水稻白叶枯病菌内源过氧化氢在细胞分裂周期中的时空定位变化

【目的】分析细菌内源过氧化氢在细胞分裂周期中的时空变化,探讨细菌增殖中过氧化氢的生理功能。【方法】采用组织化学法通过透射电子显微镜技术观察水稻白叶枯病菌内源过氧化氢的积累位置。【结果】不同菌株内源过氧化氢水平不同,在细菌的整个细胞分裂周期中观察到过氧化氢在细胞壁上的积累水平维持稳定,在多个菌株的细胞分裂过程中,除细胞壁之外,还在2个新的位点（类间体结构和核区）出现过氧化氢的大量积累,表现出数量和空间定位的显著变化。【结论】在多个水稻白叶枯病菌菌株中发现胞内额外的大量过氧化氢积累和定位与细胞分裂的进程密切相关,这种过氧化氢的时空变化很可能是细菌分裂时的普遍现象。推测过氧化氢应在细菌增殖中具有重要作用。     

Oligochitosan induces cell death and hydrogen peroxide accumulation in tobacco suspension cells

Oligochitosan has been shown to induce several plant defense responses. In the present work, the effect of oligochitosan on tobacco cell survival was investigated. The results showed that oligochitosan caused tobacco cell death in a dose-dependent manner. About 40.6 % tobacco cells died when cultured for 72 h after 500 μg ml⁻¹ oligochitosan treatment. Certain aspects of this cell death process appeared to be similar to apoptosis in animal cells. These included shrinkage of cytoplasm and condensation of chromatin. Oligochitosan also induced H₂O₂ accumulation in tobacco cell suspension culture. The role of H₂O₂ in the signal transduction that leads to cell death was investigated. Co-treatment of tobacco cells with oligochitosan and catalase inhibited H₂O₂ accumulation but did not inhibit the induction of cell death. The results suggested that apoptosis-like cell death of tobacco cells induced by oligochitosan is independent of H₂O₂ signal pathway.     

Impact of sodium cyanide on catalase activity in the freshwater exotic carp, Cyprinus carpio (Linnaeus)

The Cyprinus carpio fingerlings on exposure to lethal (1 mg/L) and sub lethal concentrations (0.066 mg/L) of sodium cyanide showed inhibition in the activity of catalase. The disruption of catalase activity in freshwater fish, C. carpio is demonstrated in the present study using UV–visible spectrophotometer at 240 nm using hydrogen peroxide as a substrate. It suggests toxic effects of sodium cyanide and consequent accumulation of hydrogen peroxide in the functionally different tissues namely, liver, gill, muscle and brain. This might lead to cellular damages, and create widespread physiological disturbance. The results suggest that catalase activity can be a good diagnostic tool for sodium cyanide toxicity in biomonitoring programme.     

棉花响应UV-B辐射的信号初探

以3种棉花为供试材料,研究紫外线-B(UV-B)辐射及外源SNP、ABA叠加处理对棉花幼苗表观形态及内源H2O2与NO水平的影响。结果表明,UV-B辐射引起棉花幼苗叶片呈现锈色伤斑,离体叶片明显失水萎蔫。叶片外源涂抹SNP、ABA能减轻UV-B辐射引起的幼叶伤斑与萎蔫症状,缓解UV-B辐射所造成的伤害。DAB及DAF-2DA染色结果显示,UV-B辐射引起棉花内源H2O2与NO含量增加,而NO的释放通过减少H2O2积累减轻紫外辐射对棉花的伤害。ABA预处理可增强棉花对紫外伤害的耐受能力,且与H2O2与NO的释放密切相关。UV-B辐射对棉花生长造成伤害,H2O2、NO及ABA都参与棉花应答UV-B胁迫的信号转导过程。     

沼液中硫化氢去除方法的研究进展

文章以去除沼液中的硫化氢为主线,围绕沼液在农业上的应用及硫化氢的治理技术,根据国内外研究现状,介绍了常用的几种去除硫化氢的方法,并进行了比较,旨在为沼液的田间精确应用提供帮助.     

谷氨酰胺对过氧化氢诱导氧化应激人结肠癌HT-29细胞损伤和凋亡的影响

本试验旨在通过研究谷氨酰胺对过氧化氢(H_2O_2)诱导氧化应激人结肠癌HT-29细胞损伤和凋亡的影响,阐明谷氨酰胺的抗氧化效果和作用机理。HT-29细胞经不同浓度[0(对照组)、0.5、2.0、10.0 mmol/L]谷氨酰胺和0.35 mmol/L H_2O_2分别处理12、24、32 h后,测定细胞的超氧化物歧化酶(SOD)活性和丙二醛(MDA)含量,并采用荧光定量PCR方法分析谷氨酰胺对H_2O_2诱导的细胞凋亡相关基因的mRNA相对表达量,以及采用膜联蛋白V-异硫氰酸荧光素/碘化丙啶双染法对HT-29细胞染色,并用流式细胞仪检测细胞的凋亡情况。结果表明:1)处理24 h后,0.5、2.0 mmol/L Gln组SOD活性显著高于对照组(P0.05);处理32 h后,0.5、2.0 mmol/L Gln组SOD活性显著高于对照组(P0.05),MDA含量显著低于对照组(P0.05)。2)处理12 h后,各组天冬氨酸蛋白水解酶-3(Caspase-3)和B淋巴细胞瘤-2相关X蛋白(Bax)mRNA相对表达量无显著差异(P0.05)。与对照组比较,0.5 mmol/L Gln组核转录因子κB(NF-κB)mRNA相对表达量显著降低(P0.05),0.5与2.0 mmol/L Gln组B淋巴细胞瘤-2(Bcl-2)mRNA相对表达量显著提高(P0.05)。处理24 h后,与对照组比较,0.5、2.0和10.0 mmol/L Gln组Caspase-3、NF-κB和Bax mRNA相对表达量均显著降低(P0.05),Bcl-2mRNA相对表达量显著升高(P0.05)。处理32 h后,与对照组比较,2.0 mmol/L Gln组细胞表面诱导凋亡分子(FAS)、Caspase-3、NF-κB、Bax mRNA相对表达量均显著降低(P0.05),Bcl-2mRNA相对表达量显著升高(P0.05);10.0 mmol/L Gln组FAS、Caspase-3、NF-κB、Bax mRNA相对表达量均显著升高(P0.05)。3)处理24 h后,与对照组比较,Gln处理使活细胞数量提高了5.32%~11.97%,坏死细胞数量降低了6.75%~12.66%。处理32 h后,与对照组比较,Gln处理使活细胞数量提高了1.39%~7.63%,坏死细胞数量降低了3.40%~4.57%。由此可见,谷氨酰胺可抑制氧化应激反应,降低H_2O_2诱导的HT-29细胞凋亡。     

城市特殊性环境问题——南京市恶臭污染浓度分布的数值模拟研究

采用数值模拟手段对南京地区近年来关于恶臭污染较为集中的居民投诉问题进行了探索性研究。模拟得到了主要恶臭物种硫化氢的时空分布特征,并与实际监测结果进行了对比。结果表明,在南京地区,当主导风向为偏北或东北风且地面风速不太大时,排放源易对主城区空气质量产生影响。模拟日当日,排放源主要影响主城区中北部地区,南部地区受影响较小。各地区硫化氢浓度与排放源相对位置远近有关,其中化纤新村处日均浓度为6.94μg/m3,玄武湖处日均浓度为3.96μg/m3。玄武湖以北地区作为硫化氢浓度高值地区恰好对应着居民投诉高发地区。大气化学反应对硫化氢环境浓度具有一定的削减作用。     

氯代甲醛-次氯酸复合物的结构和热力学性质

在B3LYP/6-311＋＋G＊＊水平上对氯代甲醛HCOCl与次氯酸HOCl可能的复合物进行结构优化与频率计算。得到5个稳定异构体,其中形成ClO-H…O=C氢键的复合物最稳定,经基组重叠误差和零点振动能校正后的相互作用能为-11.92KJ/mol。氢键的形成导致H-O伸缩振动频率红移。在298.15K和标准状态下,稳定复合物的形成反应是一个放热的非自发过程。     

Effects of Pretreatment by the Flavanol Ampelopsin on Porcine Kidney Epithelial Cell Injury Induced by Hydrogen Peroxide

This study investigated the protective effects of ampelopsin on H2O2-induced oxidative injury in porcine kidney epithelial cell line, PK-15; cells were pretreated with medium containing 0, 15, 30, and 60 ug mL-1 ampelopsin, respectively, for 1 h prior to the addition of 100 umol L-1 H2O2. After 2 h, the cell viability, intracellular superoxide dismutase （SOD） and glutathione peroxidase （GSH-Px） activity, cellular malondialdehyde （MDA） content, and DNA strand breakage were determined. Results showed that ampelopsin pretreatment did not modify the SOD and GSH-Px inactivation but significantly decreased MDA production; except for the medium dose （30 ug mL-1）, all the tested concentrations of ampelopsin did not significantly inhibit cell viability reduction and gave no influence on DNA damage. The results suggested that all the tested doses of ampelopsin pretreatment before H2O2 addition can protect PK-15 cell from H2O2-induced lipid peroxidation, which might not be mediated by the SOD and GSH-Px responsees. The appropriate dose of ampelopsin pretreatment prevents PK-15 cell from DNA damage and cell viability reduction.