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121.
AIMS: Antimicrobial resistance of Shigella sonnei from Malaysia was determined and subtyping was carried by pulsed-field gel electrophoresis (PFGE) to assess the extent of genetic diversity of these strains. METHODS AND RESULTS: A total of 62 isolates of S. sonnei from sporadic cases of shigellosis in different parts of Malaysia were studied by antimicrobial susceptibility test and PFGE. Approximately 35.5% of the strains showed resistance to three or more antimicrobial agents. Eight resistant phenotypes, i.e. RI to RVIII, was defined. Resistant phenotype RV and RVIII only appeared in year 2000. PFGE analysis with NotI and XbaI restriction showed that a great heterogeneity existed at the DNA level among Malaysian S. sonnei isolates. Fifty-eight NotI and 61 XbaI-PFGE profiles were observed in 63 S. sonnei isolates, including ATCC 11060 isolate. Drug sensitive isolates displayed very different profiles from drug-resistant isolates, with a few exceptions. Isolates of resistant phenotype RVI (SXTr.TETr.STRr) showed a greater similarity among each other compared with isolates of resistant phenotype RI and drug-sensitive isolates. CONCLUSION: Multi-drug-resistant S. sonnei were circulated in different parts of Malaysia and the emergence of new resistant phenotype was observed. Wide genetic variations among Malaysian S. sonnei were observed and the drug-sensitive strains could be differentiated from drug-resistant strains by PFGE. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study verifies the usefulness of PFGE in characterizing and comparing strains of S. sonnei. Minor variations among S. sonnei isolates could be detected by PFGE. 相似文献
122.
Mukherjee M Chow SY Yusoff P Seetharaman J Ng C Sinniah S Koh XW Asgar NF Li D Yim D Jackson RA Yew J Qian J Iyu A Lim YP Zhou X Sze SK Guy GR Sivaraman J 《The EMBO journal》2012,31(5):1308-1319
Phosphotyrosine-binding domains, typified by the SH2 (Src homology 2) and PTB domains, are critical upstream components of signal transduction pathways. The E3 ubiquitin ligase Hakai targets tyrosine-phosphorylated E-cadherin via an uncharacterized domain. In this study, the crystal structure of Hakai (amino acids 106-206) revealed that it forms an atypical, zinc-coordinated homodimer by utilizing residues from the phosphotyrosine-binding domain of two Hakai monomers. Hakai dimerization allows the formation of a phosphotyrosine-binding pocket that recognizes specific phosphorylated tyrosines and flanking acidic amino acids of Src substrates, such as E-cadherin, cortactin and DOK1. NMR and mutational analysis identified the Hakai residues required for target binding within the binding pocket, now named the HYB domain. ZNF645 also possesses a HYB domain but demonstrates different target specificities. The HYB domain is structurally different from other phosphotyrosine-binding domains and is a potential drug target due to its novel structural features. 相似文献
123.
Joo-Yong Lee Eunsil Cho Tae-Youn Kim Dong-Kyu Kim Richard D. Palmiter Irene Volitakis Jong S. Kim Ashley I. Bush Jae-Young Koh 《Biometals》2010,23(6):1085-1095
Both apolipoprotein E (apoE) and zinc are involved in amyloid β (Aβ) aggregation and deposition, in the hallmark neuropathology
of Alzheimer’s disease (AD). Recent studies have suggested that interaction of apoE with metal ions may accelerate amyloidogenesis
in the brain. Here we examined the impact of apoE deficiency on the histochemically reactive zinc pool in the brains of apoE
knockout mice. While there was no change in total contents of metals (zinc, copper, and iron), the level of histochemically
reactive zinc (principally synaptic zinc) was significantly reduced in the apoE-deficient brain compared to wild-type. This
reduction was accompanied by reduced expressions of the presynaptic zinc transporter, ZnT3, as well as of the δ-subunit of
the adaptor protein complex-3 (AP3δ), which is responsible for post-translational stability and activity of ZnT3. In addition,
the level of histochemically reactive zinc was also decreased in the cerebrovascular micro-vessels of apoE-deficient mice,
the site of cerebral amyloid angiopathy in AD. These results suggest that apoE may affect the cerebral free zinc pool that
contributes to AD pathology. 相似文献
124.
A novel zinc finger protein that inhibits osteoclastogenesis and the function of tumor necrosis factor receptor-associated factor 6. 总被引:7,自引:0,他引:7
Jin Na Shin Injune Kim Jung Sup Lee Gou Young Koh Zang Hee Lee Hong-Hee Kim 《The Journal of biological chemistry》2002,277(10):8346-8353
A variety of surface receptors eliciting diverse cellular responses have been shown to recruit tumor necrosis factor receptor-associated factor (TRAF) adaptor molecules. However, a few TRAF-interacting intracellular proteins that serve as downstream targets or regulators of TRAF function have been identified. In search of new intracellular molecules that bind TRAF6, we carried out a yeast two-hybrid cDNA library screening with an N-terminal segment of TRAF6 as the bait. A novel human C(2)H(2)-type zinc finger family protein was identified, which when coexpressed with TRAF6 led to a suppression of TRAF6-induced activation of NF-kappa B and c-Jun N-terminal kinase. This novel protein was designated TIZ (for TRAF6-inhibitory zinc finger protein). TIZ expression also inhibited the signaling of RANK (receptor activator of NF-kappa B), which together with TRAF6 has been shown to be essential for osteoclastogenesis. Furthermore, the expression level of TIZ appeared to be regulated during the differentiation of human peripheral blood monocytes into osteoclasts. More significantly, transfection of TIZ into the monocyte/macrophage cell line Raw264.7 reduced the RANK ligand-induced osteoclastogenesis of this cell line. Our findings suggest that the novel zinc finger protein TIZ may play a role during osteoclast differentiation by modulating TRAF6 signaling activity. 相似文献
125.
Brian Koh 《The Yale journal of biology and medicine》2003,76(4-6):201-202
126.
127.
T-DNA-tagged rice plants were screened under cold- or salt-stress conditions to determine the genes involved in the molecular
mechanism for their abiotic-stress response. Line 0-165-65 was identified as a salt-responsive line. The gene responsible
for this GUS-positive phenotype was revealed by inverse PCR as OsGSK1 (O
ryza
s
ativa
g
lycogen
s
ynthase
k
inase3-like gene
1), a member of the plant GSK3/SHAGGY-like protein kinase genes and an orthologue of the Arabidopsis
b
rassinosteroid
in
sensitive
2
(BIN2), AtSK21. Northern blot analysis showed that OsGSK1 was most highly detected in the developing panicles, suggesting that its expression is developmental stage specific. Knockout
(KO) mutants of OsGSK1 showed enhanced tolerance to cold, heat, salt, and drought stresses when compared with non-transgenic segregants (NT). Overexpression
of the full-length OsGSK1 led to a stunted growth phenotype similar to the one observed with the gain-of-function BIN/AtSK21 mutant. This suggests that OsGSK1 might be a functional rice orthologue that serves as a negative regulator of brassinosteroid (BR)-signaling. Therefore, we
propose that stress-responsive OsGSK1 may have physiological roles in stress signal-transduction pathways and floral developmental processes.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
Serry Koh and Sang-Choon Lee are co-first authors. 相似文献
128.
Ashworth R Devogelaere B Fabes J Tunwell RE Koh KR De Smedt H Patel S 《The Journal of biological chemistry》2007,282(19):13984-13993
Fluctuations in cytosolic Ca(2+) are crucial for a variety of cellular processes including many aspects of development. Mobilization of intracellular Ca(2+) stores via the production of inositol trisphosphate (IP(3)) and the consequent activation of IP(3)-sensitive Ca(2+) channels is a ubiquitous means by which diverse stimuli mediate their cellular effects. Although IP(3) receptors have been well studied at fertilization, information regarding their possible involvement during subsequent development is scant. In the present study we examined the role of IP(3) receptors in early development of the zebrafish. We report the first molecular analysis of zebrafish IP(3) receptors which indicates that, like mammals, the zebrafish genome contains three distinct IP(3) receptor genes. mRNA for all isoforms was detectable at differing levels by the 64 cell stage, and IP(3)-induced Ca(2+) transients could be readily generated (by flash photolysis) in a controlled fashion throughout the cleavage period in vivo. Furthermore, we show that early blastula formation was disrupted by pharmacological blockade of IP(3) receptors or phospholipase C, by molecular inhibition of the former by injection of IRBIT (IP(3) receptor-binding protein released with IP(3)) and by depletion of thapsigargin-sensitive Ca(2+) stores after completion of the second cell cycle. Inhibition of Ca(2+) entry or ryanodine receptors, however, had little effect. Our work defines the importance of IP(3) receptors during early development of a genetically and optically tractable model vertebrate organism. 相似文献
129.
Gene transfer techniques possess tremendous potential for treating diseases and for facilitating the study of basic physiological processes. However, further development of efficient and safe methods for gene transfer is needed. The purpose of this study was to test the hypothesis that mechanical strain increases the transfer of DNA to differentiated skeletal muscle cells. We tested this hypothesis by applying cyclic strain to cultured skeletal myotubes either prior to or immediately after the introduction of exogenous DNA complexed with lipids, with strains of varying magnitude (10%, 20% and 30%), number (1800, 3600 and 7200 strain cycles) and frequency (0.5, 1.0 and 1.5 Hz). Results demonstrated that DNA transfection was increased by exposing muscle cells to cyclic strain, and that strain magnitude, number and frequency each influenced DNA transfection. Optimal strain conditions (20% strain magnitude, 3600 cycles applied at 1 Hz) were utilized to examine the role of membrane transport systems in strain-induced increases in DNA transfection. Filipin III was used to inhibit caveolar transport and was found to inhibit strain-mediated increases in DNA transfection, whereas chlorpromazine, used to inhibit clathrin-coated vesicle transport, had no effect. These results indicate that mechanical strain may be an effective method for increasing DNA transfection in skeletal muscle through enhanced caveolar transport. 相似文献
130.
Hydrogen Peroxide-Dependent Uptake of Iodine by Marine Flavobacteriaceae Bacterium Strain C-21 下载免费PDF全文
Seigo Amachi Koh Kimura Yasuyuki Muramatsu Hirofumi Shinoyama Takaaki Fujii 《Applied microbiology》2007,73(23):7536-7541
The cells of the marine bacterium strain C-21, which is phylogenetically closely related to Arenibacter troitsensis, accumulate iodine in the presence of glucose and iodide (I−). In this study, the detailed mechanism of iodine uptake by C-21 was determined using a radioactive iodide tracer, 125I−. In addition to glucose, oxygen and calcium ions were also required for the uptake of iodine. The uptake was not inhibited or was only partially inhibited by various metabolic inhibitors, whereas reducing agents and catalase strongly inhibited the uptake. When exogenous glucose oxidase was added to the cell suspension, enhanced uptake of iodine was observed. The uptake occurred even in the absence of glucose and oxygen if hydrogen peroxide was added to the cell suspension. Significant activity of glucose oxidase was found in the crude extracts of C-21, and it was located mainly in the membrane fraction. These findings indicate that hydrogen peroxide produced by glucose oxidase plays a key role in the uptake of iodine. Furthermore, enzymatic oxidation of iodide strongly stimulated iodine uptake in the absence of glucose. Based on these results, the mechanism was considered to consist of oxidation of iodide to hypoiodous acid by hydrogen peroxide, followed by passive translocation of this uncharged iodine species across the cell membrane. Interestingly, such a mechanism of iodine uptake is similar to that observed in iodine-accumulating marine algae. 相似文献