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2.
Some physiological characteristics of a mutant (E 1) of Anacystis nidulans R 2, incapable of growing at air level of CO 2, are described. E 1 is capable of accumulating inorganic carbon (C i) internally as efficiently as the wild type (R 2). The apparent photosynthetic affinity for C i in E 1, however, is some 1000 times lower than that of R 2. The kinetic parameters of ribulose 1,5-bisphosphate carboxylase/oxygenase from E 1 are similar to those observed in R 2. The mutant appears to be defective in its ability to utilize the intracellular C i pool for photosynthesis and depends on extracellular supply of Ci in the form of CO 2. The very high apparent photosynthetic Km (CO 2) of the mutant indicate a large diffusion resistance for CO 2. Data obtained here are used to calculate the permeability coefficient for CO 2 between the bulk medium and the carboxylation site of cyanobacteria. 相似文献
3.
The products of short time photosynthesis and of enhanced dark 14CO 2 fixation (illumination in helium prior to addition of 14CO 2 in dark) by Chlorella pyrenoidosa and Anacystis nidulans were compared. Glycerate 3-phosphate, phosphoenolpyruvate, alanine, and aspartate accounted for the bulk of the 14C assimilated during enhanced dark fixation while hexose and pentose phosphates accounted for the largest fraction of isotope assimilated during photosynthesis. During the enhanced dark fixation period, glycerate 3-phosphate is carboxyl labeled and glucose 6-phosphate is predominantly labeled in carbon atom 4 with lesser amounts in the upper half of the C 6 chain and traces in carbon atoms 5 and 6. Tracer spread throughout all the carbon atoms of photosynthetically synthesized glycerate 3-phosphate and glucose 6-phosphate. During the enhanced dark fixation period, there was a slow formation of sugar phosphates which subsequently continued at 5 times the initial rate long after the cessation of 14CO 2 uptake. To explain the kinetics of changes in the labelling patterns and in the limited formation of the sugar phosphates during enhanced dark CO 2 fixation, the suggestion is made that most of the reductant mediating these effects did not have its origin in the preillumination phase. It is concluded that a complete photosynthetic carbon reduction cycle operates to a limited extent, if at all, in the dark period subsequent to preillumination. 相似文献
4.
Anacystis nidulans (Synechococcus) had a minimal doubling time of 5 hrs at 30 degrees C at saturating light intensity and carbon dioxide concentration. Half maximal growth rates in saturating CO2 occured at a light intensity of 0.54 mW per cm2, and there was an apparent threshold intensity of 0.13 mW per cm2 below which no growth occurred. Growth rate in saturating light was dependent on the concentration of CO2+H2CO3 in the medium, rather than on total dissolved CO2; half maximal rates were estimated at 0.1 mM CO2+H2CO3. Under saturating conditions of light and CO2, 14CO2 was fixed primarily into 3-PGA, and subsequently moved into sugar phosphates and amino acids. Incorporation into aspartate was relatively slow. CO2 fixation was strictly light-dependent. The changes in adenylate and pyridine nucleotide pools were followed in light/dark and dark/light transitions. Whereas adenylates relaxed slowly over 15-20 min to the concentrations characteristic of illuminated cells following the abrupt changes induced by darkening, the sharp drop in intracellular NADPH showed little dark recovery although rapid restoration occurred on reillumination. Other pyridine nucleotides showed no changes during these transitions. The nucleotide specificity and Km of partially purfied GAP dehydrogenase suggest a role for this enzyme in the regulation of CO2 fixation. 相似文献
6.
Exposure of crude cell lysates of Staphylococcus aureus MF-31 to 5 or 10 mM hydrogen peroxide resulted in a linear decrease in superoxide dismutase activity. Approximately 13% of the superoxide dismutase activity was lost after 16 min. Thermally stressed and nonstressed cells were exposed to a photochemically generated exogenous flux of superoxide radicals (O2.-). The death of thermally stressed cells was linear with time. Addition of superoxide dismutase or catalase to the O2.- generating system resulted in protection of thermally stressed and nonstressed cells, with the protective effect being greater for thermally stressed cells. Incorporation of O2-, hydroxyl radical, or singlet oxygen scavengers or antioxidants to tryptic soy agar containing 7.5% NaCl did not increase the enumeration of thermally stressed cells. 相似文献
7.
Cells of the blue-green alga (cyanobacterium) Anacyslis nidulanswere disintegrated, and their thylakoid membranes and cytoplasmicmembranes were isolated by floatation centrifugation on a sucrosedensity gradient. Electron micrographs revealed that the cytoplasmicmembranes formed single closed vesicles having diameters of200400 nm. These membranes contained xanthophylls asthe major constituent pigments and rß-carotene andchlorophyll a as very minor ones. The major peaks in their absorptionspectra were due to carotenoids at 435, 455 and 487 nm, witha minor one due to chlorophyll a at 673 nm. These findings areconsistent with the yellow color of the cytoplasmic membranes.The absorption spectrum of the membranes in the carotenoid regionwas markedly affected by temperature: with a decrease in temperature,the peaks at 455 and 487 nm diminished and a new peak appearedat 390 nm. (Received February 12, 1983; Accepted June 20, 1983) 相似文献
8.
Antibodies cross-reactive with specific membrane proteins were used to investigate membrane development in Anacystis nidulans R2 during recovery from iron stress. Polyclonal antibodies prepared using the iron-regulated chlorophyll (Chl)-protein CPVI-4 (HB Pakrasi, HC Riethman, LA Sherman 1985 Proc Natl Acad Sci USA 82: 6903-6907) as antigen were characterized and used to identify three iron stress-induced polypeptides of 36, 35, and 34 kilodaltons on immunoblots of polyacrylamide gels. The 34 kilodalton protein was shown to be a component of the Chlbinding CPVI-4 complex. The 36 kilodalton protein is an unrelated, intrinsic membrane protein tightly regulated by iron (designated IrpA), whereas the 35 kilodalton immunoreactive component is an extremely abundant glycoprotein (GP35). An analysis of photosystem II (PSII)-associated Chl-proteins during recovery from iron stress demonstrates that CPVI-4 is associated with most of the Chl present in iron-starved cells, whereas the PSII core polypeptides are present in very low levels; upon recovery, CPVI-4 diminishes in abundance as the relative levels of the other PSII proteins increase. The abundance of CPVI-4 in iron-stressed cells and the distribution of Chl among individual Chl-proteins during recovery suggest a possible role for CPVI-4 in the direction of membrane assembly during recovery from iron stress. 相似文献
9.
The thylakoid and the cell envelope of the blue-green alga Anacystisnidulans were separated by mechanical disruption of lysozyme-treatedcells followed by differential and density gradient centrifugation.The prepared envelope was composed of an outer membrane, a peptidoglycanlayer and possibly a part of the cytoplasmic membrane. The preparedthylakoid retained the size and intricate structure typicalof the thylakoid membrane of this alga. Light absorption andfluorescence spectra revealed that the envelope contained carotenoids,a pigment with an absorption maximum at 748 nm (P750), and asmall amount of pheophytin-like pigment with an absorption maximumat 673 nm. The thylakoid contained chlorophyll a and carotenoidsbut no P750. The thylakoid contained five kinds of carotenoids,the major ones being rß-carotene and zeaxanthin, whereasthe cell envelope contained two kinds of carotenoids, zeaxanthinand nostoxanthin. Four kinds of lipids, abundant in the blue-greenalgae, were present in both the thylakoid and the cell envelope.However, the content of sulfolipid was very low in the cellenvelope. The polypeptide compositions differed between thethylakoid and the cell envelope. Similarities between blue-greenalgal cells and eukaryotic chloroplasts are discussed with respectto the spectrophotometric and biochemical characteristics ofthe thylakoid and the envelope. (Received March 7, 1981; Accepted May 22, 1981) 相似文献
10.
Illuminated suspensions of Anacystis nidulans, supplied with saturating concentrations of CO 2 evolved O 2 at a greater rate when nitrate was simultaneously present. The extent of the stimulation of noncyclic electron flow induced by nitrate was dependent on light intensity, being maximal under light saturating conditions. Accordingly, nitrate depressed the rate of CO 2 fixation at limiting but not at saturating light, this depression reflecting the competition between both processes for assimilatory power. In contrast, ammonium stimulated CO 2 fixation at any light intensity assayed, the stimulation being dependent on the incorporation of ammonium to carbon skeletons. The positive effect of ammonium on CO 2 fixation also appeared to occur when nitrate was the nitrogen source, since with either nitrogen source an increase in the incorporation of newly fixed carbon into acid-soluble metabolites took place. From these results, the in vivo partitioning of assimilatory power between photosynthetic nitrogen and carbon assimilation and the quantitative and qualitative effects of inorganic nitrogen assimilation on CO 2 fixation are discussed. 相似文献
11.
Cyanobacteria acclimate to changes in light by adjusting the amounts of different cellular compounds, for example the light-harvesting macromolecular complex. Described are the acclimatization responses in the light-harvesting system of the cyanobacterium Anacystis nidulans following a shift from high intensity, white light to low intensity, red light. The phycocyanin and chlorophyll content and the relative amount of the two linker peptides (33 and 30 kilodaltons) in the phycobilisome were studied. Both the phycocyanin and chlorophyll content per cell increased after the shift, although the phycocyanin increased relatively more. The increase in phycocyanin was biphasic in nature, a fast initial phase and a slower second phase, while the chlorophyll increase was completed in one phase. The phycocyanin and chlorophyll responses to red light were immediate and were completed within 30 and 80 hours for chlorophyll and phycocyanin, respectively. An immediate response was also seen for the two phycobilisome linker peptides. The amount of both of them increased after the shift, although the 33 kilodalton linker peptide increased faster than the 30 kilodalton linker peptide. The increase of the content of the two linker peptides stopped when the phycocyanin increase shifted from the first to the second phase. We believe that the first phase of phycocyanin increase was due mainly to an increase in the phycobilisome size while the second phase was caused only by an increase in the amount of phycobilisomes. The termination of chlorophyll accumulation, which indicates that no further reaction center chlorophyll antennae were formed, occurred parallel to the onset of the second phase of phycocyanin accumulation. 相似文献
12.
When cells of Anacystis nidulans strain R2 grown under high CO 2 conditions (3%) were transferred to low CO 2 conditions (0.05%), their ability to accumulate inorganic carbon (C i) increased up to 8 times. Cytoplasmic membranes (plasmalemma) isolated at various stages of low CO 2 adaptation were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. There was a marked increase of a 42-kilodalton polypeptide in the cytoplasmic membrane during adaptation; a linear relationship existed between the amount of this polypeptide and the C i-accumulating capability of the cells. No significant changes were observed during this process in the amount of other polypeptides in the cytoplasmic membranes or in the polypeptide profiles of the thylakoid membranes, cell walls, and soluble fractions. Spectinomycin, an inhibitor of protein biosynthesis, inhibited both the increase of the 42-kilodalton polypeptide and the induction of high C i-accumulating capability. The incorporation of [ 35S]sulfate into membrane proteins was greatly reduced during low CO 2 adaptation. Radioautograms of the 35S-labeled membrane proteins revealed that synthesis of the 42-kilodalton polypeptide in the cytoplasmic membrane was specifically activated during the adaptation, while that of most other proteins was greatly suppressed. These results suggested that the 42-kilodalton polypeptide in the cytoplasmic membrane is involved in the active C i transport by A. nidulans strain R2 and its synthesis under low CO 2 conditions leads to high C i-transporting activity. 相似文献
13.
When cells of Anacystis nidulans grown under high CO 2 conditions(3%) were transferred to low CO 2 conditions (0.05%), their abilityto transport extracellular inorganic carbon (C i) into the cellsincreased severalfold. There was a marked increase of 42-kDapolypeptide in the cytoplasmic membranes during the adaptationto low CO 2 conditions, while no changes were observed in thepolypeptide compositions of the thylakoid membranes and cellwalls. The results suggested that the increase of the 42-kDapolypeptide during adaptation is involved in the increased abilityto transport C i (Received January 28, 1985; Accepted May 30, 1985) 相似文献
14.
The intracellular levels of glutamine synthetase (GS) in Anacystis nidulans grown under different conditions were determined using a whole-cell assay. Nitrate-grown cells have 64% more GS than cells grown in ammonium sulfate. Nitrogen starvation does not affect GS levels appreciably. Incubation of nitrate-grown cells with ammonium sulfate does not change the ratio of gamma-glutamyl transferase activities stimulated by Mg2+ and Mn2+ ions. An in vitro test of adenylylation indicates that algae do not have an endogenous adenylyl transferase (ATase) and that algal GS is not adenylylatable by the Klebsiella aerogenes ATase. Some characteristics of the GS-membrane complex were determined by centrifugation of the complex under varying conditions of pH and ionic strength. In this way, it was shown that acid pH (4.5) stabilizes the complex and high ionic strength tends to solubilize the enzyme. A simple partial purification of GS (89-fold) was developed based on the sedimentation properties of GS. 相似文献
15.
高盐浓度条件下分离了蓝细菌Anacystis nidulans R-2的藻胆体, 藻胆体中存在一种43 kD的蛋白。Western blotting 分析表明, 该蛋白能与蓝细菌Fd:NADP+氧还酶中FNR结构域的抗体发生反应, 解聚的藻胆体具有FNR黄递酶的活性, 初步证明该43 kD蛋白就是Fd:NADP+氧还酶。TritonX-114分相实验表明, 这种43 kD的蛋白不能进入TritonX-114相。对藻胆体的部分解聚合实验表明, 富含外周杆的组分中不存在43 kD的蛋白。 相似文献
16.
高盐浓度条件下分离了蓝细菌Anacystis nidulans R-2的藻胆体,藻胆体中存在一种43kD的蛋白。Western blotting分析表明,该蛋白能与蓝细菌Fd:NADP氧还酶中FNRE占构域的抗体发生反应,解聚的藻胆体具有FNR黄递酶的活性,初步证明该43kD蛋白就是Fd:NADP氧还酶。Triton X-114分相实验表明,这种43kD的蛋白不能进入Triton X-114相。对藻胆体的部分解聚合实验表明,富含外周杆的组分中不存在43kD的蛋白。 相似文献
17.
Tolerance to photoinhibition was compared between a paraquat-resistant and a sensitive biotype of Conyza bonariensis (L.). Cronq. Photoinhibitory damage was measured as a decrease in oxygen evolution or energy storage using photoacoustic spectroscopy, or as a decrease of 14CO 2-fixation. Prior to exposure to high fluence rates, both biotypes had similar quantum yields of oxygen evolution and energy storage. After exposure to high intensity light, the resistant biotype continued to evolve oxygen and to store energy with a high quantum yield while both energy storage and oxygen evolution were severely reduced in the sensitive biotype. CO 2-fixation was less rapidly inhibited in the resistant biotype compared to the sensitive one. The data show that the paraquat resistant biotype with its high constitutive levels of the chloroplast localized enzymes of the oxygen detoxification pathway, is also partially protected from photoinhibition. This supports the theory that an enhanced radical scavenging system can give temporary protection against photooxidative damage from a variety of sources. 相似文献
18.
Cytoplasmic membranes (plasma membranes), thylakoid membranesand cell walls prepared from the cyanobacterium, Anacystis nidulans,were compared for UDP-glucose: l,2-diacylglycerol glucosyltransferaseactivity. When 1,2-dipalmitoylglycerol was added as a glucosylacceptor, both cytoplasmic membranes and thylakoid membranesincorporated glucose from UDP-glucose into monoglucosyl diacylglycerol,but the cell walls containing the outer membranes did not. Thecytoplasmic membranes incorporated about twice as much glucoseas the thylakoid membranes on a protein basis. These observationssuggest that in A. nidulans the UDP-glucose: 1,2-diacylglycerolglucosyltransferase participating in glucolipid biosynthesisis located in both cytoplasmic and thylakoid membranes, butnot in the outer membrane.
1Solar Energy Research Group, The Institute of Physical andChemical Research (RIKEN), Wako-shi, Saitama 351-01, Japan. (Received November 21, 1985; Accepted January 27, 1986) 相似文献
19.
The effect of several relevant environmental factors influencing the photoproduction of ammonia from nitrate by Anacystis nidulans cells treated with the glutamine synthetase inhibitor l-methionine-dl-sulfoximine has been investigated. The optimal ratio between l-methionine-dl-sulfoximine concentration (micro-molar) and cell density (micrograms of chlorophyll per milliliter) was around 1, the process taking place at maximal rate at a temperature of about 40 degrees C, within the pH range of 7 to 10. Ammonia production was stimulated by CO(2) or bicarbonate and was not affected by the accumulation of ammonia in the medium up to concentrations of 30 mM. The rate of ammonia production was found to be determined by the interaction of at least four factors, namely, irradiance and the density, depth, and turbulence of the cell suspension. Ammonia photoproduction from nitrate and water represents an interesting process for the conversion of light energy into chemical energy, which can operate at high efficiency, around 30% of its theoretical maximum. 相似文献
20.
The mutant E 1 of Anacystis nidulans R 2 requires high CO 2 concentration for growth but was able to adapt to low CO 2 concentration. This was exhibited by the increased ability to accumulate inorganic carbon within the cells and the large increase in the amount of a 42-kilodalton polypeptide located in the cytoplasmic membrane. The adaptation occurred in E 1 cells at an extracellular CO 2 concentration as high as 0.3%, which was 8 times the concentration for maximal adaptation in R 2 cells. The ability of E 1 cells to exhibit low CO 2 characteristics at a higher CO 2 concentration was attributed to lower intracellular CO 2 concentration. 相似文献
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