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91.
Jun-Min He Zhi-Hui Liu Han Xu Xiao-Ping She Chen Huang 《Plant Growth Regulation》2006,49(2-3):199-208
Previous studies have shown that UV-B could affect pollen germination and tube growth. However, the mechanism of response of pollen to UV-B has not been clear. The purpose of this study was to investigate the role of hydrogen peroxide (H2O2) in the UV-B-induced reduction of in vitro pollen germination and tube growth of Paeonia suffruticosa Andr. and Paulownia tomentosa Steud. Exposure of pollen of the two species to 0.4 and 0.8 W m−2 UV-B radiation for 3 h resulted in not only the reduction of pollen germination and tube growth, but also the H2O2 production in pollen grain and tube. Also, exogenous H2O2 inhibited pollen germination and tube growth of the two species in a dose-dependence manner. Two scavengers of H2O2, ascorbic acid and catalase, largely prevented not only the H2O2 generation, but also the reduction of pollen germination and tube growth induced by UV-B radiation in the two species. These results indicate that H2O2 is involved in the UV-B-inhibited pollen germination and tube growth. 相似文献
92.
In screening for potent antimicrobial proteins from plant seeds, a novel heat-stable antimicrobial protein, designated LJAMP2, was purified from seeds of the motherwort (Leonurus japonicus Houtt), a medicine herb, with a procedure involving cation exchange chromatography on a CM FF column, and reverse phase HPLCs on C8 column and C18 column. LJAMP2 exhibited a molecular mass of 6.2 kDa determined. Automated Edman degradation determined the partial N-terminal sequence of LJAMP2 to be NH2-AIGCNTVASKMAPCLPYVTGKGPLGGCCGGVKGLIDAARTTPDRQAVCNCLKTLAKSYSG, which displays homology with plant non-specific lipid transfer proteins (nsLTPs). In vitro bioassays showed that LJAMP2 inhibits the growth of a variety of microbes, including filamentous fungi, bacteria and yeast. The growth of three phytopathogenic fungi, Alternaria brassicae, Botrytis maydis, and Rhizoctonia cerealis, are inhibited at 7.5 μM of LJAMP2, whereas Bacillus subtilis is about 15 μM. The IC50 of LJAMP2 for Aspergillus niger, B. maydis, Fusarium oxysporum, Penicillium digitatum and Saccharomyces cerevisiae are 5.5, 6.1, 9.3, 40.0, and 76.0 μM, respectively. 相似文献
93.
The ClC family of chloride channels and transporters includes several members in which mutations have been associated with human disease. An understanding of the structure-function relationships of these proteins is essential for defining the molecular mechanisms underlying pathogenesis. To date, the X-ray crystal structures of prokaryotic ClC transporter proteins have been used to model the membrane domains of eukaryotic ClC channel-forming proteins. Clearly, the fidelity of these models must be evaluated empirically. In the present study, biochemical tools were used to define the membrane domain boundaries of the eukaryotic protein, ClC-2, a chloride channel mutated in cases of idiopathic epilepsy. The membrane domain boundaries of purified ClC-2 and accessible cysteine residues were determined after its functional reconstitution into proteoliposomes, labelling using a thiol reagent and proteolytic digestion. Subsequently, the lipid-embedded and soluble fragments generated by trypsin-mediated proteolysis were studied by MS and coverage of approx. 71% of the full-length protein was determined. Analysis of these results revealed that the membrane-delimited boundaries of the N- and C-termini of ClC-2 and the position of several extramembrane loops determined by these methods are largely similar to those predicted on the basis of the prokaryotic protein [ecClC (Escherichia coli ClC)] structures. These studies provide direct biochemical evidence supporting the relevance of the prokaryotic ClC protein structures towards understanding the structure of mammalian ClC channel-forming proteins. 相似文献
94.
Disordered osteoclast formation in RAGE-deficient mouse establishes an essential role for RAGE in diabetes related bone loss 总被引:3,自引:0,他引:3
Ding KH Wang ZZ Hamrick MW Deng ZB Zhou L Kang B Yan SL She JX Stern DM Isales CM Mi QS 《Biochemical and biophysical research communications》2006,340(4):1091-1097
The mechanisms underlying diabetes-mediated bone loss are not well defined. It has been reported that the advanced glycation endproducts (AGEs) and receptor for AGEs (RAGEs) are involved in diabetic complications. Here, mice deficient in RAGE were used as a model for investigating the effects of RAGE on bone mass. We found that RAGE-/- mice have a significantly increased bone mass and bone biomechanical strength and a decreased number of osteoclasts compared to wild-type mice. The serum levels of IL-6 and bone breakdown marker pyridinoline were significantly decreased in RAGE-/- mice. RAGE-/- mice maintain bone mass following ovariectomy, whereas wild-type mice lose bone mass. Furthermore, osteoclast-like cells do express RAGE mRNA. Our data therefore indicate that RAGE serves as a positive factor to regulate the osteoclast formation, directly implicates a role for RAGE in diabetes-promoted bone destruction, and documents that the AGE-RAGE interaction may account for diabetes associated bone loss. 相似文献
95.
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97.
The effects of Aluminum (Al) exposure on immune functions of cultured splenic T and B lymphocytes of rats were studied. The lymphocytes were isolated from spleen of healthy male Wistar rats weighing 110-120 g. The cultured cells in RPMI-1640 medium were exposed to 0 (control group), 0.035 (low-dose group), 0.07 (medial-dose group), and 0.14 (high-dose group) mg/mL Al(3+) as aluminum trichloride (AlCl(3)) in an incubator under 5% CO(2) at 37°C for 24 h. The T and B lymphocyte proliferation was measured with a tetrazolium dye colorimetric assay. The levels of interleukin (IL)-2, IL-6, and tumor necrosis factor (TNF)-α were determined by iodine [(125)I] IL-2, IL-6, and TNF-α radioimmunoassay kits, respectively. The proportions of CD3(+), CD4(+), and CD8(+) T lymphocytes were measured with a flow cytometer. The results showed that the T and B lymphocyte proliferation, the levels of IL-2, IL-6, TNF-α, the proportions of CD3(+) and CD4(+) T lymphocytes, and the ratio of CD4(+)/CD8(+) T lymphocytes were lowered by Al treatments, while the proportion of CD8(+) T lymphocytes was increased. These findings indicate that Al exposure can inhibit the immune functions of splenic T and B lymphocytes of rats in vitro. 相似文献
98.
Cell-free formation of RNA granules: low complexity sequence domains form dynamic fibers within hydrogels 总被引:2,自引:0,他引:2
Kato M Han TW Xie S Shi K Du X Wu LC Mirzaei H Goldsmith EJ Longgood J Pei J Grishin NV Frantz DE Schneider JW Chen S Li L Sawaya MR Eisenberg D Tycko R McKnight SL 《Cell》2012,149(4):753-767
Eukaryotic cells contain assemblies of RNAs and proteins termed RNA granules. Many proteins within these bodies contain KH or RRM RNA-binding domains as well as low complexity (LC) sequences of unknown function. We discovered that exposure of cell or tissue lysates to a biotinylated isoxazole (b-isox) chemical precipitated hundreds of RNA-binding proteins with significant overlap to the constituents of RNA granules. The LC sequences within these proteins are both necessary and sufficient for b-isox-mediated aggregation, and these domains can undergo a concentration-dependent phase transition to a hydrogel-like state in the absence of the chemical. X-ray diffraction and EM studies revealed the hydrogels to be composed of uniformly polymerized amyloid-like fibers. Unlike pathogenic fibers, the LC sequence-based polymers described here are dynamic and accommodate heterotypic polymerization. These observations offer a framework for understanding the function of LC sequences as well as an organizing principle for cellular structures that are not membrane bound. 相似文献
99.
Yongmei Hu Nan Peng Wenyuan Han Yuxia Mei Zhengjun Chen Xu Feng Yun?Xiang Liang Qunxin She 《Bioscience reports》2012,32(6):609-618
A putative protease gene (tldD) was previously identified from studying tolerance of letD encoding the CcdB toxin of a toxin–antidote system of the F plasmid in Escherichia coli. While this gene is evolutionarily conserved in archaea and bacteria, the proteolytic activity of encoded proteins remained to be demonstrated experimentally. Here we studied Sso0660, an archaeal TldD homologue encoded in Sulfolobus solfataricus by overexpression of the recombinant protein and characterization of the purified enzyme. We found that the enzyme is active in degrading azocasein and FITC–BSA substrates. Protease inhibitor studies showed that EDTA and o-phenanthroline, two well-known metalloprotease inhibitors, either abolished completely or strongly inhibited the enzyme activity, and flame spectrometric analysis showed that a zinc ion is a cofactor of the protease. Furthermore, the protein forms disulfide bond via the Cys416 residue, yielding protein dimer that is the active form of the enzyme. These results establish for the first time that tidD genes encode zinc-containing proteases, classifying them as a family in the metalloprotease class. 相似文献
100.
Xia X Zhang J Zhang Y Wei F Liu X Jia A Liu C Li W She Z Lin Y 《Bioorganic & medicinal chemistry letters》2012,22(8):3017-3019
Three new pimarane diterpenes (1, 2 and 3) as well as a known compound 4, were isolated from the marine-derived fungus HS-1 from Apostichopus japonicus. Their structures and relative stereochemistry of 1-3 were elucidated using a combination of NMR spectroscopy and CD. In the primary bioassay, compounds 1, 2 and 4 inhibited the growth of KB and KBv200 with IC(50) of 3.51, 2.34 μg/mL, 20.74, 14.47 μg/mL, and 3.86, 6.52 μg/mL, respectively. 相似文献