Anacystis Nidulans Strain Research Articles

Ameliorative Effect of Cyanobacterial Extract on the Conversion of Somatic Embryos to Plantlets in Banana

Abstract The conversion of somatic embryos into plants of banana cv. Rasthali (AAB) was studied using different concentrations of cyanobacterial extracts (CYE) from Anabaena strain L-31 and Anacystis nidulans strain BD-1. Extracts from both the strains stimulated embryo to plantlet conversion with varying frequencies. L-31 extract showed maximum conversion frequency (58% at 20% CYE) followed by BD-1 (54% at 50% CYE) and control (45-46% at 0% CYE). Plantlet development as seen by root and shoot growth was also promoted in the presence of CYE. These results will be useful in optimization of methods towards the conversion frequency of somatic embryos into plantlets.

Intracellular location of cytochrome oxidase active in vivo in the cyanophytes,Synechocystis sp. PCC6714 andAnacystis nidulans Tx20 and R2, grown under various conditions

Intracellular location of cytochrome oxidase (cytoxidase) active in vivo was studied cytochemically with four strains of cyanophytes, using 3,3′-diaminobenzidine (DAB) oxidation. DAB was oxidized in the dark bySynechocystis sp. PCC6714 and two strains ofAnacystis nidulans (Tx20 and R2) grown under photoautotrophic, heterotrophic and salt-stressed conditions, respectively. Electron microscopic observations showed that DAB-oxidation in the dark occurred in the thylakoids, but was insignificant on or around the cytoplasmic membrane. However, deposition of DAB-oxidation product around the cytoplasmic membrane was observed with cells of the thylakoid-less cyanophyteGlaeobacter violaceus ATCC29082. All DAB oxidations observed with the four strains were inhibited completely by cyanide, the inhibitor of cyt-oxidase, but not by 3-amino-1,2,4-triazole, the inhibitor of peroxidase. The results show that (1) DAB was oxidized by the cyt-oxidase functioning in the respiratory system, and that (2) cyt-oxidase in thylakoids was active in vivo.

Photoinhibition and Recovery of Photosynthesis in psbA Gene-Inactivated Strains of Cyanobacterium Anacystis nidulans

The susceptibility of photosynthesis to photoinhibition and the rate of its recovery were studied in cyanobacterium Anacystis nidulans strain R2 and its two psbA gene-inactivated mutants R2S2C3 and R2K1. Changes in the fluorescence kinetics at 77K as well as the rate of O(2) evolution were measured when cells were exposed to high photosynthetic photon flux densities in the range of 0 to 2,000 micromoles per square meter per second. The R2S2C3 mutant has an active psbAI gene highly expressed under low and normal light intensities, whereas R2K1 possesses psbAII and psbAIII genes highly expressed under very high light intensities. The level of overall susceptibility of photosynthesis to photoinhibition was more pronounced in the wild type and the mutant R2S2C3 than in the mutant R2K1, especially at higher light intensities. In constrast, all three strains showed an increased but similar sensitivity to photoinhibition after addition of the translational inhibitor streptomycin; mutant R2K1 being slightly less sensitive at lower light intensities. The result is interpreted as demonstrating similar intrinsic susceptibility to photoinhibition of the two different forms of the D1 protein, form I and form II, encoded by the psbAI and psbAII/psbAIII genes, respectively. The increased resistance to photoinhibition of the R2K1 mutant was ascribed to an approximately 3 times higher rate of recovery than the wild type and the mutant R2S2C3. On the basis of our experiments we conclude that the susceptibilities to photoinhibition of the Anacystis nidulans psbA genes mutants studied are regulated mainly by modifying the rate of repair, i.e. the rate of turnover of the D1 protein.

Nucleotide sequence of Phycocyanin β-subunit gene of cyanobacterium Anacystis nidulans strain R2

Nucleotide sequence of Phycocyanin β-subunit gene of cyanobacterium Anacystis nidulans strain R2

Biosynthesis of a 42-kD Polypeptide in the Cytoplasmic Membrane of the Cyanobacterium Anacystis nidulans Strain R2 during Adaptation to Low CO2 Concentration

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 [(35)S]sulfate into membrane proteins was greatly reduced during low CO(2) adaptation. Radioautograms of the (35)S-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.

Organization and Function of Chlorophyll in Membranes of Cyanobacteria during Iron Starvation

Cells of Anacystis nidulans strain R2 and of Synechococcus cedrorum were grown in an iron-deficient medium. Iron starvation induced several pronounced effects without influencing the viability of these cells. The phycocyanin and chlorophyll contents of these cells were depressed, and the absorption maxima of membrane-bound chlorophyll was blue-shifted by 5 nanometers. Cells showed a dramatic increase in original and in maximal chlorophyll fluorescence when monitored at room temperature. Low temperature chlorophyll fluorescence revealed a loss in fluorescence at 696 and 716 nanometers; much of the remaining fluorescence emission was at 686 nanometers. These changes suggest an alteration of membrane composition and structure. This was documented by an electrophoretic analysis of iron-deficient membranes. The prominent findings were: (a) large chlorophyll-protein complexes were not observed in iron-deficient membranes, although the chlorophyll-binding proteins were present; (b) the staining of acrylamide gels with 3,3',5,5'-tetramethylbenzidine plus peroxide indicated that iron deficiency led to a decrease in the quantity of cytochromes. These results support a structural model of the relation between fluorescence and chlorophyll organization in Anacystis. In addition, they suggest a method for studying cytochrome and chlorophyll protein assembly in these membranes.

Einfluß von Sauerstoff auf die photosynthetische CO2-Fixierung von Synechococcus / Effect of Oxygen on Photosynthetic CO2 Fixation of Synechococcus

Abstract The cyanobacterium Synechococcus (Anacystis nidulans strain L 1402-1) was grown at +35 °C in air and in air enriched with 2.2 vol.% CO2. The effect of different oxygen concentrations (0, 2, 20, 50, 75 and 99.97 or 97.8 vol.%) was studied in low (0.03 vol.%) and high (2.2 vol.%) CO2 concentrations at + 35 °C. After exposure to a nitrogen atmosphere and low CO2 content I4C-bicarbonate was mainly incorporated into aspartate and glycine/serine. During oxygenic photosynthetic CO2 fixation label in aspartate decreased and a high degree of radioactivity could be found in 3-phosphoglyceric acid and sugar monophosphates. The Calvin cycle was the main fixing pathway in 2.2 vol.% CO2 during anoxygenic and oxygenic conditions independent on the O2 concentrations during the experiments. No oxygen enhancement of photosynthetic CO2 fixation could be found. Possible mechanism involved in CO2 fixation pathways and glycolate metabolism underlying the effect of oxygen was discussed.

Zur photosynthetischen CO2-Fixierung von Synechococcus / Photosynthetic CO2 Fixation of Synechococcus

The cyanobacterium Synechococcus (Anacystis nidulans strain L 1402-1) was grown at + 37 °C in 3.0 vol.% CO2. The effect of preillumination with white light on the subsequent dark 14CO2 fixation was studied under aerobic conditions at + 30 °C. The radioactive carbon first incoiporated into 3-phosphoglyceric acid was transferred during the later periods of dark 14CO2 fixation to phosphoenolpyruvate and aspartate. No labelling or a very low label in sugar monophosphates could be observed. During the dark/light transients the initial fixation product was mainly aspartate. The pattern of 14C-incorporation into photosynthetic products under steady state conditions (10 min photosynthesis) varied with the temperature during the experiments. The radioactive carbon was firstly incorporated into 3-phosphoglyceric acid. During the later periods of photosynthetic 14CO2 fixation an increased 14C-incorporation into aspartate and glutamate could be observed. Our findings were interpreted with operating of a phospho­enolpyruvate carboxylation besides the Calvin cycle.

Synthesis of DNA during the cell cycle of synchronous Anacystis nidulans

Cells of Anacystis nidulans strain 1402-1 incorporate [methyl-(3)H]thymidine or [8-(3)H]adenine into DNA; in synchronous cultures (21/2 h full light, 1/2 h weak light, 5 h dark), this incorporation occurs in the dark to different extents according to the labeled precursor offered or to its specific activity. The specific activity of in vivo, uniformly labeled DNA decreases to half the initial value when the cells are grown in the absence of radioactive DNA precursors during the light phase; it does not decrease during the following dark phase. If unlabeled thymidine is given during the dark phase, the specific activity of the DNA starts to decrease at the onset of the next light phase. The time course of the decrease supports the hypothesis that all cells start their DNA replication immediately after illumination and that the first cells have completed if after 1.25 h. The slowest cells then need 3.75 h for completion of DNA replication. It is discussed whether the incorporation during the dark might be due to pool size effects.

Carbon dioxide assimilation in blue-green algae: initial studies on the structure of ribulose 1,5-bisphosphate carboxylase.

D-Ribulose 1,5-bisphosphate carboxylase was purified from the blue-green alga Anabaena cylindrica (Lemm) by procedures involving acid precipitation, ammonium sulfate fractionation, and Sephadex G-200 gel filtration. The enzyme was homogeneous by the criterion of polyacrylamide disc gel electrophoresis and was a multimer of a single-size polypeptide chain of 54,000 daltons. The carboxylases from four species of blue-green algae (Anabaena, Nostoc strain MAC, Agmenellum quadruplicatum strain PR-6, and Anacystis nidulans strain TX20) were closely similar in molecular size, since enzyme activity was eluted at the same volume after sucrose gradient centrifugation. Further analysis by gel filtration indicated that the four blue-green algal carboxylases were nearly identical in molecular weight, ranging from 449 to 453,000. The amino acid composition of the Anabaena carboxylase was determined and was found to resemble closely the composition of the large subunit from eukaryotic photosynthetic organisms.

Potassium requirement for cell division in Anacystis nidulans.

A potassium requirement for growth can be readily demonstrated in the autotrophic blue-green bacterium Anacystis nidulans strain TX20 equivalent to 0.7% of the cellular dry weight. Starvation of this organism for potassium partially dissociates growth from cell division, thereby inducing 50% of the population to form filaments.

A New Medium for the Isolation and Growth of Auxotrophic Mutants of the Blue-green Alga Anacystis nidulans

SUMMARY: A complete medium of defined composition has been developed for quantitative growth of wild-type and auxotrophic mutant strains of Anacystis nidulans. This medium has proved to be more satisfactory than other complex media (for example casein hydrolysate, yeast extract) for both the isolation and the growth of auxo-trophs. Rigorous control of the pH of complete and other supplemented media is essential for quantitative growth on agar. Four diagnostic media are described which each contain a different combination of the supplements used in the complete medium and facilitate the identification of the nutritional requirements of mutants. By using these media a number of auxotrophs have been isolated including five with novel phenotypes which require respectively (i) thiamine, (ii) p-aminobenzoic acid, (iii) a combination of pyruvate or acetate plus malate or succinate or fumarate, (iv) serine or glycine and (v) adenine.

Occurrence of cell lytic enzymes in blue-green bacteria.

Detergent extracts of three blue-green bacteria (Agmenellum quadruplicatum strain BG1, Anacystis nidulans strain TX20, and Nostoc sp. strain MAC) contained enzymes capable of lysing suspensions of Micrococcus lysodeikticus. The enzyme preparation from A. quadruplicatum released soluble reducing fragments from purified peptidoglycan. The lytic activity exhibited a pH optimum between 6 and 7, was relatively heat stable, and was susceptible to attack by proteolytic enzymes. These results extend the range of bacterial types exhibiting cell lytic activity as well as confirm the existence of the lytic system commonly observed in "water blooms".

Mutations of Anacystis nidulans that affect cell division.

Following nitrosoguanidine treatment of the blue-green alga Anacystis nidulans strain 6311, mutants which grow predominantly as short or long filaments are commonly produced. Cytological study shows that the filaments are multinucleate, coenocytic structures. Such mutations are therefore best interpreted as ones that impair cell division in a normally unicellular organism.

Streptomycin- and Penicillin-induced Inhibition of Growth and Pigment Production in Blue-green Algae and Production of Strains ofAnacystis nidulansResistant to these Antibiotics

Relatively low concentrations of streptomycin inhibited the growth of Anacystis nidulans and Anabaena variabilis. The production of chlorophyll, carotenoid, and phycocyanin pigments in these algae was significantly but reversibly inhibited by streptomycin. Strains of Anacystis nidulans that are resistant to streptomycin and penicillin were produced by serially subculturing the alga in gradually increasing concentrations of the respective antibiotic. These strains seem stable. Evidence which suggests that the resistant strains originate primarily by mutation is presented.