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1.
Cell-free extracts with high nitrogenase activity were prepared by sonic oscillation and French press treatment from the blue-gree alga Anabaena cylindrica. Extracts were prepared from cells grown on a 95% N(2)-5% CO(2) gas mixture followed by a period of nitrogen starvation under an atmosphere of 95% argon-5% CO(2). No increase in the specific activity of extracts was achieved by breaking heterocysts. Activity (assayed by acetylene reduction) was found to be dependent on adenosine triphosphate (ATP), an ATP-generating system, and a low-potential reductant. Na(2)S(2)O(2) employed as reductant supports higher rates of nitrogenase activity than reduced ferredoxin. The activity is associated with a small-particle fraction that can be sedimented by ultracentrifugation. In contrast to the particulate nitrogenase of Azotobacter, which is stable in air, the A. cylindrica nitrogenase is an oxygen sensitive as nitrogenase prepared from anaerobic bacteria.  相似文献   

2.
An assay was developed to determine the amount of cyanophycin granules in blue-green algae. The amount of this polypeptide in cells of Anabaena cylindrica was measured as a function of culture age and was compared with changes in other proteinaceous cellular components. The data presented support the notion that the cyanophycin granule is a cellular nitrogen reserve.  相似文献   

3.
Over 90% of cells of Anabaena cylindrica growing in the medium containing 0. 1 mol/L KC1 for 7~9 d transformed into spheroplasts or semispheroplasts which were either sensitive or not sensitive to hypotonic condition. After treating the materials with 0. 1% lysozyme at 28 ℃ for 3~4 h the transformed spheroplasts were almost 100% sensitive to the hypotonic condition. The spheroplasts then regenerated and divided through culture in the inorganic medium containing 0.15 mol/L CaCl2 with a rate over 25 %. The regeneration of different spheroplasts was not synchronous, the fastest division being after 3 d. Cell division was mainly equational but also irregular division or budding.  相似文献   

4.
An investigation was made of various factors, both experimental and physiological, which influenced the formation of hydrogen gas by the heterocystous cyanobacterium Anabaena cylindrica B629 when incubated in both argon and air. A. cylindrica B629 produces hydrogen in air in the presence of carbon monoxide, acetylene, or both, with a short lag period. The rate of production in air at optimal concentrations of these compounds was found to be comparable with that in an argon atmosphere. Whereas under argon, ammonium ions (0.5 to 6 mM) were found to inhibit hydrogen formation in a manner which was dependent on light intensity and not relieved by oxygen (1 to 20% of gas phase), in air-carbon monoxide-acetylene, these ions (up to at least 0.5 mM) slightly stimulated hydrogen production for at least 24 h. Conclusions are drawn about short-term aerobic and anaerobic hydrogen formation by A. cylindrica B629 and the effects of ammonium ions, oxygen, carbon monoxide, and acetylene on these processes.  相似文献   

5.
在含KCl的条件下培养,柱胞鱼腥藻细胞膨大,球形化,色素质靠向细胞一侧,另一侧变成无色透明区。电镜检查,无色透明区形成液泡。此种结构改变是可逆的,CaCl2可抵消KCl的这种作用。在含KCl的无氮培养基中培养,柱胞鱼腥藻生长迟缓,细胞黄化,乙炔还原法测定固氮活性下降95%。  相似文献   

6.
I. Laczkó  K. Barabás 《Planta》1981,153(4):312-316
We have studied the evolution of hydrogen by photobleached filaments of the heterocystous bluegreen alga Anabaena cylindrica. The photobleached cells became orange-yellow due to the heavy accumulation of carotenoids. We found that the yellow filaments produced much larger amounts of hydrogen than the normal, green ones, while the nitrogenase activity responsible for hydrogen evolution increased to a lesser extent. We suggest that a reversible hydrogenase activity induced in photobleached filaments is responsible for the excess amount of hydrogen. 3-(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) inhibits the hydrogen evolution of the yellow filaments which produce much more oxygen and fix less CO2 than the green filaments. Therefore we consider the water to be a possible electron source for this hydrogenase. The low efficiency of light energy conversion (0.3%) in nitrogenase-catalyzed H2 evolution (Laczkó, 1980 Z. Pflanzenphysiol. 100, 241–245) is increased to 1.5–2% by the appearance of the reversible hydrogenase activity.Abbreviations Chl chlorophyll - Car carotenoids - Phy phycocyanin - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethyl-urea - PSI photosystem I - PSII photosystem II  相似文献   

7.
An enzymatic method was used to determine ATP extracted from anaerobically incubated samples of the blue-green alga Anabaena variabilis. The dark-light-dark transients of the ATP level in the whole cells were studied in the presence and in the absence of 3 (p-chlorophenyl)-l.l-dimethylurea (CMU). When O2 evolution was completely inhibited by CMU, there was no significant difference between the transient under illumination of a low intensity and that of fourfold intensity. On the other hand in the absence of CMU, the ATP level decreased more rapidly after high intensity illumination than after low intensity one. The increase in ATP content during the first 5 s illumination was smaller in the absence of CMU than in the presence of CMU. With or without CMU the increase was saturated at the vicinity of the intensity at which photosynthetic O2 evolution compensates for respiratory O2 consumption. The calculated quantum requirement of cyclic photophosphorylation in vivo was 2.2 quanta per ATP.  相似文献   

8.
The role of the oxyhydrogen reaction in the nitrogen metabolism of Anabaena cylin-drica, particularly under conditions of dinitrogen starvation, was investigated. It was shown that although this reaction supports nitrogenase activity in the dark, when the cells are deprived of nitrogen the rate of hydrogen uptake is little changed. Measurements of ammonia excretion into the medium in the presence of methionine sulfoximine under such conditions indicated that hydrogen uptake supported the turnover of cell protein as an alternative source of nitrogen. In the absence of H2 and O2 in the dark, nitrogenase activity was negligible but protein turnover continued. In their presence nitrogenase activity was greatly stimulated; turnover was also stimulated but to a greater extent in the absence of nitrogenase substrates. The oxyhydrogen reaction also stimulated uptake of ammonium ions by intact filaments in argon in the dark. Only at very low hydrogen tensions can net hydrogen formation be obtained in argon/CO2 in the light, casting considerable doubt on the suitability of hydrogenase-containing organisms for biophotolytic hydrogen formation. Addition of exogenous ammonia to the cultures incubated in argon resulted in a pronounced stimulation of H2 uptake; nitrate and its derivatives had no such effect, nor did various amino acid derivatives of ammonia.  相似文献   

9.
10.
A heterocystous, non-nitrogen-fixing mutant of the nitrogen-fixingblue-green alga Anabaena doliolum has been isolated followingtreatment with nitrosoguanidine and UV radiation. Some reversiblevariations in the habit and morphology of the alga were inducedfollowing its treatment with nitrosoguanidine.  相似文献   

11.
Cylindrical 52.5-nm-long phycobilisomes were observed in Anabaenavariabilis, differing from the generally accepted hemidiscoidalmorphology. The central part of such a phycobilisome has a network-likefine structure of slightly greater diameter (16 nm) than theconnected end parts of stacked-disc structure (12 nm in diameter).On the basis of this morphology, the molecular mass of thisphycobilisome was calculated to be 3.27?106, about 60% of whichis accounted for by phycocyanin with the rest being due to allophycocyanin.Separately prepared 23 S allophycocyanin particles with a molecularmass of 1.13?106 have the dimensions (16?23 nm) and network-likefine structure similar to the central part of phycobilisomes,while an aggregate form of phycocyanin (18 S) has a fine structureof stacked discs similar to the connecting end part of phycobilisomes,suggesting that the central part constitutes the core at whichthese phycobilisomes attach to the thylakoid membranes. (Received June 5, 1982; Accepted September 21, 1982)  相似文献   

12.
Carbonic anhydrase (CA) activity was detected in homogenatesfrom Anabaena variabilis ATCC 29413, M-2 and M-3, but not inthe suspension of the intact cells. Activity was higher in cellsgrown in ordinary air (low-CO2 cells) than in those grown inair enriched with 2–4% CO2 (high-CO2 cells). Fractionationby centrifugation indicated that the CA from A. variabilis ATCC29413 is soluble, whereas both soluble and insoluble forms existin A. variabilis M-2 and M-3. The addition of dithiothreitoland Mg2 $ greatly decreased the CA activity of A. variabilisATCC 29413. The specific activity of the CA from A. variabilis ATCC 29413was increased ca. 200 times by purification with ammonium sulfate,DEAE-Sephadex A-50 and Sephadex G-100. Major and minor CA peaksin Sephadex G-100 chromatography showed respective molecularweights of 48,000 and 25,000. The molecular weight of the CAdetermined by polyacrylamide disc gel electrophoresis was 42,000?5,000.The activity of CA was inhibited by ethoxyzolamide (I50=2.8?10-9M), acetazolamide (I50=2.5?10-7 M) and sulfanilamide (I50=2.9?10-6M). (Received January 5, 1984; Accepted April 26, 1984)  相似文献   

13.
14.
Nitrogen-starved cultures of the alga Anabaena cylindrica 629 produced hydrogen and oxygen continuously for 7 to 19 days. Hydrogen production attained a maximum level after 1 to 2 days of starvation and was followed by a slow decline. The maximum rates were 30 ml of H2 evolved per liter of culture per h or 32 mul of H2 per mg of dry weight per h. In 5 to 7 days the rate of H2 evolution by the more productive cultures fell to one-half its maximum value. The addition of 10(-4) to 5 X 10(-4) M ammonium increased the rate of oxygen evolution and the total hydrogen production of the cultures. H2-O2 ratios were 4:1 under conditions of complete nitrogen starvation and about 1.7:1 after the addition of ammonium. Thus, oxygen evolution was affected by the extent of the nitrogen starvation. Thermodynamic efficiencies of converting incident light energy to free energy of hydrogen via algal photosynthesis were 0.4%. Possible factors limiting hydrogen production were decline of reductant supply and filament breakage. Hydrogen production by filamentous, heterocystous blue-green algae could be used for development of a biophotolysis system.  相似文献   

15.
Nitrogen-starved cultures of the alga Anabaena cylindrica 629 produced hydrogen and oxygen continuously for 7 to 19 days. Hydrogen production attained a maximum level after 1 to 2 days of starvation and was followed by a slow decline. The maximum rates were 30 ml of H2 evolved per liter of culture per h or 32 mul of H2 per mg of dry weight per h. In 5 to 7 days the rate of H2 evolution by the more productive cultures fell to one-half its maximum value. The addition of 10(-4) to 5 X 10(-4) M ammonium increased the rate of oxygen evolution and the total hydrogen production of the cultures. H2-O2 ratios were 4:1 under conditions of complete nitrogen starvation and about 1.7:1 after the addition of ammonium. Thus, oxygen evolution was affected by the extent of the nitrogen starvation. Thermodynamic efficiencies of converting incident light energy to free energy of hydrogen via algal photosynthesis were 0.4%. Possible factors limiting hydrogen production were decline of reductant supply and filament breakage. Hydrogen production by filamentous, heterocystous blue-green algae could be used for development of a biophotolysis system.  相似文献   

16.
An investigation was made of certain factors involved in the formation of hydrogen gas, both in an anaerobic environment (argon) and in air, by the blue-green alga Anabaena cylindrica. The alga had not been previously adapted under hydrogen gas and hence the hydrogen evolution occurred entirely within the nitrogen-fixing heterocyst cells; organisms grown in a fixed nitrogen source, and which were therefore devoid of heterocysts, did not produce hydrogen under these conditions. Use of the inhibitor dichlorophenyl-dimethyl urea showed that hydrogen formation was directly dependent on photosystem I and only indirectly dependent on photosystem II, consistent with heterocysts being the site of hydrogen formation. The uncouplers carbonyl cyanide chlorophenyl hydrazone and dinitrophenol almost completely inhibited hydrogen formation, indicating that the process occurs almost entirely via the adenosine 5'-triphosphate-dependent nitrogenase. Salicylaldoxime also inhibited hydrogen formation, again illustrating the necessity of photophosphorylation. Whereas hydrogen formation could usually only be observed in anaerobic, dinitrogen-free environments, incubation in the presence of the dinitrogen-fixing inhibitor carbon monoxide plus the hydrogenase inhibitor acetylene resulted in significant formation of hydrogen even in air. Hydrogen formation was studied in batch cultures as a function of age of the cultures and also as a function of culture concentration, in both cases the cultures being harvested in logarithmic growth. Hydrogen evolution (and acetylene-reducing activity) exhibited a distinct maximum with respect to the age of the cultures. Finally, the levels of the protective enzyme, superoxide dismutase, were measured in heterocyst and vegetative cell fractions of the organism; the level was twice as high in heterocyst cells (2.3 units/mg of protein) as in vegetative cells (1.1 units/mg of protein). A simple procedure for isolating heterocyst cells is described.  相似文献   

17.
Filaments of the blue-green alga Anabaena variabilis permeabilized by dimethylsulfoxide (DMSO) produce increased amounts of 5-aminolevulinate in the presence of levulinic acid. The metabolic activity of the filaments remains unperturbed in the presence of up to 7.5% (v/v) DMSO. Studies utilizing DMSO-permeabilized filaments confirm that 5-aminolevulinate is synthesized preferably from glutamate and, to a lesser extent, from α-ketoglutarate in this organism.  相似文献   

18.
Light-induced proton efflux of Anabaena variabilis was found to be biphasic, the second phase being inhibited by the ATPase inhibitor nitrofen (2,4-dichloro-1-[4-nitrophenoxy]benzene). The first, fast phase was triggered by monochromatic light of 707 nanometers, whereas the second, slower phase was not. With 707 nanometers, light, respiratory O2 uptake was inhibited. Using light composed of two wavelengths (616 and 707 nanometers) a marked enhancement of both O2 evolution as well as the second phase of proton efflux was observed. The first phase was not enhanced. Thus, phase II is driven by both photosystems. As concluded from the action spectrum phase I is markedly determined by photosystem-I activity. Altogether the data show that two different mechanisms of light-induced proton efflux exist on the cytoplasmic membrane of Anabaena, the slower one being dependent on ATP and linear photosynthetic electron flow.  相似文献   

19.
The time course of hydrogen formation by Anabaena cylindrica was followed beneath an argon atmosphere alone and also beneath atmospheres of argon, nitrogen, and air in the presence of carbon monoxide (0.2%) and acetylene (5%). Hydrogen production beneath argon alone was comparable in rate and duration (7 to 12 days) to that which occurred beneath air in the presence of carbon monoxide (0.2%) and acetylene (5%). However, much greater longevity (16 to 26 days) and improved rates of hydrogen formation were obtained when algae were incubated beneath argon and particularly nitrogen, each supplemented with carbon monoxide and acetylene. The total hydrogen produced by these cultures was up to three times as much as that released by cultures incubated beneath argon alone. Hydrogen-oxygen ratios for argon cultures either with or without carbon monoxide and acetylene were initially 1:5 but approximated 1:2 when measured over the entire incubation period. In each case oxygen production and nitrogenase activity (acetylene reduction) continued at reduced rates after hydrogen evolution had ceased. The effects of methionine sulfoximine (2 μM), ammonium ions (0.5 mM), or both on oxygen production were generally negligible, while effects on hydrogen production were variable depending on the atmosphere used; in most cases, eventual destabilization of the system occurred. A brief comparison was made of the time courses of anaerobic and aerobic hydrogen formation by the marine cyanobacterium Calothrix membranacea. It was found that shaking of cultures was beneficial for hydrogen production but not strictly necessary. It is concluded that hydrogen production by A. cylindrica in air and particularly nitrogen in the presence of carbon monoxide and acetylene offers the best potential of the atmospheres considered on the basis of four criteria: rates and longevity of hydrogen formation, practicality of the atmosphere used, and tolerance of hydrogen evolution to slight changes in composition of the atmosphere.  相似文献   

20.
鱼腥藻7120细胞液泡内含物的初步测定   总被引:1,自引:1,他引:0  
对鱼腥藻7120细胞液泡内含物中4种水溶性的物质进行了测定,液泡中4种物质占整个细胞中4种物质的比例分别为:蛋白质:14.1%;还原糖:34.4%;核酸:28.5%;藻青蛋白12.1%。  相似文献   

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