Rubisco of Dunaliella tertiolecta is redistributed between the pyrenoid and the stroma as a light /shade response

 We used an immunofluorescence technique to investigate the effects of varying light regimes on ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in individual cells of the chlorophyte Dunaliella tertiolecta Butcher. These studies were carried out between September 1995 and February 1996. The population was heterogeneous with respect to Rubisco localization in the pyrenoid, i.e. in some cells Rubisco staining was highly concentrated in the pyrenoid while in others it was evenly distributed throughout the chloroplast stroma. When light intensity was varied sevenfold, the fraction of the cell population that displayed distinct Rubisco staining in the pyrenoid (PR-index) was correlated with light intensity, although the average Rubisco abundance per cell or per total cellular protein appeared fairly constant. In darkness, or when treated with 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU), the PR-index decreased markedly during the first 4 and 3 h, respectively, and then remained at low levels, while the cell division cycle progression remained unaffected. We conclude that D. tertiolecta probably possesses an adaptive mechanism, i.e. the redistribution of Rubisco between the pyrenoid (probably the active site of Rubisco activation and CO₂ fixation) and the stroma (probably a reservoir of deactivated Rubisco that is readily available for transport to the pyrenoid and activation), to respond to variations in irradiance or photosynthetic inhibition. Our results also suggest that this mechanism is insensitive to slight variations in growth irradiance and to seasonal changes in photoperiod and temperature. Received: 19 August 1996 / Accepted: 12 September 1996     

福美胂在苹果树上的残留

调查了两个果园１５～２０年树龄的苹果树在连续用福美胂喷涂７～１０年后树根、树皮、枝条、叶片、果实和土壤的砷含量，并和未使用福美胂的果树含量做了比较。结果表明，果实中有砷积累，但未超过食品卫生标准。使用福美胂的树皮、技条、叶片中砷含量比未使用福美胂的高儿倍～十几倍，树皮和短梢叶含量最高。枝条和叶片与树皮的砷含量有密切正相关。土壤表层虽有轻度积累，但不会对土壤生态环境有太大影响。     

精神文明建设与可持续发展

本文从多个层次论述了精神文明建设与可持续发展的关系。完善市场经济新秩序中丰富精神文明建设和培育文化力 ,构建以人的全面发展为战略主导的社会、经济、文化、科教、生态、资源、环境和谐统一的可持续发展机制。实现市场经济、精神文明、可持续发展的和谐统一     

农村水环境保护与经济可持续发展

我国的生态环境问题 ,如水土流失、草场退化、沙漠化、盐渍化等问题 ,归根到底还是农村水环境问题。本文分析了农村水环境保护、高效利用水资源的紧迫性 ,以及影响农村生态系统可持续性的因素和保护、改善农村水环境的主要措施 ;认为加强农村水环境保护及其持续发展能力的建设是我国整个社会特别是农村经济可持续发展的基本保障     

Influence of hydroxypropylcyclodextrins on the toxicity of mixtures

We studied the influence of hydroxypropylcyclodextrins (HPCDs) on the toxicity of some mixtures. Using the Photobacterium phosphoreum toxicity test, the joint toxicological effect for Mixture I (containing p-nitrobenzaldehyde and 1-nitronaphthalene) and Mixture II (containing p-nitrobenzaldehyde and malononitrile) were determined in water and in aqueous solutions of HPCDs. The results indicate that, although the toxicological joint effect for Mixture I (simple addition) differs from that of Mixture II (synergism), alpha- and beta-HPCD can significantly reduce the toxicity of the test compounds, whereas gamma-HPCD has only a slight effect. Explanations for these observations are given that invoke the molecular structure of the individual chemicals as well as the structures of HPCDs. This provides information to assist the application of HPCDs in remediation of environmental pollution.     

贵州省西部环境灾害与防治

本文分析了贵州西部环境灾害的形成原因，它既受自然因素的影响，也受人类活动的影响。并提出了防治贵州西部环境灾害的基本措施。     

耕地不同产量水平的面积与分布监测法

查清中低产田的面积、分布与开发条件是制定农业综台开发规划的重要依据。采用按公里网布设的农业资源动态监测系统,开展对耕地不同产量水平的面积与分布的动态监测,其方法具有准确、简便和实用的特点。