激光捕获显微切割技术纯化的鼻咽癌和正常鼻咽上皮细胞的比较蛋白质组学研究

为筛选鼻咽癌(nasopharyngeal carcinoma, NPC)的分子标志物,采用激光捕获显微切割技术(laser capture microdissection, LCM)分别从NPC组织和正常鼻咽上皮组织(normal nasopharyngal epithelial tissue, NNET)中切割纯化NPC细胞和正常鼻咽上皮细胞(normal nasopharyngal epithelial cells, NNEC),应用二维凝胶电泳(two-dimensional electrophoresis, 2-DE)分离LCM纯化细胞的蛋白质,图像分析识别差异表达的蛋白质点,基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)和电喷雾电离串联质谱(ESI-Q-TOF-MS)鉴定差异蛋白质点,Western blot检测差异蛋白cytokeratin 8 (CK8)在LCM纯化的NPC细胞和NNEC以及具有不同分化程度或转移潜能的4株NPC细胞中的表达,免疫组织化学检测CK8在63例NPC、28例NNET及20例颈淋巴结转移NPC组织中的表达水平.建立了LCM纯化的NPC细胞和NNEC的2-DE图谱,质谱鉴定了29个差异蛋白质,其中15个蛋白质只在NPC表达或表达明显增高,14个蛋白质在NPC中表达下调或缺失;Western blot结果显示,CK8的表达水平在NPC中较NNET明显下调,并与NPC细胞株的分化程度和转移潜能有关;免疫组织化学结果显示,CK8在NPC组织中的表达较NNET明显下调,在颈淋巴结转移NPC中的表达较原发NPC明显上调.研究结果提示,CK8与NPC分化及淋巴结转移相关,有望成为预测NPC转移和区别NPC分化程度的分子标志物.     

失血性休克大鼠肝脏蛋白质的差异分析

 应用蛋白质双向凝胶电泳 (two-dimensional polyacrylamide gel electrophoresis, 2-DE) 技术,分析在急性重度失血性休克 (refractory hemorrhagic shock, RHS) 条件下,大鼠肝脏蛋白质组表达的差异.16 只雄性 Wistar 大鼠随机分成正常对照组 (sham hemorrhage shock, SHS) 和 RHS 模型组,每组 8 只.采用股动脉放血的方法制备模型,在规定时间内处死大鼠并分离肝脏,提取肝脏总蛋白质后进行 2-DE.运用 Image Master 2D Platinum v 5.0 凝胶图像分析软件对 2-DE 凝胶图像进行差异表达分析.有意义的差异蛋白质点用基质辅助激光解析电离飞行时间质谱进行肽质量指纹图谱分析,借助 Swiss-prot 数据库进行蛋白质搜索和鉴定.SHS 组和 RHS 组肝脏的 2-DE 图谱,分别平均识别到 698±11 和 700±13 个蛋白质点,SHS 组和 RHS 组肝脏间平均匹配率达88%～92 %.共发现 10 个差异有意义的蛋白质点,鉴定出了肿瘤抑制性抗原gp96、葡萄糖调节蛋白58、过氧还蛋白Ⅰ、细胞色素b5、谷胱甘肽转移酶、ATP合酶β亚单位、二磷酸果糖酶 B、三磷酸甘油醛脱氢酶等8种蛋白质.结果表明,以 2-DE 技术得到重复性和分辨率都较好的 2-DE图谱,并初步鉴定急性重度失血性休克后大鼠肝脏的差异表达蛋白质,为深入研究失血性休克的生理病理机制及寻找失血性休克预防和治疗的生物标志物提供了依据.     

肺鳞癌患者与健康人血清的差异蛋白质组学研究

为筛选肺鳞癌的血清标志物,采用二维凝胶电泳(2-DE)技术分离I期肺鳞癌患者和健康人的血清蛋白质,PDquest图像分析软件识别差异蛋白质点,电喷雾串联质谱(ESI-Q-TOF MS/MS)鉴定差异蛋白,然后应用蛋白质印迹和免疫组化方法分别检测差异蛋白——结合珠蛋白-2(haptoglobin-2,HP-2)在肺鳞癌患者血清和健康人血清以及肺鳞癌组织和癌旁正常支气管上皮组织中的表达.建立了肺鳞癌患者和健康人血清的2-DE图谱,图像分析软件识别了1O个差异蛋白质点,质谱鉴定了4种差异蛋白;蛋白质印迹分析显示,HP-2在肺鳞癌血清中的表达水平显著高于健康人(P<0.05),但其表达水平与肺鳞癌的临床分期无明显相关性;免疫组化结果显示,HP-2在肺鳞癌组织中的表达水平高于癌旁正常支气管上皮组织(P<0.05).研究结果提示:HP-2是候选的肺鳞癌血清分子标志物,血清中HP-2水平对肺鳞癌诊断可能具有一定的参考价值;肺鳞癌组织中HP-2表达上调可能是患者血清中HP-2表达升高的原因之一.     

采用蛋白质组学技术筛选鼻咽癌细胞的甲基化沉默基因

为筛选鼻咽癌的甲基化沉默基因,采用二维凝胶电泳(2-DE)技术分离甲基转移酶抑制剂5-杂氮-2'-脱氧胞苷(5-aza-2-dC)处理与未处理鼻咽癌细胞5-8F的蛋白质,PDquest图像分析软件识别差异蛋白质点,基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)鉴定差异蛋白质.然后采用Western blotting和RT-PCR检测差异蛋白质nm23-H1在药物处理与未处理5.8F细胞中的表达水平,采用甲基化特异性PCR(MS-PCR)检测nm23-H1基因在药物处理与未处理5-8F细胞中的甲基化水平.建立了5-aza-2-dC处理与未处理5.8F细胞蛋白质的2-DE图谱,识别了49个差异表达的蛋白质点,鉴定了33个差异表达的蛋白质,其中包括rim23.H1在内的15个蛋白质在5-aza-2-dC处理后的5-8F细胞中表达上调,而18个蛋白质表达下调.Western blotting和RT-PCR结果显示,nm23-H1在5-aza-2-dC处理5-8F细胞后表达上调,MS-PCR结果显示,在5-aza-2-dC处理5-8F细胞后nm23-H1基因甲基化水平下降,结果证实,nm23-H1基因是5-8F细胞中的甲基化沉默基因.15个5-aza.2-dC处理后表达上调的基因可能是5-8F细胞中的甲基化沉默基因,为筛选鼻咽癌甲基化失活基因提供了科学依据.     

慢性应激大鼠海马的比较蛋白质组学研究

慢性应激可造成海马神经细胞丢失、树突萎缩等损伤,但有关其损伤机制仍有很多问题不甚明了.为了寻找应激致海马损伤相关的重要蛋白质、从蛋白质水平揭示应激致海马损伤的分子机制,应用双向凝胶电泳(2-DE)技术分离对照组和束缚应激组大鼠海马组织总蛋白质,图像分析检测差异表达的蛋白质点,基质辅助激光解析电离飞行时间质谱(MALDI-TOF-MSS)和数据库检索对差异表达的蛋白质点进行鉴定,并采用半定量的RT-PCR在mRNA水平验证2-DE结果.得到了分辨率较高、重复性较好的对照和束缚应激大鼠海马2-DE图谱,质谱分析和数据库检索鉴定了14个差异表达蛋白质点中的11个蛋白质,大多数差异蛋白的功能涉及能量代谢、信号传递等过程.研究结果为揭示应激致海马损伤的机制、提高机体的应激适应能力提供了理论依据.     

青年和老年人结肠上皮的比较蛋白质组学研究

衰老的大肠上皮不仅多种生理功能下降,而且对大肠癌在内的多种衰老相关的肠道疾病易感性显著增加,但结肠上皮衰老及衰老的结肠上皮对癌症易感的分子机制仍然不清楚.为此,应用双向凝胶电泳(2-DE)技术分离青年人及老年人的正常结肠上皮的总蛋白质,图像分析识别差异表达的蛋白质点,基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)对差异表达的蛋白质点进行鉴定,免疫组化和实时定量(real-timequantitative)PCR检测部分差异蛋白,在青年人和老年人结肠上皮中的表达水平.得到了分辨率较高、重复性较好的青年人和老年人结肠上皮的2-DE图谱,质谱分析鉴定了17个结肠上皮衰老相关的蛋白质,免疫组化和real-timequantitativeRT-PCR证实了部分差异蛋白质的表达水平.研究结果提示,线粒体功能受伤、抗氧化能力下降是结肠上皮衰老的重要原因,4个差异蛋白质即guaninenucleotide-bindingproteinbetasubunit-likeprotein(Rack1)、stress-70protein、40SribosomalproteinSA和chlorideintracellularchannelprotein1可能与衰老的结肠上皮对癌症易感有关.     

人支气管上皮不典型增生与浸润癌组织的比较蛋白质组学研究

为筛选支气管上皮鳞状不典型增生进展的分子标志物,采用改良的脱氧胆酸-三氯醋酸(deoxycholate-trichloroaetic acid, DOC-TCA)法提纯支气管上皮总蛋白质进行双向电泳（two-dimensional electrophoresis,2-DE）,应用ImageMaster 2D分析软件、Student’s t-检验识别差异蛋白质点,基质辅助激光解吸电离飞行时间质谱（matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, MALDI-TOF-MS）得到相应的肽质指纹图（peptide mass fingerprint,PMF）,搜索数据库鉴定差异蛋白质.由此获得人支气管上皮不典型增生和浸润癌组织的2-DE图谱及其凝胶的平均蛋白质点数（1 273.00±43.31,1 326.00±66.63）,且两阶段间平均差异蛋白质点数为 56.00±8.96.取38个差异蛋白质点进行PMF分析,鉴定出一些与细胞生长、分化或肿瘤发生等有关的蛋白质,随即应用免疫组化检测差异蛋白质EGFR、c-Jun、Mdm2在两类组织中的表达,其结果也显示了类似的表达差异.支气管上皮不典型增生恶性转化过程中存在蛋白质的差异表达,这些差异蛋白质可能以不同的方式参与了癌变过程,且EGFR、c-Jun、Mdm2的免疫组化验证结果与质谱结果的一致性表明,比较蛋白质组学是一种筛选癌变相关分子标志物的可靠方法之一.     

金黄色葡萄球菌肠毒素B诱导人鼻黏膜上皮细胞表达黏蛋白MUC5AC的分子机制

为了观察金黄色葡萄球菌肠毒素B(SEB)对诱导人鼻钻膜上皮细胞分泌粘蛋白MUC5AC的影响,并初步探讨其作用机制,本研究首先在体外培养人鼻黏膜上皮细胞株HNEpC,用不同浓度的SEB孵育细胞0~24 h,ELISA检测培养上清中MUC5AC和转化生长因子-α(TGF-α)的含量;实时定量PCR检测MUC5AC mRNA表达水平;Western blot分析表皮生长因子受体(EGFR)的磷酸化。同时采用肿瘤坏死因子转化酶(TALE)siRNA干扰其表达双察其对TGF-α分泌的影响最后采用TGF-α中和抗体、EGFR抑制剂AG-1478或TALE抑制剂TAPI处理细胞,观察其在介导MUC5AC分泌中的作用。结果显示,1 ng/mL、10 ng/mL和100 ng/mL SEB作用鼻黏膜上皮细胞24 h后,可明显诱导其分泌MUC5AC并表达其mRNA,且其分泌水平随着SEB浓度的增高或时间的延长而逐渐增多。SEB也能诱导鼻黏膜上皮细胞分泌TGF-α,并磷酸化EGFR。给予10μmol/L TALE抑制剂TAPI处理细胞后,TGF-α和MUC5AC分泌水平显著减少,采用TALE siRNA干扰其表达后,TGF-α和MUC5AC也得到了类似结果。采用TGF-α中和抗体预孵育细胞30 min后,可明显抑制EGFR磷酸化。此外,TGF-α和EGFR中和抗体以及AG-1478预处理也可降低MUC5AC分泌。以上结果表明SEB经TALE/TGF-α/EGFR诱导人鼻黏膜上皮细胞表达MUC5AC。     

应用蛋白质组学技术筛选胃癌耐药相关蛋白质

胃癌多药耐药性是临床胃癌化疗失败最主要的原因之一,但其分子机制仍然不太清楚.为了寻找新的胃癌耐药相关的蛋白质,揭示胃癌多药耐药的分子机制,以胃癌细胞SGC7901和长春新碱诱导的耐药胃癌细胞SGC7901/VCR为研究对象,应用二维凝胶电泳(two-dimensionalelectrophoresis,2-DE)技术分离两种细胞的总蛋白质,图像分析识别差异表达的蛋白质点,基质辅助激光解吸电离飞行时间质谱(matrix-assistedlaserdesorption/ionizationtimeofflightmassspectrometry,MALDI-TOF-MS)及电喷雾电离串联质谱(electrosprayionizationtandemmassspectrometry,ESI-Q-TOF)对差异表达的蛋白质点进行鉴定,蛋白质印迹和实时RT-PCR验证部分差异蛋白质在两株细胞中的表达水平,反义核酸转染技术分析HSP27(heatshockprotein27,HSP27)高表达与SGC7901/VCR耐药的相关性.得到了分辨率较高、重复性较好的两株细胞系的二维凝胶电泳图谱,质谱分析共鉴定了24个差异蛋白质点,蛋白质印迹和实时RT-PCR验证了部分差异蛋白的表达水平,反义寡核苷酸抑制HSP27表达能增加SGC7901/VCR对长春新碱的敏感性.研究结果不仅提示这些差异蛋白质如HSP27,Sorcin等可能与胃癌的多药耐药相关,而且为揭示胃癌细胞的多药耐药性产生机制提供了线索.     

原位鼻咽癌裸鼠模型血清蛋白质组学的研究

利用我室建立的原位鼻咽癌裸鼠模型,建立了稳定性较好的鼻咽癌裸鼠血清蛋白质2-DE方法,并比较了原位鼻咽癌裸鼠血清与对照组裸鼠血清蛋白质2-DE图谱之间的差异.与正常裸鼠血清比较,原位鼻咽癌裸鼠模型组血清增加了4个蛋白质点.利用MALDI-TOF质谱技术对血清差异蛋白点进行鉴定,发现SAA-1前体(serumamyloidA-1 protein precursor)在鼻咽癌裸鼠模型组血清中明显高表达,为寻找鼻咽癌血清生物标志物提供了有利的线索.     

Tuning of electronic properties of one-dimensional cyano-bridged Cu-Ni, Cu-Pd, and Cu-Pt bimetallic assemblies by stereochemistry of ligands

Preparations, XPS and electronic spectroscopy, and magnetism of seven new one-dimensional cyano-bridged coordination polymers, chiral [Cu(RR-chxn)₂][Pd(CN)₄] · 2H₂O (1), [Cu(trans-chxn)₂][M(CN)₄] · 2H₂O (2, 4, and 6 for M = Pd, Ni, and Pt), and [Cu(cis-chxn)₂][M(CN)₄] · 2H₂O (3, 5, and 7 for M = Pd, Ni, and Pt) (RR-chxn = cyclohexane-(1R,2R)-diamine, trans-chxn = racemic trans-cyclohexane-(1,2)-diamine, and cis-chxn = racemic cis-cyclohexane-(1,2)-diamine) have been reported in view of tuning of their electronic properties by stereochemistry of chxn ligands and metal-substitution. Comparison of Cu 2p_1/2 and 2p_3/2 peaks of XPS and broad d-d bands around 18 000 cm⁻¹ of electronic spectra are described systematically for 1-7. Variable-temperature magnetic measurement shows that complexes 1-7 indicate weak antiferromagnetic interactions via cyano-bridges. Because of semi-coordination coupled with pseudo Jahn-Teller elongation and electrostatic interaction for 1, the axial Cu-N coordination bond distances of 2.330(7) and 3.092(8) Å are considerably longer than those of equatorial ones in the range from 2.016(6) to 2.030(6) Å. The former bond distances of 1 are intermediate values among the related Ni (2.324(6) and 3.120(8) Å) and Pt (2.34(1) and 3.09(1) Å) complexes.     

Land,livestock, and livelihoods: Changing dynamics of gender,caste, and ethnicity in a Nepalese Village

Over the past 10 years, Ghusel VDC, Lalitpur District has moved from primarily subsistence agriculture into the wider cash economy aided by the Small Farmers' Development Program (SFDP), which provides credit to farmers mainly for the purchase of buffalo for milk production, and by the National Dairy Corporation, which supports local dairy cooperatives. Analysis reveals that buffalo-keeping and milk sales are increasing the well-being of many households, while at the same time creating new inequalities in gender roles and responsibilities, greater inequities between Brahmin and Tamang residents in Ghusel, and placing pressures on the ecosystem for increased supplies of fodder and fuelwood. Evidence suggests that there is critical, need for attention to the social, and particularly gender-based, implications of maintaining livestock for milk sales and to the ecological underpinnings of this livelihood system.     

Structure and function of S-adenosylhomocysteine hydrolase

In mammals, S-adenosylhomocysteine hydrolase (AdoHcyase) is the only known enzyme to catalyze the breakdown of S-adenosylhomocysteine (AdoHcy) to homocysteine and adenosine. AdoHcy is the product of all adenosylmethionine (AdoMet)-dependent biological transmethylations. These reactions have a wide range of products, and are common in all facets of biometabolism. As a product inhibitor, elevated levels of AdoHcy suppress AdoMet-dependent transmethylations. Thus, AdoHcyase is a regulator of biological transmethylation in general. The three-dimensional structure of AdoHcyase complexed with reduced nicotinamide adenine dinucleotide phosphate (NADH) and the inhibitor (1′R, 2′S, 3′R)-9-(2′,3′-dihyroxycyclopenten-1-yl)adenine (DHCeA) was solved by a combination of the crystallographic direct methods program, SnB, to determine the selenium atom substructure and by treating the multiwavelength anomalous diffraction data as a special case of multiple isomorphous replacement. The enzyme architecture resembles that observed for NAD-dependent dehydrogenases, with the catalytic domain and the cofactor binding domain each containing a modified Rossmann fold. The two domains form a deep active site cleft containing the cofactor and bound inhibitor molecule. A comparison of the inhibitor complex of the human enzyme and the structure of the rat enzyme, solved without inhibitor, suggests that a 17° rigid body movement of the catalytic domain occurs upon inhibitor/substrate binding.     

Chiral Separation of G‐type Chemical Warfare Nerve Agents via Analytical Supercritical Fluid Chromatography

Chemical warfare nerve agents (CWNAs) are extremely toxic organophosphorus compounds that contain a chiral phosphorus center. Undirected synthesis of G‐type CWNAs produces stereoisomers of tabun, sarin, soman, and cyclosarin (GA, GB, GD, and GF, respectively). Analytical‐scale methods were developed using a supercritical fluid chromatography (SFC) system in tandem with a mass spectrometer for the separation, quantitation, and isolation of individual stereoisomers of GA, GB, GD, and GF. Screening various chiral stationary phases (CSPs) for the capacity to provide full baseline separation of the CWNAs revealed that a Regis WhelkO1 (SS) column was capable of separating the enantiomers of GA, GB, and GF, with elution of the P(+) enantiomer preceding elution of the corresponding P(–) enantiomer; two WhelkO1 (SS) columns had to be connected in series to achieve complete baseline resolution. The four diastereomers of GD were also resolved using two tandem WhelkO1 (SS) columns, with complete baseline separation of the two P(+) epimers. A single WhelkO1 (RR) column with inverse stereochemistry resulted in baseline separation of the GD P(–) epimers. The analytical methods described can be scaled to allow isolation of individual stereoisomers to assist in screening and development of countermeasures to organophosphorus nerve agents. Chirality 26:817–824, 2014. © 2014 The Authors. Chirality published by John Wiley Periodicals, Inc.     

Influence of Fluoride on Rat Kidney Antioxidant System: Effects of Methionine and Vitamin E

The aim of the study has been to determine and compare the influence upon the kidney antioxidative system, exercised by administration of vitamin E, and vitamin E in combination with methionine, under conditions of oxidative stress induced by sodium fluoride. The experiment was carried out on Wistar FL rats (adult males) that, for 35 days, were administered water, NaF, NaF with vitamin E, or vitamin E with methionine (doses: 10 mg NaF/kg of body mass/24 h, 3 mg vitamin E per 10 μl per rat for 24 h, 2 mg methionine per rat for 24 h). The influence of administered sodium fluoride and antioxidants upon the antioxidative system in kidney was examined by analyzing the concentration of malondialdehyde (MDA) and the activity of the most important antioxidative enzymes (SOD, total and both its isoenzymes, GPX, GST, GR, and CAT). The studies carried out confirmed the disadvantageous effect of the administered dose of NaF upon the antixodiative system in rats (increase in the concentration MDA, decrease activity of all antioxidative enzymes). The administration of vitamin E increased the activity of studied enzymes with the exception of glutathione reductase GR; it also reduced the procesess of lipid peroxidation. It has been found that combined doses of vitamin E and methionine were most effective in inhibiting lipid peroxidation processes. The results confirmed the antioxidative properties of methionine.     

Reorientation of Microfibrils and Microtubules at the Outer Epidermal Wall of Maize Coleoptiles During Auxin-Mediated Growth

Auxin-mediated elongation growth of isolated subapical coleoptile segments of maize (Zea mays L.) is controlled by the extensibility of the outer cell wall of the outer epidermis (Kutschera et al., 1987). Here we investigate the hypothesis that auxin controls the extensibility of this wall by changing the orientation of newly deposited microfibrils through a corresponding change in the orientation of cortical microtubules. On the basis of electron micrographs it is shown that cessation of growth after removal of the endogenous source of auxin is correlated with a relative increase of longitudinally orientated microfibrils and microtubules at the inner wall surface. Conversely, reinduction of growth by exogenous auxin is correlated with a relative increase of transversely orientated microfibrils and microtubules at the inner wall surface. These changes can be detected 30–60 min after the removal and addition of auxin, respectively. The functional significance of directional changes of newly desposited wall microfibrils for the control of elongation growth is discussed.     

In vitro studies of the rabbit immune system. IV. Differential mitogen responses of isolated T and B cells.

The mitogenic responses of separated rabbit lymphocyte populations functionally analogous to mouse T and B cells have been tested in vitro. Purified T cells were prepared by passage over nylon wool (NW) and purified B cells prepared by treatment with antithymocyte serum and complement (ATS + C). ATS + C kills 70% of peripheral blood lymphocytes (PBL's) and 50% of the spleen cells while passage over NW yields 40% of the applied PBL's and 5–23% of the applied spleen cells. NW-purified T cells from the spleen or PBL's respond fully to concanavalin A (Con A) but have a reduced response to phytohemaglutinin (PHA) and little or no response to goat anti-rabbit immunoglobulin (anti-Ig). PBL's that survive ATS + C (B cells) are stimulated by anti-Ig but not by Con A or PHA. B cells purified from spleen do not respond to Con A or PHA but will respond to anti-Ig under appropriate conditions. A full spleen B-cell response to anti-Ig required removal of Ig produced by the cultures that blocked anti-Ig stimulation. It is concluded that, for rabbit lymphocytes, Con A and PHA are primarily T-cell mitogens and that anti-Ig is primarily a B-cell mitogen. However, the mitogen response of unfractionated PBL or spleen cell populations indicates an overlap in reactivity. This could be due to cells sharing T and B properties, alteration of cell populations by the fractionation procedures used, or recruitment of one population in the presence of a mitogenic response of the other population.     

八种脑-肠肽侧脑室内注射对大鼠基础胃酸分泌的影响

用乌拉坦麻醉大鼠作急性实验,采用连续灌流胃并收集流出液的方法,观察向侧脑室内注射微量脑-肠肽对大鼠基础胃酸分泌的影响。实验结果如下:(1)雨蛙肽、八肽胆囊收缩素、促甲状腺素释放激素及四肽胃泌素均使总酸排出量增加;(2)生长抑素、胰多肽、P 物质、胰高血糖素则使总酸排出量减少;(3)上述肽类用侧脑室注射的剂量作肌肉注射,除四肽胃泌素也产生明显的刺激胃酸分泌作用外,对胃酸分泌均无明显影响。以上结果提示,脑内的一些肽类可能以神经递质或调制物的方式,参与中枢对胃酸分泌的调节。     

Gamma-glutamylcysteine protects ergothioneine-deficient Mycobacterium tuberculosis mutants against oxidative and nitrosative stress

Mycobacterium tuberculosis (M.tb.), the causative agent of tuberculosis (TB), cannot synthesize GSH, but synthesizes two major low molecular weight thiols namely mycothiol (MSH) and ergothioneine (ERG). Gamma-glutamylcysteine (GGC), an intermediate in GSH synthesis, has been implicated in the protection of lactic acid bacteria from oxidative stress in the absence of GSH. In mycobacteria, GGC is an intermediate in ERG biosynthesis, and its formation is catalysed by EgtA (GshA). GGC is subsequently used by EgtB in the formation of hercynine-sulphoxide-GGC. In this study, M.tb. mutants harbouring unmarked, in-frame deletions in each of the fives genes involved in ERG biosynthesis (egtA, egtB, egtC, egtD and egtE) or a marked deletion of the mshA gene (required for MSH biosynthesis) were generated. Liquid chromatography tandem mass spectrometry analyses (LC-MS) revealed that the production of GGC was elevated in the MSH-deficient and the ERG-deficient mutants. The ERG-deficient ΔegtB mutant which accumulated GGC was more resistant to oxidative and nitrosative stress than the ERG-deficient, GGC-deficient ΔegtA mutant. This implicates GGC in the detoxification of reactive oxygen and nitrogen species in M.tb.     

A chromium-tolerant plant growing in Cr-contaminated land

In this paper, a kind of Typhaceae plant species, Typha angustifolia L, with a high tolerance to Cr is described. Experiments were carried out to examine its ability to tolerant Cr and its physiological response. The results showed that there was no difference in growth, plant height, and biomass response to external Cr (VI) between the plants exposed to 100 microM Cr (VI) and control (0 microM), while increasing Cr levels to 200-800 microM induced a significant decrease in plant height and biomass, but no significant injury was detected, even for the plants exposed to 800 microM Cr. Chromium induced significant increases in superoxide dismutase (SOD) and peroxidase (POD) activities. Meanwhile, a significantly positive correlation was found between Cr and Mn or Cu in leaves and roots, respectively. The Cr tolerance of the plant appeared to be associated with the enhancement of SOD and POD activities and the improvement in uptake and translocation of the essential microelements.