| epr characterization of an oxygen-evolving photosystem ii preparation from the transformable cyanobacterium synechocystis 6803. | the transformable cyanobacterium synechocystis 6803 has a photosynthetic apparatus that is similar to that of plants. because of the ease with which this organism can be genetically manipulated and isotopically labeled, synechocystis has been used extensively in recent studies of electron transfer in the water-splitting complex, photosystem ii. here, we present the first epr characterization of a highly active oxygen-evolving preparation from this organism. this preparation shows oxygen-evolutio ... | 1991 | 1850295 |
| gene cluster rpobc1c2 in cyanobacteria does not constitute an operon. | the core enzyme of the cyanobacterial dna-dependent rna polymerase contains a unique component, gamma, which is absent from the corresponding enzymes of other eubacteria. in the heterocystous cyanobacterium nostoc commune the gene encoding gamma, rpoc1, is immediately adjacent to, and downstream of, rpob. the rpoc1 gene, and a 3' adjacent gene, rpoc2, correspond to the single rpoc gene found in escherichia coli with respect to those domains conserved within their translational products. northern ... | 1991 | 1899176 |
| structural genes of glutamate 1-semialdehyde aminotransferase for porphyrin synthesis in a cyanobacterium and escherichia coli. | in bacteria 5-aminolevulinate, the universal precursor in the biosynthesis of the porphyrin nucleus of hemes, chlorophylls and bilins is synthesised by two different pathways: in non-sulphur purple bacteria (rhodobacter) or rhizobium 5-aminolevulinate synthase condenses glycine and succinyl-coa into 5-aminolevulinate as is the case in mammalian cells and yeast. in cyanobacteria, green and purple sulphur bacteria, as in chloroplasts of higher plants and algae a three step pathway converts glutama ... | 1991 | 1900346 |
| calcium-dependent protease of the cyanobacterium anabaena: molecular cloning and expression of the gene in escherichia coli, sequencing and site-directed mutagenesis. | it has been suggested that a calcium-dependent intracellular protease of the cyanobacterium, anabaena sp., participates in the differentiation of heterocysts, cells that are specialized for fixation of n2. clones of the structural gene (designated prca) for this protease from anabaena variabilis strain atcc 29413 and anabaena sp. strain pcc 7120 were identified via their expression in escherichia coli. the prca gene from a. variabilis was sequenced. the genes of both strains, mutated by insertio ... | 1991 | 1900347 |
| cadmium toxicity to photosynthesis and associated electron transport system of nostoc linckia. | | 1991 | 1900451 |
| isolation and complementation of nitrogen fixation mutants of the cyanobacterium anabaena sp. strain pcc 7120. | approximately 140 mutants of anabaena sp. strain pcc 7120 unable to grow aerobically on media lacking fixed nitrogen (fix-) were isolated after mutagenesis with diethyl sulfate and penicillin enrichment. a large cosmid library of wild-type anabaena sp. strain pcc 7120 dna was constructed in a mini-rk-2 shuttle vector, and seven mutants representing several morphologically abnormal heterocyst phenotypes were complemented. one of these mutants, 216, failed to differentiate heterocysts. all of thes ... | 1991 | 1900504 |
| expression of endogenous and foreign ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) genes in a rubisco deletion mutant of rhodobacter sphaeroides. | a rhodobacter sphaeroides ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) deletion strain was constructed that was complemented by plasmids containing either the form i or form ii co2 fixation gene cluster. this strain was also complemented by genes encoding foreign rubisco enzymes expressed from a rhodospirillum rubrum rubisco promoter. in r. sphaeroides, the r. rubrum promoter was regulated, resulting in variable levels of disparate rubisco molecules under different growth conditions ... | 1991 | 1900508 |
| the genetics of plant lipids. | | 1991 | 1901223 |
| crystals of anabaena pcc 7119 ferredoxin-nadp+ reductase. | crystals of ferredoxin-nadp+ reductase (fnr) from the cyanobacterium anabaena pcc 7119 are grown in the presence of polyethylene glycol 6000 and beta-octyl glucoside. they belong to the hexagonal system. the cell parameters are a = b = 87.8 a, c = 92.7 a, space group p6(1) or p6(5), and a vm of 3.0 a3/dalton for one molecule of 36,000 daltons per asymmetric unit. these crystals diffract strongly up to 1.9 a and are suitable for x-ray structural studies. | 1991 | 1901362 |
| light-dependent de-activation/re-activation of anabaena variabilis ferredoxin: nadp+ reductase. | the activity of ferredoxin: nadp+ reductase (fnr) was found to decline to approximately 20% maximal levels with little or no loss in enzyme levels when cultures of the cyanobacterium anabaena variabilis were maintained in the stationary phase of growth. re-activation of enzyme activity occurred when cells were diluted into either fresh or re-utilized media and illuminated. this reversible de-activation/re-activation process was found, in vivo, to be dependent on the intensity of light illuminati ... | 1991 | 1901489 |
| isolation and characterization of the gene encoding the principal sigma factor of the vegetative cell rna polymerase from the cyanobacterium anabaena sp. strain pcc 7120. | the filamentous cyanobacterium anabaena sp. strain pcc 7120 responds to combined nitrogen deprivation by forming specialized nitrogen-fixing cells at regular intervals along the filament. genetic and biochemical studies have indicated that regulation of gene expression during differentiation occurs at the transcriptional level. as part of a characterization of rna polymerase during differentiation, the gene encoding the 52-kda principal sigma factor of the anabaena sp. strain pcc 7120 vegetative ... | 1991 | 1901566 |
| a vector for analysis of promoters in the cyanobacterium anabaena sp. strain pcc 7120. | a plasmid vector containing a multiple-cloning site followed by a promoterless chloramphenicol acetyltransferase (cat) gene, protected by transcription terminators and mobilizable by conjugation from escherichia coli into anabaena sp. strain pcc 7120, was constructed. the utility of the vector was shown by deletion analysis of the promoter region of the anabaena psbb gene. | 1991 | 1901575 |
| ferredoxin and ribosomal protein s10 are encoded on the cyanelle genome of cyanophora paradoxa. | the petf and rsp10 genes of the cyanellar genome of the taxonomically ambiguous flagellate cyanophora paradoxa have been cloned, mapped, and sequenced. in higher plants these genes are not encoded in the chloroplast dna, but are encoded in the nucleus. the c. paradoxa petf gene predicts a protein of 99 amino acids (aa) which is more similar to type-i ferredoxins of diverse cyanobacteria than to those of green algae, dinoflagellates, and higher plants. the rsp10 gene (rspj) predicts a protein of ... | 1991 | 1901820 |
| the "anchor polypeptide" of cyanobacterial phycobilisomes. molecular characterization of the synechococcus sp. pcc 6301 apce gene. | in cyanobacteria, light energy is mainly harvested by the phycobiliproteins that form the phycobilisome rods, and funneled to the photosynthetic reaction centers through the core components. among them, allophycocyanin (alpha ap, beta ap) and the so-called lcm play a major role. this report deals with the characterization of the apce gene from synechococcus sp. pcc 6301 which specifies the lcm. it maps upstream from the apca gene (alpha ap). transcriptional analyses demonstrate that the apcabc g ... | 1991 | 1901865 |
| growth response of freshwater algae, anabaena flos-aquae and selenastrum capricornutum to atrazine and hexazinone herbicides. | | 1991 | 1902129 |
| light-activated heterotrophic growth of the cyanobacterium synechocystis sp. strain pcc 6803: a blue-light-requiring process. | a glucose-tolerant strain of synechocystis sp. strain 6803 will not grow on glucose under complete darkness unless given a daily pulse of white light, typically 5 min of 40 mumol m-2 s-1 (light-pulsed conditions). the light pulse is insufficient for photoautotrophy, as glucose is required and growth yield is dependent on glucose concentration. growth rate is independent of fluence, but growth yield is dependent on fluence, saturating at 40 to 75 mumol m-2 s-1. a synechocystis strain 6803 psba mu ... | 1991 | 1902208 |
| absence of glycosylation on cyanobacterial phycobilisome linker polypeptides and rhodophytan phycoerythrins. | the 27-, 30-, and 33-kda rod linker polypeptides and the 75-kda core linker of phycobilisomes from the cyanobacterium synechococcus sp. strain pcc 7942 have been reported to be glycoproteins with carbohydrate contents ranging from 3.2 to 18.8% and composed of n-acetylgalactosamine and glucose (h.c. riethman, t.p. mawhinney, and l.a. sherman, j. bacteriol. 170:2433-2440, 1988). synechococcus sp. strain pcc 7942 phycobilisomes were purified extensively, and the linker polypeptides were separated f ... | 1991 | 1902214 |
| the relative catalytic specificities of the large subunit core of synechococcus ribulose bisphosphate carboxylase/oxygenase. | the relative specificities of the carboxylase and oxygenase reactions catalyzed by the recombinant large subunit core (l8) of synechococcus ribulose 1,5-bisphosphate carboxylase have been determined. the l8 core still retained the ability to catalyze both reactions but at a much reduced turnover rate, about 0.6% of the holoenzyme. the fate of ribulose 1,5-bisphosphate during carboxylation and oxygenation by l8 was compared with the synechococcus holoenzyme (reconstituted from l8 and recombinant ... | 1991 | 1902218 |
| mutations in the small subunit of cyanobacterial ribulose-bisphosphate carboxylase/oxygenase that modulate interactions with large subunits. | in the cyanobacterium anacystis nidulans (synechococcus pcc6301), ribulose 1,5-bisphosphate carboxylase/oxygenase (rbu-p2 carboxylase) is composed of eight large subunits and eight small subunits. there are three regions of the small subunit that contain amino acids that are conserved throughout evolution, from bacteria to higher plants. since the function of the small subunit is not fully understood, site-directed mutagenesis was performed on highly conserved residues in the first and second co ... | 1991 | 1902220 |
| crystallization and structure determination to 2.5-a resolution of the oxidized [2fe-2s] ferredoxin isolated from anabaena 7120. | the molecular structure of the oxidized form of the [2fe-2s] ferredoxin isolated from the cyanobacterium anabaena species strain pcc 7120 has been determined by x-ray diffraction analysis to a nominal resolution of 2.5 a and refined to a crystallographic r factor of 18.7%. crystals used in this investigation belong to the space group p2(1)2(1)2(1) with unit cell dimensions of a = 37.42 a, b = 38.12 a, and c = 147.12 a and two molecules in the asymmetric unit. the three-dimensional structure of t ... | 1991 | 1902376 |
| evaluation of potential chemoprotectants against microcystin-lr hepatotoxicity in mice. | microcystin-lr (mclr) is a potent cyclic heptapeptide hepatotoxin produced by the blue-green algae, microcystis aeruginosa. toxic blooms of this cyanobacteria have been reported throughout the temperate world. in spite of the potential economic loss and health hazard posed by this toxin, few studies on the development of an antidote have been conducted. thus, a number of biologically active compounds were tested in mice for effectiveness in preventing the toxicity of a lethal dose of mclr (100 m ... | 1991 | 1902496 |
| outbreaks of diarrheal illness associated with cyanobacteria (blue-green algae)-like bodies--chicago and nepal, 1989 and 1990. | recent reports have described the detection of cyanobacteria (blue-green algae)-like bodies (clb) in the stools of persons with a prolonged syndrome of diarrhea, anorexia, and fatigue (1-3). in each of these reports, affected persons either were immunocompromised or had recently traveled to tropical countries. during 1989 and 1990, the first three reported outbreaks of this clb-associated syndrome occurred in immunocompetent populations, affecting at least 150 persons. this report summarizes inv ... | 1991 | 1902548 |
| protection against microcystin-lr-induced hepatotoxicity by silymarin: biochemistry, histopathology, and lethality. | microcystin-lr, a cyclic heptapeptide synthesized by the blue-green algae, microcystis aeruginosa, is a potent hepatotoxin. pathological examination of livers from mice and rats that received microcystin-lr revealed severe, peracute, diffuse, centrilobular hepatocellular necrosis, and hemorrhage. these changes were correlated with increased serum activities of sorbitol dehydrogenase, alanine aminotransferase, and lactate dehydrogenase. pretreatment of either rats or mice with a single dose of si ... | 1991 | 1902564 |
| a new photocatalytic material based on algal cells. | metallic platinum was deposited at surfaces of intracellular photosynthetic membranes of whole cells of a cyanobacterium (blue-green alga). the deposited platinum particles acted as a catalyst for generation of hydrogen from photosynthetic decomposition of water in the absence of other exogenous electron transfer agents. this technique represents a means of placing metal catalysts in contact with intracellular structures of microorganisms. | 1991 | 1902667 |
| effect of route of exposure and repeated doses on the acute toxicity in mice of the cyanobacterial nicotinic alkaloid anatoxin-a. | anatoxin-a (antx-a) is a potent nicotinic cholinergic alkaloid produced by some toxigenic strains of cyanobacteria. we have examined i.p. and oral ld50 values of two antx-a producing anabaena sp. and synthetic (+)-antx-a in outbred swiss webster mice. all three appeared equivalent by i.p. injection, but anabaena flos-aquae nrc-44-1 was approximately twice as potent orally as the other two. additionally, we were unable to demonstrate development of any biologically significant tolerance to acute ... | 1991 | 1903000 |
| the uptake of the cyanobacterial hepatotoxin microcystin by isolated rat hepatocytes. | microcystin-ym a cyclic heptapeptide hepatotoxin isolated from the cyanobacterium microcystis aeruginosa was radiolabeled with 125i, and used to investigate the uptake of the toxin by freshly isolated rat hepatocytes. the uptake was temperature dependent with apparent activation energy of 18 kcal/mole (77 kj/mole) for the initial rate of uptake. uptake of non-toxic (10-20 nm) doses of microcystin by hepatocytes continued with time, the intracellular to extracellular distribution ratio for the to ... | 1991 | 1903001 |
| isolation, crystallization, crystal structure analysis and refinement of constitutive c-phycocyanin from the chromatically adapting cyanobacterium fremyella diplosiphon at 1.66 a resolution. | constitutive phycocyanin from cyanobacterium fremyella diplosiphon (calothrix sp. pcc 7601) grown in green light, has been isolated and crystallized. the crystals belong to the space group r3 with cell constants a = b = 180.26 a, c = 61.24 a, alpha = beta = 90 degrees, gamma = 120 degrees. the crystal structure has been determined by patterson search techniques using the molecular model of c-phycocyanin from the cyanobacterium agmenellum quadruplicatum. the asymmetric unit of the crystal cell co ... | 1991 | 1899708 |
| sequence and expression of genes encoding the large and small subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase from chromatium vinosum. | a dna fragment bearing genes for the large (rbcl) and small (rbcs) subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) was cloned from the photosynthetic purple sulfur bacterium chromatium vinosum. enzymatically fully active rubisco was synthesized in escherichia coli cells when the cloned dna was placed downstream of tac promoter. nucleotide (nt) sequences of rbcl-rbcs were more homologous to cyanobacterial counterparts than to those from alcaligenes eutrophus or higher plants ... | 1991 | 1899846 |
| phycoerythrins of marine unicellular cyanobacteria. i. bilin types and locations and energy transfer pathways in synechococcus spp. phycoerythrins. | marine synechococcus strains wh8103, wh8020, and wh7803 each possess two different phycoerythrins, pe(ii) and pe(i), in a weight ratio of 2-4:1. pe(ii) and pe(i) differ in amino acid sequence and in bilin composition and content. studies with strain wh7803 indicated that both pe(ii) and pe(i) were present in the same phycobilisome rod substructures and that energy absorbed by pe(ii) was transferred to pe(i). strain wh8103 and wh8020 pe(i)s carried five bilin chromophores thioether-linked to cyst ... | 1991 | 1903388 |
| phycoerythrins of marine unicellular cyanobacteria. ii. characterization of phycobiliproteins with unusually high phycourobilin content. | a survey of marine unicellular cyanobacterial strains for phycobiliproteins with high phycourobilin (pub) content led to a detailed investigation of synechocystis sp. wh8501. the phycobiliproteins of this strain were purified and characterized with respect to their bilin composition and attachment sites. amino-terminal sequences were determined for the alpha and beta subunits of the phycocyanin and the major and minor phycoerythrins. the amino acid sequences around the attachment sites of all bi ... | 1991 | 1903389 |
| phycoerythrins of marine unicellular cyanobacteria. iii. sequence of a class ii phycoerythrin. | the genes for the alpha and beta subunits of a novel six bilin-bearing (class ii) phycoerythrin were cloned from synechococcus sp. wh8020 and sequenced. the cloned genes (mpea and mpeb) were detected by homology with the genes for c-phycoerythrin from pseudanabaena sp. pcc7409. the mpe locus occurs once in the genome and is arranged similarly to that of many other phycobiliproteins, with mpea shortly 3' of mpeb. sequence comparison suggests that this phycoerythrin (and perhaps all class ii phyco ... | 1991 | 1903390 |
| purification of glutamyl-trna reductase from synechocystis sp. pcc 6803. | delta-aminolevulinic acid is the universal precursor for all tetrapyrroles including hemes, chlorophylls, and bilins. in plants, algae, cyanobacteria, and many other bacteria, delta-aminolevulinic acid is synthesized from glutamate in a reaction sequence that requires three enzymes, atp, nadph, and trna(glu). the three enzymes have been characterized as glutamyl-trna synthetase, glutamyl-trna reductase, and glutamate-1-semialdehyde aminotransferase. all three enzymes have been separated and part ... | 1991 | 1903397 |
| deletion of the psbg1 gene of the cyanobacterium synechocystis sp. pcc6803 leads to the activation of the cryptic psbg2 gene. | the genes psbg1 and psbg2 in the cyanobacterium synechocystis sp. pcc6803 are homologous. the psbg1 gene is located on the chromosome and is part of the ndhc--psbg1--orf157 operon, while psbg2 is located on a plasmid and is not flanked by equivalent ndhc or orf157 genes. mutants in which psbg1 is deleted grow well under autotrophic conditions, while their growth is impeded in mixotrophic medium. these results argue against a functional role for psbg1 in photosynthesis, i.e. photosystem ii, and a ... | 1991 | 1903500 |
| a gene homologous to the subunit-2 gene of nadh dehydrogenase is essential to inorganic carbon transport of synechocystis pcc6803. | a clone that transforms the rka mutant of synechocystis pcc6803 defective in inorganic carbon (ci) transport to the wild-type phenotype was isolated from a cyanobacterial genomic library. the clone contained an 11.8-kilobase-pair dna insert. sequencing of the insert dna in the region of the mutation in rka revealed an open reading frame (designated as ndhb), which showed extensive amino acid sequence homology to the subunit-2 genes of nadh dehydrogenase (ec 1.6.99.3) (ndhb) of chloroplasts and m ... | 1991 | 1903537 |
| site-directed mutagenesis of the psbc gene of photosystem ii: isolation and functional characterization of cp43-less photosystem ii core complexes. | two mutants of synechocystis pcc 6803 lacking the psbc gene product cp43 were constructed by site-directed mutagenesis. analysis of cells and thylakoid membranes of these mutants indicates that ps ii reaction centers accumulate to a concentration of about 10% of that of wt cells. ps ii core complexes isolated from mutants lacking the cp43 subunit show light-driven electron transfer from the secondary electron donor z to the primary quinone electron acceptor qa with a quantum yield similar to tha ... | 1991 | 1903653 |
| cyanobacterial thylakoid membrane proteins are reversibly phosphorylated under plastoquinone-reducing conditions in vitro. | reversible, light-dependent protein phosphorylation was observed in isolated thylakoid membranes of the cyanobacterium synechococcus 6301. a polypeptide of 15 kda in particular was phosphorylated under plastoquinone-reducing conditions and was not phosphorylated under plastoquinone-oxidising conditions. phosphorylation and dephosphorylation reactions involving this and several other membrane polypeptides showed sensitivity to inhibitors of protein kinases and phosphatases. changes in phosphoryla ... | 1991 | 1903715 |
| carotenoid composition in the cyanobacterium phormidium laminosum. effect of nitrogen starvation. | when pigments of the non-n2-fixing cyanobacterium phormidium laminosum were carefully extracted and analyzed in a completely o2-free atmosphere, by either high performance liquid chromatography (hplc) or thin layer chromatography (tlc), the presence of only two carotenoids (namely, beta-carotene and nostoxanthin) was detected. however, exposure of pigments to an air atmosphere during their manipulation led to the rapid appearance in the organic extracts of at least three additional carotenoids ( ... | 1991 | 1903716 |
| a complex family of class-ii restriction endonucleases, dsai-vi, in dactylococcopsis salina. | a series of class-ii restriction endonucleases (enases) was discovered in the halophilic, phototrophic, gas-vacuolated cyanobacterium dactylococcopsis salina sp. nov. the six novel enzymes are characterized by the following recognition sequences and cut positions: 5'-c decreases crygg-3' (dsai); 5'-gg decreases cc-3' (dsaii); 5'-r decreases gatcy-3' (dsaiii); 5'-g decreases gwcc-3' (dsaiv); 5'-decreases ccngg-3' (dsav); and 5'-gtmkac-3' (dsavi), where w = a or t, m = a or c, k = g or t, and n = ... | 1991 | 1899848 |
| nitrogenases. | | 1991 | 1903384 |
| pyruvate is a by-product of catalysis by ribulosebisphosphate carboxylase/oxygenase. | pyruvate is a minor product of the reaction catalyzed by ribulosebisphosphate carboxylase/oxygenase from spinach leaves. labeled pyruvate was detected, in addition to the major labeled product, 3-phosphoglycerate, when 14co2 was the substrate. pyruvate production was also measured spectrophotometrically in the presence of lactate dehydrogenase and nadh. the km for co2 of the pyruvate-producing activity was 12.5 microm, similar to the co2 affinity of the 3-phosphoglycerate-producing activity. no ... | 1991 | 1903385 |
| isolation and identification of two new synechococcus-derived restriction endonucleases, slei and sspai, isoschisomers of ecorii. | | 1991 | 1904151 |
| evolutionary relationships among eubacteria, cyanobacteria, and chloroplasts: evidence from the rpoc1 gene of anabaena sp. strain pcc 7120. | rna polymerases of cyanobacteria contain a novel core subunit, gamma, which is absent from the rna polymerases of other eubacteria. the genes encoding the three largest subunits of rna polymerase, including gamma, have been isolated from the cyanobacterium anabaena sp. strain pcc 7120. the genes are linked in the order rpob, rpoc1, rpoc2 and encode the beta, gamma, and beta' subunits, respectively. these genes are analogous to the rpobc operon of escherichia coli, but the functions of rpoc have ... | 1991 | 1904436 |
| gas vesicle synthesis in the cyanobacterium pseudanabaena sp.: occurrence of a single photoregulated gene. | gas vesicles are subcellular inclusions found in a large number of aquatic prokaryotes. the gvpa gene, which frequently occurs as a multigene family, encodes the major gas vesicle structural protein. in several cyanobacteria, another gene, gvpc, encodes a different protein which might be a dispensable element for gas vesicle formation. we report here the molecular characterization of a gvpa gene in pseudanabaena sp. pcc 6901. in this planktonic cyanobacterium, it is the only gvp gene which could ... | 1991 | 1904525 |
| identification and initial utilization of a portion of the smaller plasmid of anabaena variabilis atcc 29413 capable of replication in anabaena sp. strain m-131. | anabaena variabilis atcc 29413 contains two cryptic plasmids. clones of the smaller (41 kb) plasmid, designated prds1, in cosmid vectors were used to construct a physical map. a clone bank of prds1 constructed by ligating fragments from a xhoii digest of a prds1 cosmid clone into a mobilizable plasmid was used to locate an origin of replication of prds1. because we were unable to cure a. variabilis of prds1, the clone bank was transferred by conjugation to another strain of anabaena sp., strain ... | 1991 | 1904532 |
| a neurotoxic factor associated with the bloom-forming cyanobacterium trichodesmium. | | 1991 | 1904659 |
| electromyographic assessment of the neuromuscular blockade produced in vivo by anatoxin-a in the rat. | the indirectly evoked compound action potentials (ecap) of the plantar muscles of the rat were used to investigate the pharmacodynamics in vivo of the neuromuscular blockade produced by anatoxin-a. onset time to maximum depression and the magnitude of maximum depression in amplitude of the ecap were dose-dependent. the mean maximum percent depression (+/- s.d.) of the ecap induced by single, supramaximal stimulations of the posterior tibial nerve after i.v. doses of (+)anatoxin-a hydrochloride a ... | 1991 | 1904660 |
| molecular cloning and expression of spirulina platensis acetohydroxy acid synthase genes in escherichia coli. | the coding sequence for spirulina platensis acetohydroxy acid synthase (ahas, ec 4.1.3.18) is shown to be contained within a 4.2 kb clai fragment (ilvx) that has been cloned from a recombinant lambda library. this fragment was able to complement a suitable mutant of escherichia coli when inserted into the clai site of plasmid pat153 in either orientation, demonstrating that transcription of ilvx originated within the cloned fragment. the probe used for hybridization experiments was the correspon ... | 1991 | 1904703 |
| alterations in the accumulation of adenylylated nucleotides in heavy-metal-ion-stressed and heat-stressed synechococcus sp. strain pcc 6301, a cyanobacterium, in light and dark. | heavy-metal-ion- (cd2+, cu2+, pb2+, hg2+ and zn2+) or heat (50 degrees c)-stress treatments of the unicellular cyanobacterium synechococcus sp., strain pcc 6301, under both light and dark conditions led to the accumulation of bis(5'-nucleosidyl)oligophosphates: ap4a, ap4g, ap3a, ap3g and ap3gp2. under light regimens, the accumulation of ap4a and ap4g is more characteristic of heavy-metal-ion-stressed cells, whereas the accumulation of ap3a, ap3g and ap3gp2 is the dominant feature of heavy-metal- ... | 1991 | 1904720 |
| site directed mutagenesis of the heme axial ligands of cytochrome b559 affects the stability of the photosystem ii complex. | cytochrome (cyt) b559, an integral membrane protein, is an essential component of the photosystem ii (psii) complex in the thylakoid membranes of oxygenic photosynthetic organisms. cyt b559 has two subunits, alpha and beta, each with one predicted membrane spanning alpha-helical domain. the heme cofactor of this cytochrome is coordinated between two histidine residues. each of the two subunit polypeptides of cyt b559 has one his residue. to investigate the influence of these his residues on the ... | 1991 | 1904816 |
| photosynthetic electron transport controls nitrogen assimilation in cyanobacteria by means of posttranslational modification of the glnb gene product. | a glnb gene is identified in the cyanobacterium synechococcus sp. pcc 7942, and its gene product is found to be covalently modified as a result of imbalance in electron transfer in photosynthesis, where photosystem ii is favored over photosystem i. the gene was cloned and sequenced and found to encode a polypeptide of 112 amino acid residues, whose sequence shows a high degree of similarity to the escherichia coli regulatory protein, pii. in e. coli, pii is involved in signal transduction in tra ... | 1991 | 1905010 |
| monomeric and trimeric forms of photosystem i reaction center of mastigocladus laminosus: crystallization and preliminary characterization. | photosystem i (psi) reaction centers (rcs) of the thermophilic cyanobacterium mastigocladus laminosus were purified and characterized. the psi rc was obtained in two forms, monomeric and trimeric. the two forms contained the same number of pigments per p700 and displayed similar photochemical activities. the two forms had nearly identical polypeptide subunit compositions; the only observed difference was an additional subunit of about 12 kda observed in the trimeric form. the purified preparatio ... | 1991 | 1905020 |
| immunosuppressive substances from blue-green algae. | | 1991 | 1905459 |
| fine-structural and chemical analyses on inner and outer sheath of the cyanobacterium gloeothece sp. pcc 6909. | cells of the unicellular cyanobacterium gloeothece sp. pcc 6909 are surrounded by an inner (enclosing 1-2 cells) and an outer (enclosing cell groups) sheath. using conventional epon-embedding in combination with ruthenium-red staining, the inner and outer sheaths appeared similar and displayed multiple bands of electron-dense subunits. however, embedding in nanoplast resin to avoid shrinkage led to the detection of two distinct zones (inner and outer zone) each with several distinct layers. the ... | 1991 | 1905514 |
| toxicity and toxins of natural blooms and isolated strains of microcystis spp. (cyanobacteria) and improved procedure for purification of cultures. | all samples of cyanobacterial blooms collected from 1986 to 1989 from lake kasumigaura, ibaraki prefecture, japan, were hepatotoxic. the 50% lethal doses (ld50s) of the blooms to mice ranged from 76 to 556 mg/kg of body weight. sixty-eight microcystis cell clones (67 microcystis aeruginosa and 1 m. viridis) were isolated from the blooms. twenty-three strains (including the m. viridis strain) were toxic. however, the ratio of toxic to nontoxic strains among the blooms varied (6 to 86%). microcyst ... | 1991 | 1905521 |
| oxidative stress responses in the unicellular cyanobacterium synechococcus pcc 7942. | oxidative stress responses were tested in the unicellular cyanobacterium synechococcus pcc 7942 (r-2). cells were exposed to hydrogen peroxide, cumene hydroperoxide and high light intensities. the extent and time course of oxidative stress were related to the activities of ascorbate peroxidase and catalase. ascorbate peroxidase was found to be the major enzyme involved in the removal of hydrogen peroxide under the tested oxidative stress. catalase activity was inhibited in cells, treated with hi ... | 1991 | 1905671 |
| gabaculine-resistant glutamate 1-semialdehyde aminotransferase of synechococcus. deletion of a tripeptide close to the nh2 terminus and internal amino acid substitution. | glutamate 1-semialdehyde aminotransferase (gsa-at) is the last enzyme in the c5 pathway converting glutamate into the tetrapyrrole precursor delta-aminolevulinate in plants, algae, and several bacteria. sequence analysis of the genes encoding gsa-at in barley, synechococcus, and escherichia coli revealed 50-70% similarity in the primary structures of the proteins. the enzyme is inhibited rapidly by gabaculine when added in approximately stoichiometric amounts with the enzyme. a gabaculine-tolera ... | 1991 | 1905724 |
| orientation and linear dichroism of mastigocladus laminosus phycocyanin trimer and nostoc sp. phycocyanin dodecamer in stretched poly(vinyl alcohol) films. | the linear dichroism (ld) spectra of the c-phycocyanin (c-pc) trimer disks oriented in poly(vinyl alcohol) films (pva) at room temperature and at 95 k were determined. utilizing the known atomic coordinates of the chromophores (schirmer, t., bode, w. and huber, r. (1987) j. mol. biol. 196, 677-695) and theoretical estimates of the orientations of the transition dipole moments relative to the molecular framework, the ld spectra were simulated using the pairwise exciton interaction model of sauer ... | 1991 | 1905956 |
| inhibition of no3-, nh4+, and po4(3-) uptake in anabaena doliolum exposed to a petroleum oil. | the aqueous extract of assam crude inhibited the uptake of no3-, nh4+, and po4(3-) in anabaena doliolum and the response was essentially concentration dependent. inhibition was most severe for the uptake of nh4+ followed in decreasing order by po4(3-) and no3-. uptake of nutrients was competitively inhibited as in all the cases oil extract did not change vmax; however, apparent km was increased. the nature of oil components competing with nutrient ions is not certain at present. oil-induced inhi ... | 1991 | 1905997 |
| an nad-specific glutamate dehydrogenase from cyanobacteria. identification and properties. | the unicellular cyanobacterium synechocystis sp. pcc 6803 presents a hexameric nad-specific glutamate dehydrogenase with a molecular mass of 295 kda. the enzyme differs from the nadp-glutamate dehydrogenase found in the same strain and is coded by a different gene. nad-glutamate dehydrogenase shows a high coenzyme specificity, catalyzes preferentially glutamate formation and presents km values for ammonium, nadh and 2-oxoglutarate of 4.5 mm, 50 microm and 1.8 mm respectively. an animating role f ... | 1991 | 1906012 |
| spirulina as a source of vitamin a. | experiments were carried out to assess spirulina fusiformis-a blue green algae as a source of vitamin a in rats. in one experiment, the control rats were fed synthetic vitamin a and the experimental rats spirulina as the sole source of vitamin a. the liver vitamin a concentration of spirulina-fed rats of both sexes was found to be significantly higher than that of the control rats. in another experiment the absorption of carotenes from the solvent extract of spirulina and their availability (vit ... | 1991 | 1906616 |
| facile detection of anatoxin-a in algal material by thin-layer chromatography with fast black k salt. | a method for facile high-capacity screening of algal samples for anatoxin-a (antx-a), a potent neurotoxin of anabaena flos-aquae, is presented. the method is based on in situ colour reaction of algal extracts containing antx-a on a thin-layer chromatographic plate with the diazonium reagent fast black k salt, and subsequent separation of the orange-red product. the product, shown to be a stable 3,3-dialkyltriazene, is derived from a reaction involving the aliphatic secondary amino group of antx- ... | 1991 | 1906687 |
| two-dimensional magnetization exchange spectroscopy of anabaena 7120 ferredoxin. nuclear overhauser effect and electron self-exchange cross peaks from amino acid residues surrounding the 2fe-2s* cluster. | hyperfine 1h nmr signals of the 2fe-2s* vegetative ferredoxin from anabaena 7120 have been studied by two-dimensional (2d) magnetization exchange spectroscopy. the rapid longitudinal relaxation rates of these signals required the use of very short nuclear overhauser effect (noe) mixing times (0.5-20 ms). the resulting pattern of noe cross-relaxation peaks when combined with previous 1d noe results [dugad, l. b., la mar, g. n., banci, l., & bertini, i. (1990) biochemistry 29, 2263-2271] led to el ... | 1991 | 1906741 |
| [the immunosuppressive action of contents of oscillatoria redekai van goor (cyanphyceae)]. | | 1991 | 1907011 |
| the molecular basis of resistance to the herbicide norflurazon. | we have cloned and sequenced a gene, pds, from the cyanobacterium synechococcus pcc7942 that is responsible for resistance to the bleaching herbicide norflurazon. a point mutation in that gene, leading to an amino acid substitution from valine to glycine in its polypeptide product, was found to confer this resistance. previous studies with herbicide-resistant mutants have indicated that this gene encodes phytoene desaturase (pds), a key enzyme in the biosynthesis of carotenoids. a short amino ac ... | 1991 | 1907510 |
| primary structure of the psbn-psbh-petc-peta gene cluster of the cyanobacterium synechocystis pcc 6803. | | 1991 | 1907512 |
| cyanobacteria contain a mitochondrial complex i-homologous nadh-dehydrogenase. | thylakoid and cytoplasmic membranes of the cyanobacterium synechocystis sp. pcc 6803 were purified by sucrose gradient centrifugation. both membranes oxidize nadh in a rotenone-sensitive reaction. antibodies prepared against psbg/ndhk and ndhj fusion proteins detect the corresponding polypeptides in both membrane preparations. this demonstrates that a nadh-dehydrogenase, homologous to the mitochondrial nadh-ubiquinone-oxidoreductase (complex i of the respiratory chain) is present in cyanobacteri ... | 1991 | 1907569 |
| 1h and 15n resonance assignments of oxidized flavodoxin from anacystis nidulans with 3d nmr. | proton and nitrogen-15 sequence-specific nuclear magnetic resonance assignments have been determined for recombinant oxidized flavodoxin from anacystis nidulans (169 residues, mr 19,048). assignments were obtained by using 15n-1h heteronuclear three-dimensional (3d) nmr spectroscopy on a uniformly nitrogen-15 enriched sample of the protein, ph 6.6, at 30 degrees c. for 165 residues, the backbone and a large fraction of the side-chain proton resonances have been assigned. medium- and long-range n ... | 1991 | 1907844 |
| partial conservation of the 5' ndhe-psac-ndhd 3' gene arrangement of chloroplasts in the cyanobacterium synechocystis sp. pcc 6803: implications for ndh-d function in cyanobacteria and chloroplasts. | the psac gene, which encodes the 8.9 kda iron-sulfur containing subunit of photosystem i, has been sequenced from synechocystis sp. pcc 6803 and shows greater similarity to reported plant sequences than other cyanobacterial psac sequences. the deduced amino acid sequence of the protein encoded by the synechocystis psac gene is identical to the tobacco psa-c sequence. in plants psac is located in the small single-copy region of the chloroplast genome between two genes (designated ndhe and ndhd) w ... | 1991 | 1907869 |
| toxic marine and freshwater algae: an occupational hazard? | | 1991 | 1908696 |
| orientation of carotenoids in the outer membrane of synechocystis pcc 6714 (cyanobacteria). | the orientation of outer membrane carotenoids from synechocystis pcc 6714 and synechococcus pcc 6307 was studied by linear dichroism spectrophotometry. uniaxially oriented, tilted outer membrane films revealed a significant linear dichroism after rotating the polarization vector of the incident light beam, indicating a predominant orientation of the carotenoid transition moments perpendicular to the outer membrane plane. values for the reduced dichroism at the absorbance maxima presented a linea ... | 1991 | 1908700 |
| identities of four low-molecular-mass subunits of the photosystem i complex from anabaena variabilis atcc 29413. evidence for the presence of the psai gene product in a cyanobacterial complex. | photosystem i (psi) complex of anabaena variabilis atcc 29413 consists of at least 11 subunits, 9 of which are resolved by high resolution gel electrophoresis. n-terminal amino acid sequences of the four subunits with molecular masses of 6.8, 5.2, 4.8 and 3.5 kda were determined. based on the sequence homology, the 3.5 kda subunit was revealed to correspond to psi-i (the gene product of psai), which had so far been detected only in higher plant psi complexes. the 6.8 kda protein and 4.8 kda prot ... | 1991 | 1908790 |
| analysis of paralytic shellfish poisons by capillary electrophoresis. | a capillary electrophoresis (ce) method with uv detection is described for the separation and determination of underivatized toxins associated with paralytic shellfish poisoning (psp). confirmation of the electrophoretic peaks was facilitated by mass spectrometric (ms) detection using an ionspray ce-ms interface and by high-performance liquid chromatography with fluorescence detection. the determination of psp toxins, such as saxitoxin and neosaxitoxin, in toxic dinoflagellates and scallops is d ... | 1991 | 1908861 |
| sequence analysis and phylogenetic reconstruction of the genes encoding the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase from the chlorophyll b-containing prokaryote prochlorothrix hollandica. | prochlorophytes similar to prochloron sp. and prochlorothrix hollandica have been suggested as possible progenitors of the plastids of green algae and land plants because they are prokaryotic organisms that possess chlorophyll b (chl b). we have sequenced the prochlorothrix genes encoding the large and small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase(rubisco), rbcl and rbcs, for comparison with those of other taxa to assess the phylogenetic relationship of this species. length d ... | 1991 | 1904095 |
| effect of aluminum and ph on the growth of anacystis nidulans. | | 1991 | 1903995 |
| cloning of the psbk gene from synechocystis sp. pcc 6803 and characterization of photosystem ii in mutants lacking psii-k. | we cloned and sequenced the psbk gene, coding for a small photosystem ii component (psii-k), from the transformable cyanobacterium, synechocystis sp. pcc 6803, and determined the n-terminal sequence of mature psii-k. the psbk gene product is processed by cleaving off eight amino acid residues from the n terminus. a mutant lacking psbk was constructed; this mutant grew photoautotrophically, but its growth rate was reduced. the number of photosystem ii reaction centers on a chlorophyll basis was d ... | 1991 | 1904061 |
| interactive image analysis system to determine the motility and velocity of cyanobacterial filaments. | an interactive image analysis system has been developed to analyse and quantify the percentage of motile filaments and the individual linear velocities of organisms. the technique is based on the "difference" image between two digitized images taken from a time-lapse video recording 80 s apart which is overlaid on the first image. the bright lines in the difference image represent the paths along which the filaments have moved and are measured using a crosshair cursor controlled by the mouse. ev ... | 1991 | 1908871 |
| [energy yielding metabolism of cyanophytes]. | | 1991 | 1909036 |
| [molecular organization of cyanobacterial photosystems]. | | 1991 | 1909037 |
| [nitrogen fixation in cyanophyta]. | | 1991 | 1909038 |
| [the cyanobacterial membrane architecture in relation to the low-temperature tolerance]. | | 1991 | 1909039 |
| [transport systems in cyanobacteria]. | | 1991 | 1909040 |
| [osmoregulation in cyanobacteria]. | | 1991 | 1909041 |
| [genome structure, molecular genetics and genetic engineering of cyanobacteria]. | | 1991 | 1909042 |
| [a list of cyanobacterial genes]. | | 1991 | 1909043 |
| energy transfer kinetics in c-phycocyanin from cyanobacterium westiellopsis prolifica studied by pump-probe techniques. | the relaxation processes of c-phycocyanin at different aggregates have been investigated by pump-probe techniques. the lifetimes of ground state recovery measured at various wavelengths are analyzed by computer fitting of the kinetic data to a sum of three and four exponentials for monomers and trimers according to the nonlinear least-square principle, respectively. the shortest lifetime (about 56ps) is due to beta s----beta f transfer in one monomer, that decreases to 31ps in trimer due to the ... | 1991 | 1909122 |
| arginine residues in the d2 polypeptide may stabilize bicarbonate binding in photosystem ii of synechocystis sp. pcc. | bicarbonate (hco3-) causes a significant and reversible stimulation of anion-inhibited electron flow in photosystem ii of higher plants and cyanobacteria. to test if selected arginine (arg) residues are involved in the binding of hco3-, we utilized oligonucleotide-directed mutagenesis to construct synechocystis sp. pcc 6803 mutants carrying mutations in arg residues in the d2 protein. measurements of oxygen evolution showed that the d2 mutants r233q (arginine-233----glutamine) and r251s (arginin ... | 1991 | 1909178 |
| nucleotide sequence of a 16s rrna gene from anabaena sp. strain pcc 7120. | | 1991 | 1909433 |
| ssp rf1, a novel class-ii restriction endonuclease from synechococcus rf-1 recognizing 5'tt/cgaa-3'. | | 1991 | 1909785 |
| diarrhoeal diseases. | | 1991 | 1909885 |
| 1h nmr spectra of vertebrate [2fe-2s] ferredoxins. hyperfine resonances suggest different electron delocalization patterns from plant ferredoxins. | we report the observation of paramagnetically shifted (hyperfine) proton resonances from vertebrate mitochondrial [2fe-2s] ferredoxins. the hyperfine signals of human, bovine, and chick [2fe-2s] ferredoxins are described and compared with those of anabaena 7120 vegetative ferredoxin, a plant-type [2fe-2s] ferredoxin studied previously [skjeldal, l., westler, w. m., & markley, j. l. (1990) arch. biochem. biophys. 278, 482-485]. the hyperfine resonances of the three vertebrate ferredoxins were ver ... | 1991 | 1909889 |
| modulation of the tight binding of carboxyarabinitol 1,5-bisphosphate to the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase. | the large subunit (l) of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) from synechococcus pcc 6301 was expressed in escherichia coli, purified as the octamer l8, and analyzed for its ability to tightly bind the transition state analog, 2-carboxyarabinitol 1,5-bisphosphate (cabp). [14c]cabp remained tightly bound to l8 after challenging with [12c]cabp and gel filtration, indicating that l8 alone without the small subunit (s) could tightly bind cabp. binding of cabp to l8 induced a shi ... | 1991 | 1910281 |
| purification and characterization of large and small subunits of ribulose 1,5-bisphosphate carboxylase expressed separately in escherichia coli. | procedures were developed for 95 and 80% purification to homogeneity of the large subunit (l) and small subunit (s) of ribulose 1,5-bisphosphate carboxylase/oxygenase (l8s8) from synechococcus pcc 6301, each expressed separately in escherichia coli. purified l had a low specific activity in the absence of s (0.075 mumol co2 fixed/mg holoenzyme/min). following elution on a pharmacia superose 6 or 12 gel filtration column, 50% of the purified l appeared as the octamer, l8. the rest was in equilibr ... | 1991 | 1910289 |
| modulation of fibroblast motility by a cytosolic extract of cyanobacteria. | proliferation and migratory behavior of l929 murine fibroblasts were shown to be modified in the presence of a cytosolic extract of phormidium sp. (cyanobacteria). the addition of phormidium extract to the growth medium (dulbecco's modified eagle's medium) supplemented with 0.5% newborn calf serum increased cell proliferation. the effect was shown to be cell line specific. a quantitative analysis performed according to de laat, tertoolen, and bluemink (1981, eur. j. cell biol., 23, 273-279), sho ... | 1991 | 1910290 |
| laser flash photolysis studies of the kinetics of reduction of ferredoxins and ferredoxin-nadp+ reductases from anabaena pcc 7119 and spinach: electrostatic effects on intracomplex electron transfer. | the influence of electrostatic forces on the formation of, and electron transfer within, transient complexes between redox proteins was examined by comparing ionic strength effects on the kinetics of the electron transfer reaction between reduced ferredoxins (fd) and oxidized ferredoxin-nadp+ reductases (fnr) from anabaena and from spinach, using laser flash photolysis techniques. with the anabaena proteins, direct reduction by laser-generated flavin semiquinone of the fnr component was inhibite ... | 1991 | 1910302 |
| interaction of ferredoxin-nadp+ reductase from anabaena with its substrates. | the interaction of ferredoxin-nadp+ reductase from the cyanobacterium anabaena variabilis with its substrates, nadp+ and ferredoxin, has been studied by difference absorption spectroscopy. several structural analogs of nadp+ have been shown to form complexes the stabilities of which are strongly dependent on the ionic strength of the medium. in most cases the binding energy of these complexes and their difference absorption spectra are similar to those reported for the spinach enzyme. however, n ... | 1991 | 1910307 |
| separation and partial characterization of enzymes catalyzing delta-aminolevulinic acid formation in synechocystis sp. pcc 6803. | formation of the universal tetrapyrrole precursor, delta-aminolevulinic acid (ala), from glutamate via the five-carbon pathway requires three enzymes: glutamyl-trna synthetase, glutamyl-trna reductase, and glutamate-1-semialdehyde (gsa) aminotransferase. all three enzymes were separated from extracts of the unicellular cyanobacterium synechocystis sp. pcc 6803, and two of them, glutamyl-trna synthetase and gsa aminotransferase, were partially characterized. after an initial high speed centrifuga ... | 1991 | 1910318 |
| mutations in the small subunit of ribulosebisphosphate carboxylase affect subunit binding and catalysis. | fully functional synechococcus pcc 6301 ribulose 1,5-bisphosphate carboxylase-oxygenase (kcat = 11.8 s-1) was assembled in vitro following separate expression of the large- and small-subunit genes in different escherichia coli cultures. the small subunits were expressed predominantly as monomers, in contrast to the large subunits which have been shown to be largely octameric when expressed separately [andrews, t. j. (1988) j. biol. chem. 263, 12213-12219]. this separate expression system was app ... | 1991 | 1911767 |
| cloning and sequence analysis of the phycocyanin genes of the marine cyanobacterium synechococcus sp. wh7803. | | 1991 | 1912508 |
| response of enzymes involved in the processes of antioxidation towards benthiocarb and methylparathion in cyanobacteria nostoc muscorum. | | 1991 | 1912703 |
| computer modelling of the 3-dimensional structures of the cyanobacterial hepatotoxins microcystin-lr and nodularin. | the 3-dimensional structures of two cyanobacterial hepatotoxins microcystin-lr, a cyclic heptapeptide and nodularin, a cyclic pentapeptide, and the novel amino acid adda (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-4,6-decadienoic acid) were constructed, and optimized using the chem-x molecular mechanics program. the peptide rings were planar and of rectangular shape. optimized adda formed a u-shape and a difference in the orientation of adda with respect to the peptide ring of the two hepatotox ... | 1991 | 1926190 |