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41.
Phycobilisomes (PBSs) are the main accessory light-harvesting complexes in cyanobacteria and their movement between photosystems (PSs) affects cyclic and respiratory electron transport. However, it remains unclear whether the movement of PBSs between PSs also affects the transthylakoid proton gradient (ΔpH). We investigated the effect of PBS movement on ΔpH levels in a unicellular cyanobacterium Synechocystis sp. strain PCC 6803, using glycinebetaine to immobilize and couple PBSs to photosystem II (PSII) or photosystem I (PSI) by applying under far-red or green light, respectively. The immobilization of PBSs at PSII inhibited decreases in ΔpH, as reflected by the slow phase of millisecond-delayed light emission (ms-DLE) that occurs during the movement of PBSs from PSII to PSI. By contrast, the immobilization of PBSs at PSI inhibited the increase in ΔpH that occurs when PBSs move from PSI to PSII. Comparison of the changes in ΔpH and electron transport caused by the movement of PBSs between PSs indicated that the changes in ΔpH were most likely caused by respiratory electron transport. This will further improve our understanding of the physiological role of PBS movement in cyanobacteria.  相似文献   
42.
The fecC gene encoding a putative iron (Ⅲ) dicitrate transporte rwas cloned from nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO3^- , NH1^- or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wildtype strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that the fecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed that fecC gene product is required for optimal growth under iron-deficient conditions in Anabaena sp. PCC 7120.  相似文献   
43.
根据磺基水杨酸反常大的荧光Stokes位移的实验现象,提出了它在一定条件下发生分子内质子转移的机理.据此建立了酸性锡电镀液中磺基水杨酸的直接快速荧光分析新方法.该方法不受共存组分干扰,5~10min可完成测定,测定的相对标准偏差小于3%.  相似文献   
44.
在主分量分类器(PCC)的基础上提出了二维主分量分类器方法,具有速度快、算法简便的特点.人脸性别分类结果表明,所提出的方法在识别性能上优于主分量分类器;另外,算法执行时间具有很大的改进.  相似文献   
45.
外源DNA导入Synechococcus sp.PCC7942后.通过NBT光化还原和PAGE电泳检测发现转基因藻Synechococcus sp.PCC7942的SOD活性和同工酶谱发生了改变.若外源基因整合在受体细胞染色体DNA上,根据整合位点的不同则能提高或减弱Synechococcus sp.PCC7942的SOD活性,同时增加同工酶谱带.若外源基因不是整合在染色体上而是以质粒的形式存在,则只改变Synechococcus sp.PCC7942 SOD活性而不影响其同工酶谱.  相似文献   
46.
    
The mutant lacking ORF469 fragment inSynechocystis sp. PCC 6803 (cyanobacterium) was created by means of DNA recombination. In its genome,ORF 469, the key DNA fragment controlling the light-independent pathway of chlorophyll biosynthesis was deleted and replaced by erythromycin resistance cassette. The operation resulted in the fact that the content of chlorophyll in mutant cells was fully controlled by illumination and two kinds of cells were harvested, one is high chlorophyll with concentration of 9.427 μg· mg−1 and the other is low chlorophyll with concentration of 0.695 μg · mg1. They were subjected to thermal simulation respectively at 300°C for 100 h. The alkanes biomarkers from pyrolysates were analyzed by GC-MS and main difference between high and low chlorophyll cells was found at their contents of isoprenoid hydrocarbons. Pr/nC17 and Ph/nC18 from pyrolysate of low chlorophyll cells were 0.192 and 0.216 respectively, which were about 1/3 and 1/7 of that from high chlorophyll cells. The results provide direct evidence that isoprenoid hydrocarbons such as phytane(Ph) and pristane (Pr) could be derived from chlorophyll. The lipids in algal cells would be the most important contributors to hydrocarbon production in their thermal degradation. The results also indicated that the combination of molecular biology and organic geochemistry would provide a new path to investigate the molecular sources of biomarkers.  相似文献   
47.
通过将选择性废气再循环(S-EGR)与联合循环的集成实现CO2的捕集和循环,以获得更高的系统运行效率。基于实际联合循环电厂的运行数据,探究了选择性废气再循环S-EGR集成对实际联合循环和碳捕集系统的影响。结果表明:S-EGR集成后分别提升碳捕集和联合循环Exergy效率6.9%和1.3%;燃烧室是联合循环中Exergy损失最大的部件,占比44.8%,其次是蒸汽轮机、凝汽器和余热锅炉,造成Exergy损失的主要原因是温差;碳捕集单元与联合循环集成后,热效率和Exergy效率都在S-EGR循环比为10%时达到峰值后逐渐降低。  相似文献   
48.
对大型重载船舶进行下水计算及其安全性研究时,需要考虑船体局部结构强度问题.利用船舶下水的弹性计算方法计算了船体在下水过程中的局部受力,校核船体局部结构强度能否满足下水要求;并以Excel软件为基础,利用VBA设计开发了适合于大型船舶下水计算的通用程序.实例计算表明,该通用程序在大型船舶下水分析方面具有较强的通用性和实用性,同时在与其他软件进行数据交互方面,也具有很强的通用性.  相似文献   
49.
采用封闭式光生物反应器进行了蓝藻基因工程常用宿主系统集胞藻Synechocystis sp. PCC 6803的混合营养培养,并与光自养培养进行了比较,在两种培养方式下,集胞藻6803的饱和光强基本相同,都为5000lx,当入射光强为5000lx,初始葡萄糖浓度为1.74g/L时,混合营养生长在葡萄糖消耗完(69.5h)时的藻细胞密度为1.36g/L,叶绿素浓度为20.08mg/L,能量得率为16.7%,分别为同期光自养生长的3.8倍,2.3倍和2.6倍,这表明封闭式光生物反应器混合营养培养方式在促进集胞藻6803生长和光合色素合成及提高培养过程能量得率等方面都有显著作用。  相似文献   
50.
转基因鱼腥藻7120光异养生长的研究   总被引:1,自引:0,他引:1  
研究了不同有机碳源对转基因鱼腥藻7120生长的影响,在此基础上进行了光异养条件的优化,并研究了外源添加剂L-精氨酸、生长激素2,4-D与KT对藻细胞生长的影响。结果表明:蔗糖和葡萄糖能促进藻体的生长;最优碳氮源组合为葡萄糖6g/L、NaNO31.5g/L,经高压灭菌;L-精氨酸不支持藻体的光异养生长;一定含量的2,4-D与KT能促进藻体在光异养条件下的后期生长。  相似文献   
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