CO_2对微拟球藻(Nannochloropsis sp.)利用有机碳和光合作用的影响

CO2浓度提高时,微拟球藻吸收醋酸钠的速率增加2倍。混养生长的藻细胞最大光合作用速率、光合作用效率、无机碳半饱和常数和无机碳饱和的光合作用速率均显著低于光自养条件下生长的。

Thylakoid terminal oxidases are essential for the cyanobacterium Synechocystis sp. PCC 6803 to survive rapidly changing light intensities.

Cyanobacteria perform photosynthesis and respiration in the thylakoid membrane, suggesting that the two processes are interlinked. However, the role of the respiratory electron transfer chain under natural environmental conditions has not been established. Through targeted gene disruption, mutants of Synechocystis sp. PCC 6803 were generated that lacked combinations of the three terminal oxidases: the thylakoid membrane-localized cytochrome c oxidase (COX) and quinol oxidase (Cyd) and the cytoplasmic membrane-localized alternative respiratory terminal oxidase. All strains demonstrated similar growth under continuous moderate or high light or 12-h moderate-light/dark square-wave cycles. However, under 12-h high-light/dark square-wave cycles, the COX/Cyd mutant displayed impaired growth and was completely photobleached after approximately 2 d. In contrast, use of sinusoidal light/dark cycles to simulate natural diurnal conditions resulted in little photobleaching, although growth was slower. Under high-light/dark square-wave cycles, the COX/Cyd mutant suffered a significant loss of photosynthetic efficiency during dark periods, a greater level of oxidative stress, and reduced glycogen degradation compared with the wild type. The mutant was susceptible to photoinhibition under pulsing but not constant light. These findings confirm a role for thylakoid-localized terminal oxidases in efficient dark respiration, reduction of oxidative stress, and accommodation of sudden light changes, demonstrating the strong selective pressure to maintain linked photosynthetic and respiratory electron chains within the thylakoid membrane. To our knowledge, this study is the first to report a phenotypic difference in growth between terminal oxidase mutants and wild-type cells and highlights the need to examine mutant phenotypes under a range of conditions.

聚球藻Synechococcus sp.PCC7942高CO_2需求突变株的筛选及其超微结构观察(英文)

以单细胞蓝藻聚球藻Synechococcussp.PCC7942为材料,利用甲基磺酸乙酯(EMS)进行化学诱变获得了一个高CO2 需求突变株。它能在 4%CO2 下生长而不能在空气中生长。对突变株的初检表明:其回复突变率约为 10 -7。该突变株从高CO2 条件下转到空气中后,细胞在 2～ 3d内逐渐趋于死亡;其光合作用对外源无机碳的依赖性高于野生型细胞,碳酸酐酶活性也低于野生型细胞。在超微结构水平,突变株细胞内出现了不同类型的异常羧体:有的为棒状;有的为不规则状;有的为 空羧体",而且,类囊体周围糖原颗

鱼腥藻sp.PCC 7120液泡的诱导和分离

将蓝藻培养于含 0 .0 5 mol/ L Na Cl的液体培养基 ,3d后细胞结构改变 ,出现无色透明区 .将此材料经溶菌酶处理形成原生质球 ,然后降低渗透压 ,原生质球破裂 ,液泡释放 .此液泡为极为标准的园球状 ,完全透明 ,泡体内无可辩物质 .电镜检查表明为一个单一膜所包围 ,泡内没有内囊体等细胞内物质 ,该膜亦显示典型三明治状单位膜结构 .

蓝藻Anabaena sp.PCC7120 羧体碳酸酐酶的鉴定

在丝状蓝藻Anabaena sp.PCC7120细胞粗提液的碳酸酐酶(CA)分析中,发现了两种形式的CA活性.高CO_2下生长的细胞,在35μmol/L EZ(Ethoxyzolamide,碳酸酐酶的抑制剂)存在的情况下,CA总活性的85％左右被抑制,其半抑制浓度I_(50)为7.4μmol/L;随着EZ浓度的继续增加,CA活性在EZ浓度达到约150μmol/L处出现了第二个抑制峰,在250μmol/L处抑制程度达到最大,使CA总活性的15％被抑制,其半抑制浓度I_(50)为190μmol/L。在空气条件

红球藻水生748株(Haematococcus sp.HB748)培养基的选择与对维生素B_(12)的需求

比较了红球藻HB748株在MCM，BBM及BG－11．3种培养基中的生长．结果表明：HB748在这3种培养基中前4d的平均生长速率分别为0．97d－1，0．77d－1和0．63d－1，存在显著差异；然而，在BBM和BG－11中添加MCM中所含等量VB12后，748株在3种培养基中的生长速率趋于一致，表明VB12，是HB748维持较好的前期生长的必需成分；在VB12的需求满足后．3种培养基无机组分的差异对HB748前期生长影响甚微．

鱼腥藻（Anabaena sp．）营养成分分析

研究分析了混合鱼腥藻粉的营养成分，结果表明混合鱼腥藻粉蛋白质含量为４０．５％；氨基酸组成符合联合国粮农卫生组织（ＦＡＯ／ＷＨＯ）规定的标准；并含有较丰富的糖类、脂肪酸、无机元素和色素。证实了鱼腥藻可以作为蛋白饲料资源开发和利用。

Lymph Node Colonization Dynamics after Oral Salmonella Typhimurium Infection in Mice

An understanding of how pathogens colonize their hosts is crucial for the rational design of vaccines or therapy. While the molecular factors facilitating the invasion and systemic infection by pathogens are a central focus of research in microbiology, the population biological aspects of colonization are still poorly understood. Here, we investigated the early colonization dynamics of Salmonella enterica subspecies 1 serovar Typhimurium (S. Tm) in the streptomycin mouse model for diarrhea. We focused on the first step on the way to systemic infection - the colonization of the cecal lymph node (cLN) from the gut - and studied roles of inflammation, dendritic cells and innate immune effectors in the colonization process. To this end, we inoculated mice with mixtures of seven wild type isogenic tagged strains (WITS) of S. Tm. The experimental data were analyzed with a newly developed mathematical model describing the stochastic immigration, replication and clearance of bacteria in the cLN. We estimated that in the beginning of infection only 300 bacterial cells arrive in the cLN per day. We further found that inflammation decreases the net replication rate in the cLN by 23%. In ccr7-/- mice, in which dendritic cell movement is impaired, the bacterial migration rate was reduced 10-fold. In contrast, cybb-/- mice that cannot generate toxic reactive oxygen species displayed a 4-fold higher migration rate from gut to cLN than wild type mice. Thus, combining infections with mixed inocula of barcoded strains and mathematical analysis represents a powerful method for disentangling immigration into the cLN from replication in this compartment. The estimated parameters provide an important baseline to assess and predict the efficacy of interventions. © 2013 Kaiser et al.

固氮蓝藻Anabaena sp.7120的叶绿素蛋白复合体的分离和光谱特性的研究

用光合膜片增溶和SDS-聚丙烯酰胺凝胶电泳方法,从固氮蓝藻Anabaena sp.7120分离到7条色素带。迁移率较慢的五条叶绿素蛋白复合体带,具有相同的吸收光谱和室温荧光光谱特性。它们的红区最大吸收峰在676nm;蓝区最大吸收峰在438nm。它们的室温荧光发射最高峰在672—673nm;在710,732和740nm都有小峰。这些是CPⅠ叶绿素所特有的。我们认为这5条带都是属于光系统Ⅰ的叶绿素蛋白复合体。另一条迁移率稍快的叶绿素蛋白复合体带为CPⅡ。它的红区最大吸收峰在672nm;蓝区最大吸收峰在436n

Dynamics of spread of Salmonella enterica in the systemic compartment.

Traditional microbiological and immunological tools, combined with modern imaging, and molecular and mathematical approaches, have revealed the dispersive nature of Salmonella infections. Bacterial escape from infected cells, spread in the tissues and attempts to restrain this process by the host give rise to fascinating scenarios that underpin the pathogenesis of salmonelloses.

有机磷农药在水生态系中生物净化机理研究---- ----4. Pseudomonas sp. CTP-01 的对硫磷水解酶诱导合成性质

Pseudomonas sp.CTP-01的对硫磷水解酶具有底物诱导合成性质。停滞生长期的细胞接触底物半小时即产生相应酶的合成,而指数生长期的细胞接触底物48小时后才发生酶的合成。甲基对硫磷及对硝基酚也具有诱导作用,可见合成对硫磷水解酶的诱导特异基团可能与对硝基酚及其苯环上的取代基有密切关系。

Dynamics of spread of Salmonella enterica in the systemic compartment

Traditional microbiological and immunological tools, combined with modern imaging, and molecular and mathematical approaches, have revealed the dispersive nature of Salmonella infections. Bacterial escape from infected cells, spread in the tissues and attempts to restrain this process by the host give rise to fascinating scenarios that underpin the pathogenesis of salmonelloses. © 2013 Institut Pasteur.

三带喙库蚊寄生等索线虫(Isomermis sp.)生活史的初步研究

本文首次报导了武汉市郊区三带喙库蚊(Culex tritaeniorhynchus)孑孓体内寄生等索线虫(Isomermis sp.)的生活史。等索线虫在6月至9月份对宿主的寄生率的幅度为5%～48%。等索线虫一年内可发生多代,当气温在26°～33℃时,完成一代生活史的周期为22～28天;并成功地进行了室内人工感染;此外就等索线虫对宿主的感染强度,寄生部位;雌雄性比等问题也进行了初步的研究。

蓝裸甲藻(新种)(Gymnodinium cyaneum Hu sp.nov.)藻胆素(Phycobilin)的发现及其意义

<正> 在藻类的光合色素系统中,叶绿素a是各门类所共有的.但就其采收光能的天线色素而言,因门类而有很大的差别.因此,天线色素的不同就成为研究藻类系统分类和演化问题的重要依据之一.藻胆素是某些藻类光合系统中的主要天线色素.研究表明,藻胆素仅存在于蓝藻类(cyanophyceae)、红藻类(Rhodophyceae)和隐藻类(cryptophyceae)中.甲藻(Pyrrophyceae)的某些类型因其细胞核缺乏真核生物所具有的碱性蛋白而被称为间核生物(Mcsokaryota).从细胞核的性质来说,这些类型无