Impairment of HERG K(+) channel function by tumor necrosis factor-alpha: role of reactive oxygen species as a mediator

Congestive heart failure (CHF) is associated with susceptibility to lethal arrhythmias and typically increases levels of tumor necrosis factor-alpha (TNF-alpha) and its receptor, TNFR1. CHF down-regulates rapid delayed-rectifier K(+) current (I(Kr)) and delays cardiac repolarization. We studied the effects of TNF-alpha on cloned HERG K(+) channel (human ether-a-go-go-related gene) in HEK293 cells and native I(Kr) in canine cardiomyocytes with whole-cell patch clamp techniques. TNF-alpha consistently and reversibly decreased HERG current (I(HERG)). Effects of TNF-alpha were concentration-dependent, increased with longer incubation period, and occurred at clinically relevant concentrations. TNF-alpha had similar inhibitory effects on I(Kr) and markedly prolonged action potential duration (APD) in canine cardiomyocytes. Immunoblotting analysis demonstrated that HERG protein level was slightly higher in canine hearts with tachypacing-induced CHF than in healthy hearts, and TNF-alpha slightly increased HERG protein level in CHF but not in healthy hearts. In cells pretreated with the inhibitory anti-TNFR1 antibody, TNF-alpha lost its ability to suppress I(HERG), indicating a requirement of TNFR1 activation for HERG suppression. Vitamin E or MnTBAP (Mn(III) tetrakis(4-benzoic acid) porphyrin chloride), a superoxide dismutase mimic) prevented, whereas the superoxide anion generating system xanthine/xanthine oxidase mimicked, TNF-alpha-induced I(HERG) depression. TNF-alpha caused robust increases in intracellular reactive oxygen species, and vitamin E and MnTBAP abolished the increases, in both HEK293 cells and canine ventricular myocytes. We conclude that the TNF-alpha/TNFR1 system impairs HERG/I(Kr) function mainly by stimulating reactive oxygen species, particularly superoxide anion, but not by altering HERG expression; the effect may contribute to APD prolongation by TNF-alpha and may be a novel mechanism for electrophysiological abnormalities and sudden death in CHF.     

桂林小花苣苔离体快速繁殖技术

对抗结核植物桂林小花苣苔（Chiritopsis repanda var.guilinensis）进行离体培养与快速繁殖技术研究。结果表明：桂林小花苣苔叶片外植体的最适初代诱导培养基为MS＋0.5mg·L^-16-BA＋0.05mg·L^-1IBA,pH8.0;最适继代增殖培养基为MS＋0.1mg·L^-16-BA＋0.05mg·L^-1IBA,pH6.0,繁殖系数7.0/35天;最适生根培养基为1/2MS＋0.2mg·L^-1NAA,pH6.0,生根率为93.6%。模拟桂林小花苣苔自然生境,在春季对生根试管苗进行大棚移栽,成活率达90%。根据上述快繁技术,理论上每株试管苗每年可繁殖桂林小花苣苔种苗46万株。     

Complete assignment of the chromosomes of Gossypium hirsutum L. by translocation and fluorescence in situ hybridization mapping

Significant progress has been made in the construction of genetic maps in the tetraploid cotton Gossypium hirsutum. However, six linkage groups (LGs) have still not been assigned to specific chromosomes, which is a hindrance for integrated genetic map construction. In the present research, specific bacterial artificial chromosome (BAC) clones constructed in G. hirsutum acc. TM-1 for these six LGs were identified by screening the BAC library using linkage group-specific simple-sequence repeats markers. These BAC clones were hybridized to ten translocation heterozygotes of G. hirsutum. L as BAC-fluorescence in situ hybridization probes, which allowed us to assign these six LGs A01, A02, A03, D02, D03, and D08 to chromosomes 13, 8, 11, 21, 24, and 19, respectively. Therefore, the 13 homeologous chromosome pairs have been established, and we have proposed a new chromosome nomenclature for tetraploid cotton.     

Characterization of the nitrobenzene-degrading strain Pseudomonas sp. a3 and use of its immobilized cells in the treatment of mixed aromatics wastewater

A bacterial strain Pseudomonas sp. a3 capable of degrading nitrobenzene, phenol, aniline, and other aromatics was isolated and characterized. When nitrobenzene was degraded, the release of NH(4) (+) was detected, but not of NO(2) (-). This result implied that nitrobenzene might have a partial reductive metabolic pathway in strain a3. However, aniline appeared as one of the metabolites during the aerobic degradation of nitrobenzene. Moreover, the appearance of 2-aminophenol during aniline degradation by strain a3 indicated that novel initial reactions existed during the degradation of nitrobenzene and aniline by strain a3. Strain a3 was immobilized in the mixed carrier of polyvinyl alcohol and sodium alginate to improve its degrading efficiency. The optimal concentrations of polyvinyl alcohol and sodium alginate in the mixed carrier were 9 and 3 %, respectively. The immobilized cells had stable degradation activity and good mechanical properties in the recycling tests. The immobilized cells also exhibited higher tolerances in acidic (pH 4-5) and highly saline (10 % NaCl) environments than those of free cells. The biodegradation of nitrobenzene mixed with aniline and phenol using immobilized cells of Pseudomonas sp. a3 was also greatly improved compared with those of free cells. The immobilized cells could completely degrade 300 mg L(-1) nitrobenzene within 10 h with 150 mg L(-1) aniline and 150 mg L(-1) phenol. This result revealed that the immobilized cells of Pseudomonas sp. a3 could be a potential candidate for treating nitrobenzene wastewater mixed with other aromatics.     

基于稀疏表示算法的蛋白质质谱数据特征选择

高维、小样本数据的特征选择方法在蛋白质质谱数据处理分析领域有着广泛应用。本文针对蛋白质质谱特征选择问题,结合稀疏表示这一新理论框架,提出了一种基于稀疏表示的特征选择算法(sparse representation based feature selection,SRFS)。该方法将稀疏表示分类的结果作为评定某一个特征子空间特征相对重要性的度量,然后通过对大量随机采样子空间计算结果的统计,得到特征空间中每个特征的排序,并进一步分析提炼出与肿瘤疾病相关的若干谱峰。通过在卵巢癌公共数据集OC-WCX2a和浙江省肿瘤医院乳腺癌数据集BC-WCX2a上的实验结果表明,SRFS算法可以有效应用于本文所使用的SELDI-TOF蛋白质质谱数据的分析。     

多聚亚基蛋白质在固-液界面团聚的测量与表征

以血红蛋白和乙肝表面抗原(HBsAg)为模型,联用双偏振光干涉分析仪(DPI)和原子力显微镜(AFM)研究在固-液界面上的吸附行为.结果发现:当溶液环境中血红蛋白的质量浓度为1.08 mg/mL时,测得在硅羟基表面吸附的平均厚度为3.54 nm,蛋白颗粒直径达60～ 150 nm,远高于血红蛋白的分子尺寸,说明血红蛋白在固-液界面上发生团聚.当HBsAg质量浓度为0.67 mg/mL时,测得在硅羟基表面及DEAE琼脂糖表面吸附的平均厚度分别为1.06和23.69 nm,表面吸附的蛋白颗粒直径分别为288～401和520 ～ 971 nm,是单分子HBsAg尺寸的13.1～44.1倍,表明在模型蛋白表面都形成了大的团聚体.     

Phylogenetic analysis of the species Theilovirus: emerging murine and human pathogens

The Cardiovirus genus of the family Picornaviridae includes two distinct species, Encephalomyocarditis virus and Theilovirus. We now report the complete nucleotide sequences of three Theiler's murine encephalomyelitis virus (TMEV) strains (TO Yale, TOB15, and Vie 415HTR) and of Vilyuisk human encephalomyelitis virus (VHEV). This information, together with the recently reported sequences of divergent theiloviruses (Theiler's-like rat virus [TRV] and Saffold viruses 1 and 2 [SAFV-1 and SAFV-2]), enables an updated phylogenetic analysis as well as a reexamination of several gene products important in the pathogenesis of this emerging group of viruses. In the light of the known neurotropism of TMEV and the new human SAFV-1 and SAFV-2, the resulting data suggest the existence of theiloviruses that cause human central nervous system infections. Our phylogenetic analyses point to the classification of presently known theiloviruses into five types: TMEV, VHEV, TRV, SAFV-1, and SAFV-2.