可持续发展研究的学科动向

近40年来,可持续发展的概念、理论和方法不断拓展,已成为当今国际社会普遍关心的热点问题。利用中国知网(http://epub.cnki.net)的网络平台,分别以"生态学"、"经济学"、"社会学"以及"可持续发展"为关键词,对6个数据库跨库检索1993年至2011年的所有文献。分别从以上3个学科的角度,对这些文献的研究内容、研究方法进行了统计,分析国内可持续发展研究的趋势。结果表明,可持续发展的研究在3个学科方向上都表现出多学科交叉性、领域综合性、方法定量化的总体趋势;其中生态学在研究方法上较为突出。     

荒漠破碎化生境中长爪沙鼠集合种群野外验证研究

近年来,人类活动和自然干扰,导致内蒙古阿拉善荒漠区生境的破碎化,出现了长爪沙鼠在不同斑块间的不连续分布,每一斑块内可能存在一个局域种群,而集合种群建立的前提条件,是局域种群斑块状分布在离散的栖息地环境中。2002~2012年每年的4~10月,在阿拉善荒漠区禁牧、轮牧、过牧和开垦4种人为不同利用方式形成的生境斑块中,采用标志重捕法对长爪沙鼠（Meriones unguiculatus）种群进行定点监测。通过分析长爪沙鼠种群动态,计算各局域种群的灭绝风险,利用Spearman秩相关系数检验种群动态的空间同步性,同时以种群周转率对长爪沙鼠扩散能力进行评估,以检验阿拉善荒漠区长爪沙鼠种群空间结构是否具有经典集合种群的功能。结果表明：（1） 不同生境斑块可被长爪沙鼠局域种群占据,11年间捕获长爪沙鼠2~7次不等;（2） 长爪沙鼠所有局域种群均具有灭绝风险,在轮牧区和禁牧区灭绝率高达1.000 0,开垦区灭绝率最低,也达到0.333 4,而本研究期间最大局域种群（2008年过牧区,26只/hm²）,在2010年发生了局域灭绝;（3） 不同生境斑块间没有明显的空间隔离而阻碍局域种群的重新建立,长爪沙鼠扩散能力较强,绝大部分月份的种群周转率在50.0%以上,特别是周转率达到100.0%的月份较多;（4） 不同生境斑块间仅轮牧区和禁牧区中长爪沙鼠种群密度显著正相关（P<0.05）,而其他生境斑块间相关性均不显著（P >0.05）,长爪沙鼠局域种群整体显示出明显的非同步空间动态。阿拉善荒漠区长爪沙鼠种群满足作为经典集合种群物种区域续存的4个条件,具有作为研究小哺乳动物集合种群的潜在价值。     

Impacts of dreissenid mussel invasions on chlorophyll and total phosphorus in 25 lakes in the USA

1. Invasions of zebra and quagga mussels have had long‐term, large‐scale impacts on lake ecosystems in the USA as characterised by high abundance, broad‐scale spread and effective adaption to new environmental conditions. Due to their high filtering capacity, decreases in chlorophyll a (Chl) and total phosphorus (TP) concentrations have been reported in many affected lakes. 2. In 25 US lakes, we analysed the effects of dreissenid invasions on changes in Chl and TP concentrations, measured as the probability of a concentration decrease in the post‐invasion period and changes in Chl–TP relationships using Bayesian hierarchical regressions. We also examined whether changes in Chl and TP concentrations and in the Chl–TP relationship differed according to lake hydromorphology, such as mean depth or mixing status (mixed versus stratified lakes). 3. Our results showed that dreissenid invasions were often, but not always, associated with subsequent TP and Chl declines. Dreissenid effects on Chl and TP may be influenced by lake thermal structure. Decreases in Chl and TP were consistently found in mixed lakes where benthic–pelagic coupling is tight, while the effects were less predictable in stratified lakes. Within stratified lakes, Chl and TP reductions were more clearly discernible in deeper lakes with long water residence times. 4. Regression results demonstrated that a joint increase in slope and decrease in intercept and a tighter correlation of the Chl–TP relationship were likely to occur in dreissenid‐invaded lakes; this does not support the idea of a shift from bottom‐up to top‐down control of primary production. These results have important implications for management, suggesting that a relaxation of TP standards would be unwarranted. 5. Across lakes, the slope of the Chl–TP relationship for mixed lakes was substantially higher than that for stratified lakes before mussel invasion, indicating an important role of light in limiting primary production. The slope differences between mixed and stratified lakes decreased in the post‐invasion period, possibly because mussel filtration results in a relaxation of light limitation that is more pronounced in deeper, stratified lakes.     

Extended Evolutionary Fast Learn-to-Walk Approach for Four-Legged Robots

Robot locomotion is an active research area. In this paper we focus on the locomotion of quadruped robots. An effective walking gait of quadruped robots is mainly concerned with two key aspects, namely speed and stability. The large search space of potential parameter settings for leg joints means that hand tuning is not feasible in general. As a result walking parameters are typically determined using machine learning techniques. A major shortcoming of using machine learning techniques is the significant wear and tear of robots since many parameter combinations need to be evaluated before an optimal solution is found.This paper proposes a direct walking gait learning approach, which is specifically designed to reduce wear and tear of robot motors, joints and other hardware. In essence we provide an effective learning mechanism that leads to a solution in a faster convergence time than previous algorithms. The results demonstrate that the new learning algorithm obtains a faster convergence to the best solutions in a short run. This approach is significant in obtaining faster walking gaits which will be useful for a wide range of applications where speed and stability are important. Future work will extend our methods so that the faster convergence algorithm can be applied to a two legged humanoid and lead to less wear and tear whilst still developing a fast and stable gait.     

铜绿假单胞菌SOS反应阻遏蛋白LexA的复性及活性研究

目的:对LexA蛋白复性方法进行优化,对复性后的LexA蛋白的生物学活性进行分析。方法:采用含有GSH/GSSG的缓冲液,一步稀释法对变性LexA蛋白进行复性,用镍离子亲合柱及阳离子柱层析法对复性后的LexA蛋白进行纯化,再以Sephadex G-25凝胶柱脱盐,采用非变性聚丙烯酰胺凝胶电泳和RP-HPLC法检测复性效果,Western blot法分析复性前后及经DTT处理后的LexA蛋白的免疫反应性,凝胶滞留电泳试验检测复性LexA蛋白与DNA的特异性结合能力。结果:复性后的LexA蛋白出现单体和多聚体的形式,多聚体是由单条肽链聚合而成。LexA单体和多聚体与兔抗LexA多克隆抗体均有较好的反应性。复性后的LexA蛋白能与SOS盒序列发生特异性结合。     

The anti-anginal drug fendiline elevates cytosolic Ca(2+) in rabbit corneal epithelial cells

The effect of the anti-anginal drug fendiline on intracellular free Ca(2+) levels ([Ca(2+)](i)) in a rabbit corneal epithelial cell line (SIRC) was explored using fura-2 as a fluorescent Ca(2+) indicator. At a concentration above 1 microM, fendiline increased [Ca(2+)](i) in a concentration-dependent manner with an EC(50) value of 7 microM. The [Ca(2+)](i) response consisted of an immediate rise and an elevated phase. Extracellular Ca(2+) removal decreased half of the [Ca(2+)](i )signal. Fendiline induced quench of fura-2 fluorescence by Mn(2+) (50 microM), suggesting the presence of Ca(2+) influx across the plasma membrane. This Ca(2+) influx was abolished by La(3+) (50 microM), but was insensitive to dihydropyridines, verapamil and diltiazem. Fendiline (10 microM)-induced store Ca(2+) release was largely reduced by pretreatment with thapsigargin (1 microM) (an endoplasmic reticulum Ca(2+) pump inhibitor) to deplete the endoplasmic reticulum Ca(2+). Conversely, pretreatment with 10 microM fendiline abolished thapsigargin-induced Ca(2+) release. Fendiline (10 microM)-induced Ca(2+) release was not altered by inhibiting phospholipase C with 2 microM 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122). Cumulatively, this study shows that fendiline induced concentration-dependent [Ca(2+)](i )increases in corneal epithelial cells by releasing the endoplasmic reticulum Ca(2+) in a phospholipase C-independent manner, and by causing Ca(2+) influx.     

Increased immortalization‐upregulated protein 2 (IMUP‐2) by hypoxia induces apoptosis of the trophoblast and pre‐eclampsia

In regulation of the developmental process, the balance between cellular proliferation and cell death is critical. Placental development tightly controls this mechanism, and increased apoptosis of placental trophoblasts can cause a variety of gynecological diseases. Members of the immortalization‐upregulated protein (IMUP) family are nuclear proteins implicated in SV40‐mediated immortalization and cellular proliferation; however, the mechanisms by which their expression is regulated in placental development are still unknown. We compared IMUP‐2 expression in normal and pre‐eclamptic placental tissues and evaluated the function of IMUP‐2 in HTR‐8/SVneo trophoblast cells under hypoxic conditions. IMUP‐2 was expressed in syncytiotrophoblasts and syncytial knots of the placental villi. IMUP‐2 expression was significantly higher in preterm pre‐eclampsia patients than in patients who went to term (P < 0.001); however, we observed no differences in IMUP‐2 expression between normal term patients with and without pre‐eclampsia. Hypoxic conditions increased apoptosis of HTR8/SVneo trophoblast cells and induced IMUP‐2 expression. Also, apoptosis of HTR‐8/SVneo trophoblast cells was increased after IMUP‐2 gene transfection. These results suggest that IMUP‐2 expression is specifically elevated in preterm pre‐eclampsia and under hypoxic conditions, and that IMUP‐2 induces apoptosis of the trophoblast. Therefore, IMUP‐2 might have functional involvement in placental development and gynecological diseases such as pre‐eclampsia. J. Cell. Biochem. 110: 522–530, 2010. © 2010 Wiley‐Liss, Inc.