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51.
52.
Hydroquinone is a benzene-derived metabolite. To clarify whether the reactive oxygen species (ROS) are involved in hydroquinone-induced cytotoxicity, we constructed transformants of Escherichia coli (E. coli) strains that express mammalian catalase gene derived from catalase mutant mice (Cs(b), Cs(c)) and the wild-type (Cs(a)) using a catalase-deficient E. coli UM255 as a recipient. Specific catalase activities of these tester strains were in order of Cs(a) > Cs(c) > Cs(b) > UM255, and their susceptibility to hydrogen peroxide (H2O2) showed UM255 > Cs(b) > Cs(c) > Cs(a). We found that hydroquinone exposure reduced the survival of catalase-deficient E. coli mutants in a dose-dependent manner significantly, especially in the strains with lower catalase activities. Hydroquinone toxicity was also confirmed using zone of inhibition test, in which UM255 was the most susceptible, showing the largest zone of growth inhibition, followed by Cs(b), Cs(c) and Cs(a). Furthermore, we found that hydroquinone-induced cell damage was inhibited by the pretreatment of catalase, ascorbic acid, dimethyl sulfoxide (DMSO), and ethylenediaminetetraacetic acid (EDTA), and augmented by superoxide dismutase (both CuZnSOD and MnSOD). The present results suggest that H2O2 is probably involved in hydroquinone-induced cytotoxicity in catalase-deficient E. coli mutants and catalase plays an important role in protection of the cells against hydroquinone toxicity. 相似文献
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Identification and the role of soluble antigens detected in bile from Eimeria stiedai-infected rabbits 总被引:2,自引:0,他引:2
Omata Y Sueda M Koyama T Tanabe S Uzuka Y Sarashina T Makino S Maeda R Saito A Mikami T 《The Journal of parasitology》2001,87(2):287-291
Antibodies against Eimeria stiedai sporozoites and merozoites were detected in the sera of rabbits immunized with bile obtained from infected rabbits on the 15th day post-infection. The trails made by gliding sporozoites were also detected by the sera. After penetration into the host cell, an antibody-binding region was observed on the parasitophorous vacuole membranes of the parasites. Rabbits administered a combination of the bile and cholera toxin shed fewer oocysts in the feces after infection than control rabbits. The immunized rabbits developed a high level of IgA antibody against soluble antigens in the bile. By immunoblotting, antigens with molecular masses of 32, 37, and 49 kDa were detected in the bile obtained from infected rabbits on the 15th day postinfection. Absorption treatment with sporozoites reduced or abolished the antibody reactivity to the 32-kDa antigen of merozoites and the bile antigens. However, antibody reactivity to the 37- and 49-kDa antigens still remained. These results indicate that soluble antigens are present in the bile of rabbits in the acute phase of infection, and these may be produced and released by merozoites during the host cell invasion process. 相似文献
55.
Shi C Eshleman SH Jones D Fukushima N Hua L Parker AR Yeo CJ Hruban RH Goggins MG Eshleman JR 《Nature methods》2004,1(2):141-147
We developed the LigAmp assay for sensitive detection and accurate quantification of viruses and cells with single-base mutations. In LigAmp, two oligonucleotides are hybridized adjacently to a DNA template. One oligonucleotide matches the target sequence and contains a probe sequence. If the target sequence is present, the oligonucleotides are ligated together and detected using real-time PCR. LigAmp detected KRAS2 mutant DNA at 0.01% in mixtures of different cell lines. KRAS2 mutations were also detected in pancreatic duct juice from patients with pancreatic cancer. LigAmp detected the K103N HIV-1 drug resistance mutation at 0.01% in plasmid mixtures and at approximately 0.1% in DNA amplified from plasma HIV-1. Detection in both systems is linear over a broad dynamic range. Preliminary evidence indicates that reactions can be multiplexed. This assay may find applications in the diagnosis of genetic disorders and the management of patients with cancer and infectious diseases. 相似文献
56.
Noriyoshi Arai 《Molecular simulation》2015,41(10-12):996-1001
A telechelic polymer is an amphiphilic polymer that can form micellar structures when dissolved in water. A telechelic polymer solution shows viscoelastic behaviour owing to the formation of characteristic networks, i.e. loops, bridges and dangling chains. For industrial purposes, telechelic polymers have many applications as thickening agents, such as in paints and cosmetics. Thus, it is desirable to predict and control the rheological properties of telechelic polymers. However, detailed studies at the molecular level have not yet been performed. In this study, I use the dissipative particle dynamics (DPD) method to investigate the relationship between the characteristic structural properties and the molecular structure in telechelic polymer solutions. I show that the morphology of telechelic polymer solutions depends on the concentration and chain length, the distribution of the end-to-end distance, the mean square end-to-end distance, the mean square radius of gyration and the time-averaged mean square displacement. Although an effect of entanglement is important for properties of polymer melts, the polymer chain composed of DPD particles cannot reproduce it. Therefore, I compare telechelic polymer solutions with and without the segmental repulsive potential (SRP), which can simulate the effect of entanglement in DPD simulations. The results indicate that it is necessary to include the SRP in DPD simulations to correctly analyse the behaviour of telechelic polymer solutions. 相似文献
57.
Wataru Nunomura Yuji Jinbo Noriyoshi Isozumi Shinya Ohki Yoshinobu Izumi Norio Matsushima Yuichi Takakuwa 《Cell biochemistry and biophysics》2013,66(3):545-558
Protein 4.1G (4.1G) is a widely expressed member of the protein 4.1 family of membrane skeletal proteins. We have previously reported that Ca2+-saturated calmodulin (Ca2+/CaM) modulates 4.1G interactions with transmembrane and membrane-associated proteins through binding to Four.one-ezrin–radixin–moesin (4.1G FERM) domain and N-terminal headpiece region (GHP). Here we identify a novel mechanism of Ca2+/CaM-mediated regulation of 4.1G interactions using a combination of small-angle X-ray scattering, nuclear magnetic resonance spectroscopy, and circular dichroism spectroscopy analyses. We document that GHP intrinsically disordered coiled structure switches to a stable compact structure upon binding of Ca2+/CaM. This dramatic conformational change of GHP inhibits in turn 4.1G FERM domain interactions due to steric hindrance. Based upon sequence homologies with the Ca2+/CaM-binding motif in protein 4.1R headpiece region, we establish that the 4.1G S71RGISRFIPPWLKKQKS peptide (pepG) mediates Ca2+/CaM binding. As observed for GHP, the random coiled structure of pepG changes to a relaxed globular shape upon complex formation with Ca2+/CaM. The resilient coiled structure of pepG, maintained even in the presence of trifluoroethanol, singles it out from any previously published CaM-binding peptide. Taken together, these results show that Ca2+/CaM binding to GHP, and more specifically to pepG, has profound effects on other functional domains of 4.1G. 相似文献
58.
59.
Minori Shinya Kayo Kobayashi Aki Masuda Mika Tokumoto Yuichi Ozaki Kenji Saito Toshihiro Kawasaki Yukiko Sado Noriyoshi Sakai 《Development, growth & differentiation》2013,55(9):755-765
RNA interference (RNAi) has emerged as a powerful tool to silence specific genes. Vector‐based RNAi systems have been developed to downregulate targeted genes in a spatially and temporally regulated fashion both in vitro and in vivo. The zebrafish (Danio rerio) is a model animal that has been examined based on a wide variety of biological techniques, including embryonic manipulations, forward and reverse genetics, and molecular biology. However, a heritable and tissue‐specific knockdown of gene expression has not yet been developed in zebrafish. We examined two types of vector, which produce small interfering RNA (siRNA), the direct effector in RNAi system; microRNA (miRNA) process mimicking vectors with a promoter for RNA polymerase II and short hairpin RNA (shRNA) expressing vector through a promoter for RNA polymerase III. Though gene‐silencing phenotypes were not observed in the miRNA process mimicking vectors, the transgenic embryos of the second vector (Tg(zU6‐shGFP)), shRNA expressing vector for enhanced green fluorescence protein, revealed knockdown of the targeted gene. Interestingly, only the embryos from Tg(zU6‐shGFP) female but not from the male fish showed the downregulation. Comparison of the quantity of siRNA produced by each vector indicates that the vectors tested here induced siRNA, but at low levels barely sufficient to silence the targeted gene. 相似文献
60.
Protein A from Staphylococcus aureus specifically binds to the Fc region of immunoglobulin G (IgG) and is widely used as a scaffold for the immobilization of IgG antibodies on solid supports. It is known that the oriented immobilization of Protein A on solid supports enhances its antibody-binding capability in comparison with immobilization in a random manner. In the current work, we developed a novel method for the oriented immobilization of the IgG-binding domain of Protein A based on the biotinylation reaction from archaeon Sulfolobus tokodaii. Biotinylation from S. tokodaii has a unique property in that the enzyme, biotin protein ligase (BPL), forms a stable complex with its biotinylated substrate protein, biotin carboxyl carrier protein (BCCP). Here, BCCP was fused to the IgG-binding domain of Protein A, and the resulting fusion protein was immobilized on the BPL-modified gold surface of the sensor chip for quartz crystal microbalance through complexation between BCCP and BPL. The layer of the IgG-binding domain prepared in this way successfully captured the antibody, and the captured antibody retained high antigen-binding capability. 相似文献