Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
photophysical diversity of two novel cyanobacteriochromes with phycocyanobilin chromophores: photochemistry and dark reversion kinetics.cyanobacteriochromes are phytochrome homologues in cyanobacteria that act as sensory photoreceptors. we compare two cyanobacteriochromes, rgs (coded by slr1393) from synechocystis sp. pcc 6803 and aphc (coded by all2699) from nostoc sp. pcc 7120. both contain three gaf (cgmp phosphodiesterase, adenylyl cyclase and fhla protein) domains (gaf1, gaf2 and gaf3). the respective full-length, truncated and cysteine point-mutated genes were expressed in escherichia coli together with genes for chromopho ...201222008418
hupw protease specifically required for processing of the catalytic subunit of the uptake hydrogenase in the cyanobacterium nostoc sp. strain pcc 7120.the maturation process of [nife] hydrogenases includes a proteolytic cleavage of the large subunit. we constructed a mutant of nostoc strain pcc 7120 in which hupw, encoding a putative hydrogenase-specific protease, is inactivated. our results indicate that the protein product of hupw selectively cleaves the uptake hydrogenase in this cyanobacterium.201222020512
Phosphorus limitation for the colony formation, growth and photosynthesis of an edible cyanobacterium, Nostoc sphaeroides.The percentage of spherical colonies from the trichomes of Nostoc sphaeroides reached 62-73% after 16 days with 50 and 250 µM P, but only10-15% at 0.5 and 5 µM P. During colony formation from microcolonies to macrocolonies, the growth rates were 95, 206 and 244% higher, respectively at 5, 50 and 250 µM P than that at 0.5 µM P. The light-saturated photosynthetic rate, maximum electron transport rate and light-limited photosynthetic efficiency at 0.5 µM P decreased, respectively, by 45, 51 and 32% ...201221972139
Phylogenetic, chemical and morphological diversity of cyanobacteria from Portuguese temperate estuaries.Cyanobacteria from estuarine habitats have been poorly studied regarding diversity and potential bioactive compounds production compared with their fresh and marine waters' congeners. In this work, 44 cyanobacteria isolates characterised from three Portuguese estuarine environments. Identification was performed based on diacritical morphological features of the isolates (e.g. cell shape, cell size, presence/absence of sheaths) and on 16S rRNA gene sequences phylogenetic analysis. Diversity of pr ...201222093261
E622, a miniature, virulence-associated mobile element.Miniature inverted terminal repeat elements (MITEs) are nonautonomous mobile elements that have a significant impact on bacterial evolution. Here we characterize E622, a 611-bp virulence-associated MITE from Pseudomonas syringae, which contains no coding region but has almost perfect 168-bp inverted repeats. Using an antibiotic coupling assay, we show that E622 is transposable and can mobilize an antibiotic resistance gene contained between its borders. Its predicted parent element, designated T ...201222081398
comparative analysis of cyanobacteria in the rhizosphere and as endosymbionts of cycads in drought-effected soils.does the diversity of cyanobacteria in the cycad rhizosphere relate to the cyanobiont species found in the coralloid roots of these ancient plants? the aim of this study was to identify the diversity of soil cyanobacteria occurring in the immediate vicinity of 22 colonised coralloid roots belonging to members of the cycad genera: macrozamia, lepidozamia, bowenia and cycas. the majority of coralloid roots were sampled at depths greater than 10 cm below the soil surface. a total of 32 cyanobacteri ...201222224502
effects of carbaryl and 1-naphthol on soil population of cyanobacteria and microalgae and select cultures of diazotrophic cyanobacteria.carbaryl application to soil collected from a rice fallow field was relatively less toxic to viable estimates of cyanobacteria and microalgae under nonflooded conditions than under flooded conditions. application of 1-naphthol, the hydrolysis product of carbaryl, to soil under both the regimes increased the population of both cyanobacteria and microalgae. soil application of carbaryl and 1-naphthol in combination, up to 1.0-ákg-áha(-1), was nontoxic to the viable population. the toxicity exerted ...201121706293
Split-intein mediated re-assembly of genetically encoded Ca(2+) indicators.While genetically encoded Ca(2+) indicators (GECIs) allow Ca(2+) imaging in model organisms, the gene expression is often under the control of a single promoter that may drive expression beyond, the cell types of interest. To enable more cell-type specific targeting, GECIs can be brought under the, control of the intersecting expression from two promoters. Here, we present the splitting and, reassembly of two representative GECIs (TN-XL and GCaMP2) mediated by the split intein from Nostoc, punct ...201122133610
An ATP-grasp ligase involved in the last biosynthetic step of the iminomycosporine shinorine in Nostoc punctiforme ATCC 29133.We investigated the genetic basis for mycosporine sunscreen biosynthesis by the cyanobacterium Nostoc punctiforme ATCC 29133. Heterologous expression in Escherichia coli of three contiguous N. punctiforme genes (NpR5600, NpR5599, and NpR5598, here named mysA, mysB, and mysC, respectively) led to the production of mycosporine-glycine, an oxomycosporine. Additional expression of gene NpF5597 (mysD) led to the conversion of mycosporine-glycine into iminomycosporines (preferentially shinorine but al ...201121890703
Reconstruction of structural evolution in the trnL intron P6b loop of symbiotic Nostoc (Cyanobacteria).In this study we reconstruct the structural evolution of the hyper-variable P6b region of the group I trnLeu intron in a monophyletic group of lichen-symbiotic Nostoc strains and establish it as a useful marker in the phylogenetic analysis of these organisms. The studied cyanobacteria occur as photosynthetic and/or nitrogen-fixing symbionts in lichen species of the diverse Nephroma guild. Phylogenetic analyses and secondary structure reconstructions are used to improve the understanding of the r ...201122210193
colour evaluation of a phycobiliprotein-rich extract obtained from nostoc pcc9205 in acidic solutions and yogurt.background: phycobiliproteins are coloured proteins produced by cyanobacteria, which have several applications because of their colour properties. however, there is no available information about the colour stability of phycobiliproteins from nostoc sp. in food systems. the aim of this work was to study the colour stability of a purple-coloured phycobiliprotein-rich extract from the cyanobacterium nostoc pcc9205 in acidic solutions and yogurt. results: variations of ph for nostoc pcc9205 extract ...201122095681
oxygen-independent alkane formation by non-heme iron-dependent cyanobacterial aldehyde decarbonylase: investigation of kinetics and requirement for an external electron donor.cyanobacterial aldehyde decarbonylase (cad) is, structurally, a member of the di-iron carboxylate family of oxygenases. we previously reported that cad from prochlorococcus marinus catalyzes the unusual hydrolysis of aldehydes to produce alkanes and formate in a reaction that requires an external reducing system but does not require oxygen [das et al. (2011) angew. chem. 50, 7148-7152]. here we demonstrate that cads from divergent cyanobacterial classes, including the enzyme from n. puntiformes ...201122074177
homologues and bioengineered derivatives of ltnj vary in ability to form d-alanine in the lantibiotic lacticin 3147.ltnα and ltnβ are individual components of the two-peptide lantibiotic lacticin 3147 and are unusual in that, although ribosomally synthesized, they contain d-amino acids. these result from the dehydration of l-serine to dehydroalanine by ltnm and subsequent stereospecific hydrogenation to d-alanine by ltnj. homologues of ltnj are rare but have been identified in silico in staphylococcus aureus c55 (sacj), pediococcus pentosaceus fbb61 (penn), and nostoc punctiforme pcc73102 (npnj, previously ca ...201122123251
molecular cloning of maltooligosyltrehalose trehalohydrolase gene from nostoc flagelliforme and trehalose-related response to stresses.a genomic dna fragment encoding a putative maltooligosyltrehalose trehalohydrolase (nfmth) for trehalose biosynthesis was cloned by the degenerate primer- pcr from cyanobacterium nostoc flagelliforme. the orf of nfmth is 1,848 bp in length and encodes 615 amino acid residues, constituting a 70 kda protein. the deduced amino acid sequence of nfmth contains 4 regions highly conserved for mths. by expression of nfmth in e. coli, the function of this protein was demonstrated, where the recombinant p ...201121876373
evaluation and comparison of protein splicing by exogenous inteins with foreign exteins in escherichia coli.protein splicing catalyzed by inteins has enabled various biotechnological applications such as protein ligation. successful applications of inteins are often limited by splicing efficiency. here, we report the comparison of protein splicing between 20 different inteins from various organisms in identical contexts to identify robust inteins with foreign exteins. we found that rada intein from pyrococcus horikoshii and an engineered dnab intein from nostoc punctiforme demonstrated an equally effi ...201122001202
molecular genetic and chemotaxonomic characterization of the terrestrial cyanobacterium nostoc commune and its neighboring species.the phylogeny of the terrestrial cyanobacterium nostoc commune and its neighboring nostoc species was studied using molecular genetic and chemotaxonomic approaches. at least eight genotypes of n. commune were characterized by the differences among 16s rrna gene sequences and the peth gene encoding ferredoxin-nadp(+) oxidoreductase and by random amplified polymorphic dna analysis. the genotypes of n. commune were distributed in japan without regional specificity. the nrtp gene encoding nrtp-type ...201122066798
cytochrome c6-like protein as a putative donor of electrons to photosystem i in the cyanobacterium nostoc sp. pcc 7119.most organisms performing oxygenic photosynthesis contain either cytochrome c(6) or plastocyanin, or both, to transfer electrons from cytochrome b(6)-f to photosystem i. even though plastocyanin has superseded cytochrome c(6) along evolution, plants contain a modified cytochrome c(6), the so called cytochrome c(6a), whose function still remains unknown. in this article, we describe a second cytochrome c(6) (the so called cytochrome c(6)-like protein), which is found in some cyanobacteria but is ...201121984388
Antagonistic interactions between filamentous heterotrophs and the cyanobacterium Nostoc muscorum.ABSTRACT:201121914201
integrating photobiological hydrogen production with dye-metal bioremoval from simulated textile wastewater.the study reports production of hydrogen in photobioreactors with free (pbr(fr)) and immobilized (pbr(imm)) nostoc biomass at enhanced and sustained rates. before running the photobioreactors, effects of different immobilization matrices and cyanobacterial dose on hydrogen production were studied in batch mode. as hydrogen production in the pbrs declined spent biomass from the photobioreactors were collected and utilized further for column biosorption of highly toxic dyes (reactive red 198+cryst ...201121890340
Global transcription profiles of the nitrogen stress response resulting in heterocyst or hormogonium development in Nostoc punctiforme.The filamentous cyanobacterium Nostoc punctiforme differentiates from vegetative cells into three distinct cell types, heterocysts, hormogonia, and akinetes, in response to different stimuli. Cultures growing with ammonium can be induced to form hormogonia or heterocysts upon removal of the combined nitrogen. A DNA microarray consisting of 94% of the open reading frames predicted from the 9.059-Mb N. punctiforme genome was used to generate a global transcription data set consisting of seven time ...201122001509
Second-Chance Initiation Dynamics of the Cyanobacterial Photocycle in the NpR6012 GAF4 Domain of Nostoc Punctiforme.The primary ultrafast Z-to-E isomerization photodynamics of the phytochrome-related cyanobacteri-ochrome (CBCR) NpR6012g4 from N. punctiforme were studied by transient absorption pump-dump-probe spec-troscopy. A 2-ps dump pulse resonant with the stimulated emission band depleted 21 % of the excited-state popula-tion, while the initial photoproduct Lumi-R was depleted by only 11 %. We observe a red-shifted ground-state in-termediate (GSI) that we assign to a metastable state that failed to fully ...201122107125
femtosecond photodynamics of the red/green cyanobacteriochrome npr6012g4 from nostoc punctiforme. 2. reverse dynamics.phytochromes are red/far-red photosensory proteins that utilize photoisomerization of a linear tetrapyrrole (bilin) chromophore to photoconvert reversibly between red- and far-red-absorbing forms (p(r) and p(fr), respectively). cyanobacteriochromes (cbcrs) are related photosensory proteins with more diverse spectral sensitivity. the mechanisms that underlie this spectral diversity have not yet been fully elucidated. one of the main cbcr subfamilies photoconverts between a red-absorbing 15z groun ...201122148731
within-genome evolution of repins: a new family of miniature mobile dna in bacteria.repetitive sequences are a conserved feature of many bacterial genomes. while first reported almost thirty years ago, and frequently exploited for genotyping purposes, little is known about their origin, maintenance, or processes affecting the dynamics of within-genome evolution. here, beginning with analysis of the diversity and abundance of short oligonucleotide sequences in the genome of pseudomonas fluorescens sbw25, we show that over-represented short sequences define three distinct groups ...201121698139
Antioxidative Activity and Chemical Constituents of Edible Terrestrial Alga Nostoc commune Vauch.The extract of terrestrial alga Nostoc commune Vauch. has high antioxidative activity. Our study on N. commune Vauch. resulted in the isolation of two ß-ionone derivatives, nostocionone and 3-oxo-ß-ionone, together with four indole alkaloids, scytonemin, reduced scytonemin, N-(p-coumaroyl)tryptamine, and N-acetyltryptamine. The structures of the isolated compounds were determined on the basis of 1D and 2D NMR and MS analyses. Among these isolates, nostocionone and reduced scytonemin demonstrated ...201122056440
Tolerance of the widespread cyanobacterium Nostoc commune to extreme temperature variations (-269 to 105°C), pH and salt stress.Nostoc commune is a widespread colonial cyanobacterium living on bare soils that alternate between frost and thaw, drought and inundation and very low and high temperatures. We collected N. commune from alternating wet and dry limestone pavements in Sweden and tested its photosynthesis and respiration at 20°C after exposure to variations in temperature (-269 to 105°C), pH (2-10) and NaCl (0.02-50 g NaCl kg(-1)). We found that dry field samples and rewetted specimens tolerated exposure beyond th ...201122120705
solution nmr structure of asl3597 from nostoc sp. pcc7120, the first structure from protein domain family pf12095, reveals a novel fold. 201122113821
Convergent evolution of a symbiotic duet: The case of the lichen genus Polychidium (Peltigerales, Ascomycota).• Premise of the study: Thallus architecture has long been a powerful guide for classifying lichens and has often trumped photobiont association and ascomatal type, but the reliability of these characters to predict phylogenetic affinity has seldom been tested. The cyanolichen genus Polychidium unites species that have strikingly similar gross morphology but consort with different photobiont genera. If Polychidium were found to be monophyletic, photobiont switching among closely related species ...201121980162
Fungal lectin of Peltigera canina induces chemotropism of compatible Nostoc cells by constriction-relaxation pulses of cyanobiont cytoskeleton.A glycosylated arginase acting as a fungal lectin from Peltigera canina is able to produce recruitment of cyanobiont Nostoc cells and their adhesion to the hyphal surface. This implies that the cyanobiont would develop organelles to motility towards the chemoattractant. However when visualized by transmission electron microscopy, Nostoc cells recently isolated from P. canina thallus do not reveal any motile, superficial organelles, although their surface was covered by small spindles and serrate ...201121897128
nostophycin biosynthesis is directed by a hybrid polyketide synthase-nonribosomal peptide synthetase in the toxic cyanobacterium nostoc sp. strain 152.cyanobacteria are a rich source of natural products with interesting pharmaceutical properties. here, we report the identification, sequencing, annotation, and biochemical analysis of the nostophycin (npn) biosynthetic gene cluster. the npn gene cluster spans 45.1 kb and consists of three open reading frames encoding a polyketide synthase, a mixed polyketide nonribosomal peptide synthetase, and a nonribosomal peptide synthetase. the genetic architecture and catalytic domain organization of the p ...201121948844
evidence for a sodium-dependent proline and glycine-betaine uptake in the cyanobacterium nostoc muscorum.the cyanobacterium nostoc muscorum is able to utilized proline and glycine-betaine as a nitrogen source under unstressed growth conditions. this cyanobacterium when grow in modified chu no. 10 medium (without na+) unable to utilized proline and glycine-betaine as a nitrogen source. spontaneously occurring mutant clones defective in na+ transport (na+-r) were isolated and analyzed for proline and glycine-betaine utilization. the mutant phenotype showed normal heterocyst frequency and nitrogenase ...201122073544
femtosecond photodynamics of the red/green cyanobacteriochrome npr6012g4 from nostoc punctiforme. 1. forward dynamics.phytochromes are well-known red/far-red photosensory proteins that utilize the photoisomerization of a linear tetrapyrrole (bilin) chromophore to detect the ratio of red to far-red light. cyanobacteriochromes (cbcrs) are related photosensory proteins with a bilin-binding gaf domain, but much more diverse spectral sensitivity, with five recognized subfamilies of cbcrs described to date. the mechanisms that underlie this spectral diversity have not yet been fully elucidated. one of the main cbcr s ...201122148715
post-storage potential of nostoc linckia (cyanobacteria) immobilized in ca-alginate (synthetic seed) as biofertilizer inocula. 201121914973
life cycle as a stable trait in the evaluation of diversity of nostoc from biofilms in rivers.the diversity within the genus nostoc is still controversial and more studies are needed to clarify its heterogeneity. macroscopic species have been extensively studied and discussed; however, the microscopic forms of the genus, especially those from running waters, are poorly known and likely represented by many more species than currently described. nostoc isolates from biofilms of two spanish calcareous rivers were characterized comparing the morphology and life cycle in two culture media wit ...201121223333
efficient functional analysis system for cyanobacterial or plant cytochromes p450 involved in sesquiterpene biosynthesis.tractable plasmids (pac-mv-based plasmids) for escherichia coli were constructed, which carried a mevalonate-utilizing gene cluster, towards an efficient functional analysis of cytochromes p450 involved in sesquiterpene biosynthesis. they included genes coding for a series of redox partners that transfer the electrons from nad(p)h to a p450 protein. the redox partners used were ferredoxin reductases (cama and nsred) and ferredoxins (camb and nsfer), which are derived from pseudomonas putida and ...201121229242
modification of transmembrane and gpi-anchored proteins on living cells by efficient protein trans-splicing using the npu dnae intein.the naturally split npu dnae intein can be used for ligation of an exogenous polypeptide to membrane proteins on living cells. no reducing agents or other factors are required. the approach is rapid and virtually traceless, because the intein removes itself during the reaction.201121234473
the morphogene amic2 is pivotal for multicellular development in the cyanobacterium nostoc punctiforme.filamentous cyanobacteria of the order nostocales are primordial multicellular organisms, a property widely considered unique to eukaryotes. their filaments are composed of hundreds of mutually dependent vegetative cells and regularly spaced n(2)-fixing heterocysts, exchanging metabolites and signalling molecules. furthermore, they may differentiate specialized spore-like cells and motile filaments. however, the structural basis for cellular communication within the filament remained elusive. he ...201121244533
metabolic adaptations in a h2 producing heterocyst-forming cyanobacterium: potentials and implications for biological engineering.nostoc punctiforme atcc 29133 is a photoautotrophic cyanobacterium with the ability to fix atmospheric nitrogen and photoproduce hydrogen through the enzyme nitrogenase. the h(2) produced is reoxidized by an uptake hydrogenase. inactivation of the uptake hydrogenase in n. punctiforme leads to increased h(2) release but unchanged rates of n(2) fixation, indicating redirected metabolism. system-wide understanding of the mechanisms of this metabolic redirection was obtained using complementary quan ...201121284387
characterization of complementary chromatic adaptation in gloeotrichia utex 583 and identification of a transposon-like insertion in the cpeba operon.many cyanobacteria are able to alter the pigment composition of the phycobilisome in a process called complementary chromatic adaptation (cca). the regulatory mechanisms of cca have been identified in fremyella diplosiphon, which regulates both phycoerythrin and phycocyanin levels, and nostoc punctiforme, which regulates only phycoerythrin production. recent studies show that these species use different regulatory proteins for cca. we chose to study the cca response of gloeotrichia utex 583 in a ...201121288891
influence of temperature and uvr on photosynthesis and morphology of four species of cyanobacteria.during the late austral spring of 2009 we carried out experiments (4days of duration) with four cyanobacteria species, anabaena sp., nostoc sp., arthrospira platensis and microcystis sp., to assess the combined effects of temperature and solar radiation on photosynthesis performance and morphology. two experimental temperatures (18°c and 23°c, simulating a 5°c increase under a scenario of climate change) and three radiation treatments (by using different filters/materials) were implemented: (i) ...201121296589
the sige gene is required for normal expression of heterocyst-specific genes in anabaena sp. strain pcc 7120.the filamentous cyanobacterium anabaena (nostoc) sp. strain pcc 7120 produces specialized cells for nitrogen fixation called heterocysts. previous work showed that the group 2 sigma factor sige (alr4249; previously called sigf) is upregulated in differentiating heterocysts 16 h after nitrogen step-down. we now show that the sige gene is required for normal heterocyst development and normal expression levels of several heterocyst-specific genes. mobility shift assays showed that the transcription ...201121317330
detection of formate, rather than carbon monoxide, as the stoichiometric coproduct in conversion of fatty aldehydes to alkanes by a cyanobacterial aldehyde decarbonylase.the second of two reactions in a recently discovered pathway through which saturated fatty acids are converted to alkanes (and unsaturated fatty acids to alkenes) in cyanobacteria entails scission of the c1-c2 bond of a fatty aldehyde intermediate by the enzyme aldehyde decarbonylase (ad), a ferritin-like protein with a dinuclear metal cofactor of unknown composition. we tested for and failed to detect carbon monoxide (co), the proposed c1-derived coproduct of alkane synthesis, following the in ...201121341652
effect of crowding on the electron transfer process from plastocyanin and cytochrome c6 to photosystem i: a comparative study from cyanobacteria to green algae.plastocyanin and cytochrome c(6), the alternate donor proteins to photosystem i, can be acidic, neutral or basic; the role of electrostatics in their interaction with photosystem i vary accordingly for cyanobacteria, algae and plants. the effect of different crowding agents on the kinetics of the reaction between plastocyanin or cytochrome c(6) and photosystem i from three different cyanobacteria, synechocystis pcc 6803, nostoc pcc 7119 and arthrospira maxima, and a green alga, monoraphidium bra ...201121344311
iron starvation-induced proteomic changes in anabaena (nostoc) sp. pcc 7120: exploring survival strategy.this study provides first-hand proteomic data on the survival strategy of anabaena sp. pcc 7120 when subjected to long-term iron-starvation conditions. 2d-gel electrophoresis followed by maldi-tof/ms analysis of iron-deficient anabaena revealed significant and reproducible alterations in ten proteins, of which six are associated with photosynthesis and respiration, three with the antioxidative defense system, and the last, hypothetical protein all1861, conceivably connected with iron homeostasis ...201121364295
response of diazotrophic cyanobacterium nostoc carneum under pesticide and uv-b stress.a study was under taken, under controlled laboratory conditions, to investigate the influence of non-ionizing radiation (uv-b) and an organochlorine pesticide on the growth, photosynthetic pigments, protein content and dcpip photoreduction of a cyanobacterium nostoc carneum. test algae was isolated from rice field soils of sambalpur, western orissa, india and grown in nitrogen free bg 11 culture medium. culture of algae from log phase of growth was treated with 5 pp m of the insecticide, endodha ...201121388655
dna-based prenatal diagnosis of plectin-deficient epidermolysis bullosa simplex associated with pyloric atresia.mutations in the plectin gene (plec) generally lead to epidermolysis bullosa simplex (ebs) associated with muscular dystrophy. it has been recently demonstrated that plec mutations can also cause a different clinical subtype, ebs associated with pyloric atresia (ebs-pa), which shows early lethality. prenatal diagnosis (pnd) of ebs-pa using mutation screening of plec has not been described.201121413955
overexpression of pkne blocks heterocyst development in anabaena sp. strain pcc 7120.the upstream intergenic regions for each of four genes encoding ser/thr kinases, all2334, pkne (alr3732), all4668, and all4838, were fused to a gfpmut2 reporter gene to determine their expression during heterocyst development in the cyanobacterium anabaena (nostoc) sp. strain pcc 7120. p(pkne)-gfp was upregulated after nitrogen step-down and showed strong expression in differentiating cells. developmental regulation of pkne required a 118-bp upstream region and was abolished in a hetr mutant. a ...201121421755
conversion of fatty aldehydes to alka(e)nes and formate by a cyanobacterial aldehyde decarbonylase: cryptic redox by an unusual dimetal oxygenase.cyanobacterial aldehyde decarbonylase (ad) catalyzes conversion of fatty aldehydes (r-cho) to alka(e)nes (r-h) and formate. curiously, although this reaction appears to be redox-neutral and formally hydrolytic, ad has a ferritin-like protein architecture and a carboxylate-bridged dimetal cofactor that are both structurally similar to those found in di-iron oxidases and oxygenases. in addition, the in vitro activity of the ad from nostoc punctiforme (np) was shown to require a reducing system sim ...201121462983
in vitro and in vivo safety assessment of edible blue-green algae, nostoc commune var. sphaeroides kützing and spirulina plantensis.blue-green algae (bga) have been consumed as food and herbal medicine for centuries. however, safety for their consumption has not been well investigated. this study was undertaken to evaluate in vitro and in vivo toxicity of cultivated nostoc commune var. sphaeroides kützing (no) and spirulina platensis (sp). neither no nor sp contained detectable levels of microcystin (mc)-la, mc-rr, mc-lw and mc-lr by lc/ms/ms. cell viability remained ∼70-80% when hepg2 cells were incubated with 0-500μg/ml of ...201121473896
role of the photosynthetic electron transfer chain in electrogenic activity of cyanobacteria.certain anaerobic bacteria, termed electrogens, produce an electric current when electrons from oxidized organic molecules are deposited to extracellular metal oxide acceptors. in these heterotrophic "metal breathers", the respiratory electron transport chain (r-etc) works in concert with membrane-bound cytochrome oxidases to transfer electrons to the extracellular acceptors. the diversity of bacteria able to generate an electric current appears more widespread than previously thought, and aerob ...201121484209
a simple method for culturing neonatal biomphalaria glabrata snails.abstract abstract:a simplified method for the culture of neonatal biomphalaria glabrata snails on a diet of the cyanobacteria nostoc sp. has been developed. previously, nostoc sp. used to feed neonatal snails was grown on a mud-based medium, which is difficult to prepare and gives inconsistent growth between laboratories due to variation in the soil used in its preparation. here, we report the use of bg-11 medium supplemented with sodium nitrate for the culture of nostoc sp. as a food source for ...201121506830
the extracellular-matrix-retaining cyanobacterium nostoc verrucosum accumulates trehalose, but is sensitive to desiccation.the aquatic cyanobacterium nostoc verrucosum forms macroscopic colonies, which consist of both cellular filaments and massive extracellular matrix material. in this study, the physiological features of n. verrucosum were investigated and compared with those of the anhydrobiotic cyanobacterium nostoc commune. nostoc verrucosum cells were sensitive to desiccation, but tolerant of freeze-thawing treatment in terms of both cell viability and photosynthetic o(2) evolution. natural colonies of these c ...201121507024
engineering of a plasmid-free escherichia coli strain for improved in vivo biosynthesis of astaxanthin.abstract: background: the xanthophyll astaxanthin is a high-value compound with applications in the nutraceutical, cosmetic, food, and animal feed industries. besides chemical synthesis and extraction from naturally producing organisms like haematococcus pluvialis, heterologous biosynthesis in non-carotenogenic microorganisms like escherichia coli, is a promising alternative for sustainable production of natural astaxanthin. recent achievements in the metabolic engineering of e. coli strains hav ...201121521516
antiviral effect of edaphic cyanophytes on rabies and herpes-1 viruses.five cyanophyte species (amorphonostoc punctiforme, gloeocapsa turgidus, sphaeronostoc coeruleum, stratonostoc linckia f. spongiaeforme and synechococcus cedrorum) were isolated and identified from sandy egyptian soils. polysaccharides extracted from these species showed a pronounced antiviral activity against rabies and herpes-1 viruses represented by the absence of the characteristic cytopathic effects of these viruses. it was found that 100 μg polysaccharide/ml induced 100% inhibition of the ...201121555271
biotransformation and volatilization of arsenic by three photosynthetic cyanobacteria.arsenic (as) is a pervasive and ubiquitous environmental toxin that has created world-wide human health problems. however, there are few studies about how organisms detoxify arsenic. cyanobacteria are capable of both photolithotrophic growth in the light and heterotrophic growth in the dark and are ubiquitous in soils, aquatic systems and wetlands. in this study, we investigated arsenic biotransformation in three cyanobacterial species (microcystis sp. pcc7806, nostoc sp. pcc7120 and synechocyst ...201121562336
a comparative study on effective cell disruption methods for lipid extraction from microalgae.aims:  to compare effective cell disruption methods for lipid extraction from fresh water microalgae. method and results:  chlorella sp., nostoc sp., and tolypothrix sp. were isolated from fresh water ponds in and around gandhigram, dindigul district, tamilnadu, india and used for lipid extraction. different methods, including autoclaving, bead-beating, microwave, sonication and a 10% nacl solution treatments were tested to identify the most effective cell disruption method. the total lipids fro ...201121575021
exposure of phototrophs to 548 days in low earth orbit: microbial selection pressures in outer space and on early earth.an epilithic microbial community was launched into low earth orbit, and exposed to conditions in outer space for 548 days on the european space agency expose-e facility outside the international space station. the natural phototroph biofilm was augmented with akinetes of anabaena cylindrica and vegetative cells of nostoc commune and chroococcidiopsis. in space-exposed dark controls, two algae (chlorella and rosenvingiella spp.), a cyanobacterium (gloeocapsa sp.) and two bacteria associated with ...201121593797
modeling photosystem i with the alternative reaction center protein psab2 in the nitrogen fixing cyanobacterium nostoc punctiforme.five nitrogen fixing cyanobacterial strains have been found to contain psab2, an additional and divergent gene copy for the photosystem i reaction center protein psab. in all five species the divergent gene, psab2, is located separately from the normal psaab operon in the genome. the protein, psab2, was recently identified in heterocysts of nostoc punctiforme sp. strain pcc 73102. 15 conserved amino acid replacements were identified by a multiple sequence alignment of several psab2 and psab1 seq ...201121605545
antiprotozoal, antitubercular and cytotoxic potential of cyanobacterial (blue-green algal) extracts from ireland.cyanobacteria (= blue-green algae) are prolific producers of structurally distinct and biologically active metabolites. in the continuation of our search for new sources of anti-infective natural products, we have assessed the in vitro antiprotozoal (plasmodium falciparum, trypanosoma brucei rhodesiense, t. cruzi, leishmania donovani) and antitubercular (mycobacterium tuberculosis) potential of samples of two terrestrial cyanobacteria, nostoc commune (collected when desiccated and wet) and rivul ...201121615033
purification and crystallization of the cyanobacterial cytochrome b6f complex.the cytochrome b6f complex from the filamentous cyanobacteria (mastigocladus laminosus, nostoc sp. pcc 7120) and spinach chloroplasts has been purified as a homo-dimer. electrospray ionization mass spectroscopy showed the monomer to contain eight and nine subunits, respectively, and dimeric masses of 217.1, 214.2, and 286.5 kda for m. laminosus, nostoc, and the complex from spinach. the core subunits containing or interacting with redox-active prosthetic groups are peta (cytochrome f), b (cytoch ...201120960122
purification of plastocyanin and cytochrome c6 from plants, green algae, and cyanobacteria.plastocyanin and cytochrome c6 are widely distributed over the oxygen-evolving photosynthetic organisms. the two proteins are functionally equivalent, but strongly differ in their global electrostatic charge. in fact, they are acidic in eukaryotes, but either neutral or basic in cyanobacteria. such a difference in their electrostatic features is a critical factor in designing the purification procedure, which must thus be modified and adapted accordingly. this chapter reports the methods for pro ...201120960123
a hups-gfp fusion protein demonstrates a heterocyst-specific localization of the uptake hydrogenase in nostoc punctiforme.all diazotrophic filamentous cyanobacteria contain an uptake hydrogenase that is involved in the reoxidation of h(2) produced during n(2) -fixation. in nostoc punctiforme atcc 29133, n(2) -fixation takes place in the microaerobic heterocysts, catalysed by a nitrogenase. although the function of the uptake hydrogenase may be closely connected to that of nitrogenase, the localization in cyanobacteria has been under debate. moreover, the subcellular localization is not understood. to investigate th ...201121204939
nostocyclopeptide-m1: a potent, nontoxic inhibitor of the hepatocyte drug transporters oatp1b3 and oatp1b1.we have isolated a novel cyanobacterial cyclic peptide (nostocyclopeptide m1; ncp-m1) that blocks the hepatotoxic action of microcystin (mc) and nodularin (nod). we show here that ncp-m1 is nontoxic to primary hepatocytes in long-term culture. ncp-m1 does not affect any known intracellular targets or pathways involved in mc action, like protein phosphatases, cam-kii, or ros-dependent cell death effectors. in support of this conclusion ncp-m1 had no protective effect when microinjected into cells ...201121214185
kinetic control of one-pot trans-splicing reactions by using a wild-type and designed split intein. 201121656885
transcript analysis of the extended hyp-operon in the cyanobacteria nostoc sp. strain pcc 7120 and nostoc punctiforme atcc 29133. 201121672234
novel glycosylated mycosporine-like amino acids with radical scavenging activity from the cyanobacterium nostoc commune.mycosporine-like amino acids (maas) are uv absorbing pigments, and structurally distinct maas have been identified in taxonomically diverse organisms. two novel maas were purified from the cyanobacterium nostoc commune, and their chemical structures were characterized. an maa with an absorption maximum at 335nm was identified as a pentose-bound porphyra-334 derivative with a molecular mass of 478da. another identified maa had double absorption maxima at 312 and 340nm and a molecular mass of 1050 ...201121813286
differential physiological and biochemical responses of two cyanobacteria nostoc muscorum and phormidium foveolarum against oxyfluorfen and uv-b radiation.in the present study, degree of tolerance and tolerance strategies of two paddy field cyanobacteria viz. nostoc muscorum and phormidium foveolarum against oxyfluorfen (10 and 20µgml(-1)) and uv-b (7.2kjm(-2)d(-1)) stress were investigated. oxyfluorfen and uv-b decreased growth, photosynthesis, nutrient uptake, nitrate reductase, acid and alkaline phosphatase activities, which accompanied with the increase in the level of oxidative stress. however, growth was more affected in n. muscorum than p. ...201121798597
diversity analysis of type i ketosynthase in rhizosphere soil of cucumber.fusarium wilt [fusarium oxysporum (sch1.) f.sp. cucumerinum owen.] is a major soil-borne disease of cucumber worldwide, and can cause huge yield losses. biological control of fusarium wilt of cucumber has received considerable attention. many bacteria, particularly actinomycetes, are known to produce secondary metabolites synthesized by polyketide synthases (pkss) with a diverse range of biological activities. ketosynthase (ks) gene diversity was analyzed in samples which were collected from rhi ...201121780139
directional rna deep sequencing sheds new light on the transcriptional response of anabaena sp. strain pcc 7120 to combined-nitrogen deprivation.cyanobacteria are potential sources of renewable chemicals and biofuels and serve as model organisms for bacterial photosynthesis, nitrogen fixation, and responses to environmental changes. anabaena (nostoc) sp. strain pcc 7120 (hereafter anabaena) is a multicellular filamentous cyanobacterium that can "fix" atmospheric nitrogen into ammonia when grown in the absence of a source of combined nitrogen. because the nitrogenase enzyme is oxygen sensitive, anabaena forms specialized cells called hete ...201121711558
cyanobacterial lactate oxidases serve as essential partners in n2 fixation and evolved into photorespiratory glycolate oxidases in plants.glycolate oxidase (gox) is an essential enzyme involved in photorespiratory metabolism in plants. in cyanobacteria and green algae, the corresponding reaction is catalyzed by glycolate dehydrogenases (glcd). the genomes of n(2)-fixing cyanobacteria, such as nostoc pcc 7120 and green algae, appear to harbor genes for both glcd and gox proteins. the gox-like proteins from nostoc (no-lox) and from chlamydomonas reinhardtii showed high l-lactate oxidase (lox) and low gox activities, whereas glycolat ...201121828292
development of a novel dnae intein-based assay for quantitative analysis of g-protein-coupled receptor internalization.g-protein-coupled receptor (gpcr) internalization provides a g-protein-subtype-independent method for assaying agonist-stimulated activation of receptors. we have developed a novel assay that allows quantitative analysis of gpcr internalization based on the interaction between activated gpcrs and +¦-arrestin2 and on nostoc punctiforme dnae intein-mediated reconstitution of renilla luciferase fragments. this assay system was validated using four functionally divergent gpcrs treated with agonists ...201121726524
diverse two-cysteine photocycles in phytochromes and cyanobacteriochromes.phytochromes are well-known as photoactive red- and near ir-absorbing chromoproteins with cysteine-linked linear tetrapyrrole (bilin) prosthetic groups. phytochrome photoswitching regulates adaptive responses to light in both photosynthetic and nonphotosynthetic organisms. exclusively found in cyanobacteria, the related cyanobacteriochrome (cbcr) sensors extend the photosensory range of the phytochrome superfamily to shorter wavelengths of visible light. blue/green light sensing by a well-studie ...201121712441
the apoptosis-inducing activity towards leukemia and lymphoma cells in a cyanobacterial culture collection is not associated with mouse bioassay toxicity.cyanobacteria (83 strains and seven natural populations) were screened for content of apoptosis (cell death)-inducing activity towards neoplastic cells of the immune (jurkat acute t-cell lymphoma) and hematopoetic (acute myelogenic leukemia) lineage. apoptogenic activity was frequent, even in strains cultured for decades, and was unrelated to whether the cyanobacteria had been collected from polar, temperate, or tropic environments. the activity was more abundant in the genera anabaena and micro ...201120689978
color measurements as a reliable method for estimating chlorophyll degradation to phaeopigments.the application of biocides is a traditional method of controlling biodecay of outdoor cultural heritage. chlorophyll degradation to phaeopigments is used to test the biocidal efficacy of the antimicrobial agents. in the present study, the usefulness of color measurements in estimating chlorophyll degradation was investigated. an aeroterrestrial stone biofilm-forming cyanobacterium of the genus nostoc was chosen as test organism, comparing its different behaviour in both planktonic and biofilm m ...201020714920
functional characterization of a naturally occurring trans-splicing intein from synechococcus elongatus in a mammalian cell system.we have cloned and characterized a naturally occurring split mini-dnae intein capable of protein trans-splicing in the cyanobacterium synechococcus elongatus (sel dnae intein). sel dnae intein is homologous to synechocystissp. pcc6803 (ssp) dnae intein and nostoc punctiforme (npu) dnae intein, with a protein sequence identity of 60% for the n-terminal part of intein and 61% for the c-terminal part of intein. our results demonstrate that the split reporters, split renilla luciferase (rluc) and en ...201020727340
the genetic and molecular basis for sunscreen biosynthesis in cyanobacteria.ultraviolet uv-a and uv-b radiation is harmful to living systems, causing damage to biological macromolecules. an important strategy for dealing with uv exposure is the biosynthesis of small-molecule sunscreens. among such metabolites, the mycosporine and mycosporine-like amino acids (maas) are remarkable for their wide phylogenetic distribution and their unique chemical structures. here, we report the identification of a maa biosynthetic gene cluster in a cyanobacterium and the discovery of ana ...201020813918
variability in the response of the cyanobacterium nodularia spumigena to nitrogen supplementation.nodularia spumigena is a filamentous cyanobacterium that is commonly found in brackish water bodies. the species is capable of fixing atmospheric nitrogen in specialized cells termed heterocysts. n. spumigena dominates the annual toxic summer blooms in the baltic sea causing environmental and economical problems. we have previously demonstrated that n. spumigena strain av1 exhibits a different response to the presence of combined nitrogen as compared to model cyanobacteria such as nostoc pcc7120 ...201020820471
cylindrocyclophanes with proteasome inhibitory activity from the cyanobacterium nostoc sp.material collected from a parkway in the city of chicago afforded the isolation of a nostoc species (uic 10022a). the extract of this strain displayed significant inhibition of the 20s proteasome as well as antiproliferative activity against ht29, mcf7, nci-h460, and sf268 cancer cell lines. a standardized dereplication protocol allowed for the rapid identification of three known (11-13) and nine new (1-9) chlorinated cylindrocyclophanes from less than 100 mg of organic extract. scale-up isolati ...201020825206
multiple roles of soluble sugars in the establishment of gunnera-nostoc endosymbiosis.gunnera plants have the unique ability to form endosymbioses with n(2)-fixing cyanobacteria, primarily nostoc. cyanobacteria enter gunnera through transiently active mucilage-secreting glands on stems. we took advantage of the nitrogen (n)-limitation-induced gland development in gunnera manicata to identify factors that may enable plant tissue to attract and maintain cyanobacteria colonies. cortical cells in stems of n-stressed gunnera plants were found to accumulate a copious amount of starch, ...201020833727
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
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
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
signature proteins for the major clades of cyanobacteria.the phylogeny and taxonomy of cyanobacteria is currently poorly understood due to paucity of reliable markers for identification and circumscription of its major clades.201020100331
post-translational modifications of integral membrane proteins resolved by top-down fourier transform mass spectrometry with collisionally activated dissociation.integral membrane proteins remain a challenge to proteomics because they contain domains with physicochemical properties poorly suited to today's bottom-up protocols. these transmembrane regions may potentially contain post-translational modifications of functional significance, and thus development of protocols for improved coverage in these domains is important. one way to achieve this goal is by using top-down mass spectrometry whereby the intact protein is subjected to mass spectrometry and ...201020093275
cytotoxicity and secondary metabolites production in terrestrial nostoc strains, originating from different climatic/geographic regions and habitats: is their cytotoxicity environmentally dependent?extensive selection of cyanobacterial strains (82 isolates) belonging to the genus nostoc, isolated from different climatic regions and habitats, were screened for both their secondary metabolite content and their cytotoxic effects to mammalian cell lines. the overall occurrence of cytotoxicity was found to be 33%, which corresponds with previously published data. however, the frequency differs significantly among strains, which originate from different climatic regions and microsites (particula ...201020082446
excitation energy transfer to photosystem i in filaments and heterocysts of nostoc punctiforme.cyanobacteria adapt to varying light conditions by controlling the amount of excitation energy to the photosystems. on the minute time scale this leads to redirection of the excitation energy, usually referred to as state transitions, which involves movement of the phycobilisomes. we have studied short-term light adaptation in isolated heterocysts and intact filaments from the cyanobacterium nostoc punctiforme atcc 29133. in n. punctiforme vegetative cells differentiate into heterocysts where ni ...201020036211
cala, a cyanobacterial abrb protein, interacts with the upstream region of hypc and acts as a repressor of its transcription in the cyanobacterium nostoc sp. strain pcc 7120.the filamentous, heterocystous, nitrogen-fixing cyanobacterium nostoc sp. strain pcc 7120 may contain, depending on growth conditions, up to two hydrogenases directly involved in hydrogen metabolism. hypc is one out of at least seven auxiliary gene products required for synthesis of a functional hydrogenase, specifically involved in the maturation of the large subunit. in this study we present a protein, cala (alr0946 in the genome), belonging to the transcription regulator family abrb, which in ...201020023111
comparative toxicity of bentazon and molinate on growth, photosynthetic pigments, photosynthesis, and respiration of the portuguese ricefield cyanobacterium nostoc muscorum.bentazon and molinate are selective herbicides recommended for integrated weed management in rice. their toxicity on growth and some biochemical and physiological parameters of nostoc muscorum, an abundant cyanobacterium in portuguese rice fields, was evaluated under laboratory conditions during time- and concentration-dependent exposure for 72 h. results showed that toxic concentrations (0.75-2 mm) of both herbicides have pleiotropic effects on the cyanobacterium. molinate was more toxic than b ...201019319991
structural features of the nostoc punctiforme debranching enzyme reveal the basis of its mechanism and substrate specificity.the debranching enzyme nostoc punctiforme debranching enzyme (npde) from the cyanobacterium nostoc punctiforme (pcc73102) hydrolyzes the alpha-1,6 glycosidic linkages of malto-oligosaccharides. despite its high homology to cyclodextrin/pullulan (cd/pul)-hydrolyzing enzymes from glycosyl hydrolase 13 family (gh-13), npde exhibits a unique catalytic preference for longer malto-oligosaccharides (>g8), performing hydrolysis without the transgylcosylation or cd-hydrolyzing activities of other gh-13 e ...201019768689
detection of the neurotoxin bmaa within cyanobacteria isolated from freshwater in china.the cyanobacterial neurotoxin, beta-n-methylamino-l-alanine (bmaa), has been suggested as an important environmental factor for neurodegenerative disease such as amyotrophic lateral sclerosis- parkinsonism dementia complex (als/pdc) in guam. bmaa was detected within the majority of cyanobacterial isolates surveyed in both free and symbiotic cyanobacteria, living in freshwater as well as marine environments. in this study, we report two methods using liquid chromatography-electrospray ionization- ...201019822166
synthesis, properties, and applications of diazotrifluropropanoyl-containing photoactive analogs of farnesyl diphosphate containing modified linkages for enhanced stability.photoactive analogs of farnesyl diphosphate (fpp) are useful probes in studies of enzymes that employ this molecule as a substrate. here, we describe the preparation and properties of two new fpp analogs that contain diazotrifluoropropanoyl photophores linked to geranyl diphosphate via amide or ester linkages. the amide-linked analog (3) was synthesized in 32p-labeled form from geraniol in seven steps. experiments with saccharomyces cerevisiae protein farnesyltransferase (scpftase) showed that 3 ...201019954434
characterization of a microcystin and detection of microcystin synthetase genes from a brazilian isolate of nostoc.a nostocalean nitrogen-fixing cyanobacterium isolated from an eutrophic freshwater reservoir located in piracicaba, são paulo, brazil, was evaluated for the production of hepatotoxic cyclic heptapeptides, microcystins. morphologically this new cyanobacterium strain appears closest to nostoc, however, in the phylogenetic analysis of 16s rrna gene it falls into a highly stable cluster distantly only related to the typical nostoc cluster. extracts of nostoc sp. cena88 cultured cells, investigated u ...201020003912
protein immobilization on liposomes and lipid-coated nanoparticles by protein trans-splicing.a plethora of methods exist to link proteins to surfaces in order to generate functionalized materials. however, general tools that lead to functional immobilization of recombinantly expressed proteins on membranes such as liposomes or lipid-coated nanoparticles are rare. here we present an approach that takes advantage of a double-palmitoylated peptide that mediates stable membrane anchoring in combination with protein trans-splicing for efficient immobilization of recombinant proteins fused to ...201020862726
computational analysis of lexa regulons in cyanobacteria.the transcription factor lexa plays an important role in the sos response in escherichia coli and many other bacterial species studied. although the lexa gene is encoded in almost every bacterial group with a wide range of evolutionary distances, its precise functions in each group/species are largely unknown. more recently, it has been shown that lexa genes in two cyanobacterial genomes nostoc sp. pcc 7120 and synechocystis sp. pcc 6803 might have distinct functions other than the regulation of ...201020920248
effect of psts sub-units or pknd deficiency on the survival of mycobacterium tuberculosis.the membrane-associated phosphate-specific transporter (pst) complex is composed of four different proteins: psts, pstc, psta and pstb. the psts component detects and binds pi with high affinity; the psta and pstc form transmembrane pores for pi entry, while pstb provides energy through atp hydrolysis. in the mycobacterium tuberculosis genome, four different gene clusters encode three psts, and two of each of the other sub-units. we used rt-pcr to show that these clusters represent at least thre ...201020933472
differential roles of alkaline/neutral invertases in nostoc sp. pcc 7120: inv-b isoform is essential for diazotrophic growth.the presence of two alkaline/neutral invertases (inv-a and inv-b) in the filaments of nostoc (also named anabaena) sp. strain pcc 7120 and the involvement of sucrose metabolism in nitrogen fixation led us to investigate the physiological function of those isoforms in cells growing under different nitrogen sources. the highest expression level of each encoding gene was obtained in the presence of ammonium. these results were paralleled by polypeptide and enzyme activity level. in cells of n(2)-fi ...201020938678
biological dinitrogen fixation by selected soil cyanobacteria as affected by strain origin, morphotype, and light conditions.the potential for n(2) fixation by heterocystous cyanobacteria isolated from soils of different geographical areas was determined as nitrogenase activity (na) using the acetylene reduction assay. morphology of cyanobacteria had the largest influence on na determined under light conditions. na was generally higher in species lacking thick slime sheaths. the highest value (1446 nmol/h c(2)h(4) per g fresh biomass) was found in the strain of branched cyanobacterium hassalia (a has1) from the polar ...201020941582
allelopathic effects of water hyacinth [eichhornia crassipes].eichhornia crassipes (mart) solms is an invasive weed known to out-compete native plants and negatively affect microbes including phytoplankton. the spread and population density of e. crassipes will be favored by global warming. the aim here was to identify compounds that underlie the effects on microbes. the entire plant of e. crassipes was collected from el zomor canal, river nile (egypt), washed clean, then air dried. plant tissue was extracted three times with methanol and fractionated by t ...201020949048
poly-β-hydroxybutyrate accumulation in cyanobacteria under photoautotrophy.poly-β-hydroxybutyrate (phb) is a biodegradable and biocompatible polymer that has immense potential in the field of environmental, agricultural and biomedical sciences. an alternative host system has been explored in this study for low-cost production. examination of 25 cyanobacterial species from 19 different genera for photoautrophic production of polyhydroxyalkanoates (phas) under batch culture demonstrated that 20 species were poly-β-hydroxybutyrate (phb) accumulators, while others were fou ...201020949541
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
Refresh
firstprev
12345678910
nextlast
Displaying items 1 - 100 of 954