Publications

amino acid transport in taxonomically diverse cyanobacteria and identification of two genes encoding elements of a neutral amino acid permease putatively involved in recapture of leaked hydrophobic amino acids.	the activities of uptake of thirteen 14c-labeled amino acids were determined in nine cyanobacteria, including the unicellular strains synechococcus sp. strain pcc 7942 and synechocystis sp. strain pcc 6803; the filamentous strain pseudanabaena sp. strain pcc 6903, and the filamentous, heterocyst-forming strains anabaena sp. strains pcc 7120 and pcc 7937; nostoc sp. strains pcc 7413 and pcc 7107; calothrix sp. strain pcc 7601 (which is a mutant unable to develop heterocysts); and fischerella musc ...	1997	9006043
protein tyrosine phosphorylation in the cyanobacterium anabaena sp. strain pcc 7120.	components of a protein tyrosine phosphorylation/dephosphorylation network were identified in the cyanobacterium anabaena sp. strain pcc 7120. three phosphotyrosine (p-tyr) proteins of 27, 36, and 52 kda were identified through their conspicuous immunoreactions with rc20h monoclonal antibodies specific for p-tyr. these immunoreactions were outcompeted completely by free p-tyr (5 mm) but not by phosphoserine or phosphothreonine. the p-tyr content of the three major p-tyr proteins and several mino ...	1997	9079918
discovery of cyanovirin-n, a novel human immunodeficiency virus-inactivating protein that binds viral surface envelope glycoprotein gp120: potential applications to microbicide development.	we have isolated and sequenced a novel 11-kda virucidal protein, named cyanovirin-n (cv-n), from cultures of the cyanobacterium (blue-green alga) nostoc ellipsosporum. we also have produced cv-n recombinantly by expression of a corresponding dna sequence in escherichia coli. low nanomolar concentrations of either natural or recombinant cv-n irreversibly inactivate diverse laboratory strains and primary isolates of human immunodeficiency virus (hiv) type 1 as well as strains of hiv type 2 and sim ...	1997	9210678
siderophore production in two species of nostoc as influenced by the toxicity of nitrophenolics.		1997	9211704
uv-b-induced synthesis of photoprotective pigments and extracellular polysaccharides in the terrestrial cyanobacterium nostoc commune.	liquid cultures of the terrestrial cyanobacterium nostoc commune derived from field material were treated with artificial uv-b and uv-a irradiation. we studied the induction of various pigments which are though to provide protection against damaging uv-b irradiation. first, uv-b irradiation induced an increase in carotenoids, especially echinenone and myxoxanthophyll, but did not influence production of chlorophyll a. second, an increase of an extracellular, water-soluble uv-a/b-absorbing mycosp ...	1997	9068639
a polyketide-synthase-like gene is involved in the synthesis of heterocyst glycolipids in nostoc punctiforme strain atcc 29133.	a tn5-1063-derived mutant of nostoc punctiforme strain atcc 29133 was unable to fix n2 in air although it reduced acetylene in the absence of o2. mutant strain ucd 307 formed cells morphologically similar to heterocysts, but it failed to synthesize the characteristic heterocyst glycolipids. sequence analysis around the site of insertion revealed an orf of 3,159 base pairs, termed hgle. hgle putatively encodes a 115.4-kda protein containing two domains with conserved amino acid sequences identifi ...	1997	9075624
effect of cadmium on the bioelement composition of nostoc uam208: interaction with calcium.		1997	9060371
three new cryptophycins from nostoc sp. gsv 224.	cryptophycin 46 (2), -175 (3), and -176(4) have been identified as three new trace constituents of nostoc sp. gsv 224. cryptophycin-46 is an epimer of cryptophycin-3 (5) and to date is the only naturally occurring analogue having the s configuration at c-10 (c-2 in unit b). cryptophycins-175 and -176 also differ in unit b where 3 is the o-methyl analogue of cryptophycin-45 (6) and 4 is the o-desmethyl analogue of cryptophycin-21 (8). the relative and absolute stereochemistries of the three new a ...	1997	9090872
a hormogonium regulating locus, hrmua, of the cyanobacterium nostoc punctiforme strain atcc 29133 and its response to an extract of a symbiotic plant partner anthoceros punctatus.	transposon-generated mutant strain ucd 328 of nostoc punctiforme strain atcc 29133 has a phenotype of an increased sensitivity to a hormogonium-inducing factor exuded by a symbiotic plant partner, anthoceros punctatus, and an initial increased hormogonium-dependent infection of the plant. sequence analysis showed that the transposition site in strain ucd 328 lies within a 1,251-bp open reading frame (orf), designated hrma, that displays no significant similarity to known database sequences. a se ...	1997	9057333
strain characterization and classification of oxyphotobacteria in clone cultures on the basis of 16s rrna sequences from the variable regions v6, v7, and v8.	a major problem in development of a polyphasic taxonomy is that the identification of oxyphotobacterial strains (cyanobacteria and prochlorophytes) in culture collections may be incorrect. we have therefore developed a diagnostic system using the dna sequence polymorphism in the 16s rrna regions v6 to v8 for individual strain characterization and identification. pcr primers amplifying v6 to v8 from oxyphotobacteria in unialgal cultures were constructed. direct solid-phase or cyclic sequencing wa ...	1997	9212409
rrna sequences and evolutionary relationships among toxic and nontoxic cyanobacteria of the genus microcystis.	a primary-structure analysis of the 16s rrna gene was performed with 10 strains representing five described and one unidentified species of the genus microcystis. the phylogenies determined illustrate the evolutionary affiliations among microcystis strains, other cyanobacteria, and related plastids and bacteria. a cluster of 10 strains that included hepatotoxic isolates identified as microcystis aeruginosa formed a monophyletic group. however, the genus microcystis appeared to be polyphyletic an ...	1997	9226902
ornithine cycle in nostoc pcc 73102: presence of an in vitro functional argininosuccinate lyase.	the presence of argininosuccinate lyase (asl), an enzyme catalyzing the final step of arginine biosynthesis, was demonstrated in the heterocystous cyanobacterium nostoc pcc 73102 by measuring in vitro enzyme activity and by visualization of asl in native protein gels. activity staining of a native page gel revealed one asl-dependent band with a molecular mass of about 240 kda. a colorimetric assay for asl based on the measurement of urea produced from arginine in the presence of an excess of arg ...	1997	9228773
isolation, primary sequence determination, and disulfide bond structure of cyanovirin-n, an anti-hiv (human immunodeficiency virus) protein from the cyanobacterium nostoc ellipsosporum.	a novel anti-hiv protein, cyanovirin-n (cv-n), was isolated from an aqueous cellular extract of the cultured cyanobacterium (blue-green alga) nostoc ellipsosporum, purified by reverse-phase hplc, and sequenced by n-terminal edman degradation of the intact protein and peptide fragments produced by endoproteinase digestions. cv-n consists of a single 101 amino acid chain which exhibits significant internal sequence duplication, but no significant homology to previously described proteins or to the ...	1997	9299483
characterization of cyanobacteria by sds-page of whole-cell proteins and pcr/rflp of the 16s rrna gene.	planktonic, filamentous cyanobacterial strains from different genera, both toxic and nontoxic strains, were characterized by sds-page of whole-cell proteins and pcr/rflp of the 16s rrna gene. total protein pattern analysis revealed the mutual relationships at the genus level. restriction fragment length polymorphism (rflp) of the 16s rrna gene with reference strains proved to be a good method for the cyanobacterial taxonomy. the nonheterocystous strains outgrouped from the nitrogen-fixing ones. ...	1997	9382701
glutamine synthetase from n2-fixing cyanobacterium nostoc muscorum--purification, biochemical and immunological characteristics.	a modified procedure for purification of glutamine synthetase [l-glutamate: ammonia ligase (adp-forming)] from n2-fixing cyanobacterium n. muscorum, to homogeneity is described using deae-sephadex and blue-sepharose affinity chromatography. specific activities of the purified enzyme in biosynthetic and transferase assays were 8.5 and 28 mumole product formed min-1 mg-1 protein. apparent molecular mass of native gs enzyme was about 610 kda as estimated by gel filtration. on sds-page the enzyme pr ...	1997	9475046
a comparison of physical properties, oxalate-oxalic acid soluble substances, protein content, and in vitro protein digestibility of the blue-green alga nostoc commune vauch. from the philippines and japan.	the physical properties, amount of oxalate-oxalic acid soluble substances (ooss), protein and in vitro protein digestibility of nostoc commune from the philippines and japan were determined. the samples were the spherical type from the philippines (ps), the dry field discoid type from the philippines (pd), and the dry field discoid type from japan (jd). the discoid types, pd and jd, regardless of origin showed higher settling volume in water (sv) and bulk density than ps. the ooss values obtaine ...	1997	9477423
[the destruction of microscopic organisms by their irradiation with a special form of uhf electromagnetic signals].	electromagnetic signals of special form produced by an ultra-high frequency generator were used to destroy various microorganisms: baker's yeast; blue-green alga nostoc muscorum; mold fungus; and two flagellates, plant flagellate euglena gracilis and an animal flagellate parasitizing on humans. the control samples before irradiation and experimental samples damaged and destroyed by irradiation were examined on a microscope with a computer system of image analysis. the results are presented as co ...	1997	9518060
characterization of host-range mutants of cyanophage n-1.	fifteen host-range (h) mutants of cyanophage n-1 were characterized with reference to their efficiency of plating, time of appearance, morphology and size of plaques on nostoc muscorum and its three phage-resistant (nm 1/n-1, nm 2/n-1 and nm 8/n-1) mutants. while phage n-1 did not adsorb to the three phage-resistant mutants, the h mutants differed one from the other in having lower or higher adsorption rate constants on n. muscorum or the phage-resistant mutants. the inability of majority of h m ...	1997	9607077
hydrogenases in nostoc sp. strain pcc 73102, a strain lacking a bidirectional enzyme.	the present study was carried out in order to examine and characterize the bidirectional hydrogenase in the cyanobacterium nostoc sp. strain pcc 73102. southern hybridizations with the probes av1 and av3 (hoxy and hoxh, bidirectional hydrogenase small and large subunits, respectively) revealed the occurrence of corresponding sequences in anabaena variabilis (control), anabaena sp. strain pcc 7120, and nostoc muscorum but not in nostoc sp. strain pcc 73102. as a control, hybridizations with the p ...	1997	16535596
phenotypic and genotypic comparison of symbiotic and free-living cyanobacteria from a single field site.	pcr amplification techniques were used to compare cyanobacterial symbionts from a cyanobacterium-bryophyte symbiosis and free-living cyanobacteria from the same field site. thirty-one symbiotic cyanobacteria were isolated from the hornwort phaeoceros sp. at several closely spaced locations, and 40 free-living cyanobacteria were isolated from the immediate vicinity of the same plants. one of the symbiotic isolates was a species of calothrix, a genus not previously known to form bryophyte symbiose ...	1997	16535734
uvb-induced reduction in biomass and overall productivity of cyanobacteria.	effect of middle wave ultraviolet radiation (uvb) was studied in three different species of cyanobacteria (nostoc, anabaena and scytonema) by estimating their growth pattern, biomass yield, chlorophyll content, total starch and protein content. the results show that exposure of the cyanobacteria with uvb dose corresponding to an increase or decrease of 20% in its environmental flux will have drastic effects on biomass production, photosynthetic rate and nitrogen fixation. cyanobacteria are prima ...	1998	9514891
fingerprinting of cyanobacteria based on pcr with primers derived from short and long tandemly repeated repetitive sequences.	the presence of repeated dna (short tandemly repeated repetitive [strr] and long tandemly repeated repetitive [ltrr]) sequences in the genome of cyanobacteria was used to generate a fingerprint method for symbiotic and free-living isolates. primers corresponding to the strr and ltrr sequences were used in the pcr, resulting in a method which generate specific fingerprints for individual isolates. the method was useful both with purified dna and with intact cyanobacterial filaments or cells as te ...	1998	16349487
characterization of the glnb gene product of nostoc punctiforme strain atcc 29133: glnb or the pii protein may be essential.	bacterial pii proteins, encoded by glnb genes, are central signalling molecules in nitrogen regulatory pathways and are modulated by post-translational modification in response to the cellular nitrogen status. the glnb gene was cloned from the filamentous heterocyst-forming cyanobacterium nostoc punctiforme strain atcc 29133 (pcc 73102) by heterologous hybridization to a synechococcus sp. strain pcc 7942 gene fragment. expression of the cloned gene was verified by hybridization to n. punctiforme ...	1998	9639924
multiple oligomeric forms of glucose-6-phosphate dehydrogenase in cyanobacteria and the role of opca in the assembly process.	multiple molecular forms of glucose-6-phosphate dehydrogenase (g6pdh) were detected by activity staining in non-denaturing polyacrylamide gels of cell-free extracts from a range of cyanobacteria including anabaena sp. pcc 7120, synechococcus sp. pcc 7942, plectonema boryanum pcc 73110, synechocystis sp. pcc 6803, nostoc sp. mac pcc 8009 and the marine strain synechococcus sp. wh7803. in most of the species tested, the profile of g6pdh activities was modulated by the growth of the cells in the pr ...	1998	9639925
structure and properties in solution of psad, an extrinsic polypeptide of photosystem i.	psad is a small, extrinsic polypeptide located on the stromal side (cytoplasmic side in cyanobacteria) of the photosystem i reaction centre complex. the gene from the cyanobacterium nostoc sp. pcc 8009 was expressed in escherichia coli and the structure of the recovered protein in solution investigated. size-exclusion chromatography, dynamic light scattering and measurement of 15n transverse relaxation times showed that the protein is a stable dimer in solution, whereas in the reaction centre co ...	1998	9692933
differential behaviour of two cyanobacterium species to uv radiation. artificial uv radiation induces phycoerythrin synthesis.	altitude is an important factor contributing to the local uv-b climate. in the european alps solar uv-b increases approximately 21% 1000 m-1. a nostoc muscorum (utex 389) originating from scotland and a nostoc sp. isolated from a highland lake (yanaqocha) located 3980 m above sea level (cusco, perú) have been used in a study where the tolerance to uv radiation (uvr) stress of both species was determined. following irradiation doses of 15 kj uv (uv-a plus uv-b, equivalent to approximately 6 h exp ...	1998	9800379
hydrogen uptake in nostoc sp. strain pcc 73102. cloning and characterization of a hupsl homologue.	structural genes encoding an uptake hydrogenase of nostoc sp. strain pcc 73102 were isolated. from partial libraries of genomic dna, two clones (pnfo01 and pnfo02) were selected and sequenced, revealing the complete sequence of both a hups (960 bases) and a hupl (1,593 bases) homologue in nostoc sp. strain pcc 73102. a comparison between the deduced amino acid sequences of hups and hupl of nostoc sp. strain pcc 73102 and anabaena sp. strain pcc 7120 showed that the hups proteins are 89% identica ...	1998	9531626
electrophoretic applications of phycobiliproteins.	phycobiliproteins are homologous chromoproteins which constitute the phycobilisomes, the light harvesting complexes of the photosynthetic apparatus in cyanobacteria, rhodophyta and cryptophyta. in the present work, phycocyanin (pc) and phycoerythrin (pe) from a nostoc species are proposed as protein markers for electrophoretic techniques. phycocyanin is a blue-colored phycobiliprotein; it carries phycocyanobilin as chromophoric group and is composed of two subunits, alpha and beta, with mr of 14 ...	1998	9548282
the frua signal transduction protein provides a checkpoint for the temporal co-ordination of intercellular signals in myxococcus xanthus development.	during fruiting body morphogenesis in myxococcus xanthus, the intercellular c-signal induces aggregation, sporulation and developmental gene expression. to understand how a single signal system may induce temporally separated processes, we have focused on the class ii gene, which codes for an essential component in the c-signal transduction pathway. we report that class ii is identical to frua and codes for a dna binding response regulator. transcription of frua is developmentally regulated and ...	1998	10094629
sequence variation of the trna(leu) intron as a marker for genetic diversity and specificity of symbiotic cyanobacteria in some lichens.	we examined the genetic diversity of nostoc symbionts in some lichens by using the trna(leu) (uaa) intron as a genetic marker. the nucleotide sequence was analyzed in the context of the secondary structure of the transcribed intron. cyanobacterial trna(leu) (uaa) introns were specifically amplified from freshly collected lichen samples without previous dna extraction. the lichen species used in the present study were nephroma arcticum, peltigera aphthosa, p. membranacea, and p. canina. introns w ...	1998	9435083
evolution of cyanobacteria by exchange of genetic material among phyletically related strains.	the cyanobacterial radiation consists of several lineages of phyletically (morphologically and genetically) related organisms. several of these organisms show a striking resemblance to fossil counterparts. to investigate the molecular mechanisms responsible for stabilizing or homogenizing cyanobacterial characters, we compared the evolutionary rates and phylogenetic origins of the small-subunit rrna-encoding dna (16s rdna), the conserved gene rbcl (encoding d-ribulose 1,5-bisphosphate carboxylas ...	1998	9642201
cloning and characterisation of the pknd gene encoding an eukaryotic-type protein kinase in the cyanobacterium anabaena sp. pcc7120.	protein phosphorylation catalysed by protein kinases is an important mechanism for signal transduction in both prokaryotes and eukaryotes. a novel gene, pknd, encoding a protein similar to eukaryotic-type protein kinases, was cloned from anabaena sp. pcc7120. the n-terminal region of pknd is 60% identical to that of pkna, another putative ser/thr kinase from the same strain. both pkna and pknd have c-terminal regions that are rich in pro and thr residues. expression of pknd was undetectable by r ...	1998	9613569
binding of the epoxide cryptophycin analog, ly355703 to albumin and its effect on in vitro antiproliferative activity.	cryptophycin, isolated from the cyanobacterium nostoc, is a cytotoxic dioxadiazacyclohexadecenetetrone which causes rapid depletion of microtubules in intact cells. in the present report, the effect of protein binding of a new synthetic cryptophycin analog, ly355703 (cryptophycin 52), is discussed. in handling the compound, it was found to bind extensively to surfaces, and a high degree of plasma protein binding was also observed (about 99% in human plasma). similarly, while ly355703 displays po ...	1998	9683814
a transposition-induced mutant of nostoc ellipsosporum implicates an arginine-biosynthetic gene in the formation of cyanophycin granules and of functional heterocysts and akinetes.	in strain ne1 of tn5-1058-mutagenized nostoc ellipsosporum, the transposon was found within a gene whose translation product is similar in amino acid sequence to the arginine-biosynthetic protein n-acetylglutamate semialdehyde dehydrogenase encoded by argc of bacillus subtilis. the argc reported from anabaena sp. strain pcc 7120 hybridized to a sequence different from the one interrupted by the transposon in ne1. the newly identified gene from n. ellipsosporum was denoted argl. the argl mutation ...	1998	9695912
cellular uptake of a novel cytotoxic agent, cryptophycin-52, by human thp-1 leukemia cells and h-125 lung tumor cells.	cryptophycin (cp) is a newly developed anticancer agent isolated from the terrestrial cyanobacteria of the genus nostoc. cp is a mitotic inhibitor, causing cells to accumulate in mitosis with the disappearance of intracellular microtubules. in this report, we studied the interaction and uptake of a new synthetic cp analog, cp-52, with 2 human tumor cell lines, thp-1 and h-125. in vitro colony-forming assay showed that cp-52 has antiproliferative activity against thp-1 and h-125 cell lines with i ...	1998	9714056
partial purification and characterization of ornithine carbamoyl transferase (oct) from the cyanobacterium nostoc sp. strain pcc 73102	ornithine carbamoyl transferase (oct) catalyzes the formation of citrulline and orthophosphate from ornithine and carbamoyl phosphate. we have partially purified oct from the filamentous cyanobacterium nostoc sp. strain pcc 73102, using ammonium sulfate precipitation (35-55%), a gel-filtration column (sephacryl s-200), followed by an affinity column (sepharose-6b-palo). the partially purified oct was analyzed on native-page and shown to be an active enzyme with an estimated molecular weight of a ...	1998	9732532
a pcr technique based on the hip1 interspersed repetitive sequence distinguishes cyanobacterial species and strains.	the use of primers based on the hip1 sequence as a typing technique for cyanobacteria has been investigated. the discovery of short repetitive sequence structures in bacterial dna during the last decade has led to the development of pcr-based methods for typing, i.e., distinguishing and identifying, bacterial species and strains. an octameric palindromic sequence known as hip1 has been shown to be present in the chromosomal dna of many species of cyanobacteria as a highly repetitious intersperse ...	1998	9802020
safety evaluation of nostoc flagelliforme (nostocales, cyanophyceae) as a potential food.	the safety of the alga genus nostoc flagelliforme born. etflah. as a human food source was evaluated in an oral acute toxicity study and in a 28-day oral subacute toxicity study using rats. in the acute toxicity study, the dried powder of n. flagelliforme was orally administered to male and female rats at a dose of 1250 mg/kg and 2500 mg/kg. neither mortality nor changes in general condition were observed in either the study groups or the control group over a 14-day observation period. in the su ...	1998	9862649
mutation of an alternative sigma factor in the cyanobacterium nostoc punctiforme results in increased infection of its symbiotic plant partner, anthoceros punctatus.	an alternative group 2 sigma factor was identified in the nitrogen-fixing, symbiotically competent cyanobacterium nostoc punctiforme and designated sigh. transcription of sigh was specifically induced within 1.5 h following exposure of n. punctiforme to its symbiotic plant partner, anthoceros punctatus. a mutation in sigh resulted in a sixfold-higher initial infection of a. punctatus tissue without a parallel increase in nitrogen-fixing activity.	1998	9733698
a simple procedure for purifying the major chloroplast fructose-1,6-bisphosphatase from spinach (spinacia oleracea) and characterization of its stimulation by sub-femtomolar mercuric ions.	a rapid procedure for the purification of the redox-regulated chloroplast fructose-1,6-bisphosphatase [ec 3.1.3.11] from spinach leaf extract to homogeneity is described. no thiol-reducing agents were present during the purification and the enzyme is > 99% in the oxidized form. a rapid procedure to reduce and activate the fru-1,6-p2ase by dithiothreitol in the absence of thioredoxin is described. reduction activates the enzyme up to several hundred-fold when assayed at ph 8.0 with 2 mm mg2+. the ...	1998	9735161
tenuecyclamides a-d, cyclic hexapeptides from the cyanobacterium nostoc spongiaeforme var. tenue.	four modified cyclic hexapeptides, tenuecyclamides a-d (1-4), were isolated along with the known antibiotic, borophycin (5), from the methanol extract of nostoc spongiaeforme var. tenue (tau strain il-184-6). the planar structure of tenuecyclamides a-d (1-4) was determined by homonuclear and inverse-heteronuclear 2d-nmr techniques as well as by high-resolution mass spectrometry measurements. the absolute configuration of the asymmetric centers was studied by marfey's method for hplc. the stereoc ...	1998	9784161
cyanobacteria as agents for the control of pollution by pesticides and chlorinated organic compounds.	cyanobacteria are phototrophic aquatic micro-organisms that are found in a variety of environments, including polluted ones. fifteen strains of cyanobacteria that belong to three taxonomic groups are able to degrade lindane (λ-hexachlorocyclohexane, a recalcitrant pesticide). the initial degradation pathway has been studied in two filamentous nitrogen-fixing strains of anabaena sp. pcc 7120 and nostoc ellipsosporum. these cyanobacteria dechlorinated loindane first to pentachlorocyclohexene and t ...	1998	21182708
freshwater cyanobacterium microcystis aeruginosa (utex 2385) induced dna damage in vivo and in vitro.	microcystins are a family of potent hepatotoxins and liver tumor promoters produced by several genera of cyanobacteria including microcystis, nodularia, anabena, nostoc, etc. they are chemically very stable and represent a public health threat when they occur in water used for human consumption. we investigated the dna damage effects of m. aeruginosa utex 2385 in mouse liver in vivo and also in mammalian cells in vitro. the dna damage effect is compared with purified toxin microcystin-lr (mclr) ...	1998	21781844
a cyanobacterial hemoglobin with unusual ligand binding kinetics and stability properties.	the glbn gene of the cyanobacterium nostoc commune utex 584 encodes a hemoprotein, named cyanoglobin, that has high oxygen affinity. the basis for the high oxygen affinity of cyanoglobin was investigated through kinetic studies that utilized stopped-flow spectrophotometry and flash photolysis. association and dissociation rate constants were measured at 20 degrees c for oxygen, carbon monoxide, nitric oxide, and methyl and ethyl isocyanides. the association rate constants for the binding of thes ...	1999	10026295
cyanovirin-n binds to gp120 to interfere with cd4-dependent human immunodeficiency virus type 1 virion binding, fusion, and infectivity but does not affect the cd4 binding site on gp120 or soluble cd4-induced conformational changes in gp120.	cyanovirin-n (cv-n), an 11-kda protein isolated from the cyanobacterium nostoc ellipsosporum, potently inactivates diverse strains of human immunodeficiency virus type 1 (hiv-1), hiv-2, and simian immunodeficiency virus. while it has been well established that the viral surface envelope glycoprotein gp120 is a molecular target of cv-n, the detailed mechanism of action is of further interest. we compared matched native and cv-n-treated virus preparations in a panel of assays that measure viral re ...	1999	10196334
extended heme promiscuity in the cyanobacterial cytochrome c oxidase: characterization of native complexes containing hemes a, o, and d, respectively.	the cyanobacteria anacystis nidulans (synechococcus sp. pcc6301), synechocystis sp. pcc6803, anabaena sp. pcc 7120, and nostoc sp. pcc8009 were grown photoautotrophically under reduced oxygen tension in a medium with sulfate replaced by thiosulfate and nitrate replaced by ammonium as the s- and n-sources, respectively. in addition, anabaena and nostoc were grown under dinitrogen-fixing conditions in a medium free of combined nitrogen. membranes were isolated from late-logarithmic cells (culture ...	1999	10375407
energy-dependent ca(2+) efflux from the cells of nostoc calcicola breb: role of modifying factors	energy-dependent ca(2+) efflux and its regulation from the diazotrophic cyanobacterium nostoc calcicola breb has been investigated. like ca(2+) uptake, ca(2+) efflux pattern also reflected a rapid phase for the first 10 min followed by a slower one lasting up to 1 h with a total of 80 nmol ca(2+) mg(-1) protein (31% of the ca(2+) concentration taken in by such cells at 1 h). ca(2+) efflux kinetics remained hyperbolic with a k(m) of 1.9 mm and v(max) 5.5 nmol mg(-1) protein min(-1). ca(2+) efflux ...	1999	10489433
the solution structure of photosystem i accessory protein e from the cyanobacterium nostoc sp. strain pcc 8009.	psae is a small basic subunit located on the stromal (cytoplasmic) side of photosystem i. in cyanobacteria, this subunit participates in cyclic electron transport and modulates the interactions of the complex with soluble ferredoxin. the psae protein isolated from the cyanobacterium synechococcus sp. strain pcc 7002 adopts the beta topology of an sh3 domain, with five beta strands (betaa through betae) and a turn of 3(10) helix between strands betad and betae [falzone, c. j., kao, y.-h., zhao, j ...	1999	10521281
transcriptional regulation of nostoc uptake hydrogenase.	filamentous, heterocystous cyanobacteria may contain both an uptake hydrogenase (encoded by hupsl) and a bidirectional enzyme (encoded by hoxfuyh). the present study identifies three strains (anabaena variabilis, nostoc muscorum and nostoc sp. strain pcc 73102) with a contiguous hupl in both vegetative cells and heterocysts. the two nostoc strains differ in either containing a bidirectional enzyme (n. muscorum) or lacking this enzyme (n. pcc 73102). transcriptional studies, using reverse transcr ...	1999	9919654
separation and identification of hydrocarbons and other volatile compounds from cultured blue-green alga nostoc sp. by gas chromatography-mass spectrometry using serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases.	the complex hydrocarbons and volatile compounds produced by cultured blue-green alga nostoc sp. were separated by serially coupled capillary columns with consecutive nonpolar and semipolar stationary phases. more than 130 metabolites including, cyclohexane, cyclopentane, normal saturated hydrocarbons (c7-c30), fatty acids and benzene derivatives were identified by gc-ms. the most abundant family of hydrocarbons identified were derivatives of cyclohexane (41) and cyclopentane (11). most of these ...	1999	10596980
a novel extracellular diterpenoid with antibacterial activity from the cyanobacterium nostoc commune.	a novel extracellular metabolite with an unprecedented diterpenoid skeleton, 8-[(5-carboxy-2-hydroxy)benzyl]-2-hydroxy-1,1,4a,7, 8-pentamethyl-1,2,3,4,4a,6,7,8,8a,9,10,10a-dodecahydrophenanthrene , has been isolated from the culture medium of the terrestrial cyanobacterium nostoc commune vaucher (eawag 122b) by means of bioguided isolation. the molecule was designated as noscomin. the structure was determined by spectroscopic methods, mainly nmr and mass spectrometry. noscomin exhibited antibact ...	1999	10096870
biochemical and genetic evidence for participation of devr in a phosphorelay signal transduction pathway essential for heterocyst maturation in nostoc punctiforme atcc 29133.	in a test of the hypothesis that devr is a response regulator protein that functions in a phosphorelay signal transduction system involved in heterocyst development in nostoc punctiforme atcc 29133, purified affinity-tagged devr was shown to be phosphorylated in vitro by the noncognate sensor kinase envz. site-directed mutagenesis was used to generate n. punctiforme mutants with single amino acid substitutions at the putative phosphorylation site of devr. these mutants exhibited a fox- phenotype ...	1999	10400605
host specificity in the richelia-diatom symbiosis revealed by hetr gene sequence analysis.	the filamentous heterocyst-forming cyanobacterium richelia intracellularis forms associations with diatoms and is very abundant in tropical and subtropical seas. the genus richelia contains only one species, r. intracellularis schmidt, although it forms associations with several diatom genera and has considerable variation in size and morphology. the genetic diversity, and possible host specificity, within the genus richelia is unknown. using primers against hetr, a gene unique for filamentous c ...	1999	11207763
effect of copper and lead on lipid metabolism in bryophytes and lichens.	bryophytes and lichens have a widespread occurrence and can survive under extreme environmental conditions, such as drought, low temperatures, continuous light or prolonged darkness. it has been shown that lipid metabolism is sensitive to both metal response and metal resistance mechanisms in many organisms, including yeast, silene cucubalus, and in the marine brown algae fucus spp. and ascophyllum nodosum. in the present study, the effects of lead and copper on lipid metabolism have been studie ...	2000	11171254
dual effects of pknalpha and protein kinase c on phosphorylation of tau protein by glycogen synthase kinase-3beta.	we analyzed the effects of pknalpha and protein kinase c (pkc) on phosphorylation of tau protein by glycogen synthase kinase (gsk)-3beta using monoclonal antibodies (at8, at180, and at270). these antibodies are highly specific for phosphorylated tau in alzheimer paired helical filaments, and recognize phosphorylated ser202/thr205, thr231, and thr181 of tau protein, respectively. immunoblot analysis demonstrated that pknalpha and pkc did not directly phosphorylate their sites, whereas gsk-3beta e ...	2000	10873588
intracellular accommodation of microbes by plants: a common developmental program for symbiosis and disease?	plant cells engage in mutualistic and parasitic endosymbioses with a wide variety of microorganisms, ranging from gram-negative (rhizobium, nostoc) and gram-positive bacteria (frankia), to oomycetes (phytophthora), chytridiomycetes, zygomycetes (arbuscular mycorrhizal fungi) and true fungi (erysiphe, ascomycete; puccinia, basidiomycete). endosymbiosis is characterised by the 'symbiosome', a compartment within host cells in which the symbiotic microorganism is either partially or completely enclo ...	2000	10873847
hups and hupl constitute a transcription unit in the cyanobacterium nostoc sp. pcc 73102.	the heterocystous cyanobacterium nostoc sp. pcc 73102 possesses an uptake hydrogenase encoded by hups and hupl. the genes are transcribed in cells grown under n2-fixing but not under non-n2-fixing conditions. we characterised the transcription of hups and hupl in further detail. a transcription start site was located at a position 259 bp upstream from the hups translation start. as shown by rt-pcr, hups and hupl constitute a single transcript in nostoc sp. pcc 73102. the possible function of sho ...	2000	10985753
cloning and characterization of the pkna gene from streptomyces coelicolor a3(2), coding for the mn2+ dependent protein ser/thr kinase.	a gene pkna, coding for an eukaryotic-type protein ser/thr kinase, was cloned from the streptomyces coelicolor a3(2) chromosome. the pkna protein kinase, containing the c-terminal eukaryotic-type kinase domain with an n-terminal extension, was expressed in escherichia coli and streptomyces lividans. the affinity purified mbp-pkna fusion protein was assayed for kinase activity that showed its ability to autophosphorylate in vitro in the presence of [gamma-32p]atp. the activity was mn2+ dependent. ...	2000	11162454
evidence for the involvement of a common genetic determinant in the control of thallium-resistant (tl1-r) phenotype and salinity-tolerant phenotype in the cyanobacterium nostoc muscorum.		2000	12483581
properties of cyanovirin-n (cv-n): inactivation of hiv-1 by sessile cyanovirin-n (scv-n).	cyanovirin-n (cv-n) is a novel anti-hiv protein isolated and characterized from a cyanobacterium nostoc ellipsosporum. cv-n protein is a single 101 amino acid chain containing two intrachain disulphide bonds and considerable internal sequence duplication, but no significant homology to previously described proteins or to the transcription products of known nucleotide sequences. in solution, cv-n exists largely as a beta-sheet protein with internal two-fold pseudosymmetry. cv-n irreversibly inact ...	2000	10794101
a cyanobacterial mutant resistant against a bleaching herbicide.	the nitrogen fixing cyanobacterium nostoc muscorum has been found to be sensitive to the herbicide san 6706 [4-chloro-5 (dimethylamino)-2-(a,a,a,-trifluoro-m-tolyl)-3-(2h) pyridazinon] at 30-45 microm within 15 min. the toxicity was more severe in combined nitrogen-free (ncomb-free) medium than in a combined nitrogen medium; this enhancement was reversible by supplementation of the medium with 3 mm glucose or 5 microm atp, serving as carbon and/or energy source in this organism. a mutant of this ...	2000	10986674
new antibacterial metabolites from the cyanobacterium nostoc commune(eawag 122b).	two new compounds, a diterpenoid and an anthraquinone, as well as an indane derivative, which is reported as a natural product for the first time, have been isolated from the cells of the cultured cyanobacterium nostoc commune (eawag 122b) by means of bioguided isolation. the structures were determined by spectroscopic methods, mainly nmr, infrared spectroscopy, and mass spectrometry. all isolates exhibit antibacterial activity.	2000	11000038
the use of the 2-aminobenzoic acid tag for oligosaccharide gel electrophoresis.	gel electrophoresis of fluorophore labeled saccharides provides a rapid and reliable method to screen enzymatic and/or chemical treatments of polysaccharides and glycoconjugates, as well as a sensitive and efficient microscale method to separate and purify oligosaccharides for further analysis. a simple and inexpensive method of derivatization and analysis using 2-aminobenzoic acid (anthranilic acid, aa) is described and applied to the extracellular polysaccharide released by the desiccation tol ...	2000	11005578
[spatial integration of partners and heteromorphism of cyanobacterium nostoc muscoum calu 304 in mixed culture with rauwolfia].	a comparative morphological study was conducted of nostoc muscorum calu 304 grown either as a pure culture on standard media or as a mixed culture with rauwolfia callus tissue on a medium for plant tissue cultivation. the interaction of the cyanobacterial and plant partners results in their spatial integration into aggregates of specific anatomy, which arise periodically during the mixed culture growth. the morphology of the cyanobacterial cells varies depending on their localization in the comb ...	2000	11008694
a cyanobacterial recombination study, involving an efficient n2-fixing non-heterocystous partner.	many filamentous cyanobacteria fix atmospheric nitrogen under natural conditions in specialized anaerobic compartments, heterocysts, interspersed between vegetative cells, which provide protection to the o2-sensitive nitrogenase. a few unicellular cyanobacterial strains are also known to fix nitrogen aerobically at a slower rate. filamentous cyanobacteria lacking heterocysts are not known so far to fix nitrogen. we describe the isolation and purification of a non-heterocystous filamentous cyanob ...	2000	11061181
structural investigations of the hemoglobin of the cyanobacterium synechocystis pcc6803 reveal a unique distal heme pocket.	a putative hemoglobin (hb) gene, related to those previously characterized in the green alga chlamydomonas eugametos, the ciliated protozoan paramecium caudatum, the cyanobacterium nostoc commune and the bacterium mycobacterium tuberculosis, was recently discovered in the complete genome sequence of the cyanobacterium synechocystis pcc 6803. in this paper, we report the purification of synechocystis hb and describe some of its salient biochemical and spectroscopic properties. we show that the re ...	2000	10903511
the mycobacterium bovis homologous protein of the mycobacterium tuberculosis serine/threonine protein kinase mbk (pknd) is truncated.	we previously identified a 70-kda serine/threonine protein kinase (mbk or pknd) from mycobacterium tuberculosis erdman containing a transmembrane domain and bearing a 270-amino acid n-terminal kinase domain. with the use of a polyclonal serum, mbk has now been identified by western blotting in protein extracts from m. tuberculosis and confirmed to be localised in the envelope. an identical mbk gene has been found by sequencing different m. tuberculosis and m. africanum strains. surprisingly, in ...	2000	10913696
determinative value of a portion of the nifh sequence for the genera nostoc and anabaena (cyanobacteria).	the taxonomic positions of nostoc and anabaena strains are currently disputed. we selected three nostoc and anabaena strains, using the classic criteria of morphology and life cycle. dna sequences of a part of the nifh gene were determined from these strains and aligned with homologous sequences from 10 other nostoc/anabaena strains in the public databases. phylogenetic reconstructions were carried out to test the consistency of the taxonomic placement of these strains. the phylogenetic trees do ...	2000	10915207
a primitive myoglobin from tetrahymena pyriformis: its heme environment, autoxidizability, and genomic dna structure.	a myoglobin-like protein isolated from tetrahymena pyriformis is composed of 121 amino acid residues. this is much smaller than sperm whale myoglobin by 32 residues, suggesting a distinct origin from the common globin gene. we have therefore examined this unique protein for its structural, spectral and stability properties. as a result, the rate of autoxidation of tetrahymena oxymyoglobin (mbo(2)) was found to be almost comparable to that of sperm whale mbo(2) over a wide range of ph 4-12 in 0.1 ...	2000	11087949
nostocyclyne a, a novel antimicrobial cyclophane from the cyanobacterium nostoc sp.	a novel acetylene-containing para-[14]-cyclophane, nostocyclyne a (1), possessing antimicrobial activity, is the major active metabolite of the natural bloom of the cyanobacterium nostoc sp. (tau strain il-220). homonuclear and heteronuclear 2d nmr techniques as well as hreims determined the gross structure of 1.	2000	11087597
site-specific restriction endonucleases in cyanobacteria.	planktic cyanobacteria were screened for endodeoxyribonucleases. principal component analysis (pca) was employed to demonstrate a potential relationship between certain enzymes and a group of cyanobacteria. the data were obtained from a data bank and this study.	2000	11123471
structural characterization of the released polysaccharide of desiccation-tolerant nostoc commune drh-1.	the structure of the viscous extracellular polysaccharide (glycan) of desiccation-tolerant nostoc commune drh-1 was determined through chromatographic and spectroscopic methods. the polysaccharide is novel in that it possesses a 1-4-linked xylogalactoglucan backbone with d-ribofuranose and 3-o-[(r)-1-carboxyethyl]-d-glucuronic acid (nosturonic acid) pendant groups. the presence of d-ribose and nosturonic acid as peripheral groups is unusual, and their potential roles in modulating the rheologica ...	2000	10648523
a convergent synthesis of (+)-cryptophycin b, a potent antitumor macrolide from nostoc sp. cyanobacteria.	[structure--see text] an efficient and highly stereoselective synthesis of cryptophycin b (2), a potent cytotoxic agent, is described. the ester-derived titanium-enolate-mediated syn-aldol reaction was employed to generate the stereocenters c(5) and c(6). the route is convergent and provides a convenient access to the synthesis of structural variants of cryptophycin b as well as members of its family.	2000	10841482
inhibition of croton oil-induced oedema in mice ear skin by capsular polysaccharides from cyanobacteria.	the anti-inflammatory properties of hydrophilic extracts of the capsular polymers of twelve cyanobacterial strains belonging to the genera phormidium and nostoc from marine and terrestrial habitats were tested topically on croton oil-induced oedema in mice ear skin. the screening program identified several strains as producers of anti-inflammatory products (up to 56% inhibition of the oedema). the inhibition response was dose-dependent. the application of trichloroacetic acid-treated extracts re ...	2000	10763863
comparison of conserved structural and regulatory domains within divergent 16s rrna-23s rrna spacer sequences of cyanobacteria.	pcr amplification of the internal transcribed spacer (its) between the 16s rrna and 23s rrna genes of the cyanobacterium nostoc: pcc 7120 gave three products. two represented true its regions of different sizes, while the third was a heteroduplex. the longer spacer (its-l) contained 512 nucleotides and carried trna(ile) and trna(ala) genes, separated by a large stem-loop structure (v2) composed of short tandemly repeated repetitive sequences. both trna genes, and the 5' half of the intervening s ...	2000	10846207
n-(cyclohexanecarboxyl)-o-phospho-l-serine, a minimal substrate for the dual-specificity protein phosphatase iphp.	three dual-specific phosphatases [dsps], iphp, vhr, and cdc14, and three protein-tyrosine phosphatases [ptps], ptp-1b, ptp-h1, and tc-ptpa, were challenged with a set of low molecular weight phosphoesters to probe the factors underlying the distinct substrate specificities displayed by these two mechanistically homologous families of protein phosphatases. it was observed that beta-naphthyl phosphate represented an excellent general substrate for both ptps and dsps. while dsps tended to hydrolyze ...	2000	10775432
characterization of devh, a gene encoding a putative dna binding protein required for heterocyst function in anabaena sp. strain pcc 7120.	the devh gene was identified in a screen for anabaena sp. strain pcc 7120 sequences whose transcripts increase in abundance during a heterocyst development time course. the product of devh contains a helix-turn-helix motif similar to the dna binding domain of members of the cyclic amp receptor protein family, and the protein is most closely related to the cyanobacterial transcriptional activator ntca. devh transcripts are barely detectable in vegetative cells and are induced approximately fivefo ...	2000	10852891
toxin production in cyanobacterial mats from ponds on the mcmurdo ice shelf, antarctica.	cyanobacteria are known to produce hepatotoxic substances, the functional and ecological role of these toxins, however, remains largely unclear. toxic properties of cyanobacteria collected in antarctica were investigated to determine whether toxin-producing species can also be found under these environmental conditions. samples were collected from meltwater ponds on the mcmurdo ice shelf, antarctica in the summers of 1997 to 1999. these ponds are colonized by benthic algae and cyanobacterial mat ...	2000	10858513
cyanobacteria as a biosorbent of heavy metals in sewage water.	the effect of sewage water on some physiological activities of cyanobacteria was studied. metal-tolerant cyanobacterium (nostoc linckia) and metal-sensitive (nostoc rivularis) were grown at three levels of sewage water (25, 50 and 75%). the growth rate showed significant stimulation in low and moderate levels (50% for n. linckia and 25% for n. rivularis). not only the number of cells was elevated but also, the time required to reach the exponential and the stationary phases was reduced. also, lo ...	2000	10867368
flavonoid-induced expression of a symbiosis-related gene in the cyanobacterium nostoc punctiforme.	the flavonoid naringin was found to induce the expression of hrma, a gene with a symbiotic phenotype in the cyanobacterium nostoc punctiforme. a comparative analysis of several flavonoids revealed the 7-o-neohesperidoside, 4'-oh, and c-2-c-3 double bond in naringin as structural determinants of its hrma-inducing activity.	2000	10913102
application of sequence-specific labeled 16s rrna gene oligonucleotide probes for genetic profiling of cyanobacterial abundance and diversity by array hybridization.	dna sequence information for the small-subunit rrna gene (16s rdna) obtained from cyanobacterial cultures was used to investigate the presence of cyanobacteria and their abundance in natural habitats. eight planktonic communities developing in lakes characterized by relatively low algal biomass (mesotrophic) and in lakes with correspondingly high biomass (eutrophic) were selected for the study. the organismal compositions of the water samples were analyzed genetically, using multiplex sequence-s ...	2000	10966421
active fe-containing superoxide dismutase and abundant sodf mrna in nostoc commune (cyanobacteria) after years of desiccation.	active fe-superoxide dismutase (sodf) was the third most abundant soluble protein in cells of nostoc commune chen/1986 after prolonged (13 years) storage in the desiccated state. upon rehydration, fe-containing superoxide disumutase (fe-sod) was released and the activity was distributed between rehydrating cells and the extracellular fluid. the 21-kda fe-sod polypeptide was purified, the n terminus was sequenced, and the data were used to isolate sodf from the clonal isolate n. commune drh1. sod ...	2000	10613879
solution 1h nmr study of the heme cavity and folding topology of the abbreviated chain 118-residue globin from the cyanobacterium nostoc commune.	the globin from the cyanobacterium nostoc commune, abbreviated glbn, which appears to serve as a part of a terminal oxidase rather than as a respiratory pigment, displays relatively normal o2 binding properties, despite the highly abbreviated polypeptide chain, (118 residues) relative to more conventional globins [thorsteinsson, m. v. , bevan, d. r., potts, m., dou, y., eich, r. f., hargrove, m. s., gibson, q. h., and olson, j. s. (1999) biochemistry 38, 2117-2126]. the nature of the heme cavity ...	2000	10684619
novel extracellular diterpenoids with biological activity from the cyanobacterium nostoc commune.	five novel extracellular metabolites with an unprecedented diterpenoid skeleton, 5-[(5-carboxy-2-hydroxy)benzyl]-11-hydroxymethyl-2,5,6,8a, 11-pentamethyldodecahydrocyclopenta<a>naphthalene (1), 5-[(5-carboxy-2-hydroxy)benzyl]-11-formyl-2,5,6,8a, 11-pentamethyl-dodecahydrocyclopenta<a>naphthalene (2), 5-[(5-carboxy-2-hydroxy)benzyl]-11-carboxy-2,5,6,8a, 11-pentamethyl-dodecahydrocyclopenta<a>naphthalene (3), 5-[(5-carboxy-2-hydroxy)benzyl]-11-dihydroxymethyl-2,5,6,8a, 11-pentamethyldodecahydrocy ...	2000	10757714
cyanobacterial diversity in geographically related and distant host plants of the genus gunnera.	the diversity among 45 cyanobacterial isolates from 11 different gunnera species originating from different geographical areas was examined. by means of polymerase chain reaction (pcr) fingerprinting with short tandemly repeated repetitive (strr) sequences as primers, ten groups of symbiotic cyanobacteria and five unique isolates not belonging to a particular group were identified. most groups were restricted to one geographical area, indicating a limited distribution of related cyanobacterial s ...	2000	10795680
isolation and structure determination of nostocyclopeptides a1 and a2 from the terrestrial cyanobacterium nostoc sp. atcc53789.	the isolation and total structure determination of nostocyclopeptides a1 (1) and a2 (2) are described. these cyclic heptapeptides, which possess a unique imino linkage in the macrocyclic ring, are characteristic constituents of the cryptophycin-producing cyanobacterium nostoc sp. atcc53789. 1d tocsy experiments proved to be very useful in identifying the seven amino acid residues in each compound, and hmbc and noesy correlations made it possible to sequence the seven units into a total gross str ...	2001	11170666
molecular evidence for the aerobic expression of nifj, encoding pyruvate:ferredoxin oxidoreductase, in cyanobacteria.	pyruvate:ferredoxin (flavodoxin) oxidoreductase (pfo, ec 1.2.7.1) catalyses the oxidative cleavage of pyruvate and coenzyme a to acetylcoenzyme a and co2 with the simultaneous reduction of ferredoxin or flavodoxin. pfo occurs in anaerobes and in some aerobic archaea and bacteria. for cyanobacteria, activity measurements indicated the occurrence of pfo in heterocystous forms. the completely sequenced genomes of the unicellular synechocystis sp. pcc 6803 and the heterocystous anabaena sp. pcc 7120 ...	2001	11167002
cyanovirin-n, a potent human immunodeficiency virus-inactivating protein, blocks both cd4-dependent and cd4-independent binding of soluble gp120 (sgp120) to target cells, inhibits scd4-induced binding of sgp120 to cell-associated cxcr4, and dissociates bound sgp120 from target cells.	cyanovirin-n (cv-n), an 11-kda protein originally isolated from the cyanobacterium nostoc ellipsosporum, potently inactivates diverse strains of human immunodeficiency virus type 1 (hiv-1), hiv-2, simian immunodeficiency virus, and feline immunodeficiency virus. it has been well established that the hiv surface envelope glycoprotein gp120 is a molecular target of cv-n. we recently reported that cv-n impaired the binding of virion-associated gp120 to cell-associated cd4 and that cv-n preferential ...	2001	11181340
genome evolution of the cyanobacterium nostoc linckia under sharp microclimatic divergence at "evolution canyon," israel.	we describe the genomic dna diversity and divergence of the cyanobacterium nostoc linckia from "evolution canyon," a microsite consisting of ecologically contrasting slopes, south-facing slope (sfs) and north-facing slope (nfs), at lower nahal oren, mt. carmel, israel. the opposing slopes share their limestone lithology but vary greatly in their ecology, primarily because of different levels of solar radiation (which is six times higher on the sfs than on the nfs). the warm and xeric sfs display ...	2001	12024256
a family of putative kir potassium channels in prokaryotes.	prior to this report, members of the inward rectifier family, or kir, have been found only in eukaryotes. like most k+ channels, the pore-forming part of the protein is formed by four identical, or closely related, subunits. each subunit contains a transmembrane m1-p-m2 motif that is followed by a relatively large c-terminus region unique to kir's.	2001	11806753
cyanobacteria in uruguayan rice fields: diversity, nitrogen fixing ability and tolerance to herbicides and combined nitrogen.	it has been established that cyanobacteria play a vital role in the maintenance of flooded rice field fertility. to evaluate the potential use of nitrogen-fixing cyanobacteria as a natural biofertilizer for rice in uruguay, the diversity, abundance and nitrogen fixing ability of these microorganisms were studied in the field and in the laboratory. the effect of urea fertilization on population density and diversity of heterocystous cyanobacteria was determined on a 3-year assay. the highest numb ...	2001	11566382
[features of cyanobacterial-bacterial complexes of microsymbionts of plant syncyanoses].	the morphology and ultrastructure of associative microsymbiont complexes (amc) isolated from the ferns azolla pinnata and azolla sp. and the apogeotropic roots of the cycad cycas revoluta were studied. the composition of the amc obtained includes the cyanobionts (symbiotic cyanobacteria) and satellite bacteria (sb). it was found that two types of cyanobacteria that substantially differ in their morphological organization are likely present as cyanobionts in the coralloids of c. revoluta. the iso ...	2001	11338829
binding of ferric heme by the recombinant globin from the cyanobacterium synechocystis sp. pcc 6803.	the product of the cyanobacterium synechocystis sp. pcc 6803 gene slr2097 is a 123 amino acid polypeptide chain belonging to the truncated hemoglobin family. recombinant, ferric heme-reconstituted synechocystis sp. pcc 6803 hemoglobin is a low-spin complex whose endogenous hexacoordination gives rise to optical and nmr characteristics reminiscent of cytochrome b(5) [scott, n. l., and lecomte, j. t. j. (2000) protein sci. 9, 587-597]. in this work, the sequential assignments using (15)n-(13)c-lab ...	2001	11371218
nostocyclamide m: a cyanobacterial cyclic peptide with allelopathic activity from nostoc 31.	a cyclic peptide containing thiazole and oxazole moieties was isolated from nostoc 31 and its structure determined by chemical degradation detailed nmr and mass spectroscopic analyses. the compound is stereochemically pure and closely related to nostocyclamide in which d-valine is replaced by d-methionine. therefore, it differs from tenuecyclamide c reported to contain l-methionine. it shows allelopathic activity against anabaena 7120, but is inactive against grazers.	2001	11394868
cloning and characterisation of a hyp gene cluster in the filamentous cyanobacterium nostoc sp. strain pcc 73102.	maturation of [nife]-hydrogenases requires the action of several groups of accessory genes. homologues of one group of these genes, the so-called hyp genes, putatively encoding proteins participating in the formation of an active uptake hydrogenase in the filamentous, heterocyst-forming cyanobacterium nostoc pcc 73102, were cloned. the cluster, consisting of hypf, hypc, hypd, hype, hypa, and hypb, is located 3.8 kb upstream from the uptake hydrogenase-encoding hupsl. gene expression analyses sho ...	2001	11445168
[ultrastructure of the cell surface of heteromorphic nostoc muscorum calu 304 cocultured with rauwolfia tissue].	the ultrastructure of the heteromorphic cells (hmcs) of the cyanobacterium nostoc muscorum calu 304 grown in pure culture, monoculture, and a mixed culture with the rauwolfia callus tissue was studied. the comparative analysis of the cell surface of hmcs, the frequency of the generation of cell forms with defective cell walls (dcwfs), including protoplasts and spheroplasts, and the peculiarities of the cell surface ultrastructure under different growth conditions showed that, in the early terms ...	2001	11450455
characterization by genotypic methods of symbiotic nostoc strains isolated from five species of gunnera.	the genetic diversity of ten symbiotic nostoc strains isolated from different gunnera species was investigated. the strains were analyzed using molecular methods with different taxonomic resolutions, including restriction fragment length polymorphisms (rflp) of the pcr-amplified 16s ribosomal gene and the 16s-23s internal transcribed spacer (its) region combined with computer-assisted analyses. the functional gene hetr, assigned to heterocyst differentiation, was used for denaturing gradient gel ...	2001	11511868
the hetf gene product is essential to heterocyst differentiation and affects hetr function in the cyanobacterium nostoc punctiforme.	a novel gene, hetf, was identified as essential for heterocyst development in the filamentous cyanobacterium nostoc punctiforme strain atcc 29133. in the absence of combined nitrogen, hetf mutants were unable to differentiate heterocysts, whereas extra copies of hetf in trans induced the formation of clusters of heterocysts. sequences hybridizing to a hetf probe were detected only in heterocyst-forming cyanobacteria. the inactivation and multicopy effects of hetf were similar to those of hetr, w ...	2001	11274126
expression, refolding and crystallization of the opca invasin from neisseria meningitidis.	opca is an integral outer membrane from the gram-negative pathogen neisseria meningitidis that plays a role in adhesion of meningococci to host cells. the protein was overexpressed in escherichia coli in an insoluble form and a procedure developed for refolding by rapid dilution from denaturant into detergent solution. the refolded material was identical to native opca isolated from meningococci, as judged by overall molecular weight, migration on sds-page and reaction against monoclonal antibod ...	2001	11468407
induction of mycosporine-like amino acids (maas) in cyanobacteria by solar ultraviolet-b radiation.	three filamentous and heterocystous n(2)-fixing cyanobacteria, anabaena sp., nostoc commune and scytonema sp. were tested for the presence of ultraviolet-absorbing mycosporine-like amino acids (maas) and their induction by solar ultraviolet-b (uv-b) radiation. high performance liquid chromatographic (hplc) studies revealed the presence of only one type of maas in all three cyanobacteria, that was identified as shinorine, a bisubstituted maa containing both glycine and serine groups having an abs ...	2001	11470569