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941.
While conducting experiments to investigate antimicrobial peptides of amphibians living in the Yunnan-Guizhou region of southwest China, a new family of antimicrobial peptides was identified from skin secretions of the Yunnan frog, Rana pleuraden. Members of the new peptide family named pleurain-As are composed of 26 amino acids with a unique N-terminal sequence (SIIT) and a disulfide-bridged heptapeptide sequence (CRLYNTC). By BLAST search, pleurain-As had no significant similarity to any known peptides. Native and synthetic peptides showed antimicrobial activities against tested microorganisms including Gram-negative and Gram-positive bacteria and fungi. Twenty different cDNAs encoding pleurain-As were cloned from the skin cDNA library of R. pleuraden. The precursors of pleurain-As are composed of 69 amino acid residues including predicted signal peptides, acidic propieces, and cationic mature antimicrobial peptides. The preproregion of pleurain-A precursor comprises a hydrophobic signal peptide of 22 residues followed by an 18 residue acidic propiece which terminates by a typical prohormone processing signal Lys-Arg. The preproregions of precursors are very similar to other amphibian antimicrobial peptide precursors but the mature pleurain-As are different from other antimicrobial peptide families. The remarkable similarity of preproregions of precursors that give rise to very different antimicrobial peptides in distantly related frog species suggests that the corresponding genes form a multigene family originating from a common ancestor. Furthermore, pleurain-As could exert antimicrobial capability against Helicobacter pylori. This is the first report of naturally occurring peptides with anti-H. pylori activity from Rana amphibians. 相似文献
942.
YwhB, a 4-oxalocrotonate tautomerase (4-OT) homologue in Bacillus subtilis, has no known biological role, and the gene has no apparent genomic context. The kinetic and stereochemical properties of YwhB have been examined using available enol and dienol compounds. The kinetic analysis shows that YwhB has a relatively nonspecific 1,3- and 1,5-keto-enol tautomerase activity, with the former activity prevailing. Replacement of Pro-1 or Arg-11 with an alanine significantly reduces or abolishes these activities, implicating both residues as critical ones for the activities. In D2O, ketonization of two monoacid substrates (2-hydroxy-2,4-pentadienoate and phenylenolpyruvate) produces a mixture of stereoisomers {2-keto-3-[2H]-4-pentenoate and 3-[2H]-phenylpyruvate}, where the (3R)-isomers predominate. Ketonization of 2-hydroxy-2,4-hexadienedioate, a diacid, in D2O affords mostly the opposite enantiomer, (3S)-2-oxo-[3-2H]-4-hexenedioate. The mono- and diacids apparently bind in different orientations in the active site of YwhB, but the highly stereoselective nature of the YwhB reaction using a diacid suggests that the biological substrate for YwhB may be a diacid. Moreover, of the three dienols examined, 1,3- and 1,5-keto-enol tautomerization reactions are only observed for 2-hydroxy-2,4-hexadienedioate, indicating that the C-3 and C-5 positions are accessible for protonation in this compound. Incubation of 4-OT with 2-hydroxy-2,4-hexadienedioate in D2O results in a racemic mixture of 2-oxo-[3-2H]-4-hexenedioate, suggesting that 4-OT may not catalyze a 1,3-keto-enol tautomerization reaction using this dienol. It has previously been shown that 4-OT catalyzes the near stereospecific conversion of 2-hydroxy-2,4-hexadienedioate to (5S)-[5-2H]-2-oxo-3-hexenedioate in D2O. Taken together, these observations suggest that 4-OT might function as a 1,5-keto-enol tautomerase using 2-hydroxy-2,4-hexadienedioate. 相似文献
943.
Meta-analysis: the past, present and future 总被引:1,自引:0,他引:1
944.
Angiotensin-converting enzyme inhibitor captopril attenuates ventilator-induced lung injury in rats.
Jiunn-Song Jiang Leng-Fang Wang Hsiu-Chu Chou Chung-Ming Chen 《Journal of applied physiology》2007,102(6):2098-2103
We hypothesized that lung inflammation and parenchymal apoptosis in ventilator-induced lung injury (VILI) are related to ANG II and assessed the ability of the angiotensin-converting enzyme inhibitor captopril to attenuate VILI in rats. Adult male Sprague-Dawley rats were randomized to receive two ventilation strategies for 2 h: 1) tidal volume of 40 ml/kg, respiratory rate of 25 breaths/min, and inspiratory O2 fraction of 0.21 [high-volume, 0 positive end-expiratory pressure (HVZP) group] and 2) injection of captopril (100 mg/kg ip) 30 min before HVZP ventilation (HVZP+CAP group). Another group, which did not receive ventilation, served as the control. Mean arterial pressure was significantly lower in the HVZP+CAP group than in the HVZP group at 2 h of ventilation. Total protein levels were significantly higher in bronchoalveolar lavage fluid (BALF) recovered from HVZP-ventilated rats than from controls. BALF macrophage inflammatory protein-2 and lung ANG II were significantly higher in the HVZP group than in the control and HVZP+CAP groups. Lung ANG II levels correlated positively with BALF protein and macrophage inflammatory protein-2. The number of apoptotic airway and alveolar wall cells was significantly higher in the HVZP and HVZP+CAP groups than in the control group and significantly lower in the HVZP+CAP group than in the HVZP group. These results suggest that the efficiency of captopril to attenuate VILI is related to reduction of inflammatory cytokines and inhibition of apoptosis and indicate that VILI is partly mediated by the local angiotensin system. 相似文献
945.
A weak chemiluminescence (CL) emission was observed due to the production of singlet oxygen ((1)O(2)) during the decomposition of peroxomonosulphate (HSO(5)(-)) catalysed by cobalt(II). Low molecular mass aliphatic monocarboxylic acids, such as formic, acetic, propionic, butyric and valeric acids, influenced the CL emission, and the reaction of aliphatic monocarboxylic acids with HSO(5)(-)/Co(2+) solution was further investigated using a flow injection analysis (FIA) CL method. The results indicated that the CL intensities of aliphatic monocarboxylic acids were improved with increase in the carbon chain length in the potassium peroxomonosulphate-cobalt(II) sulphate system. Generation of singlet oxygen was confirmed by the fact that the CL emission of aliphatic monocarboxylic acids with the HSO(5)(-)/Co(2+) solution was quenched by NaN(3), and from the CL spectrum of the reaction system. Additionally, a possible mechanism of aliphatic monocarboxylic acids CL emission enhancement was proposed. 相似文献
946.
Emergence of a DNA-damage response network consisting of Fanconi anaemia and BRCA proteins 总被引:1,自引:0,他引:1
Wang W 《Nature reviews. Genetics》2007,8(10):735-748
Fanconi anaemia (FA) has recently become an attractive model to study breast cancer susceptibility (BRCA) genes, as three FA genes, FANCD1, FANCN and FANCJ, are identical to the BRCA genes BRCA2, PALB2 and BRIP1. Increasing evidence shows that FA proteins function as signal transducers and DNA-processing molecules in a DNA-damage response network. This network consists of many proteins that maintain genome integrity, including ataxia telangiectasia and Rad3 related protein (ATR), Bloom syndrome protein (BLM), and BRCA1. Now that the gene that is defective in the thirteenth and last assigned FA complementation group (FANCI) has been identified, I discuss what is known about FA proteins and their interactive network, and what remains to be discovered. 相似文献
947.
Fungal endophytes of native Gossypium species in Australia 总被引:1,自引:0,他引:1
Bo Wang Michael J. Priest Amy Davidson Curt L. Brubaker Matt J. Woods Jeremy J. Burdon 《Mycological Research》2007,111(3):347-354
Fungal endophytes of 17 genera were found in stems of four native Gossypium species (G. australe, G. bickii, G. nelsonii, G. sturtianum) collected from inland areas in Queensland, the Northern Territory, and South Australia in 2001. Phoma, Alternaria, Fusarium, Botryosphaeria, Dichomera, and Phomopsis were common, accounting for 58, 18, 11, 3, 1, and 1 % of the 281 recovered isolates, respectively, and occurring in 47, 29, 19, 5, 5, and 4 % of the 79 sampled populations. Among the four Gossypium species in Queensland and the Northern Territory, Alternaria spp. and Fusarium spp. had the greatest recovery frequency in G. bickii stems. The recovery frequencies of Phoma spp. and Alternaria spp. were significantly greater in the G. sturtianum stems collected from South Australia than in those from Queensland and the Northern Territory. Pathogenicity of 42 representative isolates was tested on cultivated cotton (G. hirsutum). All isolates caused some localized discoloration in stem tissue when inoculation was conducted with the stem puncturing method, but none of the isolates could induce any foliar symptoms during the five-week experimental period by either inoculation method (root dipping or stem puncturing), suggesting that the endophytic fungi of native Gossypium species are unlikely sources of cotton pathogens. 相似文献
948.
Sheibani N Scheef EA Dimaio TA Wang Y Kondo S Sorenson CM 《Journal of cellular physiology》2007,210(3):616-625
Bcl-2 is the founding member of a family of proteins that influence apoptosis. During kidney development bcl-2 not only acts as a survival factor, but may also impact cell adhesive mechanisms and by extension branching morphogenesis. The interrelationship between cell adhesion, migration and apoptosis, important during development, is poorly understood. Here we examined the impact lack of bcl-2, an inhibitor of apoptosis, has on ureteric bud (UB) cell adhesion, migration, and branching morphogenesis. Bcl-2 -/- UB cells demonstrated increased cell migration, increased cell invasion and decreased adhesion to vitronectin and fibronectin compared with wild-type cells. Bcl-2 +/+ UB cells readily branched in collagen gel and Matrigel while bcl-2 -/- UB cells did not undergo significant branching in either matrix. Re-expression of bcl-2 in bcl-2 -/- UB cells restored their ability to undergo branching morphogenesis in Matrigel. Consistent with our in vitro data, we show that in the absence of bcl-2, embryonic kidneys undergo decreased UB branching. We observed decreased numbers of UB branch points, UB branch tips and a decreased distance to the first UB branch point in the absence of bcl-2. The alterations in bcl-2 -/- UB cell adhesion and migration was also associated with a significant alteration in expression of a number of extracellular matrix proteins. Bcl-2 -/- UB cells exhibited increased fibronectin expression and decreased thrombospondin-1 and osteopontin expression. Taken together, these data suggest that bcl-2 is required for the proper regulation of cell adhesive and migratory mechanisms, perhaps through modulation of the cellular microenvironment. 相似文献
949.
Wang W Liu X Zhao J Zhao B Zhang S Miao J 《Bioorganic & medicinal chemistry letters》2007,17(2):482-485
To understand the effects of a novel butyrolactone derivative, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO), on the apoptosis of vascular endothelial cells (VECs), we exposed 3BDO (20-60 microg/ml) to VECs deprived of serum and FGF-2 for 24 and 48 h, respectively. The results showed that 3BDO (20-60 microg/ml) increased VEC viability and inhibited VEC apoptosis induced by deprivation of serum and FGF-2 in a very weak dose-dependent manner. During this process, integrin beta4 expression was depressed, but the level of reactive oxygen species (ROS) was not changed. The data suggested that 3BDO (20-60 microg/ml) could inhibit VEC apoptosis and suppress integrin beta4 expression, but it could not depress the ROS level induced by deprivation of serum and FGF-2. 相似文献