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At least 19 recordsLinked to original sources
PubMed1978

Paracrystalline inclusions in various isolates of the blue-green bacteria Nostoc and Anabaena.

A number of different crystalline inclusions were observed in various isolates of Anabaena and Nostoc. Membrane-limited crystalline bodies were observed in 7 of 20 isolates of Anabaena and 19 of 29 isolates of Nostoc. These are spherical, single membrane-limited bodies from 0.6 to 0.1 micron in diameter. In most of the isolates they contained needle-like crystals 20 A in thickness and up to 80 nm in length. In 9 of the isolates the inclusions contained granular and fibrillar material. The number of bodies per cell varied in the different isolates from only a few, observed in many sections, up to 5 in a single section of A. subtropica (B1618). Crystalloids were observed in the cytoplasm of Anabaena sp. (1551), N. calcicola (B382), Nostoc sp. (588), and N. punctiforme (1629). In Anabaena sp. (1551) the roughly cuboidal inclusions 0.6 micron in diameter were composed of 100 A thick osmiophilic striations spaced to produce a 150 A periodicity. In Nostoc sp. (588) the elongate, 0.1 micron by 2.5 micron, crystalloids were composed of 100 A thick osmiophilic striations spaced to produce a 200 A periodicity. N. punctiforme (1629) and N. calciola (B382) contained intrathylakoidal crystalloids which consisted of short curved segments with 100 A thick osmiophilic striations producing a 200 A periodicity. Granular areas were observed in 2 isolates of Anabaena and 5 of Nostoc. These bodies found in various locations in the cells, were interpreted to be elongate structures 0.2 micron thick, 1.2 micron long and about 5 micron in depth. These inclusions were composed of 15 nm diameter granules which in some section planes appeared in rows spaced 20 nm apart. Spherical bodies up to 0.7 micron in diameter and of medium electron density were observed in 4 isolates of Anabaena and 2 of Nostoc. Convoluted inclusions were found in N. calcicola (B382) and Anabaena sp. (1551). These roughly spherical bodies up to 0.8 micron in diameter contain lighter swirled areas.

Crystallization↗
PubMed1978

Transport of D-glucose and 3-O-methyl-D-glucose in the cyanobacteria Aphanocapsa 6714 and Nostoc strain Mac.

1. The cyanobacterium Aphanocapsa 6714 which grow in the dark on D-glucose, will take up D-glucose and the analogue 3-O-methyl-D-glucose; uptake of each of these compounds was inhibited competitively by the other and by 6-deoxy-D-glucose. 2. This cyanobacterium accumulated 3-O-methyl-D-glucose up to 100-fold relative to the medium but did not modify or metabolize it to a significant degree. 3. Intracellular 3-O-methyl-D-glucose was rapidly displaced from Aphanocapsa 6714 by exogenous D-glucose and 3-O-methyl-D-glucose. 4. Although not characterized to the same extent, D-glucose and 3-O-methyl-D-glucose uptake by Nostoc strain Mac, another cyanobacterium capable of growth in the dark on D-glucose, was similar. 5. Other cyanobacteria that do not grow on D-glucose take up this compound at much lower rates which were unaffected by analogues of D-glucose that greatly reduced carbohydrate uptake by Aphanocapsa 6714 and Nostoc strain Mac. 6. It is therefore proposed that Aphanocapsa 6714 and Nostoc strain Mac possess a mechanism for the active transport of D-glucose. The absence of this transport mechanism is suggested as the reason why other strains fail to grow in the dark on this substrate. These latter organisms are therefore naturally cryptic with respect to D-glucose as a growth substrate.

Biological Transport, Active↗
PubMed2026

Molecular-networking-based characterization of cytotoxic metabolites produced by the cyanobacterium Nostoc edaphicum CCNP1411.

Cyanobacteria of the genus Nostoc, known for their large genomes and rich repertoire of biosynthetic gene clusters, represent a prolific source of structurally diverse secondary metabolites with diverse biological activities, including cytotoxic effects. However, the identification of bioactive compounds is often hindered by low metabolite abundance and difficulties in isolating sufficient quantities for individual testing. In this study, we investigated the cytotoxic potential of chromatographic fractions obtained from Nostoc edaphicum CCNP1411 using a combination of bioassay-guided fractionation and LC-MS/MS-based feature-based molecular networking (FBMN). Cytotoxic activity was evaluated using the MTT assay across a panel of epithelial and neuronal cancer cell lines, as well as normal human dermal fibroblasts. The most active fractions, eluted with 80-90% MeOH, exhibited broad cytotoxic effects across all tested cancer cell lines. Molecular networking analysis revealed that these fractions were dominated by lipid derivatives, including lysophospholipids, monoacylglycerols, and free fatty acids, whereas previously described peptide metabolites were distributed across all fractions and were unlikely to be the main agents responsible for the observed activity. Targeted testing of selected commercially available lipid compounds confirmed their cytotoxic effects, with lysophospholipids showing the highest potency in selected cell lines. However, dose-response analysis indicated that most compounds exhibited limited potency at lower concentrations, as reflected by relatively high IC₅₀ values. Overall, our results demonstrate that lipid constituents, previously overlooked as bioactive metabolites produced by N. edaphicum CCNP1411, contribute significantly to the cytotoxic activity of the tested fractions. The application of molecular networking enabled the prioritization of bioactive metabolites and highlights its utility in linking chemical composition with biological effects in complex cyanobacterial extracts.

Bioactivity-guided fractionation↗
PubMed1977

Two plant-type ferredoxins from a blue-green alga, Nostoc verrucosum.

Two plant-type ferredoxins were isolated and purified from a blue-green alga, Nostoc verrucosum. They were separable by chromatography on a DEAE-cellulose column. The slow-moving band was designated ferredoxin I (Fd I) and the fast-moving band was ferredoxin II (Fd II). The ratio of the yield of ferredoxins I and II was about 1 : 0.84. Both ferredoxins had absorption spectra similar to those of plant-type ferredoxins. Two atoms of non-heme iron and two of labile sulfur were found per mol of both ferredoxin I and ferredoxin II. Their molecular weights were identical and estimated to be about 18 000 by a gel filtration method. The biochemical activities of these Nostoc ferredoxins were studied: the NADP photoreduction activity on one hand and the NADP-cytochrome c reductase activity on the other.

Chloroplasts↗
PubMed2026

Metagenome-assembled genomes for N2-fixing cyanobacterium Nostoc sp. TISTR 8405 and co-occurring microorganisms from a long-term laboratory culture.

We report here metagenome-assembled genomes from a long-term laboratory culture of the nitrogen-fixing cyanobacterium Nostoc sp. TISTR 8405, originally sourced from a Thai freshwater lake. The community consists of two additional co-occurring microorganisms, Erythrobacter sp. THAI-01 and Allorhizobium sp. THAI-01, and contains putative plasmids associated with Nostoc and Allorhizobium, respectively.

co-culture↗
PubMed1977

Some characteristics of two morphological mutants of Nostoc linckia induced by nitrosoguanidine.

The blue-green alga Nostoc linckia was treated with nitrosoguanidine and two classes of morphological mutant clones were isolated. One class shows certain abnormal phenotypic features of vegetative cells, spores, and heterocysts. It has increased heterocyst frequency and impaired growth rate. The other class exhibits an altered heterocyst spacing pattern. Both classes of mutants have reduced nitrogenase activity.

Cyanobacteria↗
PubMed1978

Isolation of a sulphate reductase-less mutant of the blue-green alga Nostoc muscorum.

The wild type Nostoc muscorum (UW strain) has yielded various physiological mutants altered in utilization of sulphate, following mutagenic treatments with N-methyl, N'-nitro N-nitrosoguanidine (NTG). One of the mutant strains designated as Sat-20 failed to grow in a medium containing sulphate (MgSO4.7 H2O). However, the mutant strain could grow when supplemented with thiosulphate (Na2S2O3.5 H2O), while methionine could fulfil the sulphur requirement only partially. On comparative reasons, the wild type as well as the mutant showed preference for thiosulphate over other sulphur sources employed.

Cyanobacteria↗
PubMed1979

Effect of nutrients on the toxicity of pesticides carbofuran and hexachlorocyclohexane to blue-green alga Nostoc muscorum.

The effects of various levels of nutrients like potassium phosphate (dibasic), calcium nitrate, and calcium chloride individually and in combinations were studied on the toxicity of the commonly used pesticides carbofuran and hexachlorocyclohexane (HCH) in growth medium to the N2-fixing blue-green alga Nostoc muscorum. It was observed that all these chemicals had some effects on toxicity. The toxicity of both carbofuran and HCH was reduced to some extent in the presence of higher concentrations of the nutrients when compared to normal levels of the chemicals in the medium. The higher doses of nutrients in combinations antagonized the effect of individual treatment and enhanced the toxicity of pesticides.

Calcium Chloride↗
PubMed1979

Histidine sensitive variant of the blue-green alga Nostoc muscorum: response to corepressors of histidine biosynthesis.

A model has been proposed to account for growth inhibition by L-histidine in a variant strain of Nostoc muscorum. This strain has been characterized for its response to 3-amino-1,2,4-triazole and 1,2,4-triazole-3-alanine known to act as false core-pressors of the histidine biosynthesis genes. The histidine sensitive strain retained its sensitivity to triazole alanine while the inhibitory effects of aminotriazole were much reduced indicating a change in regulation of his genes. The probable interactions between nif and his genes in cyanobacteria (blue-green algae) have been discussed.

Cyanobacteria↗
PubMed1977

Effect of temperature on the adsorption and one-step growth of the Nostoc virus N-1.

This study was an attempt to observe the effects of temperature on adsorption and one-step growth of the virus N-1 infecting the nitrogen-fixing cyanobacterium Nostoc muscorum. Adsorption rate was found to maximum at 40 degrees C whereas no adsorption occurred at 10 degrees C. The Q10 value was about 2.03 and the energy of activation, Ea was 16.3 kcal/mole for the adsorption process. The development cycle of the virus was temperature sensitive. With increase in temperature, a gradual increase in inhibition of virus yield i.e. 8.33% at 30 degrees C, 35.3% at 35 degrees C and complete inhibition at 40 degrees C was observed. Out of 7 h latent period, the early 4 h were temperature sensitive and heat treatment had a reversible inhibitory effect on virus development. The temperature treatment did not affect the rise period but burst-size was reduced.

Adsorption↗
PubMed1978

Toxicity of carbofuran to blue-green alga Nostoc muscorum.

Effect of commercial grade pesticide furadan (3% a.i. as carbofuran) was studied on the survival, growth and nitrogen fixation of blue-green alga Nostoc muscorum. The lower concentration of furadan i.e. 25 microgram/ml enhanced survival, growth and nitrogen fixation in the alga whereas these were gradually inhibited in higher concentrations (50--1000 microgram/ml) and the presence of more than 1200 microgram/ml was algicidal. The preliminary observations revelaed that pesticide is biodegraded by the alga.

Carbofuran↗
PubMed1978

Comparative studies on two ferredoxins from the cyanobacterium Nostoc strain MAC.

Two ferredoxins were isolated from the cyanobacterium Nostoc strain MAC grown autotrophically in the light or heterotrophically in the dark. In either case approximately three times as much ferredoxin I as ferredoxin II was obtained. Both ferredoxins had absorption maxima at 276, 282 (shoulder), 330, 423 and 465 nm in the oxidized state, and each possessed a single 2 Fe-2S active centre. Their isoelectric points were approx. 3.2. The midpoint redox potentials of the ferredoxins differed markedly; that of ferredoxin I was --350mV and that of ferredoxin II was --445mV, at pH 8.0. The midpoint potential of ferredoxin II was unusual in being pH dependent. Ferredoxin I was most active in supporting NADP+ photoreduction by chloroplasts, whereas ferredoxin II was somewhat more active in pyruvate decarboxylation by the phosphoroclastic system of Clostridum pasteurianum. Though the molecular weights of the ferredoxins determined by ultracentrifugation were the same within experimetnal error, the amino acid compositions showed marked differences. The N-terminal amino acid sequences of ferredoxins I and II were determined by means of an automatic sequencer. There are 11--12 differences between the sequences of the first 32 residues. It appears that the two ferredoxins have evolved separately to fulfil different roles in the organism.

Amino Acid Sequence↗
PubMed1978

Dark hexose metabolism by photoautotrophically and heterotrophically grown cells of the blue-green alga (Cyanobacterium) Nostoc sp. strain Mac.

Photoautotrophically grown cells of the blue-green alga (cyanobacterium) Nostoc sp. strain Mac assimilated and oxidized both glucose and fructose in the dark at different rates. The rate of fructose metabolism in these cells could be stimulated by casein hydrolysate, the effect being most pronounced at low sugar concentrations. This stimulation was not seen in cells grown heterotrophically in the dark, suggesting that it is a transitory phenomenon which disappears during the autotrophy-heterotrophy growth transition. The stimulation of fructose assimilation by casein hydrolysate was abolished by chloramphenicol or streptomycin, suggesting there are rate-limiting steps in protein biosynthesis in the dark that ultimately lead to inhibition of fructose uptake. Glucose metabolism did not show these phenomena, indicating there are differences in the metabolism of the two sugars.

Biological Transport↗
PubMed1978

Effect of pH, light intensity and population on the toxicity of the pesticide carbofuran to the blue-green alga Nostoc muscorum.

The effect of pH, light intensity and population on the toxicity of the pesticide furadan (containing 3% carbofuran as the active ingredient) was studied on the nitrogen fixing blue-green alga Nostoc muscorum. It was observed that all these factors had effects on the toxicity of the pesticide. The blue-green alga grew better in the pH range of 7.5-10, whereas the acidic pH of 5-6 retarded growth. The pesticide was more toxic to alga in the medium of pH 5-6, whereas reduction in toxicity was noticed in alkaline pH of 7.5-10. The alga grew slowly in a light intensity of 1,500 lux in comparison to a light intensity of 3,000 lux, and no growth occurred in the dark. The toxicity of the pesticide gradually decreased with increasing light intensity. The toxic effect of the pesticide was increased when the initial population level was low, and increasing the initial population reduced the toxicity.

Carbofuran↗
PubMed1977

Variability of nitrogen fixation in some isolates of Nostoc linckia.

Four clonal isolates of Nostoc linckia isolated from different localities were compared with respect to growth, nitrogen content (cellular and extracellular), and pigment composition. A considerable range of variation was observed among these isolates. This indicates the existence of genetically distinct clonal populations of the alga in natural habitats.

Carotenoids↗
PubMed1978

Effects of host aging, ions, and pH on the adsorption of the cyanovirus N-1 to Nostoc muscorum.

The adsorption rate of the cyanovirus N-1 infecting the nitrogen-fixing blue-green alga Nostocmuscorum decreased with aging of algal cultures and the virus failed to adsorb to the dead host cells. The adsorption rate declined in saline magnesium chloride solution compared to that in algal growth medium. The addition of amino acids like L-tryptophan and L-phenylalanine failed to enhance the adsorption rate of the virus. Optimal pH of adsorption was 7.6 to 8;1.

Adsorption↗