Publications

a mechanism for slow release of biomagnified cyanobacterial neurotoxins and neurodegenerative disease in guam.	as root symbionts of cycad trees, cyanobacteria of the genus nostoc produce beta-methylamino-l-alanine (bmaa), a neurotoxic nonprotein amino acid. the biomagnification of bmaa through the guam ecosystem fits a classic triangle of increasing concentrations of toxic compounds up the food chain. however, because bmaa is polar and nonlipophilic, a mechanism for its biomagnification through increasing trophic levels has been unclear. we report that bmaa occurs not only as a free amino acid in the gua ...	2004	15295100
the iron superoxide dismutase from the filamentous cyanobacterium nostoc pcc 7120. localization, overexpression, and biochemical characterization.	the nitrogen-fixing filamentous cyanobacterium nostoc pcc 7120 (formerly named anabaena pcc 7120) possesses two genes for superoxide dismutase, a unique membrane-associated manganese superoxide dismutase (mnsod) and a soluble iron superoxide dismutase (fesod). a phylogenetic analysis of fesods shows that cyanobacterial enzymes form a well separated cluster with filamentous species found in one subcluster and unicellular species in the other. activity staining, inhibition patterns, and immunogold ...	2004	15302891
diazotrophic community structure and function in two successional stages of biological soil crusts from the colorado plateau and chihuahuan desert.	the objective of this study was to characterize the community structure and activity of n2-fixing microorganisms in mature and poorly developed biological soil crusts from both the colorado plateau and chihuahuan desert. nitrogenase activity was approximately 10 and 2.5 times higher in mature crusts than in poorly developed crusts at the colorado plateau site and chihuahuan desert site, respectively. analysis of nifh sequences by clone sequencing and the terminal restriction fragment length poly ...	2004	14766579
characterization of phytochelatin synthase-like protein encoded by alr0975 from a prokaryote, nostoc sp. pcc 7120.	phytochelatins (pcs) are well known as the heavy metal-detoxifying peptides in higher plants, eukaryotic algae, fungi, and nematode. in contrast, neither pcs nor pc synthase genes have ever been identified in any prokaryotes. the genome sequences for the cyanobacterium nostoc sp. pcc 7120 were recently completed and allowed us to identify a gene encoding a pc synthase-like protein, termed alr0975. the predicted product of alr0975 contains the conserved n-terminal domain but not the variable c-te ...	2004	14975765
isolation and structure determination of cryptophycins 38, 326, and 327 from the terrestrial cyanobacterium nostoc sp. gsv 224.	cryptophycin-38 (2), -326 (3), and -327 (4) are three new trace constituents of the terrestrial cyanobacterium nostoc sp. gsv 224. cryptophycin-38 is a stereoisomer of cryptophycin-1 (1) and to date is the only naturally occurring analogue that possesses a s,s epoxide group in unit a. cryptophycin-327 is a geometric isomer that differs from 1 in having a cis delta(2)-double bond in unit a. cryptophycin-326 is related to cryptophycin-21, but has two chlorines ortho to the methoxy group in unit b. ...	2004	15332864
microbial diversity of extant stromatolites in the hypersaline marine environment of shark bay, australia.	stromatolites have been present on earth, at various levels of distribution and diversity, for more than 3 billion years. today, the best examples of stromatolites forming in hypersaline marine environments are in hamelin pool at shark bay, western australia. despite their evolutionary significance, little is known about their associated microbial communities. using a polyphasic approach of culture-dependent and culture-independent methods, we report the discovery of a wide range of microorganis ...	2004	15344935
decomposition of microcystin-lr, microcystin-rr, and microcystin-yr in water samples submitted to in vitro dissolution tests.	the presence of cyanobacterial toxins (microcystins) in waters and food increases the risk of toxicity to animal and human health. these toxins can degrade in the human gastrointestinal tract before they are absorbed. to evaluate this possible degradation, water samples spiked with known concentrations of microcystins mc-lr, mc-rr, and mc-yr, which are the toxins most commonly produced by such toxic cyanobacteria as microcystis aeruginosa, oscillatoria spp., and nostoc spp., were submitted to a ...	2004	15366845
construction and use of gfp reporter vectors for analysis of cell-type-specific gene expression in nostoc punctiforme.	two transcriptional reporter shuttle vectors were constructed for the filamentous cyanobacterium nostoc punctiforme using the green fluorescence protein (gfp) reporter. both the ampicillin- and kanamycin-resistant versions of the plasmid allow promoters to be directionally cloned into a multiple cloning site preceding a promoterless gfp gene using an escherichia coli host. the ability of the self-replicating shuttle plasmids to report cell-type-specific gene expression in n. punctiforme was test ...	2004	15369854
molecular evolution of pas domain-containing proteins of filamentous cyanobacteria through domain shuffling and domain duplication.	when the entire genome of a filamentous heterocyst-forming n2-fixing cyanobacterium, anabaena sp. pcc 7120 (anabaena) was determined in 2001, a large number of pas domains were detected in signal-transducing proteins. the draft genome sequence is also available for the cyanobacterium, nostoc punctiforme strain atcc 29133 (nostoc), that is closely related to anabaena. in this study, we extracted all pas domains from the nostoc genome sequence and analyzed them together with those of anabaena. clu ...	2004	15449540
[effect of cadmium on the absorption and excitation energy transfer in cyanobacterium nostoc muscorum].	the absorption and energy transfer between pigments in nostoc muscorum by the action of 10(-4) m cd2+, when the cyanobacterium remains viable, and in the presence of 10(-3) m cd2+, which causes the death of cells during 3-4 weeks of incubation, were studied. a comparative study by the methods of absorption and fluorescence spectrophotometry at 295 and 77 k, including derivative spectroscopy and deconvolution of emission spectra into a number of gaussian components, showed that, in the presence o ...	2004	15458254
discovery of rare and highly toxic microcystins from lichen-associated cyanobacterium nostoc sp. strain io-102-i.	the production of hepatotoxic cyclic heptapeptides, microcystins, is almost exclusively reported from planktonic cyanobacteria. here we show that a terrestrial cyanobacterium nostoc sp. strain io-102-i isolated from a lichen association produces six different microcystins. microcystins were identified with liquid chromatography-uv mass spectrometry by their retention times, uv spectra, mass fragmentation, and comparison to microcystins from the aquatic nostoc sp. strain 152. the dominant microcy ...	2004	15466511
[bioinformatics studies on photosynthetic system genes in cyanobacteria and chloroplasts].	this study compared homology of base sequences in genes encoding photosynthetic system proteins of cyanobacteria (synechocystics sp. pcc6803, nostoc sp. pcc7120) with these of chloroplasts (from marchantia polymorpha, nicotiana tobacum, oryza sativ, euglena gracilis, pinus thunbergii, zea mays, odentella sinesis, cyanophora paradoxa, porphyra purpurea and arabidopsis thaliana) by blast method. while the gene sequence of synechocystics sp. pcc6803 was considered as the criterion (100%) the homolo ...	2004	15490883
identification and analysis of a siderophore biosynthetic gene cluster from agrobacterium tumefaciens c58.	using the complete genome sequence from agrobacterium tumefaciens c58, the authors identified a secondary metabolite gene cluster that encodes the biosynthesis of a metabolite with siderophore activity. support for this conclusion came from genetic and regulatory analysis of the gene cluster, along with the purification of a metabolite from a. tumefaciens c58 with iron-chelating activity. genetic analysis of mutant strains disrupted in this gene cluster showed that these strains grew more slowly ...	2004	15528670
comparison of light and dark nitrogenase activity in selected soil cyanobacteria.	frequency of heterocytes and nitrogenase activity (na) under light and dark cultivation conditions was determined in 12 cyanobacterial strains isolated from various soil habitats. in spite of a high variability, significant differences in na among the strains were found in response of light and dark cultivation. relatively high na (9.9-15.3 micromol/h c2h4 per g fresh mass) under light conditions and basal na after 12 h of dark cultivation were detected in anabaena, nodularia, tolypothrix, and 1 ...	2004	15530010
a correlation matrix of alkaline phosphatase and sporulation in diazotrophic cyanobacteria and its thermo-tolerant mutant.	alkaline phosphatase (phosphomonoesterase i.e. pmease) activity in heterocystous cyanobacteria anabaena flos-aquae, nostoc calcicola, calothrix brevissima, scytonema javanicum and hapalosiphon intricatus is known to be temperature and ph dependent. maximum level of enzyme activity was recorded at either 35 degrees c or 37.5 degrees c. also, the cell bound phosphomonoesterase enzyme was shown to exhibit ph optima of 10.0 or 10.2. a thermo-tolerant (tr) mutant isolated after mnng (n-methyl-n'-nitr ...	2004	15790075
real-time studies on microalgae under microgravity.	using remote sensing technique, we investigated real-time nostoc sphaeroides kütz (cyanobacterium) in closed system under microgravity by shenzhou-2 spacecraft in january 2001. the experiments had 1 g centrifuges in space for control and ground control group experiments were also carried out in the same equipments and under the same controlled condition. the data about the population growth of nostoc sp. of experiments and temperature changes of system were got from spacecraft every minute. from ...	2004	15791730
accumulation of poly-beta-hydroxybutyrate in nostoc muscorum: regulation by ph, light-dark cycles, n and p status and carbon sources.	accumulation of poly-beta-hydroxybutyrate (phb) in nostoc muscorum was studied. cells harvested at stationary phase of growth depicted maximum accumulation i.e. 8.6% (w/w) of dry cells as compared to lag (4.1%) or logarithmic (6.1%) phases of cultures. in contrast to alkaline ph, acidic ph, continuous illumination and cells grown in presence of combined nitrogen sources, such as nh(4)cl and kno(3), were found to affect phb accumulation negatively. however, p-deficiency and addition of exogenous ...	2004	15734319
cyanobacteria in antarctica: ecology, physiology and cold adaptation.	cyanobacterial species composition of fresh water and terrestrial ecosystems and chemical environment of water in schirmacher oasis in continental antarctica was investigated. over 35 species of cyanobacteria were recorded. diazotrophic species both heterocystous and unicellular contributed more than half to the count except in lake ecosystem. the species composition varied among the fresh water as well as terrestrial ecosystems. the physico-chemical analyses of water revealed its poor nurient c ...	2004	15559974
a cyanobacterial protein with similarity to phytochelatin synthases catalyzes the conversion of glutathione to gamma-glutamylcysteine and lacks phytochelatin synthase activity.	phytochelatins are glutathione-derived, non-translationally synthesized peptides essential for cadmium and arsenic detoxification in plant, fungal and nematode model systems. recent sequencing programs have revealed the existence of phytochelatin synthase-related genes in a wide range of organisms that have not been reported yet to produce phytochelatins. among those are several cyanobacteria. we have studied one of the encoded proteins (alr0975 from nostoc sp. strain pcc 7120) and demonstrate h ...	2004	15561184
bacterial life and dinitrogen fixation at a gypsum rock.	the organisms of a bluish-green layer beneath the shards of a gypsum rock were characterized by molecular techniques. the cyanobacterial consortium consisted almost exclusively of chroococcidiopsis spp. the organisms of the shards expressed nitrogenase activity (c2h2 reduction) aerobically and in light. after a prolonged period of drought at the rock, the cells were inactive, but they resumed nitrogenase activity 2 to 3 days after the addition of water. in a suspension culture of chroococcidiops ...	2004	15574902
development of a universal microarray based on the ligation detection reaction and 16s rrna gene polymorphism to target diversity of cyanobacteria.	the cyanobacteria are photosynthetic prokaryotes of significant ecological and biotechnological interest, since they strongly contribute to primary production and are a rich source of bioactive compounds. in eutrophic fresh and brackish waters, their mass occurrences (water blooms) are often toxic and constitute a high potential risk for human health. therefore, rapid and reliable identification of cyanobacterial species in complex environmental samples is important. here we describe the develop ...	2004	15574913
biotransformation of hydrocortisone by a natural isolate of nostoc muscorum.	hydrocortisone was converted in the culture of an isolated strain of the cyanobacterium nostoc muscorum ptcc 1636 into some androstane and pregnane derivatives. the microorganism was, isolated during a screening program from soil samples collected from paddy fields of north of iran. the bioproducts obtained were purified using chromatographic methods and identified as 11beta-hydroxytestosterone, 11beta-hydroxyandrost-4-en-3,17-dione and 11beta,17alpha,20beta,21-tetrahydroxypregn-4-en-3-one on th ...	2004	15587704
first documented cure of a suggestive exogenous reinfection in polymyositis with same but multidrug resistant m. tuberculosis.	mdr mycobacterium tuberculosis is the major cause of treatment failure in tuberculosis patients, especially in immunosuppressed. we described a young polymyositis patient on immunosuppressive therapy who was started with antituberculosis therapy as a susceptible strain of m. tuberculosis was isolated from a single cutaneous abscess in his neck and from regional lymph nodes.	2004	15617569
[cloning and analysis of cdna encoding key enzyme gene (dxr) of the non-mva pathway in taxus chinensis cells].	two distinct routes (classical mevalonate pathway and a novel mevalonate-independent pathway) are utilized by plants for the biosynthesis of isopentenyl diphosphate, the universal precursor of isoprenoids (fig. 1). present researches indicated that taxol was synthesized mainly via non-mevalonate pathway, but not genetic evidence was showed. the second step in non-mevalonate pathway involves an intramolecular rearrangement and subsequent reduction of deoxyxylulose phosphate to yield 2-c-methyl-d- ...	2004	15968987
a dna adenine methyltransferase of escherichia coli that is cell cycle regulated and essential for viability.	dna sequence analysis revealed that the putative yhdj dna methyltransferase gene of escherichia coli is 55% identical to the nostoc sp. strain pcc7120 gene encoding dna methyltransferase avaiii, which methylates adenine in the recognition sequence, atgcat. the yhdj gene was cloned, and the enzyme was overexpressed and purified. methylation and restriction analysis showed that the dna methyltransferase methylates the first adenine in the sequence atgcat. this dna methylation was found to be regul ...	2004	15028690
evidence for multiple lateral transfers of the circadian clock cluster in filamentous heterocystic cyanobacteria nostocaceae.	cyanobacteria are the first prokaryotes reported to show circadian rhythmicity, which is regulated by a cluster of three genes: kaia, kaib, and kaic. phylogenetic analysis of the kaibc cluster in filamentous cyanobacteria of the family nostocaceae including nodularia spumigena and nostoc linckia from arubotaim cave, mt. sedom, israel, indicated that this cluster has experienced multiple lateral transfers. the transfers have occurred in different periods of the species' evolution. the data obtain ...	2004	15045489
role of cyanobacteria in the persistence of vibrio cholerae o139 in saline microcosms.	recently, a new strain of cholera, vibrio cholerae o139, has emerged as an epidemic strain, but there is little information about its environmental reservoir. the present investigation was aimed to determine the role of cyanobacteria in the persistence of v. cholerae o139 in microcosms. an environmental isolate of v. cholerae o139 and three cyanobacteria (anabaena sp., nostoc sp., and hapalosiphon sp.) were used in this study. survival of culturable v. cholerae o139 in microcosms was monitored u ...	2004	15052315
studies on phosphate uptake, accumulation and activity of alkaline phosphatase of nostoc muscorum under cd stress.		2004	15057710
gas exchange in the filamentous cyanobacterium nostoc punctiforme strain atcc 29133 and its hydrogenase-deficient mutant strain nhm5.	nostoc punctiforme atcc 29133 is a nitrogen-fixing, heterocystous cyanobacterium of symbiotic origin. during nitrogen fixation, it produces molecular hydrogen (h(2)), which is recaptured by an uptake hydrogenase. gas exchange in cultures of n. punctiforme atcc 29133 and its hydrogenase-free mutant strain nhm5 was studied. exchange of o(2), co(2), n(2), and h(2) was followed simultaneously with a mass spectrometer in cultures grown under nitrogen-fixing conditions. isotopic tracing was used to se ...	2004	15066806
comprehensive analysis system using liquid chromatography-mass spectrometry for the biosynthetic study of peptides produced by cyanobacteria.	microcystins are hepatotoxic heptapeptides and general tumor promoters produced by several species of the genera microcystis, anabaena, oscillatoria and nostoc. they are non-ribosomally synthesized via a mixed polyketide synthase/non-ribosomal peptide synthetase system called microcystin synthetase. we have carried out the detection, isolation and structural determination of non-toxic peptides produced together with microcystins by toxic cyanobacteria, which are classified into several groups on ...	2004	15072295
devr-devs is a bona fide two-component system of mycobacterium tuberculosis that is hypoxia-responsive in the absence of the dna-binding domain of devr.	two-component systems play a central role in the adaptation of pathogenic bacteria to the environment prevailing within host tissues. the genes encoding the response regulator devr (rv3133c/dosr) and the cytoplasmic portion (devs(201)) of the histidine kinase devs (rv3132c/doss), a putative two-component system of mycobacterium tuberculosis, were cloned and the protein products were overexpressed, purified and refolded as n-terminally his(6)-tagged proteins from escherichia coli. devs(201) under ...	2004	15073296
expression of cyanobacterial genes involved in heterocyst differentiation and dinitrogen fixation along a plant symbiosis development profile.	members of the cyanobiont genus nostoc, forming an endosymbiosis with members of the angiosperm genus gunnera, undergo a number of characteristic phenotypic changes during the development of the symbiosis, the genetic background of which is largely unknown. transcription patterns of genes related to heterocyst differentiation and dinitrogen fixation and corresponding protein profiles were examined, using reverse transcription-polymerase chain reaction and western blots, along a developmental (ap ...	2004	15077676
ecosystems on ice: the microbial ecology of markham ice shelf in the high arctic.	microbial communities occur throughout the cryosphere in a diverse range of ice-dominated habitats including snow, sea ice, glaciers, permafrost, and ice clouds. in each of these environments, organisms must be capable of surviving freeze-thaw cycles, persistent low temperatures for growth, extremes of solar radiation, and prolonged dormancy. these constraints may have been especially important during global cooling events in the past, including the precambrian glaciations. one analogue of these ...	2004	15094087
a preliminary investigation of the nostoc punctiforme proteome.	nostoc punctiforme atcc 29133 is a filamentous terrestrial cyanobacterium (prokaryote) that expresses several different phenotypes in response to environmental cues. when grown in nitrogen-deficient media the most abundant proteins in addition to phycobiliproteins were superoxide dismutase, atp synthase, and peptidyl-prolyl cis-trans isomerases. a methylated peptide from an akinete marker protein was also identified, suggesting that methylation could potentially play a regulatory role through si ...	2004	15094385
generation of reactive oxygen species undergoing redox cycle of nostocine a: a cytotoxic violet pigment produced by freshwater cyanobacterium nostoc spongiaeforme.	nostocine a (1) is an extracellular cytotoxic violet pigment produced by the freshwater cyanobacterium, nostoc spongiaeforme tistr 8169. treatment with 1 was found to accelerate the generation of reactive oxygen species (ros) in the green alga, chlamydomonas reinhardtii, in the light. in vitro analysis revealed that 1 specifically eliminated superoxide radical anion (o(2)(-)) among several ros tested. during the course of the reaction, oxygen (o(2)) was simultaneously synthesized and the o(2) sy ...	2004	15099903
[phagoresistance of filamentous cyanobacteria clones].	the paper deals with formation regularities of phagoresistant clones of cyanobacteria in two productive virus-cell systems: heterocyst cyanobacterium nostoc linckia--cyanophage n-2, and mutant in heterocysts strain of anabaena variabilis--cyanophage a-1. frequency of spontaneous formation of phagoresistant clones of cyanobacterium n. linckia varies within 1.0-8.0 x 10(-6) per a cell, a. variabilis--5.0 x 10(-6)-7.0 x 10(-7) per cell. all the studied phagoresistant clones of n. linckia have ident ...	2004	15104055
cross talk between devs sensor kinase homologue, rv2027c, and devr response regulator of mycobacterium tuberculosis.	rv2027c is a putative orphan histidine sensor kinase that bears strong homology to devs of the hypoxia-responsive devr-devs two-component system in m. tuberculosis. the cytosolic c-terminal domain of rv2027c protein (rv2027c(194)) was overexpressed in e. coli and biochemically characterized. rv2027c(194) underwent autophosphorylation at a conserved his(392) residue and engaged in phosphotransfer with devr response regulator. the rates of autophosphorylation and the stabilities of the phosphoryla ...	2004	15135056
sensor domain of the mycobacterium tuberculosis receptor ser/thr protein kinase, pknd, forms a highly symmetric beta propeller.	diverse pathogenic bacteria produce transmembrane receptor ser/thr protein kinases (stpks), but little is known about the signals mediated by these "eukaryotic-like" proteins. to explore the basis for signaling in the bacterial stpk receptor family, we determined the structure of the sensor domain of mycobacterium tuberculosis pknd. in two crystal forms, the pknd sensor domain forms a rigid, six-bladed beta-propeller with a flexible tether to the transmembrane domain. the pknd sensor domain is t ...	2004	15136047
impact of nitrophenols on the photosynthetic electron transport chain and atp content in nostoc muscorum and chlorella vulgaris.	concentration-dependent inhibition of the photosynthetic electron transport chain (photosystem i (ps i), photosystem ii (ps ii) and whole chain reaction) and atp content was observed in nostoc muscorum and chlorella vulgaris grown with o-nitrophenol, m-nitrophenol, or 2,4-dinitrophenol. although the extents of inhibition of the photosynthetic electron transport chain in both organisms were similar, ps ii was more sensitive than ps i and whole chain reaction to the nitrophenols. depletion of the ...	2004	15157580
light-induced intramolecular charge movements in microbial rhodopsins in intact e. coli cells.	microbial rhodopsins undergo cyclic photochemical reactions (photocycles) in which proton transfers and conformational changes result in charge displacements during transitions between photocycle intermediates. we report a new photoelectric method to monitor charge movements during rhodopsin photocycling with fast kinetic resolution in suspensions of intact e. coli cells. the method monitors electrical currents resulting from asymmetric photoexcitation of microbial rhodopsins by a unilateral las ...	2004	15170484
evaluation of nostoc strain atcc 53789 as a potential source of natural pesticides.	the cyanobacterium nostoc strain atcc 53789, a known cryptophycin producer, was tested for its potential as a source of natural pesticides. the antibacterial, antifungal, insecticidal, nematocidal, and cytotoxic activities of methanolic extracts of the cyanobacterium were evaluated. among the target organisms, nine fungi (armillaria sp., fusarium oxysporum f. sp. melonis, penicillium expansum, phytophthora cambivora, p. cinnamomi, rhizoctonia solani, rosellinia, sp., sclerotinia sclerotiorum, an ...	2004	15184126
comparative toxicological evaluation of untreated and treated tannery effluent with nostoc muscorum l. (algal assay) and microtox bioassay.	the relative sensitivity of tannery effluent before and after treatment was compared by employing nostoc muscorum and microtox assay in laboratory. the effect on chlorophyll, protein and biomass content of nostoc muscorum was studied with the luminescent property inhibition of photobacterium phosphorium and compared with algal bioassay. the results of microtox assay after 5, 15 and 30 min of exposure were compared with data obtained from algal bioassay. it was observed that the luminescent prope ...	2004	15195832
combined directed ortho and remote metalation-cross-coupling strategies. general method for benzo[a]carbazoles and the synthesis of an unnamed indolo[2,3-a]carbazole alkaloid.	[reaction: see text] an efficient route to benzo[a]carbazoles via a metalation-cross-coupling sequence has been demonstrated and its application to the synthesis of the antitumor and antiviral alkaloid 6-cyano-5-methoxy-12-methylindolo[2,3-a]carbazole has been achieved.	2004	15228262
novel classes of mutants of the cyanobacterium nostoc muscorum showing absolute requirement of cs1 or rb1 for diazotrophy.		2004	15248149
response of desert biological soil crusts to alterations in precipitation frequency.	biological soil crusts, a community of cyanobacteria, lichens, and mosses that live on the soil surface, occur in deserts throughout the world. they are a critical component of desert ecosystems, as they are important contributors to soil fertility and stability. future climate scenarios predict alteration of the timing and amount of precipitation in desert environments. because biological soil crust organisms are only metabolically active when wet, and as soil surfaces dry quickly in deserts du ...	2004	14689292
cloning, sequencing, and biochemical characterization of the nostocyclopeptide biosynthetic gene cluster: molecular basis for imine macrocyclization.	nostocyclopeptides a1 and a2 are novel cyclic heptapeptides produced by the terrestrial cyanobacterium nostoc sp. atcc53789 that possess a unique imino linkage in the macrocyclic ring. herein we report the cloning, sequencing, annotation, and biochemical analysis of the 33-kb nostocyclopeptide (ncp) biosynthetic gene cluster, which includes seven open reading frames predicted to be involved in the biosynthesis and transport of these natural products. the genetic architecture and domain organizat ...	2004	14697508
sequence based data supports a single nostoc strain in individual coralloid roots of cycads.	the genetic diversity of cyanobacteria associated with cycads was examined using the trna(leu) (uaa) intron as a genetic marker. coralloid roots of both natural populations of the cycad macrozamia riedlei (fischer ex gaudichaud-beaupré) c.a. gardner growing in perth, australia and cycads growing in greenhouses, also in perth, were used and their respective cyanobionts analyzed. several nostoc strains were found to be involved in this symbiosis, both in natural populations and greenhouse-originat ...	2004	19712296
growth and heavy metals removal efficiency of nostoc muscorum and anabaena subcylindrica in sewage and industrial wastewater effluents.	the growth of nostoc muscorum and anabaena subcylindrica in sterilized sewage wastewater and n. muscorum in sterilized wastewater of el-soda company was higher than those grown in allen synthetic medium. whereas, the growth of a. subcylindrica in el-soda company sterilized wastewater and n. muscorum as well as a. subcylindrica grown in verta company sterilized wastewater was slightly lower than that grown in the standard synthetic medium. the contents of chlorophyll a, carotenoids and protein of ...	2005	21783496
role of the surface charges d72 and k8 in the function and structural stability of the cytochrome c from nostoc sp. pcc 7119.	we investigated the role of electrostatic charges at positions d72 and k8 in the function and structural stability of cytochrome c6 from nostoc sp. pcc 7119 (cyt c6). a series of mutant forms was generated to span the possible combinations of charge neutralization (by mutation to alanine) and charge inversion (by mutation to lysine and aspartate, respectively) in these positions. all forms of cyt c6 were functionally characterized by laser flash absorption spectroscopy, and their stability was p ...	2005	15978038
mycobacterium tuberculosis serine/threonine kinases pknb, pknd, pkne, and pknf phosphorylate multiple fha domains.	the physiologic roles and the substrates of the mycobacterium tuberculosis (mtb) serine/threonine kinases are largely unknown. here, we report six novel interactions of pknb, pknd, pkne, and pknf with the forkhead-associated (fha) domains of rv0020c and the putative abc transporter rv1747. purified pknb and pknf kinase domains phosphorylated multiple fha-domain proteins in vitro. although they remain to be verified in vivo, these reactions suggest a web of interactions between stpks and fha doma ...	2005	15987910
a high proportion of baltic sea benthic cyanobacterial isolates contain apoptogens able to induce rapid death of isolated rat hepatocytes.	to assess the potential hepatotoxicity of benthic cyanobacteria, we isolated 41 strains from the baltic sea. the bacteria were differentially extracted with solvents of decreasing polarity. the extracts were tested for ability to induce death of primary rat hepatocytes in suspension culture. mainly morphological criteria were used to discriminate between cell death with apoptotic features (shrinkage, chromatin hypercondensation, budding) or necrotic features (swelling, loss of plasma membrane in ...	2005	15990143
distribution and evolution of multiple-step phosphorelay in prokaryotes: lateral domain recruitment involved in the formation of hybrid-type histidine kinases.	although most two-component signal transduction systems use a simple phosphotransfer pathway from one histidine kinase (hk) to one response regulator (rr), a multiple-step phosphorelay involving a phosphotransfer scheme of his-asp-his-asp was also discovered. central to this multiple-step-type signal transduction pathway are a hybrid-type hk, containing both an hk domain and an rr receiver domain in a single protein, and a histidine-containing phosphotransfer (hpt) that can exist either as a dom ...	2005	16000707
the anti-hiv cyanovirin-n domain is evolutionarily conserved and occurs as a protein module in eukaryotes.	a novel protein family homologous to the sugar-binding antiviral protein cyanovirin-n (cvn) is described. cvn, an 11-kda protein that, by binding to the high-mannose moiety of certain viral surface glycoproteins, blocks virus entry into target cells, has thus far been identified only in the cyanobacterium nostoc ellipsosporum. here we show that cvn belongs to a protein family identified by analysis of transcript sequences deriving from a gene expression profiling study conducted in the truffle t ...	2005	16003744
isolation of an antiviral polysaccharide, nostoflan, from a terrestrial cyanobacterium, nostoc flagelliforme.	a novel acidic polysaccharide, nostoflan, was isolated from a terrestrial cyanobacterium, nostoc flagelliforme. nostoflan exhibited a potent anti-herpes simplex virus type 1 (hsv-1) activity with a selectivity index (50% cytotoxic concentration/50% inhibitory concentration against viral replication) of 13,000. sugar composition and methylation analyses revealed that it was mainly composed of -->4)-d-glcp-(1-->, -->6,4)-d-glcp-(1-->, -->4)-d-galp-(1-->, -->4)-d-xylp-(1-->, d-glcap-(1-->, d-manp-( ...	2005	16038544
inhibition of several protein phosphatases by a non-covalently interacting microcystin and a novel cyanobacterial peptide, nostocyclin.	microcystins produced by cyanobacterial 'blooms' in reservoirs and lakes pose significant public health problems because they are highly toxic due to potent inhibition of protein serine/threonine phosphatases in the ppp family. a dehydrobutyrine (dhb)-containing microcystin variant [asp3, admadda5, dhb7]microcystin-htyr isolated from nostoc sp. was found to potently inhibit pp1, pp2a, ppp4 and ppp5 with ic50 values similar to those of microcystin-lr. however, in contrast to microcystin-lr, which ...	2005	16046071
heterocyst-specific excision of the anabaena sp. strain pcc 7120 hupl element requires xisc.	in nitrogen-limiting conditions, approximately 10% of the vegetative cells in filaments of the cyanobacterium anabaena (nostoc) sp. strain pcc 7120 differentiate into nitrogen-fixing heterocysts. during the late stages of heterocyst differentiation, three dna elements, each embedded within an open reading frame, are programmed to excise from the chromosome by site-specific recombination. the dna elements are named after the genes that they interrupt: nifd, fdxn, and hupl. the nifd and fdxn eleme ...	2005	16109944
nitrogen deprivation stimulates symbiotic gland development in gunnera manicata.	gunnera is the only genus of angiosperms known to host cyanobacteria and the only group of land plants that hosts cyanobacteria intracellularly. motile filaments of cyanobacteria, known as hormogonia, colonize gunnera plants through cells in the plant's specialized stem glands. it is commonly held that gunnera plants always possess functional glands for symbiosis. we found, however, that stem gland development did not occur when gunnera manicata plants were grown on nitrogen (n)-replete medium b ...	2005	16113217
toxicity assessment of heavy metals with nostoc muscorum l.	heavy metals in aquatic ecosystem (mn, ni, zn, cu) were tested for their toxicity against nostoc muscorum l., a common fresh water phytoplankton, with respect to chlorophyll, protein, total carbohydrate and starch contents along with growth (od). mn showed stimulatory effect up to 1.5 ppm for all the observed parameters. however, ni, zn and cu (0.1, 0.2, 0.3, 0.4 and 0.5 ppm) showed adverse effects even at 0.1 ppm. chlorophyll was most sensitive parameter followed by carbohydrate, protein and st ...	2005	16114473
laser flash-induced kinetic analysis of cytochrome f oxidation by wild-type and mutant plastocyanin from the cyanobacterium nostoc sp. pcc 7119.	oxidation of the soluble, truncated form of cytochrome f by wild-type and mutant species of plastocyanin has been analyzed by laser flash absorption spectroscopy in the cyanobacterium nostoc (formerly, anabaena) sp. pcc 7119. at low ionic strengths, the apparent electron transfer rate constant of cytochrome f oxidation by wild-type plastocyanin is 1.34 x 10(4) s(-)(1), a value much larger than those determined for the same proteins from other organisms. upon site-directed mutagenesis of specific ...	2005	16114897
the application of micro-ftir spectroscopy to analyze nutrient stress-related changes in biomass composition of phytoplankton algae.	micro-fourier transform infrared (ftir) spectroscopy was used to study changes in spectral features of three species of cyanobacteria (microcystis aeruginosa, croococcus minutus, and nostoc sp.) and two bacillariophyceae (cyclotella meneghiniana, and phaeodactylum tricornutum) in response to nutrient stress. the change of physiological state of the cells was followed during a 4-week starvation period on the basis of physiological key parameters and by means of ftir spectroscopy. changes in the i ...	2005	16122937
clustered genes required for synthesis and deposition of envelope glycolipids in anabaena sp. strain pcc 7120.	photoreduction of dinitrogen by heterocyst-forming cyanobacteria is of great importance ecologically and for subsistence rice agriculture. their heterocysts must have a glycolipid envelope layer that limits the entry of oxygen if nitrogenase is to remain active to fix dinitrogen in an oxygen-containing milieu (the fox+ phenotype). genes alr5354 (hgld), alr5355 (hglc) and alr5357 (hglb) of the filamentous cyanobacterium, anabaena sp. strain pcc 7120, and hgle of nostoc punctiforme are required fo ...	2005	16164561
cyanopeptolin 954, a chlorine-containing chymotrypsin inhibitor of microcystis aeruginosa niva cya 43.	a new depsipeptide, cyanopeptolin 954 (1), was isolated from the freshwater cyanobacterium microcystis aeruginosa niva cya 43. the structure of the compound was elucidated by chemical and spectroscopic analyses, including 2d nmr and gc-ms of the hydrolysate. the major structural differences compared to previously characterized heptadepsipeptides of microcystis are the replacement of the basic amino acid in position 4 by l-leucine, the presence of l-phenylalanine in position 6, and the uncommon r ...	2005	16180807
uv irradiation and desiccation modulate the three-dimensional extracellular matrix of nostoc commune (cyanobacteria).	cyanobacterium nostoc commune can tolerate the simultaneous stresses of desiccation, uv irradiation, and oxidation. acidic wspa, of approximately 33.6 kda, is secreted to the three-dimensional extracellular matrix and accounts for greater than 70% of the total soluble protein. the wspa gene of n. commune strain drh1 was cloned and found in a single genomic copy, in a monocistronic operon. transcription of wspa and sodf (superoxide dismutase), and synthesis and secretion of wspa, were induced upo ...	2005	16192267
reconstitution of phycobilisome core-membrane linker, lcm, by autocatalytic chromophore binding to apce.	the core-membrane linker, lcm, connects functionally the extramembraneous light-harvesting complex of cyanobacteria, the phycobilisome, to the chlorophyll-containing core-complexes in the photosynthetic membrane. genes coding for the apoprotein, apce, from nostoc sp. pcc 7120 and for a c-terminally truncated fragment apce(1-240) containing the chromophore binding cysteine-195 were overexpressed in escherichia coli. both bind covalently phycocyanobilin (pcb) in an autocatalytic reaction, in the p ...	2005	15620367
phylogenetic and morphological evaluation of the genera anabaena, aphanizomenon, trichormus and nostoc (nostocales, cyanobacteria).	the heterocytous cyanobacteria form a monophyletic group according to 16s rrna gene sequence data. within this group, phylogenetic and morphological studies have shown that genera such as anabaena and aphanizomenon are intermixed. moreover, the phylogeny of the genus trichormus, which was recently separated from anabaena, has not been investigated. the aim was to study the taxonomy of the genera anabaena, aphanizomenon, nostoc and trichormus belonging to the family nostocaceae (subsection iv.i) ...	2005	15653847
enhancement of poly-beta-hydroxybutyrate accumulation in nostoc muscorum under mixotrophy, chemoheterotrophy and limitations of gas-exchange.	nostoc muscorum, a heterocystous cyanobacterium, produced poly-beta-hydroxybutyrate ( phb) up to 8% (w/w) dry cells when grown photoautotrophically but 35% when grown mixotrophically with 0.4% (w/v) glucose and acetate after 21 d. gas-exchange limitations under mixotrophy and chemoheterotrophy with 0.4% (w/v) acetate enhanced the accumulation up to 40-43% (w/w) dry cells, the value almost 5-fold higher with respect to photoautotrophic condition.	2005	15685421
myxol and 4-ketomyxol 2'-fucosides, not rhamnosides, from anabaena sp. pcc 7120 and nostoc punctiforme pcc 73102, and proposal for the biosynthetic pathway of carotenoids.	we identified the molecular structures of carotenoids in some anabaena and nostoc species. the myxoxanthophyll and ketomyxoxanthophyll in anabaena (also known as nostoc) sp. pcc 7120, anabaena variabilis iam m-3, nostoc punctiforme pcc 73102 and nostoc sp. hk-01 were (3r,2's)-myxol 2'-fucoside and (3s,2's)-4-ketomyxol 2'-fucoside, respectively. the glycoside moiety of the pigments was fucose, not rhamnose. the major carotenoids were beta-carotene and echinenone, and the minor ones were beta-cryp ...	2005	15695449
structure of the complex between plastocyanin and cytochrome f from the cyanobacterium nostoc sp. pcc 7119 as determined by paramagnetic nmr. the balance between electrostatic and hydrophobic interactions within the transient complex determines the relative orientation of the two proteins.	the complex between cytochrome f and plastocyanin from the cyanobacterium nostoc has been characterized by nmr spectroscopy. the binding constant is 16 mm(-1), and the lifetime of the complex is much less than 10 ms. intermolecular pseudo-contact shifts observed for the plastocyanin amide nuclei, caused by the heme iron, as well as the chemical-shift perturbation data were used as the sole experimental restraints to determine the orientation of plastocyanin relative to cytochrome f with a precis ...	2005	15705583
photochromicity of anabaena sensory rhodopsin, an atypical microbial receptor with a cis-retinal light-adapted form.	we characterize changes in isomeric states of the retinylidene chromophore during light-dark adaptation and photochemical reactions of anabaena (nostoc) sp. pcc7120 sensory rhodopsin (asr). the results show that asr represents a new type of microbial rhodopsin with a number of unusual characteristics. the three most striking are: (i) a primarily all-trans configuration of retinal in the dark-adapted state and (ii) a primarily 13-cis light-adapted state with a blue-shifted and lower extinction ab ...	2005	15710603
different modes of interaction in cyanobacterial complexes of plastocyanin and cytochrome f.	the highly efficient electron-transfer chain in photosynthesis demonstrates a remarkable variation among organisms in the type of interactions between the soluble electron-transfer protein plastocyanin and it partner cytochrome f. the complex from the cyanobacterium nostoc sp. pcc 7119 was studied using nuclear magnetic resonance spectroscopy and compared to that of the cyanobacterium phormidium laminosum. in both systems, the main site of interaction on plastocyanin is the hydrophobic patch. ho ...	2005	15736928
conserved pore-forming regions in polypeptide-transporting proteins.	transport of solutes and polypeptides across membranes is an essential process for every cell. in the past, much focus has been placed on helical transporters. recently, the beta-barrel-shaped transporters have also attracted some attention. the members of this family are found in the outer bacterial membrane and the outer membrane of endosymbiotically derived organelles. here we analyze the features and the evolutionary development of a specified translocator family, namely the beta-barrel-shap ...	2005	15752354
a retinoic acid binding cytochrome p450: cyp120a1 from synechocystis sp. pcc 6803.	at least 35 cytochrome p450 (p450, cyp) or cytochrome p450-like genes have been identified in 10 cyanobacterial genomes yet none have been functionally characterized. cyp110 and cyp120 represent the two largest cyanobacterial p450 families with 16 and four members, respectively, identified to date. the synechocystis sp. pcc 6803 cyp120a1 protein sequence shares high degrees of conservation with cyp120a2 from trichodesmium erythraeum ims101 and cyp120b1 and cyp120c1 from nostoc punctiforme pcc 73 ...	2005	15752715
response of growth, photosynthesis and photoinhibition of the edible cyanobacterium nostoc sphaeroides colonies to thiobencarb herbicide.	effects of thiobencarb on growth, photosynthesis and photoinhibition of nostoc sphaeroides colonies were examined. thiobencarb concentrations higher than 2 mg/l led to a significant decrease in phycoerythrin, phycocyanin and allophycocyanin content, but no significant effect on chlorophyll a (chl a) content. biomass yield, protein content and photosynthetic rate were reduced only in the highest thiobencarb concentration (10 mg/l). colonies exposed to high thiobencarb dose (10 mg/l) were more sen ...	2005	15788179
the cyanobacterium anabaena sp. pcc 7120 has two distinct beta-carotene ketolases: crto for echinenone and crtw for ketomyxol synthesis.	two beta-carotene ketolases, crtw and crto, are widely distributed in bacteria, although they show no significant sequence homology with each other. the cyanobacterium anabaena sp. pcc 7120 was found to have two homologous genes. in the crtw deleted mutant, myxol 2'-fucoside was present, but ketomyxol 2'-fucoside was absent. in the crto deleted mutant, beta-carotene was accumulated, and the amount of echinenone was decreased. therefore, crtw catalyzed myxol 2'-fucoside to ketomyxol 2'-fucoside, ...	2005	16242129
modulation of carbonic anhydrase activity in two nitrogen fixing cyanobacteria, nostoc calcicola and anabaena sp.	the activity of enzyme carbonic anhydrase (ca) was investigated in two diazotrophic cyanobacteria, anabaena sp. (arm 629) and nostoc calcicola, in the presence of co2/nahco3 and different inhibitors. the ca activity increased when the cells were pretreated with a high concentration of co2/nahco3 and then transferred to ambient level co2. maximum activity of ca was observed after 8 h of incubation in light on transfer of cells from high ci to ambient level co2, and was low when incubated in dark. ...	2005	16255166
competition among symbiotic cyanobacterial nostoc strains forming artificial associations with rice (oryza sativa).	competition among four symbiotically competent nostoc strains, colonizing rice roots, was examined using hetr-dgge (denaturing gradient gel electrophoresis) as strain identification. although mixed in various combinations, only one strain at a time associated with the rice roots. nostoc strain 8964:3 was the most competitive and our data suggest that its competitive fitness was dependent on rapid hormogonial spreading as displayed on agar plates. furthermore, rice roots induced hormogonia in all ...	2005	15796991
cyanobacteria from brazilian building walls are distant relatives of aquatic genera.	the 16s-rdna from 22 cyanobacteria isolated from biofilms on walls of modern and historic buildings in brazil was partially sequenced (approximately 350 bp) using specific primers. the cyanobacteria with the closest matching sequences were found using the blast tool. the sequences were combined with 52 other cyanobacterial sequences already deposited in public data banks and a dendrogram constructed, after deletion from each sequence of one of the variable 16s rdna regions (vi). the newly sequen ...	2005	15805777
comparative analysis of the two-step reaction catalyzed by prokaryotic and eukaryotic phytochelatin synthase by an ion-pair liquid chromatography assay.	genes encoding phytochelatin (pc) synthase have been found in higher plants, fission yeast and worm. recently, kinetic and mutagenic analyses of recombinant pc synthase have been revealing the molecular mechanisms underlying pc synthesis, however, a conclusive model has not been established. to clarify the mechanism of pc synthase found in eukaryotes, we have compared the two-step reactions catalyzed by the prokaryotic nostoc pc synthase (nspcs) and the eukaryotic arabidopsis pc synthase (atpcs1 ...	2005	15809863
diversity within cyanobacterial mat communities in variable salinity meltwater ponds of mcmurdo ice shelf, antarctica.	this study investigated the diversity of cyanobacterial mat communities of three meltwater ponds--fresh, orange and salt ponds, south of bratina island, mcmurdo ice shelf, antarctica. a combined morphological and genetic approach using clone libraries was used to investigate the influence of salinity on cyanobacterial diversity within these ecosystems without prior cultivation or isolation of cyanobacteria. we were able to identify 22 phylotypes belonging to phormidium sp., oscillatoria sp. and ...	2005	15816929
an nmr-based docking model for the physiological transient complex between cytochrome f and cytochrome c6.	the physiological transient complex between cytochrome f (cf) and cytochrome c(6) (cc(6)) from the cyanobacterium nostoc sp. pcc 7119 has been analysed by nmr spectroscopy. the binding constant at low ionic strength is 8 +/- 2 mm(-1), and the binding site of cc(6) for cf is localized around its exposed haem edge. on the basis of the experimental data, the resulting docking simulations suggest that cc(6) binds to cf in a fashion that is analogous to that of plastocyanin but differs between prokar ...	2005	15876432
characterization of a 4 kb variant of the nifd element in anabaena sp. strain atcc 33047.	heterocyst differentiation in some cyanobacteria is accompanied by a programmed dna rearrangement within the nitrogen fixation gene nifd. the nifd element is excised from within nifd during the latter stages of heterocyst differentiation by site-specific recombination. there is considerable variation in those nifd elements examined thus far, with nostoc sp. strain pcc 7120 and anabaena variabilis having 11 kb elements, and nostoc punctiforme having a 24 kb element. here we characterize a 4 kb ni ...	2005	15883871
benthic cyanobacteria from the baltic sea contain cytotoxic anabaena, nodularia, and nostoc strains and an apoptosis-inducing phormidium strain.	benthic cyanobacteria from aquatic environments have been reported to produce biologically active metabolites. however, the toxicity and other biological activities of benthic cyanobacteria from the baltic sea are not well known. we determined the biological activities of 21 anabaena, calothrix, nodularia, nostoc, and phormidium strains isolated from benthic littoral habitats of the baltic sea. we studied whether benthic cyanobacterial extracts caused cytotoxicity by necrosis or induced apoptosi ...	2005	15892066
the role of potassium as an ionic signal in the regulation of cyanobacterium nostoc muscorum response to salinity and osmotic stress.	spontaneously occurring thallium-resistant (tl+ -r) mutant of diazotrophic, heterocystous cyanobacterium nostoc muscorum is described in which tl+ -r phenotype is the cause of defective salinity-inducible k+ uptake activity and proline uptake activity. the results indicate that mutant strain is more sensitive to salinity and osmotic stresses than its parent. the mutational inactivation of salinity-inducible proline uptake was found associated with increased sensitivity of the cyanobacterial phot ...	2005	15900550
toxic cyanobacteria and microcystin concentrations in a public water supply reservoir in the brazilian amazonia region.	toxic cyanobacteria in public water supply reservoirs represent a serious health risk as they can release potent cyanotoxins into the water. in the present study we analyzed surface water collected from the utinga reservoir, the main source of drinking water for the city of belem-pa, in order to characterize the reservoir's cyanobacterial biota and to determine the toxicity of these organisms and the concentration of microcystins in raw and treated water. the cyanobacterial biota included potent ...	2005	15904685
characterization of a model system for the study of nostoc punctiforme akinetes.	nostoc punctiforme is a filamentous cyanobacterium that is capable of dark heterotrophy and cellular differentiation into nitrogen-fixing heterocysts, motile hormogonia, or spore-like akinetes. the study of akinete differentiation at the molecular level has been limited by the asynchronous development and limited number of akinetes formed within a filament. a system in which to study the development and genetic regulation of akinetes was investigated using a zwf mutant lacking glucose-6-phosphat ...	2005	15905999
raman spectroscopic analysis of cyanobacterial gypsum halotrophs and relevance for sulfate deposits on mars.	the raman spectra of cyanobacterial species, gloecapsa and nostoc, in clear gypsum crystals from the haughton crater, devon island, canadian high arctic, site of a meteorite impact during the miocene some 23 mya, have been recorded using several visible and near-infrared excitation wavelengths. the best spectra were obtained using a green wavelength at 514.5 nm and a confocal microscope with an image footprint of about 2 micro in diameter and 2 micro theoretical depth. raman biosignatures for be ...	2005	15912241
efficient and versatile stereoselective synthesis of cryptophycins.	the cryptophycins are a family of cyclic depsipeptides with four retrosynthetic units a to d which correspond to the respective amino acids and hydroxy acids. a new synthetic route to unit a allows the selective generation of all four stereogenic centres by introducing two of them in a catalytic asymmetric dihydroxylation, followed by substrate-controlled diastereoselective reactions. the diol also serves as the epoxide precursor. this approach provides selective access to stereoisomers of unit ...	2005	15915529
growth of cyanophage n-1 under the influence of heavy metal ions.	the growth of cyanophage n-1 in the cyanobacterium nostoc muscorum under the influence of heavy metal ions, namely co2+, cr6+, cu2+, mn2+ and ni2+ has been studied. one-step growth experiments revealed that heavy metal ions extended the latent period by 1-2 hrs with a concomitant decrease in the phage burst size. the latter was reduced in the order cu2/mn2+, ni2+, co2+ and cr6+. the treatment of the phage-infected bacteria with heavy metal ions did not induce mutations affecting either the phage ...	2005	15929395
the evolutionarily related beta-barrel polypeptide transporters from pisum sativum and nostoc pcc7120 contain two distinct functional domains.	several beta-barrel-type channels are involved in the translocation or assembly of outer membrane proteins of bacteria or endosymbiotically derived organelles. here we analyzed the functional units of the beta-barrel polypeptide transporter toc75 (translocon in outer envelope of chloroplasts) of the outer envelope of chloroplasts and of a protein, alr2269, from nostoc pcc7120 with homology to toc75, both proteins having a similar domain organization. we demonstrated that the n-terminal region fu ...	2005	15951438
three-dimensional architecture of phycobilisomes from nostoc flagelliforme revealed by single particle electron microscopy.	phycobilisomes are protein complexes that harvest light and transfer energy to the photo system. here, the three dimensional structure of intact phycobilisomes from nostoc flagelliforme is studied by a combination of negative stain electron microscopy and cryo-electron microscopy. results show that the intact phycobilisomes are composed of a tricylindrical core and six rods. each allophycocyanin cylinder presents a double-layered structure when viewed from the side and a triangular shape when vi ...	2005	15961084
respiratory cytochrome c oxidase can be efficiently reduced by the photosynthetic redox proteins cytochrome c6 and plastocyanin in cyanobacteria.	plastocyanin and cytochrome c6 are two small soluble electron carriers located in the intrathylacoidal space of cyanobacteria. although their role as electron shuttle between the cytochrome b6f and photosystem i complexes in the photosynthetic pathway is well established, their participation in the respiratory electron transport chain as donors to the terminal oxidase is still under debate. here, we present the first time-resolved analysis showing that both cytochrome c6 and plastocyanin can be ...	2005	15963511
carbohydrate, glycolipid, and lipid components from the photobiont (scytonema sp.) of the lichen, dictyomema glabratum.	the photobiont of the lichen, dictyonema glabratum (scytonema sp.), was isolated and cultivated in a soil-extract medium and submitted to chemical analysis. successive extractions with chcl3-meoh, aqueous meoh, and h2o gave rise to solutions of lipids (25%), low-molecular-weight carbohydrates (22%), and polysaccharides (4%), respectively. tlc of the lipid extract showed the presence of glycolipids, which were further purified and examined by nmr spectroscopy and gc-ms. monogalactosyldiacylglycer ...	2005	15963960
phylogeny of symbiotic cyanobacteria within the genus nostoc based on 16s rdna sequence analyses.	a phylogenetic analysis of selected symbiotic nostoc strain sequences and available database 16s rdna sequences of both symbiotic and free-living cyanobacteria was carried out using maximum likelihood and bayesian inference techniques. most of the symbiotic strains fell into well separated clades. one clade consisted of a mixture of symbiotic and free-living isolates. this clade includes nostoc sp. strain pcc 73102, the reference strain proposed for nostoc punctiforme. a separate symbiotic clade ...	2005	15549268
biolingua: a programmable knowledge environment for biologists.	biolingua is an interactive, web-based programming environment that enables biologists to analyze biological systems by combining knowledge and data through direct end-user programming. biolingua embeds a mature symbolic programming language in a frame-based knowledge environment, integrating genomic and pathway knowledge about a class of similar organisms. the biolingua language provides interfaces to numerous state-of-the-art bioinformatic tools, making these available as an integrated package ...	2005	15308539
a papain-like enzyme at work: native and acyl-enzyme intermediate structures in phytochelatin synthesis.	phytochelatin synthase (pcs) is a key enzyme for heavy-metal detoxification in plants. pcs catalyzes the production of glutathione (gsh)-derived peptides (called phytochelatins or pcs) that bind heavy-metal ions before vacuolar sequestration. the enzyme can also hydrolyze gsh and gs-conjugated xenobiotics. in the cyanobacterium nostoc, the enzyme (nspcs) contains only the catalytic domain of the eukaryotic synthase and can act as a gsh hydrolase and weakly as a peptide ligase. the crystal struct ...	2005	16339904
transcription and autoregulation of the rv3134c-devr-devs operon of mycobacterium tuberculosis.	devr is a transcriptional regulator that mediates the genetic response of mycobacterium tuberculosis to oxygen limitation and nitric oxide exposure. devr is co-transcribed along with devs, which encodes its cognate sensor kinase, and an upstream gene, rv3134c. the transcriptional activity of this operon was characterized by primer extension, transcriptional fusion and electrophoretic mobility shift assays (emsas) under aerobic conditions. transcription start points (tsps) were detected upstream ...	2005	16339949
physiological and molecular diversity of feather moss associative n2-fixing cyanobacteria.	cyanobacteria colonizing the feather moss pleurozium schreberi were isolated from moss samples collected in northern sweden and subjected to physiological and molecular characterization. morphological studies of isolated and moss-associated cyanobacteria were carried out by light microscopy. molecular tools were used for cyanobacteria identification, and a reconstitution experiment of the association between non-associative mosses and cyanobacteria was conducted. the influence of temperature on ...	2005	16263908
crucial role of extracellular polysaccharides in desiccation and freezing tolerance in the terrestrial cyanobacterium nostoc commune.	the cyanobacterium nostoc commune is adapted to the terrestrial environment and has a cosmopolitan distribution. in this study, the role of extracellular polysaccharides (eps) in the desiccation tolerance of photosynthesis in n. commune was examined. although photosynthetic o2 evolution was not detected in desiccated colonies, the ability of the cells to evolve o2 rapidly recovered after rehydration. the air-dried colonies contained approximately 10% (wt/wt) water, and field-isolated, natural co ...	2005	16269775
characterization of nitrogen-fixing cyanobacteria in the brazilian amazon floodplain.	the diversity of the free-living nitrogen-fixing cyanobacterial community in the floodplain sediments along the solimões and amazon rivers and some of their tributaries (japurá, negro and madeira) was investigated. five cyanobacterial genera were morphologically identified, four of which (nostoc, calothrix, cylindrospermum and fischerella) have not previously been isolated from the brazilian amazon floodplain. nostoc strains were the most commonly found heterocyst-forming cyanobacteria. five str ...	2005	16289234
a study on the correlation of nucleotide skews and the positioning of the origin of replication: different modes of replication in bacterial species.	deviations from chargaff's 2nd parity rule, according to which a approximately t and g approximately c in single stranded dna, have been associated with replication as well as with transcription in prokaryotes. based on observations regarding mainly the transcription-replication co-linearity in a large number of prokaryotic species, we formulate the hypothesis that the replication procedure may follow different modes between genomes throughout which the skews clearly follow different patterns. w ...	2005	16321966