杆状病毒在昆虫宿主内的感染途径及其复制

昆虫病毒的发现始于１６世纪,但直到本世纪５０年代,伴随着电子显微镜的发明,昆虫病毒学的研究才得到飞速发展．近年来,昆虫病毒学的研究已引起人们的高度重视,主要是因为：１．杆状病毒可做为载体,以表达外源基因;２．做为杀虫剂,可有效地控制农业病虫害的发生,...     

间甲酚降解Citrobacter farmeri 的降解特性及代谢途径解析

考察了在不同温度、pH值、摇床转速、氮源等环境和营养条件下,间甲酚降解菌Citrobacter farmeri对降解速率和降解过程中反应液的TOC值、紫外吸收及酶活的变化.结果表明,Citrobacter,farmeri降解间甲酚的最适温度为35℃,培养基初始pH值为6.5-8.0,摇床转速为170 r·min~(-1),无机氮比有机氮和氨态氮比硝态氮更利于Citrobacter farmeri对间甲酚的降解;当间甲酚初始浓度低于375mg·l~(-1)时,Citrobacter farmeri降解间甲酚符合零级动力学方程;间甲酚初始浓度约为60 mg·l~(-1)时约4 h完全降解,TOG的去除率8 h内可达到77%,之后几乎不变;Citrobacter farmeri可完全降解约600 mg·l~(-1)的间甲酚,表现出高效与强耐受能力的结合.对酶活的测定发现,儿茶酚1,2-双加氧酶有明显增大,初步判断Citrobacter farmeri以邻位裂解的途径对间甲酚进行降解.     

内源性气态SO2对血管的舒张作用及其机制Ⅲ：信号转导途径

为了从信号转导途径的角度探讨内源性气态SO2引起血管舒张的机制,采用将气态SO2或SO2生理盐水溶液加入孵育液的方法,使SO2分子直接作用于离体大鼠胸主动脉血管环,同时使用不同信号转导途径抑制剂,研究了内源性气态SO2诱发血管舒张的信号转导机制,并采用类比法研究了SO2对Krebs液pH的影响及其与血管舒张的关系.结果显示:1)内源性气态SO2对大鼠血管的舒张作用是SO2分子直接作用引起的,与SO2引起的pH值轻度降低无关;2)气态SO2在生理浓度和低浓度(<450μmol·L-1)引起的舒血管作用主要是通过NO/cGMP途径介导;3)很低浓度的气态SO(23μmol·L-1)和NO(3或5nmol·L-1)在引起血管舒张作用时有协同作用,二者在体内联合发挥对血管张力的调节作用.结论:1)SO2是血管组织的一种内源性气体舒张因子;2)SO2与NO可以协同调节血管张力,二者可能存在某种形式的交叉对话作用.     

Vitamins E and C reduce oxidative stress and mitochondrial permeability transition caused by camptothecin – an in vitro study

Camptothecin (CPT), a broad spectrum antineoplastic agent, is known to induce oxidative stress and mitochondria are among the main sources of intracellular reactive oxygen species (ROS). We investigated the merit of vitamins E and C supplementation on CPT-induced mitochondrial alterations in vitro. Following treatment of isolated liver mitochondria with CPT, we assessed the mitochondrial membrane permeability transition (MPT), concentration of malondialdehyde, antioxidants and activities of the enzymes of the respiratory chain and Krebs cycle. Our results provide evidence that CPT caused mitochondrial swelling, increased lipid peroxidation and transition of mitochondrial permeability. The CPT lowered the levels of reduced mitochondrial thiols suggesting that thiol oxidation is the mechanism underlying CPT-induced MPT. Identical experiments were also performed after preincubating the mitochondria with vitamins E and C. It was found that vitamins E and C pretreatment inhibited the deleterious effects of CPT and loss of enzyme activity was restored by antioxidant supplementation. Our results suggest that the toxicity of CPT was mediated by an increase in ROS production by mitochondria. However, the addition of vitamins E or C ameliorated the oxidative stress. We propose that an attempt to counteract the deleterious consequences of chemotherapy with nutritional therapies may be a rational approach in superior patient care especially in a disease like cancer.     

Toxicity of cigarette smoke on isolated lung,heart, and brain mitochondria: induction of oxidative stress and cytochrome c release

Cigarette smoking is one of the main risk factors for premature human death which is associated with a variety of respiratory and vascular diseases, and cancer due to exposure to hundreds of toxicants. Rat mitochondria were obtained by differential ultracentrifugation and incubated with different concentrations (1%, 10%, or 100%) of standardized cigarette smoke extract (CSE). Our results showed that CSE induced a rise in mitochondrial reactive oxygen species (ROS) formation, lipid peroxidation, and mitochondrial membrane potential (MMP) collapse before mitochondrial swelling ensued in isolated pulmonary mitochondria. Disturbance in oxidative phosphorylation was also confirmed by decrease in ATP concentration in the CSE-treated mitochondria. In addition, collapse of MMP and mitochondrial swelling produced release of cytochrome c via outer membrane rupture or mitochondrial permeability transition (MPT) pore opening. Our results suggested that CSE-induced toxicity in lung tissue is the result of disruptive effect on mitochondrial respiratory chain that leads to ROS formation, lipid peroxidation, MMP decline, and cytochrome c expulsion which results in apoptosis signaling and cell loss.     

间氟苯酚的好氧生物降解性及降解途径研究

利用活性污泥法考察了间氟苯酚的好氧生物降解性.结果表明,100 mg/L间氟苯酚经16 h降解,溶液中基本检测不到间氟苯酚,有机氟原子几乎全部降解为无机氟离子.间氟苯酚可以用作微生物生长的唯一碳源和能源,活性污泥中的微生物可以有效地降解间氟苯酚.利用高效液相色谱和色质联机技术研究了间氟苯酚的好氧生物降解途径,研究表明间氟苯酚首先羟基化生成中间产物氟邻苯二酚,羟基化中间产物通过邻位途经裂解开环,然后环化脱氟.     

萝卜对邻苯二甲酸酯(PAEs)吸收累积特征及途径的初步研究

利用玻璃室处理和覆土处理(人工污染土壤上覆盖原土壤)的方法控制萝卜的PAEs来源进行盆栽试验,试验处理分别为:(1)原土壤,暴露于大气中(空白1);(2)原土壤,置于玻璃室中(空白2);(3)人工污染土壤,暴露于大气中;(4)人工污染土壤,置于玻璃室中;(5)人工污染土壤上覆盖2 cm厚原土壤,暴露于大气中;(6)人工污染土壤上覆盖2 cm厚原土壤,置于玻璃室中.盆栽后应用GC/MS对土壤和植株样品中的PAEs进行分析,初步研究了萝卜对PAEs的吸收累积特征及途径.研究结果表明,萝卜茎叶和直根中邻苯二甲酸二乙酯(DEP)的含量均低于检测限,邻苯二甲酸正二丁酯(DBP)和邻苯二甲酸二(2-乙基己基)酯(DEHP)的含量与土壤污染浓度成正相关关系,DBP的含量高于DE-HP,两者主要分布在茎叶中.未覆土处理与覆土处理相比,前者盆栽的萝卜茎叶中DBP和DEHP的含量均高于后者,但在2个处理之间差异不显著,表明萝卜茎叶可以吸收污染土壤中挥发出来的DBP和DEHP,但直根吸收运移是茎叶中DBP和DEHP的主要来源途径.玻璃室处理导致萝卜茎叶中DBP含量的提高,在大棚蔬菜生产中值得注意.     

中国深度脱碳路径及政策分析

《巴黎协定》开启了全球气候治理的新进程,进一步明确了全球应对气候变化的紧迫性和目标要求。对中国来说,如何尽快推动经济增长和碳排放的脱钩,不仅是实现应对气候变化中长期战略目标的核心任务,更是保障经济社会可持续发展的必然要求。为此,本文基于中国经济、社会、能源和重要的终端能源消费行业历史发展趋势的分析,通过"自下而上"的模型方法考察了能源、工业、建筑、交通等行业和领域的深度碳减排潜力,并基于详细的技术分析提出了中国中长期的深度脱碳路径。研究表明,在深度脱碳路径下,中国将顺利完成国家自主贡献提出的2030年左右碳排放达峰和碳强度较2005年下降60%—65%的目标;此后非化石能源发展进一步加速,到2050年非化石能源在一次能源中占比达到44%左右,工业、建筑、交通等终端耗能行业的低碳转型进一步加速,2050年碳排放回落至2005年前水平,碳强度较2005年下降90%以上。为实现深度脱碳,本文从强化碳排放总量约束和相关制度规范建设、完善产业低碳发展激励政策、加强相关市场机制作用、倡导低碳生活和消费等四方面提出了相应的政策建议,以供决策者参考。     

Biodegradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) by using Serratia marcescens NCIM 2919

A solvent tolerant bacterium Serratia marcescens NCIM 2919 has been evaluated for degradation of DDT (1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane). The bacterium was able to degrade up to 42% of initial 50 mg L^?1 of DDT within 10 days of incubation. The highlight of the work was the elucidation of DDT degradation pathway in S. marcescens. A total of four intermediates metabolites viz. 2,2-bis (chlorophenyl)-1,1-dichloroethane (DDD), 2,2-bis (chlorophenyl)-1,1-dichloroethylene (DDE), 2,2-bis (chlorophenyl)-1-chloroethylene (DDMU), and 4-chlorobenzoic acid (4-CBA) were identified by GC-Mass and FTIR. 4-CBA was found to be the stable product of DDT degradation. Metabolites preceding 4-CBA were not toxic to strain as reveled through luxuriant growth in presence of varying concentrations of exogenous DDD and DDE. However, 4-CBA was observed to inhibit the growth of bacterium. The DDT degrading efficiency of S. marcescens NCIM 2919 hence could be used in combination with 4-CBA utilizing strains either as binary culture or consortia for mineralization of DDT. Application of S. marcescens NCIM 2919 to DDT contaminated soil, showed 74.7% reduction of initial 12.0 mg kg^?1 of DDT after 18-days of treatment.     

MnO2吸附-氧化去除草甘膦的研究

草甘膦是一种被广泛使用的除草剂,天然矿物的吸附-氧化作用对草甘膦的降解具有重要影响.本文研究了草甘膦在MnO2表面的吸附-氧化行为,考察了草甘膦在MnO2表面的降解动力学,以及反应体系pH和共存阳离子对MnO2吸附-氧化降解草甘膦的影响,初步分析了草甘膦的降解产物和可能的降解途径.结果表明,MnO2可有效降解草甘膦,草甘膦在MnO2表面的降解符合表观准一级动力学模型,表观反应动力学常数随草甘膦浓度的增大而减小;酸性条件有利于MnO2对草甘膦的去除,共存Cu2+对MnO2去除草甘膦有明显的抑制作用;草甘膦的降解产物包括肌氨酸、氨基乙酸、羟基乙酸、甲酸和乙酸及PO3-4、NH+4和NO-3.