Publications

regulation of nitrate reductase levels in the cyanobacteria anacystis nidulans, anabaena sp. strain 7119, and nostoc sp. strain 6719.	the effect of the nitrogen source on the cellular activity of ferredoxin-nitrate reductase in different cyanobacteria was examined. in the unicellular species anacystis nidulans, nitrate reductase was repressed in the presence of ammonium but de novo enzyme synthesis took place in media containing either nitrate or not nitrogen source, indicating that nitrate was not required as an obligate inducer. nitrate reductase in a. nidulans was freed from ammonium repression by l-methionine-d,l-sulfoximi ...	1981	6780511
new anabaena and nostoc cyanophages from sewage settling ponds.		1981	6269286
light and dark reactions of the uptake hydrogenase in anabaena 7120.	reactions of the uptake hydrogenase from anabaena 7120 (a.t.c.c. 27893, nostoc muscorum) were examined in whole filaments, isolated heterocysts, and membrane particles. whole filaments or isolated heterocysts that contained nitrogenase consumed h(2) in the presence of c(2)h(2) or n(2) in a light-dependent reaction. if nitrogenase was inactivated by o(2) shock, filaments catalyzed h(2) uptake to an unidentified endogenous acceptor in the light. addition of no(3) (-) or no(2) (-) enhanced these ra ...	1981	16661985
formation of hybrid phycobilisomes by association of phycobiliproteins from nostoc and fremyella.	formation of phycobilisomes has been accomplished in vitro from isolated phycobiliprotein fractions obtained from the same blue-green alga (intrageneric) and from different blue-green algae (intergeneric). phycobilisomes, which are supra-molecular complexes of phycobiliproteins, serve as major light-harvesting antennae for photosynthesis in blue-green and red algae. intrageneric association into energetically functional phycobilisomes, previously reported to occur with nostoc sp. allophycocyanin ...	1982	16593223
allophycocyanin i and the 95 kilodalton polypeptide : the bridge between phycobilisomes and membranes.	allophycocyanin was isolated from dissociated phycobilisomes from nostoc sp. and was separated into allophycocyanin i, ii, iii, and b as described elsewhere. if the separation of the proteins following phycobilisome isolation is done in the presence of the protease inhibitor, phenylmethylsulfonylfluoride, associated with allophycocyanin i are two colored polypeptides of 95 kilodalton (kd) and 80 kd, belonging to the class of group i polypeptides as defined by tandeau de marsac and cohen-bazire ( ...	1982	16662612
isolation and characterization of the central component of the phycobilisome core of nostoc sp.	freshly isolated allophycocyanin is recovered from linear sucrose gradients made in 0.75 molar potassium phosphate buffer (ph 7.0) in three sizes: 19s, 10.3s, and 5.5s. the largest aggregate is a complex of a 680 nm fluorescing allophycocyanin i in the form (alphabeta)(3)gamma, where gamma is the 95 kilodalton (kd) polypeptide, and two 660 nanometer fluorescing allophycocyanin ii (alphabeta)(3) molecules; the complex, stabilized in high phosphate concentrations, fluoresces maximally at 675 nanom ...	1982	16662613
growth and chromatic adaptation of nostoc sp. strain mac and the pigment mutant r-mac.	a spontaneous, stable, pigmentation mutant of nostoc sp. strain mac was isolated. under various growth conditions, this mutant, r-mac, had similar phycoerythrin contents (relative to allophycocyanin) but significantly lower phycocyanin contents (relative to allophycocyanin) than the parent strain. in saturating white light, the mutant grew more slowly than the parent strain. in nonsaturating red light, mac grew with a shorter generation time than the mutant; however, r-mac grew more quickly in n ...	1982	16662715
a physical map of plasmid pdu1 from the cyanobacterium nostoc pcc 7524.		1982	6283572
nostoc pcc7524, a cyanobacterium which contains five sequence-specific deoxyribonucleases.	five nucleotide sequence-specific deoxyribonucleases present in cell-free extracts of the filamentous cyanobacterium nostoc pcc7524 have been purified and characterized. one of these enzymes, designated nsp(7524)i cleaves at a new kind of nucleotide sequence, i.e. 5'-pucatg py-3'. the other four restriction enzymes in this organism, designated nsp(7524)ii, nsp(7524)iii, nsp(7524)iv and nsp(7524)v, are isoschizomers of enzymes which have been previously described. the cleavage site of nsp(7524)ii ...	1982	6298063
amino acid sequences of nostoc strain mac ferredoxins i and ii.	the amino acid sequences of ferredoxins i and ii from a blue-green alga, nostoc strain mac were determined. this alga is able to grow autotrophically in the light or heterotrophically in the dark. analyses of tryptic peptides of cm-proteins by conventional methods including solid-phase edman degradation gave the complete amino acid sequences. both molecules consisted of 98 amino acid residues and 34 amino acid differences including two deletions were found between the two. comparing these sequen ...	1982	6818220
biochemical diversity for biosynthesis of aromatic amino acids among the cyanobacteria.	we examined the enzymology and regulatory patterns of the aromatic amino acid pathway in 48 strains of cyanobacteria including representatives from each of the five major grouping. extensive diversity was found in allosteric inhibition patterns of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase, not only between the major groupings but also within several of the generic groupings. unimetabolite inhibition by phenylalanine occurred in approximately half of the strains examined; in the other s ...	1982	6119309
oxidation of c-type cytochromes by the membrane-bound cytochrome oxidase (cytochrome aa(3)) of blue-green algae.	respiratory particles containing an aa(3)-type cytochrome oxidase were prepared from anacystis nidulans, synechocystis 6714, synechococcus lividus, anabaena variabilis, nostoc sp. strain mac, nostoc muscorum, and mastigocladus laminosus. oxidation of c-type cytochromes by membrane preparations of the different blue-green algae was observed using purified cytochromes from horse heart, candida krusei, tuna, saccharomyces oviformis, rhodospirillum rubrum, rhodospirillum molischianum, rhodopseudomon ...	1982	16662253
role of the colorless polypeptides in phycobilisome reconstitution from separated phycobiliproteins.	a phycoerythrin (pe) and phycocyanin (pc) mixture was separated from allophycocyanin on calcium phosphate chromatography from completely dissociated phycobilisomes of the blue-green alga, nostoc sp. after dialysis of the pe-pc mixture in 0.75 m potassium phosphate, ph 7, which allows reassociation of the dissociated pigment-proteins, complexes of pe and pc in a 2:1 m ratio (pe/pc complex) as well as complexes predominantly of pc (pc/pe complex) were then separated by sedimentation on linear sucr ...	1982	16662378
freeze-recovery physiology of nitrogenase activity in terrestrial nostoc sp. colonies.	nostoc sp. colonies from field collections were cultured and propagated on silica sand with aqueous n-free bg-11 medium. laboratory experiments were conducted to characterize the in vivo freeze-recovery physiology of nitrogenase activity. nitrogenase activity was monitored by the acetylene reduction technique. frozen nostoc sp. colonies were thawed and warmed to 10, 15, 20, 25, or 30 degrees c. at 25 and 30 degrees c, nitrogenase activity was detected within 6 h after thawing. at 20 degrees c or ...	1983	16346394
studies of osmoregulation in salt adaptation of cyanobacteria with esr spin-probe techniques.	sucrose is accumulated in response to nacl-induced stress in the cyanobacterium synechococcus 6311. internal cell volume was measured by esr spectra with 2,2,6,6-tetramethyl-4-oxopiperidinoxy free radical (tempone) as a spin probe in order to calculate sucrose concentrations inside the cell. this method is rapid and reliable and provides an unambiguous measurement of absolute volumes in different osmotic environments. because the osmolar concentration of sucrose does not counter-balance the osmo ...	1983	16593309
thylakoid morphology of the cyanobacteria anabaena variabilis and nostoc mac grown under light and dark conditions.	anabaena variabilis (atcc 29413) and nostoc sp. strain mac were grown photoautotrophically and chemoheterotrophically. thylakoid morphology of cells from both types of culture was investigated by freeze-etching electron microscopy. peripheral and concentric arrays of thylakoid membranes seen in autotrophic cells were replaced, in heterotrophic cells, by numerous vesicular or tubular structures; the changes were reversible. heterotrophic cells showed a reduced overall content of chlorophyll but s ...	1983	6402604
regulation of nostoc sp. phycobilisome structure by light and temperature.	nostoc sp. strain mac cyanobacteria were green in color when grown in white light at 30 degrees c and contained phycobilisomes that had phycoerythrin and phycocyanin in a molar ratio of 1:1. cells grown for 4 to 5 days in green light at 30 degrees c or white light at 39 degrees c turned brown and contained phycoerythrin and phycocyanin in a molar ratio of greater than 2:1. in addition to the change in pigment composition, phycobilisomes from brown cells were missing a 34.5-kilodalton, rod-associ ...	1983	6411691
inhibition of photosystem ii of nitrogen-fixing blue-green alga nostoc linckia by the rice-field herbicide benthiocarb.	effects of rice-field herbicide benthiocarb (s(4-chlorobenzyl)-n,n-diethyl thiolcarbamate) was studied on the nitrogen-fixing blue-green alga nostoc linckia. the herbicide caused inhibition of growth and heterocyst formation, an increase in intensity of photoacoustic signals, and a four-fold reduction in oxygen evolution, but did not affect dark o2-uptake. the inhibition of growth and heterocyst formation was relieved by 500 micrograms/ml glucose. a het-nif- mutant of nostoc muscorum failed to s ...	1983	6415936
a restriction map of plasmid pdc1 from the filamentous cyanobacterium nostoc sp. mac pcc 8009.	a plasmid designated pdc1 from the cyanobacterium nostoc sp. mac pcc 8009 was incubated with 16 different restriction enzymes, of which 8 cleaved pdc1. plasmid pdc1 has a single site for clai, two sites for each of bgli, ecori, ecorv, and mlui, three sites for hpai, and four for hindiii. a restriction map of pdc1 for these 7 enzymes was constructed.	1983	6314412
polyadenylated rna in two filamentous cyanobacteria.	polyadenylated rna was detected in the cyanobacteria nostoc sp. strain mac and anabaena variabilis by oligodeoxythymidylic acid-cellulose chromatography and by hybridization to [3h]polyuridylic acid. polyadenylate tracts from a. variabilis were located at the 3' end of rna chains and had an estimated length of 15 to 22 nucleotides.	1983	6195149
the isocitrate dehydrogenase from cyanobacteria.	the present communication describes the properties of isocitrate dehydrogenase in crude extracts from the unicellular anacystis nidulans and from heterocysts and vegetative cells of nostoc muscorum and anabaena cylindrica. the activity levels of this enzyme are much higher in heterocysts than in vegetative cells of n. muscorum and a. cylindrica. isocitrate dehydrogenase is virtually inactive in vegetative cells of a. cylindrica. the enzyme is negatively regulated by the reduction charge and scar ...	1983	6409049
metabolic activities of isolated akinetes of the cyanobacterium nostoc spongiaeforme.	intact akinetes (spores) of the cyanobacterium nostoc spongiaeforme can be isolated free of vegetative cells and heterocysts. the akinetes remain viable for at least 2 weeks in distilled water. they do not germinate in water but do so readily when transferred subsequently to cyanobacterial growth medium. isolated, nongerminating akinetes incorporated 35s from na235so4 into protein and lipid. similar incorporation was observed when akinetes were isolated from old cultures (containing primarily ak ...	1983	6413494
isolation of polysomes from nostoc sp. mac and translation of messenger rna in a heterologous cell-free system.	a method has been established which isolated polysomes from the lysozyme/edta-shocked cyanobacterium, nostoc sp. mac. in a typical preparation the total recovery of rna as polysomes was 83%, in which 77% of the polysome fraction was present at sizes greater than 5-mers and 23% as 2-4-mers. messenger rna isolated from such a preparation of polysomes produced a 10-fold stimulation in the incorporation of [35s]methionine into polypeptides by a cell-free system of escherichia coli. the in vitro-synt ...	1983	6415228
transfer of nitrate reductase genes of the cyanobacterium nostoc muscorum into rhizobium japonicum.	transformation of rhizobium japonicum cb1809 was studied using dna from the cyanobacterium nostoc muscorum atcc 27893. a spontaneous nitrate reductase deficient (nar-) mutant (nr-6) of r. japonicum cb1809 was isolated with a frequency of 8.4 x 10(-7). streptomycin (sm) and neomycin (neo) resistance markers were introduced into strain nr-6, and the resulting strain was designated nr-6 smr neor. experiments with cyanobacterial dna and live cells of strain nr-6 smr neor indicated transformation of ...	1983	6415231
role of the colorless polypeptides in phycobilisome assembly in nostoc sp.	we have identified the function of the ;extra' polypeptides involved in phycobilisome assembly in nostoc sp. these phycobilisomes, as those of other cyanobacteria, are composed of an allophycocyanin core, phycoerythrin- and phycocyanin-containing rods, and five additional polypeptides of 95, 34.5, 34, 32, and 29 kilodaltons. the 95 kilodalton polypeptide anchors the phycobilisome to the thylakoid membrane (rusckowski, zilinskas 1982 plant physiol 70: 1055-1059); the 29 kilodalton polypeptide att ...	1983	16662834
nucleotide sequence of a multiple-copy gene for the b protein of photosystem ii of a cyanobacterium.	chloroplast photogene 32 codes for the 32-kilodalton triazine herbicide-binding protein at the b site of electron transport in photosystem ii of the photosynthetic apparatus-its product is the b protein and the gene is accordingly designated ps2b here. the cyanobacteria anacystis nidulans r2, fremyella diplosiphon, and nostoc sp. mac each contain several copies of ps2b. the sequence of one copy of ps2b from fremyella, ps2b-1, has been determined. the longest open reading frame would code for a p ...	1984	16578775
resistance of dna from filamentous and unicellular cyanobacteria to restriction endonuclease cleavage.	chromosomal dna from nine species of filamentous cyanobacteria as diverse as nostoc, gloeotrichia and plectonema is suggested to be extensively modified (methylated) by its resistance to cleavage by a number of restriction endonucleases. a remarkably similar pattern of dna modification in these species contrasts with the known heterogeneity of their type ii restriction endonuclease content. in particular, nostoc pcc 73102, which lacks detectable sequence-specific endonucleases, is shown to posse ...	1984	6320895
the role of na2s in anoxygenic photosynthesis and h2 production in the cyanobacterium nostoc muscorum.	na2s is known to support anoxygenic photosynthesis in some strains of cyanobacteria and to stimulate h2 production in n2 fixing filaments of nostoc muscorum. we have shown electron transfer between na2s and photosystem i to be dependent on cytochrome b559 which was detected only in vegetative cells. an electron mediator was required to support na2s driven nitrogenase activity in isolated heterocysts. na2s was also found to deplete the atp pool, probably by inhibiting electron transfer from photo ...	1984	6091649
[fractionation of phycobilisomes from the blue-green alga nostoc muscorum].	phycobilisomes (pbs) isolated from nostoc muscorum contain eight spectral forms of phycobiliproteins. pbs partially dissociated by osmotic or temperature shock, were separated into 42s and 34s particles by centrifugation in sucrose density gradient. the 42s particles are enriched with phycocyanin, the 34s ones--with allophycocyanin. the 42s particles dissociate to free pigments by repeated osmotic or temperature shock and the 34s ones dissociate to subparticles i and ii having the constant pigme ...	1984	6423967
redox potentials of algal and cyanobacterial flavodoxins.	the redox potentials of flavodoxins from the cyanobacteria synechococcus pcc 6301 (formerly anacystis nidulans) and nostoc strain mac, and from the red alga chondrus crispus, were determined by potentiometric titration. for the oxidized-semiquinone interconversion the potentials at ph 7.0 of the three flavodoxins were between -210 and -235 mv, and these were ph-dependent over the range ph 6.9-8.2. for the semiquinone-reduced interconversion the potentials of the cyanobacterial flavodoxins were c ...	1984	6424653
[energy migration in phycobilisomes].	fluorescence emission and polarization spectra of the phycobilisomes (pbs) of the blue-green alga nostoc muscorum were measured at 20, -73 and -196 degrees c while exciting at the absorption maximum of each pigment in the pbs. the emission spectra were deconvoluted into a number of gaussian components and energy migration coefficients and quantum yields of fluorescence for the 8 forms of the phycobilins constituting the pbs were calculated. the overlap integrals and the critical and real distanc ...	1984	6425643
powerful mutagenicity of a bipyridylium herbicide in a nitrogen-fixing blue-green alga nostoc muscorum.	the herbicide, paraquat (1,1'-dimethyl-4,4'-bipyridylium ion), was found to be toxic and lytic to nostoc muscorum in n2 (at the expense of elemental nitrogen, i.e. unsupplemented with any combined nitrogen source) and no-3 media, without any apparent inhibitory or stimulatory effect on its nitrogen-fixing apparatus, i.e. heterocyst formation. at a dose of paraquat resulting in 20, 50 and 75% survival, induction of reverse mutations (from het- nif- auxotrophy to het+ nif+ prototrophy), forward mu ...	1984	6436694
contrasting modes of photosynthetic enzyme regulation in oxygenic and anoxygenic prokaryotes.	enzymes that are regulated by the ferredoxin/thioredoxin system in chloroplasts--fructose-1,6-bis-phosphatase (fbpase), sedoheptulose-1,7-bisphosphatase (sbpase), and phosphoribulokinase (prk)--were partially purified from two different types of photosynthetic prokaryotes (cyanobacteria, purple sulfur bacteria) and tested for a response to thioredoxins. each of the enzymes from the cyanobacterium nostoc muscorum, an oxygenic organism known to contain the ferredoxin/thioredoxin system, was activ ...	1984	11536590
constant phycobilisome size in chromatically adapted cells of the cyanobacterium tolypothrix tenuis, and variation in nostoc sp.	phycobilisomes of tolypothrix tenuis, a cyanobacterium capable of complete chromatic adaptation, were studied from cells grown in red and green light, and in darkness. the phycobilisome size remained constant irrespective of the light quality. the hemidiscoidal phycobilisomes had an average diameter of about 52 nanometers and height of about 33 nanometers, by negative staining. the thickness was equivalent to a phycocyanin molecule (about 10 nanometers). the molar ratio of allophycocyanin, relat ...	1985	16664550
protein synthesis and proteolysis in immobilized cells of the cyanobacterium nostoc commune utex 584 exposed to matric water stress.	cells of the cyanobacterium nostoc commune utex 584 in exponential growth were subjected to acute water stress by immobilizing them on solid supports and drying them at a matric water potential (psi m) of -99.5 mpa. cells which had been grown in the presence of na235so4 before immobilization and rapid drying continued to incorporate 35s into protein for 90 min. this incorporation was inhibited by chloramphenicol. no unique proteins appeared to be synthesized during this time. upon further drying ...	1985	3934134
a low potential iron-sulfur cluster bound to membranes in blue-green algae.	a new low temperature epr signal at g = 1.92 was found in photoreduced membrane fractions prepared from blue-green algae, nostoc muscorum, tolypothrix tenuis, phormidium persicinum, and anabaena variabilis. the signal also appeared when the sample was chemically reduced in the dark. judging from the spectrum, the signal was probably due to the reduced form of a membrane-bound iron-sulfur cluster, tentatively designated as cluster d. the midpoint potential of cluster d was determined to be -0.27 ...	1985	2987203
prokaryotic triterpenoids. 1. 3 beta-methylhopanoids from acetobacter species and methylococcus capsulatus.	3 beta-methylbacteriohopanepolyol derivatives were isolated from three bacteria, acetobacter pasteurianus ssp. pasteurianus, methylococcus capsulatus and nostoc muscorum, and identified by spectroscopic methods and direct comparison with 3 beta-methyldiplopterol and 3 beta-methylhopan-29-ol synthesized from 22-hydroxyhopan-3-one. the 3 beta-methylhopanoid content of a. pasteurianus ssp. pasteurianus could be dramatically increased (up to 60% of the total hopanoid content) by addition of l-methio ...	1985	3926494
the role of glutathione and ascorbate in hydroperoxide removal in cyanobacteria.	the antioxidative potential of cyanobacteria to scavenge hydroperoxides formed as by-products of photosynthetic activity was investigated in nostoc muscorum 7119 and synechococcus 6311. these cells contained a high concentration of glutathione, 2-5 mm, and a low concentration of ascorbate, 20-100 um. no glutathione peroxidase was detected while the activity of ascorbate peroxidase was high, reacting with hydrogen peroxide, t-butyl hydroperoxide, and cumene hydroperoxide. dehydroascorbate reducta ...	1985	3933503
prokaryotic triterpenoids. 2. 2 beta-methylhopanoids from methylobacterium organophilum and nostoc muscorum, a new series of prokaryotic triterpenoids.	2 beta-methylhopanoids, a new series of triterpenoids was identified from two prokaryotes. 2 beta-methyldiplopterol was isolated from the methylotrophic bacterium methylobacterium organophilum, and three different 2 beta-methylbacteriohopanepolyols from the cyanobacterium nostoc muscorum. the structures of these compounds was deduced by direct comparison with 2 beta-methyldiplopterol synthesized from 22-hydroxyhopan-3-one.	1985	3926495
identification of facultatively heterotrophic, n2-fixing cyanobacteria able to receive plasmid vectors from escherichia coli by conjugation.	plasmid vectors transferable by conjugation from escherichia coli to obligately photoautotrophic strains of anabaena spp. are also transferred to and maintained in heterotrophic, filamentous cyanobacteria of the genus nostoc. these organisms can be used for the genetic analysis of oxygenic photosynthesis, chromatic adaptation, nitrogen fixation, and heterocyst development.	1985	3922953
characterization of several tropical strains of anabaena and nostoc: morphological and physiological properties, and plasmid content.	thirty anabaena and nostoc strains isolated from west african soils were characterized for their morphological and physiological properties, and surveyed for plasmids. most strains were found to harbour one to five plasmids whose molecular masses ranged from 1.5 to 120-150 x 10(6) daltons. no relationship between these plasmids and phenotypic properties such as carbon source utilization, antibiotic resistance or cyanophage and toxin production could be established.	1986	3122637
analysis of fluorescence kinetics and energy transfer in isolated alpha subunits of phycoerythrin from nostoc sp.		1986	3081920
[role of temperate phage in bacterial dissociation].	the analysis of literary and own data testifies that the dissociants may appear in bacteria population from spontaneous mutations and transfer of genetic material (conjugation, transformation, transduction). the phage conversion and different dna reorganizations within a cell where prophage plays an active role, probably introduce the largest contribution into the dissociative transitions of variants which occur with high frequency (about 10(-2)-10(-4). the dissociation of various bacteria has b ...	1986	3011128
oxidative phosphorylation and energy buffering in cyanobacteria.	the onset of respiration in the cyanobacteria anacystis nidulans and nostoc sp. strain mac upon a shift from dark anaerobic to aerobic conditions was accompanied by rapid energization of the adenylate pool (owing to the combined action of atp synthase and adenylate kinase) and also the guanylate, uridylate, and cytidylate pools (owing to nucleoside diphosphate and nucleoside monophosphate kinases). rates of the various transphosphorylation reactions were comparable to the rate of oxidative phosp ...	1986	3023299
production, by filamentous, nitrogen-fixing cyanobacteria, of a bacteriocin and of other antibiotics that kill related strains.	colonies of sixty-five filamentous cyanobacteria were screened for the production of temperate phages and/or antibiotics on solid medium. none of them was observed to release phages. however, seven n2-fixing strains were found to produce antibiotics very active against other cyanobacteria. the antibiotic produced by nostoc sp. 78-11a-e represents a bacteriocin of low molecular weight. nostoc sp. atcc 29132 appears to secrete, together with an antibiotic, a protein that inhibits its action.	1986	3094472
polysome turnover in immobilized cells of nostoc commune (cyanobacteria) exposed to water stress.	water stress induced changes in the polysome content of immobilized cells of the desiccation-tolerant cyanobacterium nostoc commune utex 584. cells maintained an intact protein synthesis complex during 2 h of drying at -99.5 mpa. polysomes were not recovered from cells subjected to extended periods of desiccation.	1986	2430937
effect of tryptophan on 2,4-dichlorophenoxyacetic acid toxicity in the nitrogen-fixing-cyanobacterium nostoc linckia.	the combined effect of a hormone weed killer 2,4-dichlorophenoxyacetic acid (2,4-d) and an amino acid (tryptophan) has been studied on growth and heterocyst differentiation in the cyanobacterium nostoc linckia. 2.4-d at 100 micrograms/ml stimulated growth and heterocyst frequency in combined nitrogen-free medium while its higher concentrations inhibited both. tryptophan under similar conditions promoted much growth yield with 3-4 fold enhanced heterocyst frequency than the control. such heterocy ...	1986	3083089
regulation of glutamate dehydrogenase activity and ammonia production in a nitrogen fixing cyanobacterium.	a glutamate auxotroph was obtained in nostoc muscorum by induced mutagenesis with nitrosoguanidine. the metabolic pathway leading to glutamate synthesis was traced by selecting several enzymes. the strain was found to be lacking glutamate dehydrogenase. other enzymes, however, were normal in their activity including isocitric dehydrogenase, glutamine synthetase and glutamate synthase. nitrogen metabolism of the auxotroph and wild type was compared. the strain released exceedingly high amounts of ...	1986	2880448
hydroperoxide metabolism in cyanobacteria.	the enzymes involved in antioxidative activity and the cellular content of the antioxidants glutathione and ascorbate in the cyanobacteria nostoc muscorum 7119 and synechococcus 6311 have been examined for their roles in hydroperoxide removal. high activities of ascorbate peroxidase and catalase were found in vegetative cells of both species and in the heterocysts of n. muscorum. the affinity of ascorbate peroxidase for h2o2 was 15- to 25-fold higher than that of catalase. increased activity of ...	1986	3083778
mutagenesis by ethidium bromide, proflavine and mitomycin c in the cyanobacterium nostoc sp.	ethidium bromide, proflavine, and mitomycin c were strongly lethal but weakly mutagenic to the cyanobacterium nostoc sp. with a view to studying the mode of action of these weak mutagens, their binding to nostoc dna was studied. the spectral changes resulting from the binding of these mutagens to the dna in vitro indicated that probably only electrostatic forces may be involved in the mutagen-dna binding. a similar low level of dna binding in vivo would explain the weakly mutagenic action of the ...	1986	3088444
purification and biochemical analysis of the cytoplasmic membrane from the desiccation-tolerant cyanobacterium nostoc commune utex 584.	the cytoplasmic membrane of the heterocystous cyanobacterium nostoc commune utex 584 was isolated free of thylakoids and phycobiliprotein-membrane complexes by flotation centrifugation. purified membranes had a buoyant density of 1.07 g cm and were bright orange. twelve major proteins were detected in the membrane, and of these, the most abundant had molecular masses of 83, 71, 68, 51, and 46 kilodaltons. the ester-linked fatty acids of the methanol fraction contained 16:0, 18:0, 18:1omega9c, 20 ...	1986	16347165
the immunologically conserved phycobilisome-thylakoid linker polypeptide.	we have isolated phycobilisomes from two classes of red algae, several subdivisions of the cyanobacteria, and the cyanelles of cyanophora paradoxa. in addition to the major light harvesting biliproteins, these phycobilisomes also contain several other polypeptides, the largest of which ranges from 75 to 120 kilodaltons in the different species surveyed. this protein, previously isolated and characterized from three species, was shown to be the final emitter of excitation energy in phycobilisomes ...	1986	16664726
tyrosine-induced heterocyst division in nostoc muscorum.	heterocyst size variation in nostoc muscorum has been surveyed in the presence and absence of tyrosine. the heterocyst size exhibited two major peaks under both conditions but one of the peaks shifted towards larger size in tyrosine-containing medium. heterocysts of larger volume exhibited division in the latter medium which was not observed in medium lacking tyrosine. it is suggested that signals for cell division did not decay following differentiation of heterocyst in the presence of tyrosine ...	1987	18425684
variation in phospholipid ester-linked fatty acids and carotenoids of desiccated nostoc commune (cyanobacteria) from different geographic locations.	profiles of phospholipid fatty acids and carotenoids in desiccated nostoc commune (cyanobacteria) collected from china, federal republic of germany, and antarctica and in axenic cultures of the desiccation-tolerant strains n. commune utex 584 and hydrocoleum strain goei were analyzed. the phospholipid fatty acid contents of the three samples of desiccated nostoc species were all similar, and the dominant compounds were 16:1omega7c, 16:0, 18:2omega6, 18:3omega3, and 18:1omega7c. in comparison wit ...	1987	16347265
sodium requirement for photosynthesis and its relationship with dinitrogen fixation and the external co(2) concentration in cyanobacteria.	cells of anabaena pcc 7119 and of a mutant strain of nostoc muscorum unable to fix dinitrogen, grown at ph 8 and under low co(2) tension (air), showed a reduced capacity for photosynthesis when cultured in the absence of sodium, this inhibition being followed by symptoms of photooxidation, such as chlorosis, oxygen consumption in the light, and decrease of superoxide dismutase activity. the impairment of photosynthesis preceded that of nitrogenase activity, indicating that the requirement for so ...	1987	16665740
immunological conservation of phycobilisome rod linker polypeptides.	monospecific polyclonal antibodies raised against the phycobilisome rod linker polypeptides of nostoc sp. were used to assess structural similarities among phycobilisome linker proteins from diverse, phycobilisome-containing organisms. while a remarkable conservation of antigenic determinants was demonstrated for two of these rod linker proteins, the third linker polypeptide appeared to be conserved only among closely related species.	1987	16665695
the evolution of glutathione metabolism in phototrophic microorganisms.	of the many roles ascribed to glutathione (gsh) the one most clearly established is its role in the protection of higher eucaryotes against oxygen toxicity through destruction of thiol-reactive oxygen byproducts. if this is the primary function of gsh then gsh metabolism should have evolved during or after the evolution of oxygenic photosynthesis. that many bacteria do not produce gsh is consistent with this view. in the present study we have examined the low-molecular-weight thiol compositio ...	1987	11542078
influence of cypermethrin and fenvalerate on a green alga and three cyanobacteria isolated from soil.	the effects of two pyrethroid insecticides, cypermethrin and fenvalerate, on a green alga (scenedesmus bijugatus) and three species of cyanobacteria (synechococcus elongatus, nostoc linckia, and phormidium tenue), all isolated from a black cotton soil, were studied using either cell number or chlorophyll a as toxicity criterion. all the four species were either unaffected or stimulated at 5 micrograms ml-1. of the two insecticides, cypermethrin, at 10 to 50 micrograms ml-1, inhibited s. bijugatu ...	1987	3121278
ferredoxin-thioredoxin reductase, an iron-sulfur enzyme linking light to enzyme regulation in oxygenic photosynthesis: purification and properties of the enzyme from c3, c4, and cyanobacterial species.	ferredoxin-thioredoxin reductase (ftr), an enzyme involved in the light regulation of chloroplast enzymes, was purified to homogeneity from leaves of spinach (a c3 plant) and corn (a c4 plant) and from cells of a cyanobacterium (nostoc muscorum). the enzyme is a yellowish brown iron-sulfur protein, containing four nonheme iron and labile sulfide groups, that catalyzes the activation of nadp-malate dehydrogenase and fructose 1,6-bisphosphatase in the presence of ferredoxin and of thioredoxin m an ...	1987	3028266
toxicity of nickel and silver to nostoc muscorum: interaction with ascorbic acid, glutathione, and sulfur-containing amino acids.	exposure of nostoc muscorum to different concentrations of ni and ag brought about reduction in growth, carbon fixation, heterocyst production, and nitrogenase activity and increase in the loss of ions (k+, na+). in an attempt to ameliorate the toxicity of test metals by ascorbic acid, glutathione, and sulfur-containing amino acids (l-cysteine and l-methionine), it was found that the level of protection by ascorbic acid and glutathione was more for ag than ni. however, metal-induced inhibition o ...	1987	3123194
regulation of expression of glutamine synthetase in a symbiotic nostoc strain associated with anthoceros punctatus.	a characteristic of n2-fixing cyanobacteria in symbiotic associations appears to be release of n2-derived nh4+. the specific activity of the primary ammonium-assimilating enzyme, glutamine synthetase (gs), was found to be three- to fourfold lower in nostoc sp. strain 7801 grown in symbiotic association with the bryophyte anthoceros punctatus than in free-living nostoc sp. strain 7801. quantitative immunological assays with antisera against gs purified from nostoc sp. strain 7801 and from escheri ...	1987	2884210
glutamine synthetase specific activity and protein concentration in symbiotic anabaena associated with azolla caroliniana.	glutamine synthetase (gs) is the primary nh4+ assimilating enzyme of cyanobacteria. the specific activities and cellular protein concentration of gs in symbiotic cyanobacteria associated with the water fern azolla caroliniana were determined and compared to free-living cultures of nostoc sp. strain 7801, a strain originally isolated from symbiotic association with the bryophyte anthoceros punctatus. both the in vitro specific activity and concentration of gs in symbiotic cyanobacteria separated ...	1988	2902827
distinct fractions of genomic dna from cyanobacterium nostoc commune that differ in the degree of methylation.		1988	2854807
an analysis of restriction endonuclease sites in cyanophages infecting the heterocystous cyanobacteria anabaena and nostoc.	an analysis of restriction endonuclease cleavage of dna isolated from cyanophages that infect anabaena and nostoc species of cyanobacteria has provided evidence for counter-selection of restriction endonuclease sites. these include sites containing subsequences which are methylated by host (anabaena pcc 7120) methylase(s) akin to the dam and dcm enzymes of escherichia coli. other sites which are counter-selected have no common sequence structure. the latter include those of the endogenous restri ...	1988	2832536
identification of the region of cyanobacterial plasmid pdu1 necessary for replication in anabaena sp. strain m-131.	shuttle vectors based on plasmid pdu1 from nostoc sp. strain pcc7524 are able to replicate both in escherichia coli and in strains of anabaena and nostoc spp. derivatives partially deleted in the pdu1 portion were tested for their ability to replicate in anabaena sp. strain m-131. plasmid prl6he containing a 1.75-kb hindiii-scai fragment of pdu1 replicated stably in that cyanobacterium and also in anabaena sp. strain pcc7120. plasmid prl6hc, containing an even smaller hpai-scai fragment (1.3 kb) ...	1988	3131190
cloning of nifhd from nostoc commune utex 584 and of a flanking region homologous to part of the azotobacter vinelandii nifu gene.	the heterocystous cyanobacterium nostoc commune utex 584 contains two nifh-like sequences (nifh1 and nifh2) in addition to nifhd. a region of dna 1 kilobase upstream from the 5' end of nifh showed considerable sequence similarity to part of the published nifu sequences of azotobacter vinelandii and klebsiella pneumoniae.	1988	3133363
antibiotic effects on growth and heterocyst differentiation of the cyanobacterium nostoc muscorum.	in a medium free of combined nitrogen, 1.0-6.0 micrograms/ml chloramphenicol gradually decreased the growth of the nitrogen-fixing cyanobacterium nostoc muscorum; at 2.0 micrograms/ml the culture appeared yellowish, heterocyst frequency was not evident up to 3.0 micrograms/ml, whereas 4.0 micrograms/ml suppressed heterocyst differentiation. lower concentrations (0.0125-0.75 microgram/ml) of rifampicin suppressed the growth but had no significant effect on heterocyst frequency in liquid medium, w ...	1988	3142201
effect of insecticides and phenolics on nitrogen fixation by nostoc linckia.		1988	3145048
characterization of two operons encoding the cytochrome b6-f complex of the cyanobacterium nostoc pcc 7906. highly conserved sequences but different gene organization than in chloroplasts.	we have isolated and determined the nucleotide and derived protein sequences for the four genes, petca and bd, which encode the cytochrome b6-f, electron-transfer complex of the filamentous cyanobacterium, nostoc pcc 7906. the primary structure and cotranscription of the petca genes encoding the rieske-fes (nuclear encoded in plants) and apocytochrome f proteins has been described previously (kallas, t., spiller, s., and malkin, r. (1988) proc. natl. acad. sci. u.s.a., in press). the petbd genes ...	1988	2844767
organization of the nif genes in cyanobacteria in symbiotic association with azolla and anthoceros.	the sizes of endonuclease digestion fragments of dna from cyanobacteria in symbiotic association with azolla caroliniana or anthoceros punctatus, or in free-living culture, were compared by southern hybridization using cloned nitrogenase (nif) genes from anabaena sp. pcc 7120 as probes. the restriction fragment pattern produced by cyanobacteria isolated from a. caroliniana by culture through symbiotic association with anthoceros differed from that of the major symbiotic cyanobacterium freshly se ...	1988	2841912
primary structure of cotranscribed genes encoding the rieske fe-s and cytochrome f proteins of the cyanobacterium nostoc pcc 7906.	the thylakoid membrane cytochrome b6-f complex (plastoquinol:oxidized-plastocyanin oxidoreductase, ec 1.10.99.1) catalyzes electron-transfer and proton-translocation reactions essential for oxygenic photosynthesis. we have isolated and determined the nucleotide sequences of the petc and peta genes encoding the rieske fe-s and cytochrome f polypeptides from the filamentous cyanobacterium nostoc pcc 7906. these genes occur as single genomic copies, are tightly linked, and, as indicated by hybridiz ...	1988	2842748
phycotoxicity of linear alkylbenzene sulfonate.	dose- and time-dependent effects of linear alkylbenzene sulfonate, a major component of synthetic detergent, to the blue-green alga nostoc muscorum, were studied under laboratory conditions. toxicity was evident, at doses above 0.001%, from the decrease in biomass, heterocyst number, and protein content and pathomorphological alterations.	1988	2837383
impact of chromium and lead on nostoc muscorum: regulation of toxicity by ascorbic acid, glutathione, and sulfur-containing amino acids.	nostoc muscorum can be protected from cr and pb toxicity by supplementing 10 micrograms/ml of ascorbic acid, reduced glutathione, and 5 micrograms/ml of sulfur-containing amino acids (l-methionine and l-cysteine). appreciable stimulation of different parameters of nostoc by ascorbic acid and glutathione was noticed in the untreated culture. these substances when used in the presence of metals were found to restore ionic loss, growth, 14co2 uptake, heterocyst production, and nitrogenase activity ...	1988	3132363
n-terminus conservation in the terminal pigment of phycobilisomes from a prokaryotic and eukaryotic alga.	high molecular weight polypeptides from phycobilisomes, believed to be involved in facilitating the energy flow from phycobilisomes to thylakoids, are conserved in the prokaryote nostoc sp. and the eukaryote porphyridium cruentum. partial n-terminal sequence analysis of the phycobilisome-polypeptides of nostoc (94 kilodalton) and porphyridium (92 kilodalton) revealed 55% identity in the first 20 residues, but no significant homology with sequences of other phycobiliproteins or phycobilisome-link ...	1988	16666079
a new uv-a/b protecting pigment in the terrestrial cyanobacterium nostoc commune.	a new ultraviolet (uv)-a/b absorbing pigment with maxima at 312 and 330 nanometers from the cosmopolitan terrestrial cyanobacterium nostoc commune is described. the pigment is found in high amounts (up to 10% of dry weight) in colonies grown under solar uv radiation but only in low concentrations in laboratory cultures illuminated by artificial light without uv. its experimental induction by uv as well as its capacity to efficiently protect nostoc against uv radiation is reported.	1988	16666420
the effect of crude oil and oil spill chemicals on nitrogen fixation in the cyanobacteria nostoc sp.	the effects of crude oil and three oil spill dispersants (corexit 9600, 9550 and 7664) on nitrogenase activity in the cyanobacteria nostoc sp. were examined. the addition of oil to nostoc sp. cultures resulted in a catastrophic decline in nitrogenase activity with activity ceasing 7 h after treatment. the addition of a dispersant with the oil did not ameliorate this effect. cultures exposed to high concentrations of dispersants showed lower rates on nitrogenase activity than untreated cultures. ...	1988	15092640
microscale vertical profiles of n(2) fixation, photosynthesis, o(2), chlorophyll a, and light in a cyanobacterial assemblage.	profiles of n(2) fixation, o(2) production (gross photosynthesis), o(2) concentration, chlorophyll a concentration, and photon fluence rates were measured with 50-mum resolution in colonies of the heterocyst-forming cyanobacterium nostoc parmelioides. microelectrode measurements were made after 20 h of incubation under n(2) gas. colonies were frozen, and 50-mum sections were prepared by using a freezing microtome and analyzed for n enrichment and chlorophyll a concentration. colonies exhibited s ...	1989	16347893
characteristics of hormogonia formation by symbiotic nostoc spp. in response to the presence of anthoceros punctatus or its extracellular products.	nostocacean cyanobacteria typically produce gliding filaments termed hormogonia at a low frequency as part of their life cycle. we report here that all nostoc spp. competent in establishing a symbiotic association with the hornwort anthoceros punctatus formed hormogonial filaments at a high frequency in the presence of a. punctatus. the hormogonia-inducing activity was produced by a. punctatus under nitrogen-limited culture conditions. the hormogonia of the symbiotically competent nostoc spp. we ...	1989	16347816
effect of bimetallic combinations of ni, cr, and pb on growth, uptake of nitrate and ammonia, 14co2 fixation, and nitrogenase activity of nostoc muscorum.	the toxicity of cr, ni, and pb individually as well as in combination (cr + ni, cr + pb, ni + pb) on growth, final yield, uptake of no3- and nh4+, photosynthesis, and nitrogenase activity of nostoc muscorum has been studied. all test metals, when used individually, depicted toxicity against the above-mentioned processes of test cyanobacterium. however, their interactive effect was found to be mostly of antagonistic type. antagonism was more prevalent in those combinations containing nickel. in a ...	1989	2496971
toxicity of three herbicides to some nitrogen-fixing cyanobacteria.	the effects of some common rice field herbicides, such as 2,4-dichlorophenoxyacetic acid (2,4-d), machete, and saturn, on the paddy field nitrogen-fixing cyanobacteria nostoc linckia, nostoc calcicola, nostoc sp., and anabaena doliolum were studied. these cyanobacteria were found to be more tolerant to 2,4-d (lethal doses 1500-2000 micrograms/ml) than to machete and saturn (lethal doses 6-8 micrograms/ml). the effects of these three herbicides on some physiological processes of n. linckia were s ...	1989	2500323
nitrogen fixation (nif) genes of the cyanobacterium anabaena species strain pcc 7120. the nifb-fdxn-nifs-nifu operon.	a second nitrogen fixation (nif) operon in the cyanobacterium (blue-green alga) anabaena (nostoc) sp. strain pcc 7120 has been identified and sequenced. it is located just upstream of the nifhdk operon and consists of four genes in the order nifb, fdxn, nifs, and nifu. the three nif genes were identified on the basis of their similarity with the corresponding genes from other diazotrophs. the fourth gene, fdxn, codes for a bacterial type ferredoxin (mulligan, m. e., buikema, w. j., and haselkorn ...	1989	2553733
comparison of dna restriction fragment length polymorphisms of nostoc strains in and from cycads.	dna was prepared from cyanobacteria freshly isolated from coralloid roots of natural populations of five cycad species: ceratozamia mexicana mexicana (mexico), c. mexicana robusta (mexico), dioon spinulosum (mexico), zamia furfuraceae (mexico) and z. skinneri (costa rica). using the southern blot technique and cloned anabaena pcc 7120 nifk and glna genes as probes, restriction fragment length polymorphisms of these cyanobacterial symbionts were compared. the five cyanobacterial preparations show ...	1989	2569858
cyanobacterial rna polymerase genes rpoc1 and rpoc2 correspond to rpoc of escherichia coli.	the dna-dependent rna polymerase (ribonucleoside triphosphate:rna nucleotidyltransferase, ec 2.7.7.6) of cyanobacteria contains a unique core component, gamma, which is absent from the rna polymerases of other eubacteria (g. j. schneider, n. e. tumer, c. richaud, g. borbely, and r. haselkorn, j. biol. chem. 262:14633-14639, 1987). we present the complete nucleotide sequence of rpoc1, the gene encoding the gamma subunit, from the heterocystous cyanobacterium nostoc commune utex 584. the derived a ...	1989	2495268
novel water stress protein from a desiccation-tolerant cyanobacterium. purification and partial characterization.	a desiccation-tolerant cyanobacterium nostoc commune accumulates a novel group of acidic proteins when colonies are subjected to repeated cycles of drying and rehydration. the proteins occur in high concentrations; they have isoelectric points between 4.3 and 4.8 and apparent molecular masses between 30 and 39 kda. the purification of three of these proteins with molecular masses of 33, 37, and 39 kda is described. the amino-terminal sequence of the 39-kda protein is ala-leu-tyr-gly-tyr-thr-ile- ...	1989	2501307
effects of three pesticides on msx-induced ammonia photoproduction by the cyanobacterium nostoc linckia.	three pesticides (2,4-d, basalin, aldrin) inhibited l-methionine-dl-sulfoximine (msx)-induced photoproduction of ammonia by the nitrogen-fixing cyanobacterium nostoc linckia. combinations of pesticides and msx were inhibitory except at low concentrations (100 and 500 micrograms/ml) of 2,4-d which stimulated nh+4 production. similar results were obtained when pesticides were added 6 hr after the addition of msx, but the inhibition was weaker. when msx was added to the culture 6 hr after the addit ...	1989	2509191
photosynthetic co2 fixation and ribulose bisphosphate carboxylase/oxygenase activity of nostoc sp. strain ucd 7801 in symbiotic association with anthoceros punctatus.	the cyanobacterium nostoc sp. strain ucd 7801, immediately after separation from pure cultures of a reconstituted symbiotic association with the bryophyte anthoceros punctatus, exhibited a rate of light-dependent co2 fixation that was eightfold lower than that measured in the free-living growth state. ribulose bisphosphate carboxylase/oxygenase (rubpc/o) specific activity was also eightfold lower in cell extracts of symbiotic strain 7801 relative to that in free-living cultures. the in vitro act ...	1989	2509431
nostoc commune utex 584 gene expressing indole phosphate hydrolase activity in escherichia coli.	a gene encoding an enzyme capable of hydrolyzing indole phosphate was isolated from a recombinant gene library of nostoc commune utex 584 dna in lambda gt10. the gene (designated iph) is located on a 2.9-kilobase ecori restriction fragment and is present in a single copy in the genome of n. commune utex 584. the iph gene was expressed when the purified 2.9-kilobase dna fragment, free of any vector sequences, was added to a cell-free coupled transcription-translation system. a polypeptide with an ...	1989	2536677
occurrence and localization of phycoerythrin in symbiotic nostoc of cycas revoluta and in the free-living isolated nostoc 7422.	the phycobiliprotein phycoerythrin was localized in symbiotic and free-living nostoc of the cycad cycas using immunocytochemistry. in symbiotic nostoc, phycoerythrin was associated with the thylakoid membranes of vegetative cells and absent from heterocysts. similar cellular/subcellular localization was observed between symbiotic nostoc and the free-living cycas isolate nostoc 7422.	1989	16666621
immunologically cross-reactive and redox-competent cytochrome b6/f-complexes in the chlorophyll-free plasma membrane of cyanobacteria.	plasma and thylakoid membranes were separated and purified from cell-free extracts of the cyanobacteria anacystis nidulans, synechocystis 6714, anabaena variabilis and nostoc sp. strain mac. immunoblots of the membrane proteins using antisera raised against subunits i-iv of the chloroplast b6/f-complex gave evidence for the presence of a homologous complex in both plasma and thylakoid membranes from the four species of cyanobacteria investigated. both plasma and thylakoid membranes catalyzed the ...	1990	2121543
reconstitution of electron transport in photosystem i with psac and psad proteins expressed in escherichia coli.	a fusion protein, denoted psac1, which contains an amino-terminal extension of five amino acids (mehsm...) and is derived from an in vitro modified form of the psac gene of synechococcus sp. pcc 7002, has been over-expressed in escherichia coli. the product of the psad gene of nostoc sp. pcc 8009 has similarly been over-expressed. the psac1 and psad proteins can be combined with the photosystem i core protein of synechococcus sp. pcc 6301 to reconstitute electron transport from p700 to the termi ...	1990	2125006
identification of a periplasmic c-type cytochrome as electron donor to the plasma membrane-bound cytochrome oxidase of the cyanobacterium nostoc mac.	photoautotrophically grown cyanobacterium nostoc sp. strain mac (pcc 8009) released up to about 10 nmol of a c-type cytochrome per ml packed cells after treatment with edta under conditions that left the plasma membrane absolutely intact as judged from the absence of cytosolic proteins in the supernatant. spectra of the ascorbate reduced cytochrome revealed peaks at 553, 522 and 416 nm. the protein was purified to an a-553/a-275 ratio of 0.8. midpoint potential (at ph 7), isoelectric point and a ...	1990	2162667
chemical composition, in vitro protein digestibility and in vitro available iron of blue green alga, nostoc commune.	blue-green alga, nostoc commune, contained moderate amounts of protein and iron. its in vitro protein digestibility was 43.50%. the soluble and ionic iron from the alga was extractable to some extent at ph 1.5 but was not detectable at ph 8.0. the digestion by protease did not affect the iron detection. heat processing at 100 and 120 degrees c failed to increase the digestibility and the content of available iron. the dietary fiber in the alga may be responsible for low protein digestion and low ...	1990	2170966
effect of four heavy metals on the biology of nostoc muscorum.	this study presents the effects of cr, pb, ni and ag on growth, pigments, protein, dna, rna, heterocyst frequency, uptake of nh4+ and no3-, loss of electrolytes (na+ and k+), nitrate reductase and glutamine synthetase activities of nostoc muscorum. the statistical tests revealed a direct positive correlation between the metal concentration and inhibition of different processes. ni was found to be more toxic against growth, pigments and heterocyst differentiation compared to the other metals. inh ...	1990	1975195
genetic transformation of glutamine auxotrophy to prototrophy in the cyanobacterium nostoc muscorum.	glutamine auxotrophic (gln-) and l-methionine d,l-sulfoximine (msx) resistant (msxr) mutants of n. muscorum were isolated and characterized for nitrogen nutrition, nitrogenase activity, glutamine synthetase (gs) activity and glutamine amide, alpha-keto-glutarate amido transferase (gogat) activity. the glutamine auxotroph was found to the gogat-containing gs-defective, incapable of growth with n2 or nh4+ but capable of growth with glutamine as nitrogen source, thus, suggesting gs to be the primar ...	1990	1978772
structural and chemical properties of a flavodoxin from anabaena pcc 7119.	structural and chemical properties of a flavodoxin from anabaena pcc 7119 are described. the first 36 residues of the amino-terminal amino acid sequence have been determined and show extensive homology with flavodoxins isolated from other sources. anabaena flavodoxin exhibits a net negative change (-3) in the helix-1 segment as found with other cyanobacterial flavodoxins synechococcus 6301 (anacystis nidulans) and nostoc mac, but in contrast to the net positive charge found in this region in the ...	1990	2119231
isolation and characterization of hepatotoxic microcystin homologs from the filamentous freshwater cyanobacterium nostoc sp. strain 152.	a strain of the filamentous cyanobacterium nostoc sp. isolated from a lake in finland was found to produce at least nine hepatotoxic peptides with chemical and toxicological properties similar to those of the hepatotoxic hepta- and pentapeptides produced by other cyanobacteria. toxins were isolated and purified by high-performance liquid chromatography. amounts available for five of the purified toxins (p6, p14, p15, p16, and p18) were adequate for high-performance liquid chromatography amino ac ...	1990	2125813
cytotoxic, antiviral indolocarbazoles from a blue-green alga belonging to the nostocaceae.	6-cyano-5-methoxy-12-methylindolo[2,3-alpha]carbazole and 6-cyano-5-methoxyindolo[2,3-alpha]carbazole are responsible for most of the cytotoxicity and antiviral activity associated with the blue-green alga nostoc sphaericum ex-5-1. the compounds are active against hsv ii and show weak cytotoxicity against kb and lovo human carcinoma cell lines.	1990	2175302
dna probes show genetic variation in cyanobacterial symbionts of the azolla fern and a closer relationship to free-living nostoc strains than to free-living anabaena strains.	twenty-two isolates of anabaena azollae derived from seven azolla species from various geographic and ecological sources were characterized by dna-dna hybridization. cloned dna fragments derived from the genomic sequences of three different a. azollae isolates were used to detect restriction fragment length polymorphism among all symbiotic anabaenas. dna clones were radiolabeled and hybridized against southern blot transfers of genomic dnas of different isolates of a. azollae digested with restr ...	1990	16348182
boron requirement in cyanobacteria : its possible role in the early evolution of photosynthetic organisms.	the effect of boron on heterocystous and nonheterocystous dinitrogen fixing cyanobacteria was examined. the absence of boron in culture media inhibited growth and nitrogenase activity in nodularia sp., chlorogloeopsis sp., and nostoc sp. cultures. examinations of boron-deficient cultures showed changes in heterocyst morphology. however, cultures of nonheterocystous cyanobacteria, gloeothece sp. and plectonema sp., grown in the absence of boron did not show any alteration in growth or nitrogenase ...	1990	16667889
n(2)-fixation by freshly isolated nostoc from coralloid roots of the cycad macrozamia riedlei (fisch. ex gaud.) gardn.	nitrogenase (ec 1.7.99.2) activity (acetylene reduction) and nitrogen fixation ((15)n(2) fixation) were measured in cyanobacteria freshly isolated from the coralloid roots of macrozamia riedlei (fisch. ex gaud.) gardn. light and gas phase oxygen concentration had marked interactive effects on activity, with higher (up to 100-fold) rates of acetylene reduction and (15)n(2) fixation in light. the relationship between ethylene formation and n(2)-fixation varied in the freshly isolated cyanobacteria ...	1991	16668050