Publications

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complementary uv-absorption of mycosporine-like amino acids and scytonemin is responsible for the uv-insensitivity of photosynthesis in nostoc flagelliforme.mycosporine-like amino acids (maas) and scytonemin are uv-screening compounds that have presumably appeared early in the history of life and are widespread in cyanobacteria. natural colonies of the uv-insensitive nostoc flagelliforme were found to be especially rich in maas (32.1 mg g dw(-1)), concentrated in the glycan sheath together with scytonemin. maas are present in the form of oligosaccharide-linked molecules. photosystem ii activity, measured using pam fluorescence and oxygen evolution, ...201020161974
molecular mechanisms of microcystin toxicity in animal cells.microcystins (mc) are potent hepatotoxins produced by the cyanobacteria of the genera planktothrix, microcystis, aphanizomenon, nostoc and anabaena. these cyclic heptapeptides have strong affinity to serine/threonine protein phosphatases (pps) thereby acting as an inhibitor of this group of enzymes. through this interaction a cascade of events responsible for the mc cytotoxic and genotoxic effects in animal cells may take place. moreover mc induces oxidative stress in animal cells and together w ...201020162015
nostotrebin 6, a bis(cyclopentenedione) with cholinesterase inhibitory activity isolated from nostoc sp. str. lukesová 27/97.nostotrebin 6, a new polyphenolic compound with a fully substituted 2,2'-bis(cyclopent-4-en-1,3-dione) skeleton, was isolated from a methanolic extract of the cyanobacterial strain nostoc sp. str. lukesová 27/97. the structure of this compound was determined using x-ray crystallography and further supported by nmr, ir spectroscopy, and ms. nostotrebin 6 is an s-parabolic i-parabolic noncompetitive inhibitor of acetylcholinesterase (ic(50) = 5.5 microm) and an s-parabolic i-parabolic mixed inhibi ...201020233015
design and characterization of molecular tools for a synthetic biology approach towards developing cyanobacterial biotechnology.cyanobacteria are suitable for sustainable, solar-powered biotechnological applications. synthetic biology connects biology with computational design and an engineering perspective, but requires efficient tools and information about the function of biological parts and systems. to enable the development of cyanobacterial synthetic biology, several molecular tools were developed and characterized: (i) a broad-host-range biobrick shuttle vector, ppmqak1, was constructed and confirmed to replicate ...201020236988
bacterial diversity, pigments and nitrogen fixation of biological desert crusts from the sultanate of oman.biological desert crusts are relatively common in the arid deserts of the sultanate of oman; however, little is known about their microbial community composition and role in soil fertilization. we compared three crusts from geographically different locations for their soil texture, bacterial community structure, pigment composition and nitrogenase activity. the crusts were growing on alkaline (ph 7.6-8.7) loamy sand and silty loam soils. microscopically, microcoleus vaginatus was the most abunda ...201020298501
exploiting cyanobacterial p450 pathways.cytochrome p450s are hemoprotein oxygenases involved in natural product synthetic pathways. cyanobacteria are oxygenic photosynthetic microorganisms and are considered a rich source of natural products, and are now known to harbour p450s. a variety of cyanobacterial species have been found to contain multiple copies of p450s in their genomes, and over 100 have been predicted. interestingly, some are membrane-bound as in eukaryotes, as opposed to cytoplasmic in bacteria. furthermore, they can com ...201020299274
two alternative starter modules for the non-ribosomal biosynthesis of specific anabaenopeptin variants in anabaena (cyanobacteria).anabaenopeptins are a diverse family of cyclic hexapeptide protease inhibitors produced by cyanobacteria that contain a conserved ureido bond and d-lys moiety. here we demonstrate that anabaenopeptins are assembled on a nonribosomal peptide synthetase enzyme complex encoded by a 32 kb apt gene cluster in the cyanobacterium anabaena sp. strain 90. surprisingly, the gene cluster encoded two alternative starter modules organized in separate bimodular proteins. the starter modules display high subst ...201020338518
molecular cloning and characterization of maltooligosyltrehalose synthase gene from nostoc flagelliforme.a genomic dna fragment encoding a putative maltooligosyltrehalose synthase (nfmts) for trehalose biosynthesis was cloned by the degenerate primer-pcr from cyanobacterium nostoc flagelliforme. the orf of nfmts was 2,799 bp in length and encoded 933 amino acid residues constituting a 106.6 kda protein. the deduced amino acid sequence of nfmts contained 4 regions highly conserved for mtss. by expression of nfmts in e. coli, it was demonstrated that the recombinant protein catalyzed the conversion o ...201020372031
cyanobacteriochrome ccas regulates phycoerythrin accumulation in nostoc punctiforme, a group ii chromatic adapter.responding to green and red light, certain cyanobacteria change the composition of their light-harvesting pigments, phycoerythrin (pe) and phycocyanin (pc). although this phenomenon-complementary chromatic adaptation-is well known, the green light-sensing mechanism for pe accumulation is unclear. the filamentous cyanobacterium nostoc punctiforme atcc 29133 (n. punctiforme) regulates pe synthesis in response to green and red light (group ii chromatic adaptation). we disrupted the green/red-percei ...201020404166
cala, a cyabrb protein, binds to the upstream region of ftsz and is down-regulated in heterocysts in anabaena sp. pcc 7120.a protein of cyabrb family of regulators, alr0946 (cala), was identified by dna affinity chromatography using dna fragments from the promoter region of ftsz in anabaena/nostoc sp. pcc 7120. electrophoretic mobility shift assays showed that the protein could bind to upstream regions of ftsz (as biotin-labeled dna fragments) and that the binding was inhibited by the same dna fragments and a fragment upstream of hetc but not by 3 fragments upstream of glna, hetr or ntca. both transcriptional fusion ...201020405108
primary screening of the bioactivity of brackishwater cyanobacteria: toxicity of crude extracts to artemia salina larvae and paracentrotus lividus embryos.cyanobacteria are a diverse group of gram-negative bacteria that produce an array of secondary compounds with selective bioactivity against vertebrates, invertebrates, plants, microalgae, fungi, bacteria, viruses and cell lines. the aim of this study was to assess the toxic effects of aqueous, methanolic and hexane crude extracts of benthic and picoplanktonic cyanobacteria isolated from estuarine environments, towards the nauplii of the brine shrimp artemia salina and embryos of the sea urchin p ...201020411110
relationship between color and pigment production in two stone biofilm-forming cyanobacteria (nostoc sp. pcc 9104 and nostoc sp. pcc 9025).previous studies have provided evidence that color measurements enable on site quantification of superficial biofilms, thereby avoiding the need for sampling. in the present study, the efficiency of color measurements to evaluate to what extent pigment production is affected by environmental parameters such as light intensity, combined nitrogen and nutrient availability, was tested with two cyanobacteria, nostoc sp. strains pcc 9104 and pcc 9025, which form biofilms on stone. both strains were a ...201020425659
hideo iwai. interview by daniela ruffell. 201020450913
cyanobacterial heterocysts.many multicellular cyanobacteria produce specialized nitrogen-fixing heterocysts. during diazotrophic growth of the model organism anabaena (nostoc) sp. strain pcc 7120, a regulated developmental pattern of single heterocysts separated by about 10 to 20 photosynthetic vegetative cells is maintained along filaments. heterocyst structure and metabolic activity function together to accommodate the oxygen-sensitive process of nitrogen fixation. this article focuses on recent research on heterocyst d ...201020452939
host selection of symbiotic cyanobacteria in 31 species of the australian cycad genus: macrozamia (zamiaceae).the nitrogen-fixing cyanobacterium nostoc is a commonly occurring terrestrial and aquatic cyanobacterium often found in symbiosis with a wide range of plant, algal, and fungal species. we investigated the diversity of cyanobacterial species occurring within the coralloid roots of different macrozamia cycad species at diverse locations throughout australia. in all, 74 coralloid root samples were processed and 56 endosymbiotic cyanobacteria were cultured. dna was isolated from unialgal cultures an ...201020459320
structure of cinaciguat (bay 58-2667) bound to nostoc h-nox domain reveals insights into heme-mimetic activation of the soluble guanylyl cyclase.heme is a vital molecule for all life forms with heme being capable of assisting in catalysis, binding ligands, and undergoing redox changes. heme-related dysfunction can lead to cardiovascular diseases with the oxidation of the heme of soluble guanylyl cyclase (sgc) critically implicated in some of these cardiovascular diseases. sgc, the main nitric oxide (no) receptor, stimulates second messenger cgmp production, whereas reactive oxygen species are known to scavenge no and oxidize/inactivate t ...201020463019
morphological and genetic diversity of symbiotic cyanobacteria from cycads.the morphological and genetic diversity of cyanobacteria associated with cycads was examined using pcr amplification techniques and 16s rrna gene sequence analysis. eighteen symbiotic cyanobacteria were isolated from different cycad species. one of the symbiotic isolates was a species of calothrix, a genus not previously reported to form symbioses with cycadaceae family, and the remainder were nostoc spp. axenic cyanobacterial strains were compared by dna amplification using pcr with either shor ...201020473963
multiple origins of high reciprocal symbiotic specificity at an intercontinental spatial scale among gelatinous lichens (collemataceae, lecanoromycetes).because the number of fungal species (mycobionts) exceeds the number of algae and cyanobacteria (photobionts) found in lichens by more than two orders of magnitude, reciprocal one-to-one specificity between one fungal species and one photobiont across their entire distribution is not expected in this symbiotic system, and has not previously been observed. the specificity of the cyanobacterium nostoc found in lichens was evaluated at a broad geographical scale within one of the main families of l ...201020493269
expansion of ribosomally produced natural products: a nitrile hydratase- and nif11-related precursor family.a new family of natural products has been described in which cysteine, serine and threonine from ribosomally-produced peptides are converted to thiazoles, oxazoles and methyloxazoles, respectively. these metabolites and their biosynthetic gene clusters are now referred to as thiazole/oxazole-modified microcins (tomm). as exemplified by microcin b17 and streptolysin s, tomm precursors contain an n-terminal leader sequence and c-terminal core peptide. the leader sequence contains binding sites for ...201020500830
microvirin, a novel alpha(1,2)-mannose-specific lectin isolated from microcystis aeruginosa, has anti-hiv-1 activity comparable with that of cyanovirin-n but a much higher safety profile.microvirin (mvn), a recently isolated lectin from the cyanobacterium microcystis aeruginosa pcc7806, shares 33% identity with the potent anti-human immunodeficiency virus (hiv) protein cyanovirin-n (cv-n) isolated from nostoc ellipsosporum, and both lectins bind to similar carbohydrate structures. mvn is able to inhibit infection by a wide variety of hiv-1 laboratory-adapted strains and clinical isolates of different tropisms and subtypes in peripheral blood mononuclear cells. mvn also inhibits ...201020507987
treatment of cr(vi)-containing wastewaters with exopolysaccharide-producing cyanobacteria in pilot flow through and batch systems.seven exopolysaccharide-producing cyanobacteria were tested with regard to their capability to remove cr(vi) from the wastewater of a plating industry. the cyanobacterium which showed, under lab conditions, the most promising features with regard to both cr(vi) removal (about 12 mg of cr(vi) removed per gram of dry biomass) and growth characteristics (highest growth rate and simplest culture medium) was nostoc pcc7936. furthermore, in lab experiments, it was also found that a hcl pretreatment is ...201020508931
the cyabrb transcription factor cala regulates the iron superoxide dismutase in nostoc sp. strain pcc 7120.in the present investigation the results of induced over-production of the cyabrb transcription factor cala (cyanobacterial abrb-like, annotated as alr0946) in the cyanobacterium nostoc sp. pcc 7120 were analysed. the cala overexpression strain showed a bleaching phenotype with lower growth rate and truncated filaments 2 days after induction of overexpression. the phenotype was even more pronounced when illumination was increased from 35 to 125 µmol m(-2) s(-1). using gel-based quantitative prot ...201020545738
use of protein trans-splicing to produce active and segmentally (2)h, (15)n labeled mannuronan c5-epimerase alge4.alginate epimerases are large multidomain proteins capable of epimerising c5 on beta-d-mannuronic acid (m) turning it into alpha-l-guluronic acid (g) in a polymeric alginate. azotobacter vinelandii secretes a family of seven epimerases, each of which is capable of producing alginates with characteristic g distribution patterns. all seven epimerases consist of two types of modules, denoted a and r, in varying numbers. attempts to study these enzymes with solution-state nmr are hampered by their s ...201020552686
is nostoc h-nox a no sensor or redox switch?nostoc sp. (ns) h-nox is a heme protein found in symbiotic cyanobacteria, which has approximately 35% sequence identity and high structural homology to the beta subunit of soluble guanylyl cyclase (sgc), suggesting a no sensing function. however, uv-vis, epr, nir mcd, and ligand binding experiments with ferrous and ferric ns h-nox indicate significant functional differences between ns h-nox and sgc. (1) after no binding to sgc, the proximal histidine dissociates from the heme iron, causing a con ...201020572679
a novel cyanobacterial nostocyclopeptide is a potent antitoxin against microcystins.cyanobacterial hepatotoxins (microcystins and nodularins) cause numerous animal poisonings worldwide each year and are threats to human health. however, we found that extracts from several cyanobacteria isolates failed to induce hepatotoxicity even if they contained high concentrations of the liver toxin microcystin. the antitoxic activity abolishes all morphological hallmarks of microcystin-induced apoptosis, and therefore invalidates cell-based assays of the microcystin content of bloom-formin ...201020575133
[expression, purification and activity determination of cyanovirin-n].cyanovirin-n (cvn) is an 11 kda anti-hiv protein originally isolated from extracts of a cyanobacterium, nostoc ellipsosporum. the protein binds with high affinity to the viral envelope glycoprotein gp120 and irreversibly inactivates diverse hiv strains. a fusion gene consisting of cvn, sumo and 6xhis tag was synthesized by pcr according to the codon bias of escherichia coli. the fusion protein is expressed in the cytoplasm of e. coli in a soluble form and up to 28% of the total protein. the reco ...201020575444
the cell recognition model in chlorolichens involving a fungal lectin binding to an algal ligand can be extended to cyanolichens.leptogium corniculatum, a cyanolichen containing nostoc as photobiont, produces and secretes arginase to culture medium containing arginine. this secreted arginase was pre-purified by affinity chromatography on beads of activated agarose to which a polygalactosylated urease, purified from evernia prunastri, was attached. arginase was eluted from the beads with 50 mm alpha-d-galactose. the eluted arginase binds preferentially to the cell surface of nostoc isolated from this lichen thallus, althou ...201020636904
occurrence of brackish water phytoplankton species at a closed coral reef in nansha islands, south china sea.the phytoplankton assemblage of zhubi reef, a closed coral reef in nansha islands (south china sea, scs) was studied in june 2007. a total of 92 species belonging to 53 genera and four phyla have been identified. the dominant taxa in the lagoon were the diatom chaetoceros and cyanobacteria nostoc and microcystis, while in reef flats were cyanobacteria trichodesmium erythraeum, dinoflagellates gymnodinium and prorocentrum. the species richness and diversity were consistently lower in the lagoon t ...201020656304
exposure of the cyanobacterium nostoc muscorum from portuguese rice fields to molinate (ordram(®)): effects on the antioxidant system and fatty acid profile.herbicide contamination of aquatic ecosystems is a serious global environmental concern. several herbicides enhance the intracellular formation of reactive oxygen species, and can lead to the damage of macromolecules and to a decrease of oxidant defenses in a wide range of non-target microorganisms including cyanobacteria. the effects of molinate (a thiocarbamate herbicide used for controlling grassy weeds in rice fields) on the activities of antioxidant enzymes such as superoxide dismutase, cat ...201021216347
hydrogen production and metal-dye bioremoval by a nostoc linckia strain isolated from textile mill oxidation pond.biohydrogen production by nostoc linckia ha-46, isolated from a textile-industry oxidation-pond was studied by varying light/dark period, ph, temperature and ratio of carbon-dioxide and argon in the gas-mixture. hydrogen production rates were maximum under 18 h of light and 6 h of darkness, ph 8.0, 31°c, a co(2):ar ratio 2:10. hydrogen production of the strain acclimatized to 20 mg/l of chromium/cobalt and 100 mg/l of reactive red 198/crystal violet dye studied in n-supplemented/deficient medium ...201021109423
assessment of salinity-induced antioxidative defense system of diazotrophic cyanobacterium nostoc muscorum.the present study examines the salinity-induced oxidative damage and differential response of enzymatic and non-enzymatic antioxidants of nostoc muscorum. as compared to carotenoid content which showed induction the chlorophyll and phycocyanin contents were inhibited after salt stress. acceleration of lipid peroxidation and peroxide production suggested onset of oxidative damage. the activities of all studied enzymatic antioxidants were significantly increased by salt stress with maximum inducti ...201021124054
a pulsed epr method to determine distances between paramagnetic centers with strong spectral anisotropy and radicals: the dead-time free ridme sequence.methods to determine distances between paramagnetic metal centers and radicals are scarce. this is unfortunate because paramagnetic metal centers are frequent in biological systems and so far have not been employed much as distance markers. successful pulse sequences that directly target the dipolar interactions cannot be applied to paramagnetic metal centers with fast relaxation rates and large g-anisotropy, if no echos can be detected and the excitation bandwidth is not sufficient to cover a s ...200919758831
crystal structure of npun_r1517, a putative negative regulator of heterocyst differentiation from nostoc punctiforme pcc 73102. 200919089958
physiological characterization and electron microscopic investigation of cyanobacteria associated with wheat rhizosphere.physiological attributes of a set of cyanobacterial strains, isolated from the rhizosphere of wheat (var. hd 2687), identified as belonging to the genera calothrix (n = 3), westiellopsis (1), hapalosiphon (2) and nostoc (2), were axenized and evaluated. the concentrated culture filtrates of three cyanobacterial strains - c. ghosei, h. intricatus and nostoc sp. were able to enhance germination percentage, radicle and coleoptile length in inhibition experiments with wheat seeds. indole-3-acetic ac ...200919330544
molecular characterization and the effect of salinity on cyanobacterial diversity in the rice fields of eastern uttar pradesh, india.salinity is known to affect almost half of the world's irrigated lands, especially rice fields. furthermore, cyanobacteria, one of the critical inhabitants of rice fields have been characterized at molecular level from many different geographical locations. this study, for the first time, has examined the molecular diversity of cyanobacteria inhabiting indian rice fields which experience various levels of salinity.200919344531
solution structure of dnae intein from nostoc punctiforme: structural basis for the design of a new split intein suitable for site-specific chemical modification.naturally split dnae intein from nostoc punctiforme (npu) has robust protein trans-splicing activity and high tolerance of sequence variations at the splicing junctions. we determined the solution structure of a single chain variant of npudnae intein by nmr spectroscopy. based on the nmr structure and the backbone dynamics of the single chain npudnae intein, we designed a functional split variant of the npudnae intein having a short c-terminal half (c-intein) composed of six residues. in vivo an ...200919344715
current trends in high throughput proteomics in cyanobacteria.advancements in genome sequencing and high throughput proteomics of cyanobacterial strains led to 13 published reports, from a small number of laboratories. these successful studies focused on synechocystis, nostoc and anabaena strains, prochlorococcus, and halotolerant euhalothece. the implications of emerging quantitative aspects developed and applied in these large-scale studies are assessed in the wake of advanced cyanobacterial research. furthermore, contributions from traditional and early ...200919345218
solid-phase/supercritical-fluid extraction for liquid chromatography of phenolic compounds in freshwater microalgae and selected cyanobacterial species.in the present paper a new extraction technique based on the combination of solid-phase/supercritical-fluid extraction (spe/sfe) with subsequent reversed-phase hplc is described. the spe/sfe extractor was originally constructed from spe-cartridge incorporated into the sfe extraction cell. selected groups of benzoic acid derivatives (p-hydroxybenzoic, protocatechuic, gallic, vanillic and syringic acid), hydroxybenzaldehydes (4-hydroxybenzaldehyde and 3,4-dihydroxybenzaldehyde) and cinnamic acid d ...200919111311
structure of the biliverdin radical intermediate in phycocyanobilin:ferredoxin oxidoreductase identified by high-field epr and dft.the cyanobacterial enzyme phycocyanobilin:ferredoxin oxidoreductase (pcya) catalyzes the two-step four-electron reduction of biliverdin ixalpha to phycocyanobilin, the precursor of biliprotein chromophores found in phycobilisomes. it is known that catalysis proceeds via paramagnetic radical intermediates, but the structure of these intermediates and the transfer pathways for the four protons involved are not known. in this study, high-field electron paramagnetic resonance (epr) spectroscopy of f ...200919159240
structure-function, stability, and chemical modification of the cyanobacterial cytochrome b6f complex from nostoc sp. pcc 7120.the crystal structure of the cyanobacterial cytochrome b(6)f complex has previously been solved to 3.0-a resolution using the thermophilic mastigocladus laminosus whose genome has not been sequenced. several unicellular cyanobacteria, whose genomes have been sequenced and are tractable for mutagenesis, do not yield b(6)f complex in an intact dimeric state with significant electron transport activity. the genome of nostoc sp. pcc 7120 has been sequenced and is closer phylogenetically to m. lamino ...200919189962
structural basis of murein peptide specificity of a gamma-d-glutamyl-l-diamino acid endopeptidase.the crystal structures of two homologous endopeptidases from cyanobacteria anabaena variabilis and nostoc punctiforme were determined at 1.05 and 1.60 a resolution, respectively, and contain a bacterial sh3-like domain (sh3b) and a ubiquitous cell-wall-associated nlpc/p60 (or chap) cysteine peptidase domain. the nlpc/p60 domain is a primitive, papain-like peptidase in the ca clan of cysteine peptidases with a cys126/his176/his188 catalytic triad and a conserved catalytic core. we deduced from st ...200919217401
immunolocalization of the uptake hydrogenase in the marine cyanobacterium lyngbya majuscula ccap 1446/4 and two nostoc strains.in n(2)-fixing cyanobacteria, the reduction of n(2) to nh(3) is coupled with the production of molecular hydrogen, which is rapidly consumed by an uptake hydrogenase, an enzyme that is present in almost all diazotrophic cyanobacteria. the cellular and subcellular localization of the cyanobacterial uptake hydrogenase remains uncertain, and it is definitely strain dependent. previous studies focused mainly on heterocystous cyanobacteria and used heterologous antisera. the present work represents t ...200919222582
biosynthesis of a linoleic acid allylic epoxide: mechanistic comparison with its chemical synthesis and leukotriene a biosynthesis.biosynthesis of the leukotriene a (lta) class of epoxide is a lipoxygenase-catalyzed transformation requiring a fatty acid hydroperoxide substrate containing at least three double bonds. here, we report on biosynthesis of a dienoic analog of lta epoxides via a different enzymatic mechanism. beginning with homolytic cleavage of the hydroperoxide moiety, a catalase/peroxidase-related hemoprotein from anabaena pcc 7120, which occurs in a fusion protein with a linoleic acid 9r-lipoxygenase, dehydrat ...200919244216
nitrogen fixation in mixed hylocomium splendens moss communities.the pleurocarpus feather moss, hylocomium splendens, is one of two co-dominant moss species in boreal forest ecosystems and one of the most common mosses on earth, yet little is known regarding its capacity to host cyanobacterial associates and thus contribute total ecosystem n. in these studies, we evaluated the n-fixation potential of the h. splendens-cyanobacteria association and contrasted the n-fixation activity with that of the putative n-fixing moss-cyanobacteria association of pleurozium ...200919252932
directed biosynthesis of phytotoxic alkaloids in the cyanobacterium nostoc 78-12a.nostocarboline, a chlorinated and n-methylated carbolinium alkaloid, displays potent and selective inhibition of photoautotrophic organisms as well as the malaria parasite plasmodium falciparum, while showing very low toxicity to bacterial and fungal pathogens, rat myoblasts and crustaceans. new derivatives of nostocarboline incorporating br, f or methyl substituents have been obtained through precursor-directed biosynthesis in nostoc 78-12a (identical to nostoc sp. atcc 43238) by feeding this c ...200919263450
diversity and transcription of proteases involved in the maturation of hydrogenases in nostoc punctiforme atcc 29133 and nostoc sp. strain pcc 7120.the last step in the maturation process of the large subunit of [nife]-hydrogenases is a proteolytic cleavage of the c-terminal by a hydrogenase specific protease. contrary to other accessory proteins these hydrogenase proteases are believed to be specific whereby one type of hydrogenases specific protease only cleaves one type of hydrogenase. in cyanobacteria this is achieved by the gene product of either hupw or hoxw, specific for the uptake or the bidirectional hydrogenase respectively. the f ...200919284580
characterization of the hupsl promoter activity in nostoc punctiforme atcc 29133.in cyanobacteria three enzymes are directly involved in the hydrogen metabolism; a nitrogenase that produces molecular hydrogen, h2, as a by-product of nitrogen fixation, an uptake hydrogenase that recaptures h2 and oxidize it, and a bidirectional hydrogenase that can both oxidize and produce h2.nostoc punctiforme atcc 29133 is a filamentous dinitrogen fixing cyanobacterium containing a nitrogenase and an uptake hydrogenase but no bidirectional hydrogenase. generally, little is known about the t ...200919284581
role of ntca, a cyanobacterial global nitrogen regulator, in the regulation of sucrose metabolism gene expression in anabaena sp. pcc 7120.in the heterocyst-forming cyanobacterium anabaena sp. pcc 7120 (also known as nostoc sp. pcc 7120), it has been shown that spsb and susa, the genes coding for proteins related to sucrose synthesis and cleavage, respectively, exhibit converse expression regarding the nitrogen source. in the nitrogen-fixing filament, spsb expression is mostly localized to the heterocysts and susa is only expressed in vegetative cells. the aim of this work was to investigate the participation of ntca, a global nitr ...200919082579
characterization of a novel debranching enzyme from nostoc punctiforme possessing a high specificity for long branched chains.a novel debranching enzyme from nostoc punctiforme pcc73102 (npde) exhibits hydrolysis activity toward both alpha-(1,6)- and alpha-(1,4)-glucosidic linkages. the action patterns of npde revealed that branched chains are released first, and the resulting maltooligosaccharides are then hydrolyzed. analysis of the reaction with maltooligosaccharide substrates labeled with (14)c-glucose at the reducing end shows that npde specifically liberates glucose from the reducing end. kinetic analyses showed ...200919010304
bioinformatic and expression analyses of genes mediating zinc homeostasis in nostoc punctiforme.zinc homeostasis was investigated in nostoc punctiforme. cell tolerance to zn(2+) over 14 days showed that zncl(2) levels above 22 microm significantly reduced cell viability. after 3 days in 22 microm zncl(2), ca. 12% of the zn(2+) was in an edta-resistant component, suggesting an intracellular localization. zinquin fluorescence was detected within cells exposed to concentrations up to 37 microm relative to 0 microm treatment. radiolabeled (65)zn showed zn(2+) uptake increased over a 3-day peri ...200919011078
quantitative overview of n2 fixation in nostoc punctiforme atcc 29133 through cellular enrichments and itraq shotgun proteomics.nostoc punctiforme atcc 29133 is a photoautotrophic cyanobacterium with the capacity to fix atmospheric n 2. its ability to mediate this process is similar to that described for nostoc sp. pcc 7120, where vegetative cells differentiate into heterocysts. quantitative proteomic investigations at both the filament level and the heterocyst level are presented using isobaric tagging technology (itraq), with 721 proteins at the 95% confidence interval quantified across both studies. observations from ...200919012430
new insights into the role of fur proteins: furb (all2473) from anabaena protects dna and increases cell survival under oxidative stress.fur (ferric uptake regulator) is a prokaryotic transcriptional regulator that controls a large number of genes mainly related to iron metabolism. several fur homologues with different physiological roles are frequently found in the same organism. the genome of the filamentous cyanobacterium anabaena (nostoc) sp. pcc 7120 codes for three different fur genes. fura is an essential protein involved in iron homoeostasis that also modulates dinitrogen fixation. fura interacts with haem, impairing its ...200918945213
screening for acetylcholinesterase inhibitory activity in cyanobacteria of the genus nostoc.fifty-four cyanobacterial strains of the genus nostoc from different habitats were screened for acetylcholinesterase inhibitory activity. water-methanolic extracts from freeze-dried biomasses were tested for inhibitory activity using ellman's spectrophotometric method. acetylcholinesterase inhibitory activity higher than 90% was found in the crude extracts of nostoc sp. str. lukesova 27/97 and nostoc ellipsosporum rabenh. str. lukesova 51/91. extracts from nostoc ellipsosporum str. lukesova 52/9 ...200918951237
the 2a resolution crystal structure of hetl, a pentapeptide repeat protein involved in regulation of heterocyst differentiation in the cyanobacterium nostoc sp. strain pcc 7120.the hetl gene from the cyanobacterium nostoc sp. pcc 7120 encodes a 237 amino acid protein (25.6kda) containing 40 predicted tandem pentapeptide repeats. nostoc sp. pcc 7120 is a filamentous cyanobacterium that forms heterocysts, specialized cells capable of fixing atmospheric n(2) during nitrogen starvation in its aqueous environment. under these conditions, heterocysts occur in a regular pattern of approximately one out of every 10-15 vegetative cells. heterocyst differentiation is highly regu ...200918952182
gobase: an organelle genome database.the organelle genome database gobase, now in its 21st release (june 2008), contains all published mitochondrion-encoded sequences (approximately 913,000) and chloroplast-encoded sequences (approximately 250,000) from a wide range of eukaryotic taxa. for all sequences, information on related genes, exons, introns, gene products and taxonomy is available, as well as selected genome maps and rna secondary structures. recent major enhancements to database functionality include: (i) addition of an in ...200918953030
an evaluation of four phylogenetic markers in nostoc: implications for cyanobacterial phylogenetic studies at the intrageneric level.the success of some phylogenetic markers in cyanobacteria owes to the design of cyanobacteria-specific primers, but a few studies have directly investigated the evolution "behavior" of the loci. in this study, we performed a case study in nostoc to evaluate rpoc1, hetr, rbclx, and 16s rrna-trna(ile)-trna(ala)-23s rrna internal transcribed spacer (its) as phylogenetic markers. the results indicated that the gene trees of these loci are not congruent with the phylogeny based on 16s rrna gene. the ...200918972163
the role of the c-terminal region of cyanophycin synthetase from nostoc ellipsosporum ne1 in its enzymatic activity and thermostability: a key function of glu(856).the biosynthesis of cyanophycin granule polypeptides is catalyzed by cyanophycin synthetase, cpha. in this study, the role of the c-terminal region of cpha from nostoc ellipsosporum ne1, cpha(ne1), was analyzed using a tailor-made c-terminus truncated library. the expression level of truncated cpha(ne1) in e. coli depended on the stop codons that were used. the expression vector that had the amber stop codon tag produced more than twice amount of cpha(ne1) as a vector that contained the ochre co ...200918977318
in vivo and in vitro protein ligation by naturally occurring and engineered split dnae inteins.protein trans-splicing by naturally occurring split dnae inteins is used for protein ligation of foreign peptide fragments. in order to widen biotechnological applications of protein trans-splicing, it is highly desirable to have split inteins with shorter c-terminal fragments, which can be chemically synthesized.200919365564
electron transfer protein complexes in the thylakoid membranes of heterocysts from the cyanobacterium nostoc punctiforme.filamentous, heterocystous cyanobacteria are capable of nitrogen fixation and photoautotrophic growth. nitrogen fixation takes place in heterocysts that differentiate as a result of nitrogen starvation. heterocysts uphold a microoxic environment to avoid inactivation of nitrogenase, e.g. by downregulation of oxygenic photosynthesis. the atp and reductant requirement for the nitrogenase reaction is considered to depend on photosystem i, but little is known about the organization of energy convert ...200919366613
hypocholesterolemic effect of nostoc commune var. sphaeroides kützing, an edible blue-green alga.intake of an edible blue-green alga nostoc commune var. sphaeroides kützing (n. commune) has been shown to lower plasma total cholesterol concentration, but the mechanisms behind the hypocholesterolemic effect have not been elucidated.200919404563
diversity of 23s rrna genes within individual prokaryotic genomes.the concept of ribosomal constraints on rrna genes is deduced primarily based on the comparison of consensus rrna sequences between closely related species, but recent advances in whole-genome sequencing allow evaluation of this concept within organisms with multiple rrna operons.200919415112
gene expression patterns associated with the biosynthesis of the sunscreen scytonemin in nostoc punctiforme atcc 29133 in response to uva radiation.under exposure to uv radiation, some cyanobacteria synthesize sunscreen compounds. scytonemin is a heterocyclic indole-alkaloid sunscreen, the synthesis of which is induced upon exposure to uva (long-wavelength uv) radiation. we previously identified and characterized an 18-gene cluster associated with scytonemin biosynthesis in the cyanobacterium nostoc punctiforme atcc 29133; we now report on the expression response of these genes to a step-up shift in uva exposure. using quantitative pcr on c ...200919429608
water-stress induced trehalose accumulation and control of trehalase in the cyanobacterium nostoc punctiforme iam m-15.we investigated the biochemical properties of the enzymes involved in trehalose metabolism in the cyanobacterium nostoc punctiforme strain iam m-15 to elucidate the mechanism of trehalose accumulation in response to desiccation and salt stress. there was no detectable trehalose in fully hydrated n. punctiforme cells; however, these cells accumulated trehalose upon desiccation. moreover, nacl treatment also induced trehalose accumulation. the three genes for trehalose metabolism, trez (maltooligo ...200919436130
microcystin production in the tripartite cyanolichen peltigera leucophlebia.we show that the cyanobacterial symbionts of a tripartite cyanolichen can produce hepatotoxic microcystins in situ. microcystins were detected with high-performance liquid chromatography mass spectrometry both from cephalodia of the tripartite cyanolichen peltigera leucophlebia and from a symbiotic nostoc strain isolated from the same lichen specimen. genetic identities of symbiotic nostoc strains were studied by amplifying and sequencing the 16s rrna gene. also, the presence of the microcystin ...200919445594
a versatile photoactivatable probe designed to label the diphosphate binding site of farnesyl diphosphate utilizing enzymes.farnesyl diphosphate (fpp) is a substrate for a diverse number of enzymes found in nature. photoactive analogues of isoprenoid diphosphates containing either benzophenone, diazotrifluoropropionate or azide groups have been useful for studying both the enzymes that synthesize fpp as well as those that employ fpp as a substrate. here we describe the synthesis and properties of a new class of fpp analogues that links an unmodified farnesyl group to a diphosphate mimic containing a photoactive benzo ...200919447628
alteration of the gastrointestinal microbiota of mice by edible blue-green algae.to characterize the effect of edible blue-green algae (cyanobacteria) on the gastrointestinal microbiota of mice.200919486425
on the contributions of diffusion and thermal activation to electron transfer between phormidium laminosum plastocyanin and cytochrome f: brownian dynamics simulations with explicit modeling of nonpolar desolvation interactions and electron transfer events.the factors that determine the extent to which diffusion and thermal activation processes govern electron transfer (et) between proteins are debated. the process of et between plastocyanin (pc) and cytochrome f (cytf) from the cyanobacterium phormidium laminosum was initially thought to be diffusion-controlled but later was found to be under activation control (schlarb-ridley, b. g.; et al. biochemistry 2005, 44, 6232). here we describe brownian dynamics simulations of the diffusional associatio ...200919518050
a comparative genomics approach to understanding the biosynthesis of the sunscreen scytonemin in cyanobacteria.the extracellular sunscreen scytonemin is the most common and widespread indole-alkaloid among cyanobacteria. previous research using the cyanobacterium nostoc punctiforme atcc 29133 revealed a unique 18-gene cluster (npr1276 to npr1259 in the n. punctiforme genome) involved in the biosynthesis of scytonemin. we provide further genomic characterization of these genes in n. punctiforme and extend it to homologous regions in other cyanobacteria.200919630972
assessment of sampling strategies for gas chromatography-mass spectrometry (gc-ms) based metabolomics of cyanobacteria.metabolomics is the comprehensive analysis of the small molecules that compose an organism's metabolism. the main limiting step in microbial metabolomics is the requirement for fast and efficient separation of microbes from the culture medium under conditions in which metabolism is rapidly halted. in this article we compare three different sampling strategies, quenching, filtering, and centrifugation, for arresting the metabolic activities of two morphologically diverse cyanobacteria, the unicel ...200919631594
nmr resonance assignment of dnae intein from nostoc punctiforme.dnae intein from nostoc punctiforme (npu) is one of naturally occurring split inteins, which has robust protein splicing activity. highly efficient trans-splicing activity of npudnae intein could widen various biotechnological applications. however, structural basis of the efficient protein splicing activity is poorly understood. as a first step toward better understanding of protein trans-splicing mechanism, we present the backbone and side-chain resonance assignments of a single chain variant ...200919636943
site-specific two-color protein labeling for fret studies using split inteins.fluorescence resonance energy transfer (fret) is an ideal tool for studying protein conformational changes and dynamics. strategies to specifically label proteins with multiple colors at structurally important sites, a prerequisite for such studies, however, need to be devised on a protein-by-protein basis. here we describe a simple yet widely applicable two-color site-specific protein labeling method utilizing npu dnae split intein.200919645470
analysis of current and alternative phenol based rna extraction methodologies for cyanobacteria.the validity and reproducibility of gene expression studies depend on the quality of extracted rna and the degree of genomic dna contamination. cyanobacteria are gram-negative prokaryotes that synthesize chlorophyll a and carry out photosynthetic water oxidation. these organisms possess an extended array of secondary metabolites that impair cell lysis, presenting particular challenges when it comes to nucleic acid isolation. therefore, we used the nhm5 strain of nostoc punctiforme atcc 29133 to ...200919660145
unique carotenoids in the terrestrial cyanobacterium nostoc commune nies-24: 2-hydroxymyxol 2'-fucoside, nostoxanthin and canthaxanthin.cyanobacteria produce some carotenoids. we identified the molecular structures, including the stereochemistry, of all the carotenoids in the terrestrial cyanobacterium, nostoc commune nies-24 (iam m-13). the major carotenoid was beta-carotene. its hydroxyl derivatives were (3r)-beta-cryptoxanthin, (3r,3'r)-zeaxanthin, (2r,3r,3'r)-caloxanthin, and (2r,3r,2'r,3'r)-nostoxanthin, and its keto derivatives were echinenone and canthaxanthin. the unique myxol glycosides were (3r,2's)-myxol 2'-fucoside a ...200919669835
microcystin producing cyanobacterium nostoc sp. bhu001 from a pond in india.the cyanobacterium nostoc sp. bhu001 is a new isolate from a pond in india. the cyanobacterium produces more than ten peptides including five microcystin (mc) variants, mc-lr, -wr, -ar, -la and methylated mc-lr, and a new peptide similar to cyanopeptolin. total mc content determined by elisa was 25.2 microg g(-1) dry wt of the cyanobacterium, dominated by mc-lr (54%). this is the first report of mc producing nostoc strain from india.200919673105
gated electron transfer of cytochrome c6 at biomimetic interfaces: a time-resolved serr study.the electron shuttle heme protein cyt-c(6) from the photosynthetic cyanobacterium nostoc sp. pcc 7119 was immobilized on nanostructured ag electrodes coated with sams that mimic different possible interactions with its natural reaction partner psi. the structure, redox potential, and electron-transfer dynamics of the sam-cyt-c(6) complexes were investigated by tr-serr spectroelectrochemistry. it is shown that the heterogeneous electron-transfer process is gated both in electrostatic and hydropho ...200919690710
slippery when wet: phylogeny and character evolution in the gelatinous cyanobacterial lichens (peltigerales, ascomycetes).many lichen fungi form symbioses with filamentous nostoc cyanobacteria, which cause the lichen to swell and become extremely gelatinous when moist. within the lecanoromycetes, such gelatinous lichens are today mainly classified in the collemataceae (peltigerales, ascomycota). we performed bayesian mcmc, maximum likelihood, and maximum parsimony analyses of three independent markers (mtssu rdna, nulsu rdna, and rpb1), to improve our understanding of the phylogeny and classification in the peltige ...200919695332
improvement and analysis of computational methods for prediction of residual dipolar couplings.we describe a new, computationally efficient method for computing the molecular alignment tensor based on the molecular shape. the increase in speed is achieved by re-expressing the problem as one of numerical integration, rather than a simple uniform sampling (as in the pales method), and by using a convex hull rather than a detailed representation of the surface of a molecule. this method is applicable to bicelles, peg/hexanol, and other alignment media that can be modeled by steric restrictio ...200919700353
identification and quantification of microcystins from a nostoc muscorum bloom occurring in oukaïmeden river (high-atlas mountains of marrakech, morocco).health risks generated by cyanobacterial toxins in drinking and recreational waters are clearly recognised. during the monitoring programme on the distribution of toxic freshwater cyanobacteria in various water bodies including reservoirs, ponds and rivers of morocco, many toxigenic cyanobacteria bloom-forming species have been identified. particular attention was given to the investigation of the toxicology of a benthic nostoc species-nostoc muscorum ag. (cyanobacteria, nostocales, nostocaceae) ...200918288580
structure of a bacterial dynamin-like protein lipid tube provides a mechanism for assembly and membrane curving.proteins of the dynamin superfamily mediate membrane fission, fusion, and restructuring events by polymerizing upon lipid bilayers and forcing regions of high curvature. in this work, we show the electron cryomicroscopy reconstruction of a bacterial dynamin-like protein (bdlp) helical filament decorating a lipid tube at approximately 11 a resolution. we fitted the bdlp crystal structure and produced a molecular model for the entire filament. the bdlp gtpase domain dimerizes and forms the tube su ...200920064379
an enzymatic cyclopentyl[b]indole formation involved in scytonemin biosynthesis.previous studies of the biosynthetic enzymes involved in the assembly of scytonemin (1), a cyanobacterial sunscreen, have identified beta-ketoacid 2 as an important intermediate that is produced by thdp-dependent enzyme scya. we now report that scyc, previously annotated as a hypothetical protein, catalyzes cyclization and decarboxylation of 2 to generate ketone 5. assembly of the cyclopentyl[b]indole structure in this manner has little precedent in the chemical literature. additional mechanisti ...200919780555
overexpression, isolation, and spectroscopic characterization of the bidirectional [nife] hydrogenase from synechocystis sp. pcc 6803.the bidirectional [nife] hydrogenase of the cyanobacterium synechocystis sp. pcc 6803 was purified to apparent homogeneity by a single affinity chromatography step using a synechocystis mutant with a strep-tag ii fused to the c terminus of hoxf. to increase the yield of purified enzyme and to test its overexpression capacity in synechocystis the psbaii promoter was inserted upstream of the hoxe gene. in addition, the accessory genes (hypf, c, d, e, a, and b) from nostoc sp. pcc 7120 were express ...200919801638
2-methylhopanoids are maximally produced in akinetes of nostoc punctiforme: geobiological implications.2-methylhopanes, molecular fossils of 2-methylbacteriohopanepolyol (2-mebhp) lipids, have been proposed as biomarkers for cyanobacteria, and by extension, oxygenic photosynthesis. however, the robustness of this interpretation is unclear, as 2-methylhopanoids occur in organisms besides cyanobacteria and their physiological functions are unknown. as a first step toward understanding the role of 2-mebhp in cyanobacteria, we examined the expression and intercellular localization of hopanoids in the ...200919811542
isolation and characterization of a cyanobacterium-binding protein and its cell wall receptor in the lichen peltigera canina.peltigera canina, a cyanolichen containing nostoc as cyanobiont, produces and secretes arginase to a medium containing arginine. secreted arginase acts as a lectin by binding to the surface of nostoc cells through a specific receptor which develops urease activity. the enzyme urease has been located in the cell wall of recently isolated cyanobionts. cytochemical detection of urease is achieved by producing a black, electron-dense precipitate of cobalt sulfide proceeding from co(2) evolved from u ...200919820309
consumption of fa cai nostoc soup: a potential for bmaa exposure from nostoc cyanobacteria in china?grown in arid regions of western china the cyanobacterium nostoc flagelliforme--called fa cai in mandarin and fat choy in cantonese--is wild-harvested and used to make soup consumed during new year's celebrations. high prices, up to $125 usd/kg, led to overharvesting in inner mongolia, ningxia, gansu, qinghai, and xinjiang. degradation of arid ecosystems, desertification, and conflicts between nostoc harvesters and mongol herdsmen concerned the chinese environmental authorities, leading to a gov ...200919929731
the naturally split npu dnae intein exhibits an extraordinarily high rate in the protein trans-splicing reaction.we have studied the naturally split alpha subunit of the dna polymerase iii (dnae) intein from nostoc punctiforme pcc73102 (npu) using purified proteins and determined an apparent first-order rate constant of (1.1+/-0.2)x10(-2) s(-1) at 37 degrees c. this represents the highest rate reported for the protein trans-splicing reaction so far (t(1/2) of approximately 60s). furthermore, the reaction was very robust and high-yielding with respect to different extein sequences, temperatures from 6 to 37 ...200919302791
do lichens domesticate photobionts like farmers domesticate crops? evidence from a previously unrecognized lineage of filamentous cyanobacteria.phylogenetic diversity of lichen photobionts is low compared to that of fungal counterparts. most lichen fungi are thought to be associated with just four photobiont genera, among them the cyanobacteria nostoc and scytonema, two of the most important nitrogen fixers in humid ecosystems. although many nostoc photobionts have been identified using isolated cultures and sequences, the identity of scytonema photobionts has never been confirmed by culturing or sequencing. we investigated the phylogen ...200921628288
quantitative shotgun proteomics of enriched heterocysts from nostoc sp. pcc 7120 using 8-plex isobaric peptide tags.the filamentous cyanobacterium nostoc sp. strain pcc 7120 is capable of fixing atmospheric nitrogen. the labile nature of the core process requires the terminal differentiation of vegetative cells to form heterocysts, specialized cells with altered cellular and metabolic infrastructure to mediate the n2-fixing process. we present an investigation targeting the cellular proteomic expression of the heterocysts compared to vegetative cells of a population cultured under n2-fixing conditions. new 8- ...200818290607
5s rrna-recognition module of ctc family proteins and its evolution.the effects of amino acid replacements in the rna-binding sites of homologous ribosomal proteins tl5 and l25 (members of the ctc family) on ability of these proteins to form stable complexes with ribosomal 5s rna were studied. it was shown that even three simultaneous replacements of non-conserved amino acid residues by alanine in the rna-binding site of tl5 did not result in noticeable decrease in stability of the tl5-5s rrna complex. however, any replacement among five conserved residues in th ...200818298371
differential patterns of evolution and distribution of the symbiotic behaviour in nostocacean cyanobacteria.many cyanobacteria commonly identified as belonging to the genus nostoc are well-known cyanobionts (symbionts) of a wide variety of plants and fungi. they form symbioses with bryophytes, pteridophytes, gymnosperms and angiosperms that are considerably different in the type of reciprocal interaction between the host and the cyanobiont. the phylogenetic and taxonomic relationships among cyanobionts isolated from different hosts and nostoc strains isolated from free-living conditions are still not ...200818319454
biosorption of lead(ii) from aqueous solutions by non-living algal biomass oedogonium sp. and nostoc sp.--a comparative study.industrial wastewaters containing heavy metals pose a major environmental problem that needs to be remedied. the present study reports the ability of two non-living (dried) fresh water algae, oedogonium sp. and nostoc sp. to remove lead(ii) from aqueous solutions in batch system under varying range of ph (2.99-7.04), contact time (5-300 min), biosorbent dose (0.1-0.8 g/l), and initial metal ion concentrations (100 and 200mg/l). the optimum conditions for lead biosorption are almost same for the ...200818321684
genetic diversity in cyanobacterial symbionts of thalloid bryophytes.two species of thalloid liverworts, blasia pusilla and cavicularia densa, form stable symbioses with nitrogen-fixing cyanobacteria. both bryophytes promote the persistence of their cyanobacterial associations by producing specialized gemmae, which facilitate the simultaneous dispersal of the host and its nitrogen-fixing symbionts. here the genetic diversity of cyanobacterial symbionts of blasia and cavicularia is examined. the results indicate that the primary symbionts of both bryophytes are cl ...200818325923
analysis of the cryptophycin p450 epoxidase reveals substrate tolerance and cooperativity.cryptophycins are potent anticancer agents isolated from nostoc sp. atcc 53789 and nostoc sp. gsv 224. the most potent natural cryptophycin analogues retain a beta-epoxide at the c2'-c3' position of the molecule. a p450 epoxidase encoded by c rpe recently identified from the cryptophycin gene cluster was shown to install this key functional group into cryptophycin-4 (cr-4) to produce cryptophycin-2 (cr-2) in a regio- and stereospecific manner. here we report a detailed characterization of the cr ...200818366166
pas-mediated dimerization of soluble guanylyl cyclase revealed by signal transduction histidine kinase domain crystal structure.signal transduction histidine kinases (sthk) are key for sensing environmental stresses, crucial for cell survival, and attain their sensing ability using small molecule binding domains. the n-terminal domain in an sthk from nostoc punctiforme is of unknown function yet is homologous to the central region in soluble guanylyl cyclase (sgc), the main receptor for nitric oxide (no). this domain is termed h-noxa (or h-noba) because it is often associated with the heme-nitric oxide/oxygen binding (h- ...200818006497
a lipoxygenase with linoleate diol synthase activity from nostoc sp. pcc 7120.the dioxygenation of pufas (polyunsaturated fatty acids) in plants is mainly catalysed by members of the lox (lipoxygenase) enzyme family. lox products may be further metabolized, and are known as signalling substances in plant development and in responses to wounding and pathogen attack. in contrast with the situation in eukaryotes, information on the relevance of lipid peroxide metabolism in prokaryotic organisms is scarce. therefore, we aimed to analyse loxs and oxylipin patterns of cyanobact ...200818031288
nezha, a novel active miniature inverted-repeat transposable element in cyanobacteria.miniature inverted-repeat transposable elements (mites) were first identified in plants and exerted extensive proliferations throughout eukaryotic and archaeal genomes. but very few mites have been characterized in bacteria. we identified a novel mite, called nezha, in cyanobacteria anabaena variabilis atcc 29413 and nostoc sp. pcc 7120. nezha, like most previously known mites in other organisms, is small in size, non-coding, carrying tir and dr signals, and of potential to form a stable rna sec ...200818035045
mechanisms to avoid photoinhibition in a desiccation-tolerant cyanobacterium, nostoc commune.a desiccation-tolerant cyanobacterium, nostoc commune, shows unique responses to dehydration. these responses are: (i) loss of psii activity in parallel with the loss of photosynthesis; (ii) loss of psi activity; and (iii) dissipation of light energy absorbed by pigment-protein complexes. in this study, the deactivation of psii is shown to be important in avoiding photoinhibition when the calvin-benson cycle is repressed by dehydration. furthermore, our evidence suggests that dissipation of ligh ...200818252733
a common transport system for methionine, l-methionine-dl-sulfoximine (msx), and phosphinothricin (ppt) in the diazotrophic cyanobacterium nostoc muscorum.we present evidence, for the first time, of the occurrence of a transport system common for amino acid methionine, and methionine/glutamate analogues l-methionine-dl-sulfoximine (msx) and phosphinothricin (ppt) in cyanobacterium nostoc muscorum. methionine, which is toxic to cyanobacterium, enhanced its nitrogenase activity at lower concentrations. the cyanobacterium showed a biphasic pattern of methionine uptake activity that was competitively inhibited by the amino acids alanine, isoleucine, l ...200818266032
cyanobacteria-bryophyte symbioses.cyanobacteria are a large group of photosynthetic prokaryotes of enormous environmental importance, being responsible for a large proportion of global co(2) and n(2) fixation. they form symbiotic associations with a wide range of eukaryotic hosts including plants, fungi, sponges, and protists. the cyanobacterial symbionts are often filamentous and fix n(2) in specialized cells known as heterocysts, enabling them to provide the host with fixed nitrogen and, in the case of non-photosynthetic hosts ...200818267939
nitrogen fixation by phyllosphere bacteria associated with higher plants and their colonizing epiphytes of a tropical lowland rainforest of costa rica.leaf surfaces (phyllospheres) have been shown to provide appropriate conditions for colonization by microorganisms including diazotrophic bacteria that are able to fix atmospheric nitrogen (n(2)). in this study, we determined leaf-associated n(2) fixation of a range of rainforest plants in costa rica, under different environmental conditions, by tracing biomass n incorporation from (15)n(2). n(2)-fixing bacterial communities of the plant species carludovica drudei, grias cauliflora and costus la ...200818273066
sequestration of chromium by exopolysaccharides of nostoc and gloeocapsa from dilute aqueous solutions.this article reports the chromium removal potential of exopolysaccharides (eps) of two indigenously isolated cyanobacterial strains, gloeocapsa calcarea and nostoc punctiforme. the biosorption was studied by varying ph from 2 to 6 and initial chromium concentration from 5 to 20mg/l to find out the optimized conditions for maximum chromium removal by eps. two equilibrium models, langmuir and freundlich, were used to explain these results. the freundlich model was found to be better applicable to ...200818280649
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