeled 3D structure, we selected several positions for the replacement of amino acids by site-directed mutagenesis to change substrate specificity, alter coenzyme requirements, and improve overall catalytic activity. Replacement of Val161 and Tyr212 in the substrate-binding region by Gly and Ala, respectively, increased the initial rates for the conversion of androstenedione to testosterone. Replacement of Tyr49 within the coenzyme binding site by Asp changed the coenzyme specificity of the enzyme. This latter mutant can convert the steroids not only in the presence of NADP(+) and NADPH, but also in the presence of NADH and NAD(+). The replacement of His164, located in the non-flexible part of the 'lid' covering the active center resulted in a conformation of the enzyme that possessed a higher catalytic activity. 相似文献
143.
144.
145.
Infections with gastrointestinal (GI) nematodes are amongst the most prevalent worldwide, especially in tropical climates. Control of these infections is primarily through treatment with anthelmintic drugs, but the rapid development of resistance to all the currently available classes of anthelmintic means that alternative treatments are urgently required. Cysteine proteinases from plants such as papaya, pineapple and fig are known to be substantially effective against three rodent GI nematodes, Heligmosomoides polygyrus, Trichuris muris and Protospirura muricola, both in vitro and in vivo. Here, based on in vitro motility assays and scanning electron microscopy, we extend these earlier reports, demonstrating the potency of this anthelmintic effect of plant cysteine proteinases against two GI helminths from different taxonomic groups - the canine hookworm, Ancylostoma ceylanicum, and the rodent cestode, Rodentolepis microstoma. In the case of hookworms, a mechanism of action targeting the surface layers of the cuticle indistinguishable from that reported earlier appears to be involved, and in the case of cestodes, the surface of the tegumental layers was also the principal location of damage. Hence, plant cysteine proteinases have a broad spectrum of activity against intestinal helminths (both nematodes and cestodes), a quality that reinforces their suitability for development as a much-needed novel treatment against GI helminths of humans and livestock. 相似文献
146.
Zhai Y Wang Y Wu Z Kupiec-Weglinski JW 《Journal of immunology (Baltimore, Md. : 1950)》2007,179(7):4529-4534
We have shown that alloreactive CD8 T cell activation may proceed via CD4-dependent and CD4-independent pathways, and that CD8 T cell activation in Ag-primed animals is independent of CD154 costimulation. In this report, we further analyzed the activation and function of alloreactive CD8 CTL effectors in CD4 knockout (KO) skin/cardiac allograft recipients. FACS analysis showed that alloreactive CD8 T cells were activated at a significantly reduced level in CD4 KO mice. Importantly, these helpless CD8 T cells failed to develop CD154 blockade resistance following reactivation by the same alloantigen, indicative of defective memory formation. Only transient CD4 help was required, as short-term CD4 blockade at the time of first skin graft challenge only delayed alloreactive CD8 activation, without affecting the CD8 T cell memory response to a second skin graft. Moreover, postoperative CD4 blockade had no effect on alloreactive CD8 activation. Alloreactive CD8 cells generated in the absence of CD4 help exhibited decreased effector responses. Interestingly, intragraft induction of T cell-targeted chemokines early after transplant was also dependent on CD4 help, as the induction kinetics of CXCL9 and CCL5 in CD4 KO recipients was significantly delayed, coupled with similarly delayed infiltration by CD3/CD8 cells. Remarkably, helpless CD8 cells ultimately entering the graft still displayed significantly diminished T cell effector molecules (IFN-gamma, granzyme B). Thus, CD4 help is critical for alloreactive CD8 activation, function, and memory formation. 相似文献
147.
Serum soluble Fas ligand (sFasL) in patients with primary squamous cell carcinoma of the esophagus 总被引:1,自引:0,他引:1
Kozlowski M Kowalczuk O Sulewska A Dziegielewski P Lapuc G Laudanski W Niklinska W Chyczewski L Niklinski J Laudanski J 《Folia histochemica et cytobiologica / Polish Academy of Sciences, Polish Histochemical and Cytochemical Society》2007,45(3):199-204
Esophageal carcinomas have been shown to express Fas ligand (FasL) and down-regulate Fas to escape from host immune surveillance. Circulating soluble FasL (sFasL) has been suggested to provide protection from Fas-mediated apoptosis. The aim of this study was to assess serum sFasL levels in esophageal cancer. The pretreatment levels of sFasL in the serum of 100 patients with esophageal squamous cell cancer and 41 healthy volunteers were determined by ELISA. Probability of survival was calculated according to the method of Kaplan-Meier. The prognostic influence of high and low level of sFasL was analyzed with the log-rank test. The mean serum level of sFasL in patients with esophageal cancer was significantly higher than that in healthy donors (1.567+/-1.786 vs 0.261+/-0.435, p<0.0001). The levels of serum sFasL were significantly higher in advanced stages (II vs IV p<0.034; III vs IV p<0.041; except II vs III p=0.281), patients with lymph node (N0 vs N1 p<0.0389) or distant (M0 vs. M1 p<0.0388) metastases and significantly lower in patients with well differentiated tumors (G1 vs G2 p<0.0272). The serum levels of soluble FasL were not related to gender, age, tumor size, T-stage, tobacco smoking and history of chronic alcohol intake. The survival difference between pretreatment high and low level of sFasL in surgery and chemio- and/or radiotherapy group was not statistically significant (p=0.525; p=0.840). Our results indicate that elevated serum sFasL levels might be associated with a disease progression in patients with esophageal squamous cell carcinoma. 相似文献
148.
17beta-Hydroxysteroid dehydrogenase from the fungus Cochliobolus lunatus (17beta-HSDcl) is an NADPH-dependent member of the short-chain dehydrogenase/ reductase superfamily. To study the catalytic properties of this enzyme, we prepared several specific mutations of 17beta-HSDcl (Tyr167Phe, His164Trp/Gly, Tyr212Ala). Wild-type 17beta-HSDcl and the 17beta-HSDcl mutants were evaluated by chromatographic, kinetic and thermodynamic means. The Tyr167Phe mutation resulted in a complete loss of enzyme activity, while substitution of His164 with Trp and Gly both resulted in higher specificity number (V/K) for the steroid substrates, which are mainly a consequence of easier accessibility of steroid substrates to the active-site hollow under optimized conditions. The Tyr212Ala mutant showed increased activity in the oxidative direction, which appears to be a consequence of increased NADPH dissociation. The kinetic characterizations and thermodynamic analyses also suggest that His164 and Tyr212 in 17beta-HSDcl have a role in the opening and closing of the active site of this enzyme and in the discrimination between oxidized and reduced coenzyme. 相似文献
149.
Polish Arabian horses are one of the oldest and the most important Arab populations in the world. The Polish Arabian Stud Book and the Genealogical Charts by Skorkowski are the main sources of information on the ancestors of Polish Arabs. Both publications were viewed as credible sources of information until the 1990s when the data regarding one of the dam lines was questioned. The aim of the current study was to check the accuracy of the pedigree data of Polish dam lines using mtDNA analysis. The analyses of a 458 bp mtDNA D-loop fragment from representatives of 15 Polish Arabian dam lines revealed 14 distinct haplotypes. The results were inconsistent with pedigree data in the case of two lines. A detailed analysis of the historical sources was performed to explain these discrepancies. Our study revealed that representatives of different lines shared the same haplotypes. We also noted a genetic identity between some lines founded by Polish mares of unknown origin and lines established by desert-bred mares. 相似文献
150.
Recent findings showing that acrylamide is formed in heat-treated foods rich in asparagine and reducing sugars such as glucose, have accelerated the needs for the development of new analytical methods to determine this potential human carcinogen. Acrylamide forms adduct with hemoglobin (Hb) as a result of the reaction with the alpha-NH2 group of N-terminal valine of Hb. This interaction is the basis of a new voltammetric biosensor to detect acrylamide. The biosensor was constructed using a carbon-paste electrode modified with hemoglobin (Hb), which contains four prosthetic groups of heme--Fe(III). Such an electrode displays a reversible reduction/oxidation process of Hb-Fe(III)/Hb-Fe(II). Interaction between Hb and acrylamide was observed through decreasing of the peak current of Hb-Fe(III) reduction. The electrodes presented a very low detection limit (1.2 x 10(-10)M). The validation made in the matrix obtained by water extraction of potato chips showed that the electrodes presented are suitable for the direct determination of acrylamide in food samples. 相似文献