多变鱼腥藻半稳定状态连续培养的若干特征

分别使用恒化装置和全玻璃发酵罐连续培养多变鱼腥藻。在稳定条件下加以周期性的光照(L∶D=12∶12),经5—6d得到半稳定状态连续培养物。在光照阶段,培养物的生物量增长速度约等于稀释速度D的两倍,叶绿素的增长速度略小于D的两倍,糖原的累积速度几乎高出D~5的一个数量级。细胞内糖原和蛋白质含量变化的时间过程反映出培养物在光-暗条件下的碳氮物质合成与消耗相互联系的代谢特点。半稳定状态连续培养受培养物内在的生理活性支配,生长参数的变化符合方程X=X_(oe)~((μ-D)~t),但不同于恒浊培养和恒化培养。外界因素的强弱变化只改变生长参量变化的强度。本法适用于研究微藻的生态生理。     

Porin from Thiobacillus versutus

The porin of Thiobacillus versutus IFO 14567 was isolated by extraction of cell-envelopes with sodium dodecyl sulfate. It exhibited strong porin-activity after reconstitution into artificial lipid bilayer membranes. The diameter of the pore was determined as 1.6 nm, with a weak selectivity for cations being observed. The porin migrated as a single band (Mr 35 kDa) on SDS-polyacrylamide gel-electrophoresis after heating (100 degrees C, 5 min). The porin oligomer was not sensitive towards EDTA. Analytical ultracentrifugation studies demonstrated the native oligomer to be a trimer.     

The effect of nickel on the hydrogen metabolism of the cyanobacterium Anabaena cylindrica

Abstract The oxyhydrogen reaction of the cyanobacterium Anabaena cylindrica was shown to be dependent on the availability of nickel ions in the growth medium. The rate of nitrogenase-catalyzed hydrogen formation was shown to be inversely related to the capacity of the cells to consume hydrogen gas as seen by experiments in which the nickel ion concentration was systematically varied. Nickel-depleted cultures released hydrogen in air and dinitrogen.     

Note on the survival of algal resting cells during long-term maintenance in darkness and minimum lake bottom temperature. Comparison of Anabaena (cyanobacteria) and Haematococcus (volvocales)

Resting cell formation in algae and cyanobacteria is one of the strategies developed for withstanding adverse environmental conditions. This note informs about the different capacities of such resting cells to germinate after long-term dark preservation at 4 °C in Anabaena variabilis (Cyanobacteria, Cyanophyta) and Haematococcus lacustris (Chlorophyta, Volvocales).     

Ultrafast photochemistry of Anabaena Sensory Rhodopsin: Experiment and theory

Light induced isomerization of the retinal chromophore activates biological function in all retinal protein (RP) driving processes such as ion-pumping, vertebrate vision and phototaxis in organisms as primitive as archea, or as complex as mammals. This process and its consecutive reactions have been the focus of experimental and theoretical research for decades. The aim of this review is to demonstrate how the experimental and theoretical research efforts can now be combined to reach a more comprehensive understanding of the excited state process on the molecular level. Using the Anabaena Sensory Rhodopsin as an example we will show how contemporary time-resolved spectroscopy and recently implemented excited state QM/MM methods consistently describe photochemistry in retinal proteins. This article is part of a Special Issue entitled: Retinal Proteins — You can teach an old dog new tricks.     

在光、暗及高温下氧与鱼腥藻7120固氮的关系

鱼腥藻7120从光转暗不同时间后，照光检测固氮活性的损失速度与氧量直接相关。在黑暗12小时后，复光时的活性恢复被氧霉素、氯化铵或38—40℃空气氧所阻遏，黑暗中生成的酶易被氧失活。在光下和黑暗中短时暴露于不同氧压时，黑暗中氧引起固氮活性的下降比光下快得多。抗坏血酸大大减少高氧引起的失活，高温可能增加固氮酶活性对氧的敏感性。在光下100％O2处理120分钟，活性没有进一步下降，也没有活性的恢复，没有观察到构型保护。讨论了环境条件与氧保护的关系。     

多变鱼腥藻在不同氮源培养条件下光能转换效率的研究

依公式PE=KY,其中K等于生物量的热值(每克干重千卡),Y等于产率即每吸收千卡光能所产生的生物量的干重,测试了在无氮和有结合氮培养下的多变鱼腥藻(Anabaena variabilis)的光能转化效率。结果指出在无氮培养下的最高PE_(N2)为8.1%,在结合氮(NH_4Cl)培养下PE_(NH_4~ )为5.8%。对这种差异性作了简要讨论。     

Characterization of HetR protein turnover in Anabaena sp. PCC 7120

The hetR gene plays an important role in heterocyst development and pattern formation in heterocystous cyanobacteria. The hetR gene from Anabaena sp. PCC 7120 was overexpressed in Escherichia coli. Antibodies raised against the recombinant HetR protein (rHetR) were used to characterize metabolism of the HetR of Anabaena sp. PCC 7120 in vivo. HetR was present at a low level when Anabaena sp. PCC 7120 was grown in the presence of combined nitrogen. Shifting from nitrogen repletion conditions to nitrogen depletion conditions led to a two fold increase of HetR in total cell extracts, and most of HetR was located in heterocysts. The amount of HetR in total cellular extracts increased rapidly after shifting to nitrogen depletion conditions and reached a maximum level 3 h after the shift. Isoelectrofocusing electrophoresis revealed that the native HetR had a more acidic isoelectric point than did rHetR. After combined nitrogen was added to the nitrogen-depleted cultures, the degradation of HetR depended on culture conditions: before heterocysts were fully developed, HetR was rapidly degraded; after heterocysts were fully developed, HetR was degraded much more slowly. The distribution of HetR in other species of cyanobacteria was also studied. Received: 24 June 1997 / Accepted: 5 December 1997