Mechanisms of photosynthetic inactivation on growth suppression of Microcystis aeruginosa under UV-C stress

This study aims to investigate the effects of UV-C irradiation on photosynthetic processes of Microcystis aeruginosa to unravel the mechanism(s) involved in how and in what ways UV-C mediates growth suppression and cellular recovery. Changes in the concentration of photosynthetic pigments, photochemical efficiency, PS II core protein (D1) content, and the coding genes expressions were measured. The results indicate that UV-C doses at 20–200 mJ cm⁻² lead to rapid reduction in gene expression of both psbA (for D1) and cpc (for phycocyanin), but the suppression was short term and recoverable within 3 d of post-UV incubation. Conversely, UV-C doses at ?50 mJ cm⁻² could induce marked decline in photochemical efficiency (represented by the optimal PS II quantum yield, F_V/F_M, and the effective PS II quantum yield, Y) as well as decreases in D1 content and water soluble pigments (phycoerythrins, phycocyanins, allophycocyanins) in M. aeruginosa during the post UV-C incubation period. The results suggest that interruption of both the light energy harvesting apparatus (especially the water soluble pigments) and the photochemical process mainly accounted for the growth suppression effect in UV-C irradiated M. aeruginosa.     

钢管陶粒混凝土柱火灾后轴压性能试验研究

对26根受火后的钢管陶粒混凝土短柱进行了轴压力学性能试验,试件考虑了钢管的几何参数、陶粒混凝土配合比及火灾条件等因素的变化。基于试验结果,分析了轻骨料钢管混凝土短柱受火后的轴压承载力、破坏形态及其他力学性能的变化及相关参数的影响规律。所讨论的主要影响参数包括试验最高炉温、最高炉温持续时间、钢管长细比、混凝土配合比等,并基于对试验数据的分析给出了轻骨料钢管混凝土短柱火灾后轴压承载力的计算公式。结果表明,以轻质材料———陶粒为骨料制成的钢管混凝土短柱受火后仍然具有较高的承载力和良好的延性,而当钢管表面响应温度超过500℃时,试件的轴压承载力出现了明显的下降。所给出的轻骨料钢管混凝土柱火灾后的轴压承载力计算公式可作为该类构件火灾后修复计算的参考依据。     

Gene expression responses of paper birch (Betula papyrifera) to elevated CO2 and O3 during leaf maturation and senescence

Gene expression responses of paper birch (Betula papyrifera) leaves to elevated concentrations of CO₂ and O₃ were studied with microarray analyses from three time points during the summer of 2004 at Aspen FACE. Microarray data were analyzed with clustering techniques, self-organizing maps, K-means clustering and Sammon's mappings, to detect similar gene expression patterns within sampling times and treatments. Most of the alterations in gene expression were caused by O₃, alone or in combination with CO₂. O₃ induced defensive reactions to oxidative stress and earlier leaf senescence, seen as decreased expression of photosynthesis- and carbon fixation-related genes, and increased expression of senescence-associated genes. The effects of elevated CO₂ reflected surplus of carbon that was directed to synthesis of secondary compounds. The combined CO₂ + O₃ treatment resulted in differential gene expression than with individual gas treatments or in changes similar to O₃ treatment, indicating that CO₂ cannot totally alleviate the harmful effects of O₃.     

Effluent impact assessment using microarray-based analysis in common carp: a systems toxicology approach

Effluents are a main source of direct and continuous input of pollutants to the aquatic environment, and can cause ecotoxicological effects at different levels of biological organization. Since gene expression responses represent the primary interaction site between environmental contaminants and biota, they provide essential clues to understand how chemical exposure can affect organismal health. The aim of the present study was to investigate the applicability of a microarray approach for unraveling modes of action of whole effluent toxicity and impact assessment. A chronic toxicity test with common carp (Cyprinus carpio) was conducted where fish were exposed to a control and 100% effluent for 21 days under flow-through conditions. Microarray analysis revealed that effluent treatment mainly affected molecular pathways associated with the energy balance of the fish, including changes in carbohydrate and lipid metabolism, as well as digestive enzyme activity. These gene expression responses were in clear agreement with, and provided additional mechanistic information on various cellular and higher level effects observed for the same effluent. Our results demonstrate the benefit of toxicogenomic tools in a “systems toxicology” approach, involving the integration of adverse effects of chemicals and stressors across multiple levels of biological complexity.     

Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed

A new anaerobic reactor, Jet-loop anaerobic fluidized bed （JLAFB）, was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO42 ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fiuidized bed （AFB） reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4^2- ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids （VFA） in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8. 1 kg/（m^3.d）, the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.     

全期表达外源基因的重组杆状病毒

构建了含早期、晚期、极晚期启动子、全期表达ＨＢｓＡｇ 基因的重组杆状病毒ｖＴｎＮＰＶＰ３５ＨＢｓＯＣＣ＋ ．结果ＨＢｓＡｇ 表达时间由感染后１２ ｈ 提前到４ ｈ,而其表达量,特别是病毒感染早期的表达水平亦显著提高,其中２４ ｈ 和９６ ｈ 的表达量分别比对照提高１８０ ％ 和６０ ％ ． 转录起始位点分析结果显示,该重组毒株可在病毒感染的早、晚期形成多个转录本     

氯化甲基汞对大鼠海马c-jun蛋白表达的影响

为了探讨氯化甲基汞(MMC)对大鼠海马损伤的分子机制,应用免疫组织化学方法观察了氯化甲基汞对大鼠海马JUN蛋白表达的影响(对照组为0.9%生理盐水、暴露组浓度分别为0.05,0.5,5mg/kg;取样时间分别为20,60,240,1440min).结果发现,暴露组大鼠海马JUN蛋白表达均高于对照组,氯化甲基汞对大鼠海马JUN蛋白表达与其浓度之间有一定的剂量反应关系,表明即刻早期基因(c-jun)参与了氯化甲基汞对海马损害的毒性过程.