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991.
改进了一种分析磷酸酶活性的终止酶反应方法.该方法通过在酶反应进行到一定程度时,在反应混合物中加入酶反应终止液(1mol/L NaOH-0.2mol/L EDTA),从而使测定更简捷、精确. 相似文献
992.
993.
甜菜碱对呼吸酶的保护效应 总被引:13,自引:0,他引:13
以菠菜(Spinacia oleracea L.)叶片为材料,研究了不同浓度的甜菜碱和NaCl对三羧酸循环、末端氧化和光呼吸的组成酶的活性的影响。与电解质NaCl不同,高浓度的甜菜碱对这些酶的活性是非抑制性的,并对NaCl的抑制作用有一定保护效应。甜菜碱是很好的有机渗透调节剂。这与甜菜碱在细胞质中起渗透调节作用,以及是无机渗透调节剂的配伍溶质的假设是一致的。 相似文献
994.
利用光能驱动二氧化碳(carbon dioxide, CO2)还原生产化学品对于缓解环境压力、解决能源危机具有重要意义。光捕获、光电转化和CO2固定等作为影响光合作用效率的关键因素,同时也制约着CO2的资源化利用效率。为了解决上述问题,本文从生物化学与代谢工程相结合的角度,系统总结了光驱动杂合系统的构建、优化与应用,并从酶杂合系统、生物杂合系统以及杂合系统应用3个方面分析了光驱动CO2还原合成化学品的最新研究进展。在酶杂合系统方面,采用的策略主要有提升酶催化活性、增强酶稳定性等;在生物杂合系统方面,采用的方法主要包括增强生物捕光能力、优化还原力供应以及改善能量再生等;在杂合系统应用方面,主要阐述了光驱动CO2还原生产一碳含能化合物、生物燃料以及生物食品等。最后,从纳米材料(包括有机材料和无机材料)和生物催化剂(包括酶和微生物)两个方面,展望了人工光合系统的进一步发展方向。 相似文献
995.
繁殖器官在竹类植物的分类学研究中具有重要意义,研究组在广西马山县观察到竹亚科单枝竹属芸香竹正在开花,该文根据观察到的开花状况和采集到的标本解剖观察结果,对其花枝和繁殖器官特征做了详细的中文及拉丁文补充描述。经对比芸香竹与属内已知繁殖器官结构的单枝竹和小花单枝竹的繁殖器官,3个竹种有相同的繁殖器官结构特征,但在小花数目和大小等方面具有差异。繁殖器官比较表明该属竹种的繁殖器官对喀斯特地貌环境有特殊的适应性,也支持依据营养器官差异划分为3个独立竹种。 相似文献
996.
The aim of this study was to determine the therapeutic efficacy of starting naringin treatment 1 day after spinal cord injury (SCI) in rat and to investigate the underlying mechanism. SCI was induced using the modified weight-drop method in Sprague-Dawley rats. The SCI animals were randomly divided into three groups: vehicle-treated group; 20 mg/kg naringin-treated group; 40 mg/kg naringin-treated group, and additionally with sham group (laminectomy only). Locomotors functional recovery was assessed during the 6 weeks post operation period by performing open-field locomotors tests and inclined-plane tests. At the end of the study, the segments of spinal cord encompassing the injury site were removed for histopathological analysis. Immunohistochemistry was performed to observe the expression of the brain-derived neurotrophic factor (BDNF). The expression of vascular endothelial growth factor (VEGF), B-cell CLL/lymphoma-2 (Bcl-2), BCL-2-associated X protein (Bax) and caspase-3 were detected by Western blot analysis. The apoptotic neural cells were assessed using the TUNEL method. The results showed that the naringin-treated animals had significantly better locomotor function recovery, less myelin loss, and higher expression of BDNF and VEGF. In addition, naringin treatment significantly increased in Bcl-2:Bax ratio, reduced the enzyme activity of caspase-3 and decreased the number of apoptotic cells after SCI. These findings suggest that naringin treatment starting 1 day after SCI can significantly improve locomotor recovery, and this neuroprotective effect may be related to the upregulation of BDNF and VEGF and the inhibition of neural apoptosis. Therefore, naringin may be useful as a promising therapeutic agent for SCI. 相似文献
997.
Yu J Li H Tang Q Rayner S Han N Guo Z Liu H Adams J Fang W Tao X Wang S Liang G 《PLoS neglected tropical diseases》2012,6(5):e1640
Background and Objectives
Recent years have seen a rapid increase in the number of rabies cases in China and an expansion in the geographic distribution of the virus. In spite of the seriousness of the outbreak and increasing number of fatalities, little is known about the phylogeography of the disease in China. In this study, we report an analysis of a set of Nucleocapsid sequences consisting of samples collected through the trial Chinese National Surveillance System as well as publicly available sequences. This sequence set represents the most comprehensive dataset from China to date, comprising 210 sequences (including 57 new samples) from 15 provinces and covering all epidemic regions. Using this dataset we investigated genetic diversity, patterns of distribution, and evolutionary history.Results
Our analysis indicates that the rabies virus in China is primarily defined by two clades that exhibit distinct population subdivision and translocation patterns and that contributed to the epidemic in different ways. The younger clade originated around 1992 and has properties that closely match the observed spread of the recent epidemic. The older clade originated around 1960 and has a dispersion pattern that suggests it represents a strain associated with a previous outbreak that remained at low levels throughout the country and reemerged in the current epidemic.Conclusions
Our findings provide new insight into factors associated with the recent epidemic and are relevant to determining an effective policy for controlling the virus. 相似文献998.
999.
神经干细胞的分化调控一直是发育神经生物学的重要研究课题。综述了调节胚胎和成体神经干细胞分化的细胞内在因素和外部环境因素,初步探讨了胚胎和成体神经干细胞分化机制的差异。 相似文献
1000.
We investigated the composition and organization of chlorophylls in monomers, trimers and oligomers (small aggregates) of the main light-harvesting complex (LHC II) isolated from marine alga, Bryopsis corticulans, using a combination of measurements with reversed-phase high performance liquid chromatography (RP-HPLC) and steady-state spectroscopy of absorption, circular dichroism (CD) and low temperature fluorescence. The composition and organization of the chlorophylls in monomeric and trimeric LHC II were essentially identical to those of LHC II from higher plants. For LHC II oligomers, a large decrease of chlorophyll (Chl) b absorption and of CD signals corresponding to Chl b was consistent with the quantitative analysis of Chl b by RP-HPLC, indicating that oligomerization of the LHC II proteins significantly influenced spectroscopic properties and led to the dissociation of Chl b molecules from LHC II. Our data strongly suggested that protein oligomerization constitutes a structural basis for the decrease of Chl b molecules in LHC II of B. corticulans. The LHC II of B. corticulans might play a photoprotective role with the reduction of the ability of light absorption via alteration of its own structural conformation. 相似文献