TitleAbstractYear(sorted ascending)
role of some macro and microelements on the nitrogen fixation by the blue-green alga calothrix sp. 19744212329
effect of pesticides on blue-green algae and nitrogen-fixation.the effects of the pesticides, amitrol, a derivative of amitrol (viz. 3,5-diamino-1,2,4-triazole), diquat, paraquat, linuron, mcpa, malathion, and monuron, were studied on the nitrogen-fixing algae, anabaena cylindrica, aulosira sp., calothrix elenkenii. chlorogloeae frischii, cylindrospermum muscicola, nostoc sp. from collema tenax, nostoc muscorum tolypothrix tenuis, and westiellopsis sp. in general, two types of response were discernible; an initial period of depression succeeded by an increa ...1975808179
studies on growth, nitrogen fixation and protein synthesis in a blue-green alga calothrix sp. 1975164760
nitrogen fixation in a coral reef community.algal reef flats at enewetak atoll, marshall islands, fix atmospheric nitrogen at rates comparable to those in managed agriculture. the dominant nitrogen fixer appears to be the blue-green alga calothrix crustacea. since this nutrient enrichment contributes to the high productivity of adjacent coral reefs and undoubtedly to atoll lagoons, it is recommended that the algal reef flats receive increased conservation priority.197517800402
influence of sewage discharge on nitrogen fixation and nitrogen flux from coral reefs in kaneohe bay, hawaii.nitrogen fixation was investigated in kaneohe bay, oahu, hawaii, a subtropical eutrophic estuary, by using the acetylene reduction technique on algal samples. no active, planktonic, n2-fixing blue-green algae or bacteria were observed. however, calothrix and nostoc capable of fixing n2 were cultured from navigational buoys and dead coral heads. nitrogen fixation associated with these structures was greater in the middle sector than in the south and north sectors of the estuary. experiments demon ...19767198
tubular elements - a new structure in blue-green algal cell inclusions, 'tubular elements' are described from the blue-green alga calothrix marchica. these structures are found in about 20% of all cells observed. they are 18-22 nm in diameter, apparently composed of sub-units of which the estimated number, as seen in transverse section, is 8-10.1977413838
effect of rifampicin (3-(4-methylpiperazinyl-iminomethyl)rifamycin) on heterocyst differentiation in the blue-green algae anabaena and calothrix.chains of multiple heterocysts form in anabaena und calothrix filaments on treatment with rifampicin. the multiple heterocysts form irrespective of whether the rifampicin treatment is given in combined nitrogen-free or supplemented medium. this suggests the possibility of involvement of a species of rna or of protein as intracellular heterocyst inhibitor and indicates that some latent pattern-determining mechanism may operate in the combined nitrogen medium.1978104451
duration of hydrogen formation by anabaena cylindrica b629 in atmospheres of argon, air, and nitrogen.the time course of hydrogen formation by anabaena cylindrica was followed beneath an argon atmosphere alone and also beneath atmospheres of argon, nitrogen, and air in the presence of carbon monoxide (0.2%) and acetylene (5%). hydrogen production beneath argon alone was comparable in rate and duration (7 to 12 days) to that which occurred beneath air in the presence of carbon monoxide (0.2%) and acetylene (5%). however, much greater longevity (16 to 26 days) and improved rates of hydrogen format ...197916345438
response of n(2)-fixing cyanobacteria to salt.the effect of salt on photosynthetic activity, acetylene reduction, and related activities was examined in two species of cyanobacteria, nostoc muscorum and calothrix scopulorum. photosynthesis was more resistant to high salt concentration than was n(2) fixation. the salt resistance of both activities increased after a period of exposure of the cells to salinity. the transfer of electrons via ferredoxin and ferredoxin-nicotinamide adenine dinucleotide phosphate reductase was found to be extremel ...198016345644
the photoregulated expression of multiple phycocyanin species. a general mechanism for the control of phycocyanin synthesis in chromatically adapting cyanobacteria.the regulation of phycocyanin synthesis in response to growth in chromatic illumination was studied in 69 strains of cyanobacteria. cyanobacteria (24 of 31 strains examined), which chromatically adapt by modulating the synthesis of both phycocyanin and phycoerythrin, controlled phycocyanin synthesis through the differential, photoregulated expression of two phycocyanin species (two alpha-type and two beta-type subunits). for these strains the expression of one pair of phycocyanin subunits was co ...19816796414
biochemical diversity for biosynthesis of aromatic amino acids among the cyanobacteria.we examined the enzymology and regulatory patterns of the aromatic amino acid pathway in 48 strains of cyanobacteria including representatives from each of the five major grouping. extensive diversity was found in allosteric inhibition patterns of 3-deoxy-d-arabinoheptulosonate 7-phosphate synthase, not only between the major groupings but also within several of the generic groupings. unimetabolite inhibition by phenylalanine occurred in approximately half of the strains examined; in the other s ...19826119309
the structural nif genes of the cyanobacteria gloeothece sp. and calothrix sp. share homology with those of anabaena sp., but the gloeothece genes have a different arrangement.probes carrying the anabaena sp. strain pcc 7120 nitrogenase reductase (nifh) and nitrogenase (nifk and nifd) genes were hybridized to southern blots of dna from the unicellular, aerobic nitrogen-fixing cyanobacterium gloeothece sp. strain pcc 6909 and from the filamentous cyanobacterium calothrix sp. strain pcc 7601. these data suggest that the gloeothece sp. nif structural proteins must be similar to those of other diazotrophs and that the ability for aerobic nitrogen fixation does not reside ...19836305921
molecular cloning and nucleotide sequence of a developmentally regulated gene from the cyanobacterium calothrix pcc 7601: a gas vesicle protein gene.since the gas vesicle protein (gvp) is highly conserved among the different gas-vacuolate prokaryotes, a 29-mer oligonucleotide corresponding to a portion of the anabaena flos-aquae gvp gene was synthesized and used to isolate the gvp structural gene from calothrix pcc 7601 (= fremyella diplosiphon). gas vacuole production in this filamentous cyanobacterium is restricted to hormogonia which occur at a specific stage during the developmental cell cycle. the gvp gene (gvpa) was localized on a 709 ...19852997744
nitrogen fixation associated with the new zealand mangrove (avicennia marina (forsk.) vierh. var. resinifera (forst. f.) bakh.).nitrogenase activity in mangrove forests at two locations in the north island, new zealand, was measured by acetylene reduction and n(2) uptake. nitrogenase activity (c(2)h(2) reduction) in surface sediments 0 to 10 mm deep was highly correlated (r = 0.91, n = 17) with the dry weight of decomposing particulate organic matter in the sediment and was independent of light. the activity was not correlated with the dry weight of roots in the top 10 mm of sediment (r = -0.01, n = 13). seasonal and sam ...198516346771
complete amino acid sequence of cyanobacterial gas-vesicle protein indicates a 70-residue molecule that corresponds in size to the crystallographic unit cell.gas vesicles of cyanobacteria are formed by a protein called 'gas-vesicle protein' (gvp). the complete amino acid sequence has been determined of gvp from anabaena flos-aquae. it is 70 residues long and has an mr of 7388. this corresponds to the size of the repeating unit cell demonstrated by x-ray crystallography of intact gas vesicles. details of the sequence are related to the secondary beta-sheet structure of the protein and its contrasting hydrophilic and hydrophobic surfaces. extensive ami ...19863098234
green light induces transcription of the phycoerythrin operon in the cyanobacterium calothrix 7601.phycobilisomes, the major light-harvesting complexes of cyanobacteria are multimolecular structures made up of chromophoric proteins called phycobiliproteins and non chromophoric linker polypeptides. we report here the isolation and nucleotide sequence of the genes, cpea and cpeb, which in calothrix pcc 7601 encode the alpha and beta subunits of phycoerythrin, one of the major phycobiliproteins. in calothrix pcc 7601, modulation of the polypeptide composition of the phycobilisomes occurs in resp ...19862431391
transcriptional analysis of the cyanobacterial gvpabc operon in differentiated cells: occurrence of an antisense rna complementary to three overlapping transcripts.cyanobacteria are photosynthetic prokaryotes able to colonize almost all kinds of ecosystems. some of them exhibit differentiation processes and/or may establish tight symbiotic associations. upon changes in the environmental conditions, the cyanobacterium calothrix 7601 differentiates hormogonia which are short filaments of small cells resulting from cellular division and fragmentation of the long filaments of vegetative cells. in calothrix, hormogonia are characterized by their gliding motilit ...19872450053
a developmentally regulated gvpabc operon is involved in the formation of gas vesicles in the cyanobacterium calothrix the filamentous cyanobacterium calothrix pcc7601, gas-vesicle (gv) formation is restricted to specialized filaments, called hormogonia. the differentiation of these cells is controlled by environmental factors, such as light intensity and/or wavelength. the structural gene (gvpa) encoding a gv protein in this cyanobacterium has been previously cloned and sequenced. two other genes, gvpb and gvpc have been found in the sequence downstream from gvpa. the gvpb gene corresponds to a second copy o ...19873111941
isolation and localization of n4-methylasparagine in phycobiliproteins from the cyanobacterium mastigocladus laminosus.the occurrence of post-translationally methylated asparagine residues in beta ap from anabaena variabilis, synechococcus pcc 6301 and porphyridium cruentum has recently been reported (klotz, a.v., leary, j.a. & glazer, a.n. (1986) j. biol. chem. 261, 15891-15894). we reinvestigated the amino-acid compositions of all phycobiliproteins from mastigocladus laminosus. during total hydrolysis of beta ap, beta 16.2 and beta pc one mol methylamine per mol protein was released. these proteins were chemic ...19873122783
cloning and nucleotide sequence of the thrb gene from the cyanobacterium calothrix pcc 7601.the cyanobacterium calothrix pcc 7601 thrb gene, encoding homoserine kinase (ec, was cloned via complementation of an escherichia coli threonine auxotroph, and its nucleotide sequence was determined. the comparison of the homoserine kinase amino acid sequences from calothrix pcc 7601, e. coli k12 and bacillus subtilis 168 indicates a closer relationship between cyanobacteria and bacillaceae than between cyanobacteria and enterobacteriaceae. sequence analysis of the 5' and 3' flanking r ...19872838727
action spectra for nitrate and nitrite assimilation in blue-green algae.action spectra for the assimilation of nitrate and nitrite have been obtained for several blue-green algae (cyanobacteria) with different accessory pigment composition. the action spectra for both nitrate and nitrite utilization by nitrate-grown anacystis nidulans l-1402-1 cells exhibited a clear peak at about 620 nanometers, corresponding to photosystem ii (psii) c-phycocyanin absorption, the contribution of chlorophyll a (chl a) being barely detectable. the action spectrum for nitrate reductio ...198816666041
complete nucleotide sequence of the red-light specific set of phycocyanin genes from the cyanobacterium calothrix pcc 7601. 19883126486
isolation and molecular characterization of the gene encoding allophycocyanin b, a terminal energy acceptor in cyanobacterial phycobilisomes.phycobilisomes are the major constituents of the light-harvesting apparatus in both cyanobacteria and red algae and consist of a central core with radiating rods. from a genomic library of the cyanobacterium calothrix 7601, a dna fragment encoding allophycocyanin b, one of the two terminal energy acceptors of the core, was isolated and its nucleotide sequence was determined. unlike all the other known genes encoding phycobiliproteins, the allophycocyanin b gene, apcd, is transcribed as a monocis ...19883130540
the protein encoded by gvpc is a minor component of gas vesicles isolated from the cyanobacteria anabaena flos-aquae and microcystis sp.the proteins present in gas vesicles of the cyanobacteria anabaena flos-aquae and microcystis sp. were separated by sds-polyacrylamide gel electrophoresis. each contained a protein of mr 22k whose n-terminal amino acid sequences showed homology with that of the calothrix sp. pcc 7601 gvpc gene product. the gvpc gene from a. flos-aquae was cloned and sequenced. the derived amino acid sequence for the gene product indicated a protein, gvpc, of 193 residues and mr 21985 containing five highly conse ...19883141741
utilization of organic substrates by two filamentous cyanobacteria under various growth conditions.two filamentous cyanobacteria calothrix marchica lemm. var. intermedia rao and scytonema schmidlei de toni grew heterotrophically in light with or without dcmu and in the dark when supplemented with glucose, fructose or sucrose. galactose, mannitol and sorbitol were utilized less efficiently. mannose, xylose and organic acids did not support the heterotrophic growth of both the cyanobacteria. by continuous incubation and sub-cultivation in sucrose supplemented medium in the dark, heterotrophic a ...19883142200
genes encoding core components of the phycobilisome in the cyanobacterium calothrix sp. strain pcc 7601: occurrence of a multigene family.the phycobilisome is the major light-harvesting complex of cyanobacteria. it is composed of a central core from which six rods radiate. allphycocyanin, an alpha beta oligomer (alpha ap and beta ap), is the main component of the core which also contains three other phycobiliproteins (alpha apb, beta 18.3, and l92cm) and a small linker polypeptide (l7.8c). by heterologous dna hybridization, two ecori dna fragments of 3.5 and 3.7 kilobases have been cloned from the chromatically adapting cyanobacte ...19882461358
occurrence and distribution of gas vesicle genes among cyanobacteria.gas vesicles (gv) are specialized cell inclusions providing many aquatic procaryotes with buoyancy. in the cyanobacterium calothrix sp. strain pcc 7601, at least four genes are involved in gv formation. one of those, gvpa1, encodes the major structural gv protein (70 amino acids) and belongs to a multigene family (gvpa1, gvpa2, gvpd). the fourth gene, gvpc, encodes a 162-amino-acid protein, the function of which is still unclear. we used the calothrix gvpa1 and gvpc genes as probes to perform so ...19892493445
the complete amino-acid sequence of the alpha and beta subunits of b-phycoerythrin from the rhodophytan alga porphyridium cruentum.determination of the complete amino-acid sequence of the subunits of b-phycoerythrin from porphyridium cruentum has shown that the alpha subunit contains 164 amino-acid residues and the beta subunit contains 177 residues. when the sequences of b- and c-phycoerythrins are aligned with those of other phycobiliproteins, it is obvious that b-phycoerythrin lacks a deletion at beta-21-22 present in c-phycoerythrin. however, relative to c-phycoerythrin from fremyella diplosiphon (calothrix) (sidler, w. ...19892495805
adaptive eradication of methionine and cysteine from cyanobacterial light-harvesting proteins.sulphur is unique among the main elements of living cells in that it is covalently bound to biopolymers but does not occur in the biopolymer backbone. indeed, most of the bacterial sulphur content resides in the methionine and cysteine side-chains of proteins. the growth yield of an organism under conditions of sulphur limitation could therefore be greatly enhanced by mutations that substitute met and cys in the organism's proteins for sulphur-free amino acids. because the saving in sulphur woul ...19892506452
phosphomonoesterase activity of the cyanobacterium (blue-green alga) calothrix parietina.cellular and extracellular phosphomonoesterase activities were compared in calothrix parietina d550, a strain whose original environment has been studied in detail. activity in both fractions became detectable at about the same stage in batch culture. differences in the influence of environmental factors between the two were slight, suggesting a common origin. the optimum temperatures for cellular and extracellular activities were 40 degrees c and 30 degrees c, respectively, and the upper limits ...19892549342
purification and properties of glutamine synthetases from the cyanobacteria synechocystis sp. strain pcc 6803 and calothrix sp. strain pcc 7601.glutamine synthetases (gss) from two cyanobacteria, one unicellular (synechocystis sp. strain pcc 6803) and the other filamentous (calothrix sp. strain pcc 7601 [fremyella diplosiphon]), were purified to homogeneity. the biosynthetic activities of both enzymes were strongly inhibited by adp, indicating that the energy charge of the cell might regulate the gs activity. both cyanobacteria exhibited an ammonium-mediated repression of gs synthesis. in addition, the synechocystis sp. showed an inacti ...19901973929
molecular characterization of the terminal energy acceptor of cyanobacterial phycobilisomes.cyanobacteria harvest light energy through multimolecular structures, the phycobilisomes, regularly arrayed at the surface of the photosynthetic membranes. phycobilisomes consist of a central core from which rods radiate. a large polypeptide (lcm, 75-120 kda) is postulated to act both as terminal energy acceptor and as a linker polypeptide that stabilizes the phycobilisome architecture. we report here the characterization of the gene (apce) that encodes this lcm polypeptide in calothrix sp. pcc ...19902107546
highly repetitive dna sequences in cyanobacterial genomes.we characterized three distinct families of repeated sequences in the genome of the cyanobacterium calothrix sp. strain pcc 7601. these repeated sequences were present at a level of about 100 copies per calothrix genome and consisted of tandemly amplified heptanucleotides. these elements were named short tandemly repeated repetitive (strr) sequences. we used the three different calothrix strr sequences as probes to perform southern hybridization experiments with dnas extracted from various cyano ...19902110150
characterization of two insertion sequences, is701 and is702, from the cyanobacterium calothrix species pcc 7601.we describe the characterization of two insertion elements, is701 and is702, isolated from calothrix species pcc 7601. these insertion elements were cloned from spontaneous pigmentation mutants. both show the characteristics of typical bacterial insertion sequences, i.e. they present long terminal inverted repeats and they duplicate target dna upon insertion. these elements share no homology with the only other cyanobacterial insertion sequence described so far, is891. at least 15 copies of is70 ...19911662761
[photocontrol of the synthesis of chlorophyll a and phycocyanin in the cyanobacterium calothrix crustacea schousboe].chlorophyll a and phycocyanin synthesis in the cyanobacterium calothrix crustacea schousboe (ecophene rivularia bullata) have been studied in white light after the application of red and green light pulses. the light quality produces a complementary pattern in the pigment synthesis. chlorophyll synthesis is stimulated by red light pulses whereas phycocyanin synthesis is by green light pulses. because the effect of red light on chlorophyll synthesis shows some far-red photoreversibility, the acti ...19911798852
molecular cloning and transcriptional analysis of the cpeba operon of the cyanobacterium pseudanabaena species pcc7409.the cpeba operon of the group iii chromatically adapting cyanobacterium pseudanabaena species pcc 7409 was cloned, sequenced and characterized. the cpeba genes are transcribed in green-light-grown cells as an abundant 1400-nucleotide mrna which initiates 69 nucleotides upstream from the cpeb translation start. extensive sequence identity, extending 70 nucleotides 5' to the transcription start, occurs among cpeba promoters of group ii and iii chromatic adapters. cell extracts of green-light-grown ...19911809846
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 ...19911899708
the amino-acid sequence of three proteins of photosystem i of the cyanobacterium fremyella diplosiphon (calothrix sp pcc 7601).three proteins containing 138 amino acids (psad protein), 80 amino acids (psac protein) and 66 amino acids (psae protein) of the photosystem i (ps i) complex of the cyanobacterium fremyella diplosiphon (calothrix sp pcc 7601) were isolated and sequenced. comparison with previously known sequences showed a close relationship to homologous proteins of nostoc, another filamentous cyanobacterium.19911930733
hormogonium differentiation in the cyanobacterium calothrix: a photoregulated developmental process.hormogonium differentiation is part of the developmental cycle in many heterocystous cyanobacteria. hormogonia are involved in the dispersal and survival of the species in its natural habitat. the formation of these differentiated filaments has been shown to depend on several environmental conditions, including spectral light quality. we report here morphological and ultrastructural changes associated with the formation of hormogonia, as well as optimal light conditions required for their differ ...199112324595
analysis of the gene encoding the rna subunit of ribonuclease p from cyanobacteria.the genes encoding the rna subunit of ribonuclease p from the unicellular cyanobacterium synechocystis sp. pcc 6803, and from the heterocyst-forming strains anabaena sp. pcc 7120 and calothrix sp. pcc 7601 were cloned using the homologous gene from anacystis nidulans (synechococcus sp. pcc 6301) as a probe. the genes and the flanking regions were sequenced. the genes from anabaena and calothrix are flanked at their 3'-ends by short tandemly repeated repetitive (strr) sequences. in addition, two ...19921282240
molecular characterization of the gene encoding glutamine synthetase in the cyanobacterium calothrix sp. pcc order to study the regulation of the synthesis of glutamine synthetase in response to changes in environmental parameters (light and nitrogen sources), we have cloned and sequenced the glna gene from the filamentous cyanobacterium calothrix pcc 7601. this gene consists of 472 codons and encodes a polypeptide of m(r) 52,290 highly homologous to that from anabaena pcc 7120, but more distant from those identified from other procaryotes. the relative abundance of the two glna transcripts (1.6 and ...19921362348
purification, characterization and function of dihydrolipoamide dehydrogenase from the cyanobacterium anabaena sp. strain p.c.c. 7119.a dihydrolipoamide dehydrogenase (dihydrolipoamide: nad+ oxidoreductase, ec (dld) has been found in the soluble fraction of cells of both unicellular (synechococcus sp. strain p.c.c. 6301) and filamentous (calothrix sp. strain p.c.c. 7601 and anabaena sp. strain p.c.c. 7119) cyanobacteria. dld from anabaena sp. was purified 3000-fold to electrophoretic homogeneity. the purified enzyme exhibited a specific activity of 190 units/mg and was characterized as a dimeric fad-containing protein ...19921471997
three c-phycoerythrin-associated linker polypeptides in the phycobilisome of green-light-grown calothrix sp. pcc 7601 (cyanobacteria).microanalyses by sds-page and microsequencing demonstrate that, under green-light conditions, 3 c-phycoerythrin associated rod-linker polypeptides with different n-terminal amino acid sequences are present in phycobilisomes (pbs) from calothrix sp. 7601 cells. two of these polypeptides, corresponding to sds-page bands at 36 and 37 kda, could be assigned, respectively, to the cpec and cpcd genes found on a separate cpecd-operon in calothrix sp. 7601 (federspiel, n.a. and grossman, a.r. (1990) j. ...19921551428
phycobilisome structure in the cyanobacteria mastigocladus laminosus and anabaena sp. pcc 7120.phycobilisomes of the cyanobacteria mastigocladus laminosus and anabaena sp. pcc7120 differ from typical tricylindrical, hemidiscoidal phycobilisomes in three respects. firstly, size comparisons of the core-membrane linker phycobiliproteins (lcm) in different cyanobacteria by sds/page reveal an apparent molecular mass of 120 kda for the lcm of m. laminosus and anabaena sp. pcc7120. this observation suggests that the polypeptides of these species have four linker-repeat domains. secondly, phycobi ...19921577008
coding sequence of a heterocyst ferredoxin gene (fdxh) isolated from the nitrogen-fixing cyanobacterium calothrix sp. pcc 7601. 19921581559
phytochrome assembly. the structure and biological activity of 2(r),3(e)-phytochromobilin derived from phycobiliproteins.the unicellular rhodophyte, porphyridium cruentum, and the filamentous cyanobacterium, calothrix sp. pcc 7601, contain phycobiliproteins that have covalently bound phycobilin chromophores. overnight incubation of solvent-extracted cells at 40 degrees c with methanol liberates free phycobilins that are derived from the protein-bound bilins by methanolytic cleavage of the thioether linkages between bilin and apoprotein. two of the free bilins were identified as 3(e)-phycocyanobilin and 3(e)-phycoe ...19921634523
construction of shuttle plasmids which can be efficiently mobilized from escherichia coli into the chromatically adapting cyanobacterium, fremyella some strains of cyanobacteria the composition of the light-harvesting antennae is determined by the color of available light. the mechanism of this chromatic adaptation involves the regulation of gene expression by red and green light and has been most studied in fremyella diplosiphon (calothrix sp. pcc 7601), a filamentous cyanobacterium for which there has been no reported means of genetic manipulation. we have constructed shuttle plasmids which can be efficiently mobilized by rp4 from esch ...19938234495
an osmotic stress protein of cyanobacteria is immunologically related to plant dehydrins.dehydrins are a family of desiccation proteins that were identified originally in plants (t.j. close, a.a. kortt, p.m. chandler [1989] plant mol biol 13: 95-108; g. galau, t.j. close [1992] plant physiol 98: 1523-1525). dehydrins are characterized by the consensus amino acid sequence domain ekkgimdkikeklpg found at or near the carboxy terminus; the core of this domain (kikeklpg) may be repeated from one to many times within the complete polypeptide. dehydrins generally accumulate in plants in re ...19938310057
general distribution of the nitrogen control gene ntca in cyanobacteria.the ntca gene from synechococcus sp. strain pcc 7942 encodes a regulatory protein which is required for the expression of all of the genes known to be subject to repression by ammonium in that cyanobacterium. homologs to ntca have now been cloned by hybridization from the cyanobacteria synechocystis sp. strain pcc 6803 and anabaena sp. strain pcc 7120. sequence analysis has shown that these ntca genes would encode polypeptides strongly similar (77 to 79% identity) to the synechococcus ntca prote ...19938366058
cloning of the phycobilisome rod linker genes from the cyanobacterium synechococcus sp. pcc 6301 and their inactivation in synechococcus sp. pcc 7942.the phycobilisome rod linker genes in the two closely related cyanobacteria synechococcus sp. pcc 6301 and synechococcus sp. pcc 7942 were studied. southern blot analysis showed that the genetic organization of the phycobilisome rod operon is very similar in the two strains. the phycocyanin gene pair is duplicated and separated by a region of about 2.5 kb. the intervening region between the duplicated phycocyanin gene pair was cloned from synechococcus sp. pcc 6301 and sequenced. analysis of thi ...19938455571
transduction of the light signal during complementary chromatic adaptation in the cyanobacterium calothrix sp. pcc 7601: dna-binding proteins and modulation by phosphorylation.the cyanobacterium calothrix sp. pcc 7601 can adapt its pigment content in response to changes in the incident light wavelength. it synthesizes, as major light-harvesting pigments, either phycocyanin 2 (pc2, encoded by the cpc2 operon) under red light or phycoerythrin (pe, encoded by the cpeba operon) under green light conditions. the last step of the signal transduction pathway is characterized by a transcriptional control of the expression of these operons. partially purified protein extracts ...19938458347
an in vivo approach to define the role of the lcm, the key polypeptide of cyanobacterial cyanobacteria, phycobilisomes are regularly arrayed on the surface of the photosynthetic membranes, and their role is to funnel light energy to the underlying photosystem ii reaction center. a model has recently been proposed that ascribes to the so-called lcm, a central role in the building up of the phycobilisome, in addition to its role of terminal energy acceptor (capuano, v., braux, a.-s., tandeau de marsac, n., and houmard, j. (1991) j. biol. chem. 266, 7239-7247). the phycobilisomes of ...19937681841
electron transport regulates cellular differentiation in the filamentous cyanobacterium calothrix.differentiation of the filamentous cyanobacteria calothrix sp strains pcc 7601 and pcc 7504 is regulated by light spectral quality. vegetative filaments differentiate motile, gas-vacuolated hormogonia after transfer to fresh medium and incubation under red light. hormogonia are transient and give rise to vegetative filaments, or to heterocystous filaments if fixed nitrogen is lacking. if incubated under green light after transfer to fresh medium, vegetative filaments do not differentiate hormogo ...199312271071
a phosphorylated dna-binding protein is specific for the red-light signal during complementary chromatic adaptation in cyanobacteria.complementary chromatic adaptation is a mechanism by which some cyanobacteria that are able to synthesize phycoerythrin can adapt their pigment (phycobiliprotein) content to the incident wavelengths of the light. in calothrix sp. pcc 7601 it concerns phycoerythrin (cpe operon), synthesized under green light, and phycocyanin-2 (cpc2 operon), expressed under red light, and involves transcriptional controls. with cell-free extracts from calothrix sp. pcc 7601 grown under various light regimes, a pr ...19947815945
specific initiation of transcription at a cyanobacterial promoter with rna polymerase purified from calothrix sp. pcc 7601.although in cyanobacteria many genes have been shown to be transcriptionally controlled by specific stimuli, little is known about promoter structure and the form of rna polymerase that recognizes individual promoters. rna polymerase holoenzyme has been purified from calothrix sp. pcc 7601. its polypeptide composition resembles that of the plant chloroplast enzymes. to study transcription in cyanobacteria further, we have analysed the promoter-recognition properties of the purified enzyme. in vi ...19947815946
isl2, a new mobile genetic element in lactobacillus helveticus.spontaneous, phenotypically stable mutations at the beta-galactosidase locus (lacl-lacm) in lactobacillus helveticus were identified and analyzed. we found that a significant number of mutations were caused by integration of a new is element, isl2, into these lac genes. isl2 is 858 bp long, flanked by 16-bp perfect inverted repeats and generates 3-bp target duplications upon insertion. it contains one open reading frame, which shows significant homology (40.1% identity) to the putative transposa ...19947816043
nonenzymatic bilin addition to the alpha subunit of an apophycoerythrin.c-phycoerythrin is a light-harvesting protein whose alpha and beta subunits carry thioether-linked phycoerythrobilin (peb) at cysteine residues alpha-82, alpha-139, beta-48,59 (doubly-linked), beta-80, and beta-165. the two subunits of calothrix sp. pcc 7601 c-phycoerythrin, overexpressed together as apopolypeptides in escherichia coli, formed inclusion bodies. purified apo-alpha was soluble in the absence of urea, whereas the apo-beta subunit was only soluble at high urea concentrations. produc ...19947961862
rhodopsin(s) in eubacteria.while the biochemical basis of photosynthesis by bacteriochlorophyll-based reaction centres in purple phototrophic eubacteria and retinal-based bacteriorhodopsin in the archaebacterium halobacterium salinarium has been elucidated in great detail, much less is known about photosensory signal transduction; this is especially the case for eubacteria. recent findings on two different photosensory proteins in two different eubacteria, which both show clear resemblances to the rhodopsins, will be pres ...199517023324
tabulation of thirty-one putative new genes from the context of other research cyanobacterial dna sequences were obtained from genomic clones selected from libraries at random. sequences from synechococcus pcc 6301, calothrix pcc 7601 and calothrix d253 are now available from the genbank/embl/ddbj databases (accession number z47089 to z47128, z47129 to z47149 and z47150 to z47197, respectively) and have been searched for similarity to known sequences. thirty-one putative new genes (encoding putative products with at least 40% identity over ...19958534857
effect of the nitrogen source on phycobiliprotein synthesis and cell reserves in a chromatically adapting filamentous cyanobacterium.cyanobacteria can utilize nitrate or ammonium as a source of fixed nitrogen for cell growth. in the filamentous calothrix sp. strain pcc 7601, these two sources of nitrogen differently influenced the phycobiliprotein composition of the phycobilisomes, the major light-harvesting antennae. when compared to nitrate, growth in the presence of ammonium resulted in intracellular steady-state levels 35% lower for phycoerythrin and 46% higher for phycocyanin. besides these differences in cell pigmentati ...19968868436
observations on the mechanisms of attachment of some marine fouling blue-green algae.using scanning electron microscopy (sem), differential interference contrast microscopy (dicm) and cytochemical staining techniques, preliminary observations have been made on the mechanisms of attachment of some common, marine, benthic fouling blue-green algae ("cyanobacteria") isolated into culture from various toxic and non-toxic surfaces in langstone harbour, south coast of england. blue-green algae investigated included species of calothrix, dermocarpa, plectonema, phormidium and xenococcus ...199622115109
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 ...199716535734
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 ...19979006043
a new insertion sequence is1452 from acetobacter pasteurianus.a new insertion sequence element, is1452, was found to be associated with inactivation of the alcohol dehydrogenase by insertion in the adhs gene encoding subunit iii of the three-component membrane-bound alcohol dehydrogenase complex in acetobacter pasteurianus. cloning and sequencing analyses of the mutated subunit iii gene locus revealed that is1452 was inserted at or near the ribosome-binding sequence of adhs. analysis of transcription using the chloramphenicol acetyltransferase gene as the ...19979043130
identification and characterization of is1381, a new insertion sequence in streptococcus pneumoniae.a new insertion sequence (is1381) was identified in the genome of streptococcus pneumoniae r6 as an 846-bp segment containing 20-bp terminal inverted repeats and flanked by 7-bp direct repeats. the three sequenced copies of this element have two overlapping open reading frame (orf) genes named orfa and orfb. however, significant variations between individual copies were found, suggesting that inactivating mutations have occurred in an original single orf. accordingly, the consensus is1381 elemen ...19979079939
a survey of polypeptide deformylase function throughout the eubacterial lineage.n-terminal formylation of ribosome-synthesized polypeptides is assumed to be among the most conserved features that distinguish the eubacterial line of descent from other living phyla. in order to assess the ancientness of this trait, def genes encoding polypeptide deformylase were characterized from four eubacterial species, lactococcus lactis, bacillus subtilis, calothrix pcc7601 and thermotoga maritima, taking advantage of the conditional viability of the def mutants of escherichia coli. alto ...19979086272
promoter recognition by a cyanobacterial rna polymerase: in vitro studies with the calothrix sp. pcc 7601 transcriptional factors rcaa and study the transcriptional apparatus and the mechanisms that control gene expression in cyanobacteria, the rna polymerase was purified from the filamentous calothrix sp. pcc 7601 and used in in vitro transcription assays. conditions required for specific transcription initiation to occur were analyzed with the eleven calothrix pcc 7601 genes for which the 5' ends have been mapped. most of the transcripts directly obtained did not have the expected size, providing a test for looking at specific ...19989526497
characterization of is1515, a functional insertion sequence in streptococcus pneumoniae.we describe the characterization of a new insertion sequence, is1515, identified in the genome of streptococcus pneumoniae i41r, an unencapsulated mutant isolated many years ago (r. austrian, h. p. bernheimer, e. e. b. smith, and g. t. mills, j. exp. med. 110:585-602, 1959). a copy of this element located in the cap1ei41r gene was sequenced. the 871-bp-long is1515 element possesses 12-bp perfect inverted repeats and generates a 3-bp target duplication upon insertion. the is encodes a protein of ...19989580131
complete sequence of the mitochondrial dna of the red alga porphyra purpurea. cyanobacterial introns and shared ancestry of red and green algae.the mitochondrial dna (mtdna) of porphyra purpurea, a circular-mapping genome of 36,753 bp, has been completely sequenced. a total of 57 densely packed genes has been identified, including the basic set typically found in animals and fungi, as well as seven genes characteristic of protist and plant mtdnas and specifying ribosomal proteins and subunits of succinate:ubiquinone oxidoreductase. the mitochondrial large subunit rrna gene contains two group ii introns that are extraordinarily similar t ...199910488235
antibiotic production by the cyanobacteria oscillatoria angustissima and calothrix parietina.the accumulation of antibiotic in the medium is temperature dependent and not in direct proportion to growth parameters. the cyanobacterial product suppressed growth of some natural isolates of cyanobacteria and green algae. it inhibits the growth rate and oxygen evolution of the green alga, chlorella fusca. the antibiotic also inhibits the growth of bacteria and some fungi, especially the dermatophytes. generally eukaryotic organisms were less sensitive than prokaryotic. experimental mice were ...199921781939
a new appraisal of the prokaryotic origin of eukaryotic phytochromes.the evolutionary origin of the phytochromes of eukaryotes is controversial. three cyanobacterial proteins have been described as "phytochrome-like" and have been suggested to be potential ancestors of these essential photoreceptors: cph1 from synechocystis pcc 6803, showing homology to phytochromes along its entire length and known to attach a chromophore; and plpa from synechocystis pcc 6803 and rcae from fremyella diplosiphon, both showing homology to phytochromes most strongly only in the c-t ...200011029065
inhibition of bacterial rna polymerase by the cyanobacterial metabolites 12-epi-hapalindole e isonitrile and calothrixin a.the alkaloid 12-epi-hapalindole e isonitrile, from a cyanobacterial fischerella species, and the indolophenanthridine calothrixin a, from calothrix, inhibited escherichia coli rna polymerase competitively with respect to atp, and non-competitively with respect to utp. the inhibition was dependent on the order of addition of the inhibitors. the k(i) values, with atp as the variable substrate, were 1.3+/-0.2 mm and 0.23+/-0.11 mm, respectively. based on comparisons with the sensitivity of whole ce ...200111267769
molecular characterization of planktic cyanobacteria of anabaena, aphanizomenon, microcystis and planktothrix genera.toxic and non-toxic cyanobacterial strains from anabaena, aphanizomenon, calothrix, cylindrospermum, nostoc, microcystis, planktothrix (oscillatoria agardhii), oscillatoria and synechococcus genera were examined by rflp of pcr-amplified 16s rrna genes and 16s rrna gene sequencing. with both methods, high 16s rrna gene similarity was found among planktic, anatoxin-a-producing anabaena and non-toxic aphanizomenon, microcystin-producing and non-toxic microcystis, and microcystin-producing and non-t ...200111321098
is the 16s-23s rrna internal transcribed spacer region a good tool for use in molecular systematics and population genetics? a case study in cyanobacteria.we amplified, ta-cloned, and sequenced the 16s-23s internal transcribed spacer (its) regions from single isolates of several cyanobacterial species, calothrix parietina, scytonema hyalinum, coelodesmium wrangelii, tolypothrix distorta, and a putative new genus (isolates srs6 and srs70), to investigate the potential of this dna sequence for phylogenetic and population genetic studies. all isolates carried its regions containing the sequences coding for two trna molecules (trna and trna). we retri ...200111371594
phosphorylation of proteins in the light-dependent signalling pathway of a filamentous cyanobacterium.the genome of the filamentous cyanobacterium calothrix sp. pcc7601 contains two genes, cpha and cphb, encoding proteins with similarity to plant phytochromes and bacterial histidine kinases. in vitro, cpha and cphb readily attach a tetrapyrrole chromophore to develop spectrally active holoproteins that are photointerconvertible between a red light-absorbing and a far-red light-absorbing form. together with the putative response regulators, rcpa and rcpb, the putative histidine kinases, cpha and ...200111422367
co-ordinated expression of phycobiliprotein operons in the chromatically adapting cyanobacterium calothrix pcc 7601: a role for rcad and the cyanobacterium calothrix sp. pcc 7601 the cpc2 operon encoding phycocyanin 2 (pc2) is expressed if red radiations are available. rcad was previously identified in extracts from red-light-grown cells as an alkaline phosphatase-sensitive protein that binds upstream of the transcription start point (tsp) of the cpc2 operon. in this work, rcad was purified, and the corresponding gene cloned with a pcr probe obtained using degenerated primers based on rcad peptide sequences (accession no. aj31 ...200211929529
phytochromes with noncovalently bound chromophores: the ability of apophytochromes to direct tetrapyrrole photoisomerization.chromophore-apoprotein interactions were studied with recombinant apoproteins, oat phytochrome (phya) and cphb of the cyanobacterium calothrix pcc7601, which were both incubated with the bilin compounds biliverdin (bv) ixalpha, phycocyanobilin (pcb) and the 3'-methoxy derivative of pcb. previously it was shown that cphb and its homolog in calothrix, cpha, show strong sequence similarities with each other and with the phytochromes of higher and lower plants, despite the fact that cphb carries a l ...200212017484
two independent, light-sensing two-component systems in a filamentous cyanobacterium.two orfs, cpha and cphb, encoding proteins cpha and cphb with strong similarities to plant phytochromes and to the cyanobacterial phytochrome cph1 of synechocystis sp. pcc 6803 have been identified in the filamentous cyanobacterium calothrix sp. pcc7601. while cpha carries a cysteine within a highly conserved amino-acid sequence motif, to which the chromophore phytochromobilin is covalently bound in plant phytochromes, in cphb this position is changed into a leucine. both orfs are followed by rc ...200212047374
cellular fatty acids as chemotaxonomic markers of the genera anabaena, aphanizomenon, microcystis, nostoc and planktothrix (cyanobacteria).the cellular fatty acid content of 22 cyanobacterial strains belonging to the genera anabaena, aphanizomenon, calothrix, cylindrospermum, nostoc, microcystis and planktothrix were analysed. the identities of the major peaks were confirmed by ms. correspondence analysis of the data revealed three distinct groups formed by the microcystis strains, the nostoc/planktothrix strains and the anabaena/aphanizomenon/cylindrospermum strains. the calothrix strain did not cluster with the other heterocystou ...200212054217
cyanobacteria a potential source of antiviral substances against influenza virus.aqueous and methanolic extracts of cultured cyanobacteria of several genera, microcystis, nodularia, oscillatoria, scytonema, lyngbya and calothrix were evaluated for their in vitro antiviral activity against influenza a virus in madin darby canine kidney cells. none of the methanolic extracts showed cytotoxic effects. the inhibitory concentration (ic(50)) of antiviral activity ranged between 20.0 micro g to 79.0 micro g extract/ml. the most active extract in this screening derived from genus mi ...200212458356
characterization and implications of the cell surface reactivity of calothrix sp. strain kc97.the cell surface reactivity of the cyanobacterium calothrix sp. strain kc97, an isolate from the krisuvik hot spring, iceland, was investigated in terms of its proton binding behavior and charge characteristics by using acid-base titrations, electrophoretic mobility analysis, and transmission electron microscopy. analysis of titration data with the linear programming optimization method showed that intact filaments were dominated by surface proton binding sites inferred to be carboxyl groups (ac ...200212324327
[associative cyanobacteria isolated from the roots of epiphytic orchids].associative cyanobacteria were isolated from the rhizoplane and velamen of the aerial roots of the epiphytic orchids acampe papillosa, phalaenopsis amabilis, and dendrobium moschatum and from the substrate roots of acampe papillosa and dendrobium moschatum. cyanobacteria were isolated on complete and nitrogen-free variants of bg-11 medium. on all media and in all samples, cyanobacteria of the genus nostoc predominated. nostoc, anabaena, and calothrix were isolated from the surface of the a. papi ...200312698800
uv-acclimation responses in natural populations of cyanobacteria (calothrix sp.).phenotypic acclimation to changing conditions is typically thought to be beneficial to organisms in the environment. uv radiation is an important parameter affecting photosynthetic organisms in natural environments. we measured the response of photosynthetic carbon fixation in populations of cyanobacteria inhabiting a hot spring following acclimation to different uv treatments. these two very closely related populations of cyanobacteria, differing in their content of the extracellular uv-screeni ...200312755714
the synthesis of the uv-screening pigment, scytonemin, and photosynthetic performance in isolates from closely related natural populations of cyanobacteria (calothrix sp.).two populations of the cyanobacterium calothrix sp. found in yellowstone thermal spring outflows differ greatly in their contents of scytonemin, a uv-screening pigment, and in their photosynthetic carbon assimilation rates. clonal isolates from both populations were used to investigate these phenotypic differences. identical partial 16s rdna sequences ( approximately 900 bp) suggest a very close relationship between the two calothrix populations and indicate that environmental differences may, i ...200312755715
molecular characterization of endolithic cyanobacteria inhabiting exposed dolomite in central switzerland.the phototrophic microbial community inhabiting exposed dolomite in the alpine piora valley (switzerland) forms a distinct endolithic bilayer that features adjacent red dolomite (exterior) and green dolomite (interior) layers that are c. 0.5-1 mm below the rock surface. characterization of the community, with an emphasis on cyanobacteria, was conducted with culture-dependent and -independent approaches. direct microscopy of green dolomite revealed four distinct morphotypes consistent with chloro ...200312823194
recent horizontal intron transfer to a chloroplast genome.evidence is presented for the recent, horizontal transfer of a self-splicing, homing group ii intron from a cyanobacteria to the chloroplast genome of euglena myxocylindracea. the psba gene of e.myxocylindracea was found to contain a single 2566 nt group ii intron with a gene in domain 4 for a 575 amino acid maturase. the predicted secondary structure and tertiary interactions of the group ii intron, as well as the derived maturase primary sequence, most closely resemble the homing intron of the ...200414762207
chromophore selectivity in bacterial phytochromes: dissecting the process of chromophore attachment.bacterial phytochromes (bphs) are ancestors of the well characterized plant photoreceptors. whereas plant phytochromes perform their photoisomerization exclusively via a covalently bound bilin chromophore, bphs are variable in their chromophore selection. this is demonstrated in the cyanobacterium calothrix pcc7601 that expresses two bphs, cpha and cphb. cpha binds phycocyanobilin (pcb) covalently, whereas cphb, lacking the covalently binding cysteine of the plant phytochromes, carries biliverdi ...200415009190
effect of glucose and light-dark environment on pigmentation profiles in the cyanobacterium calothrix elenkenii.calothrix elenkenii was evaluated for accumulation of chlorophyll, beta-carotene and phycobiliproteins when grown under light-dark cycles and darkness, in the presence of glucose. highest values of beta-carotene, chlorophyll, proteins and acetylene-reducing activity were recorded when the organism was grown in the presence of glucose under light-dark cycles after 15 d of incubation. the presence of glucose in the medium stimulated pigment production, especially of beta-carotene and chlorophyll, ...200415114861
volatile organic compound (voc) analysis and sources of limonene, cyclohexanone and straight chain aldehydes in axenic cultures of calothrix and plectonema.the volatile organic compounds (vocs) in four standing cultures of axenic benthic cyanobacteria (calothrix and plectonema) were studied by gc/ms analysis. to verify the biogenic origin of the vocs, 13c-labelling experiments were performed, and the differences in labelling were used to differentiate between biogenic and non-biogenic sources. strongly labelled biogenic compounds were derived from the shikimate (cresol, skatole), isoprenoid (beta-cyclocitral, beta-ionone, geosmin) and fatty acid pa ...200415237606
crystal structures of two cyanobacterial response regulators in apo- and phosphorylated form reveal a novel dimerization motif of phytochrome-associated response regulators.the structures of two response regulators (rrs) from the cyanobacterium calothrix pcc7601, rcpa and rcpb, were solved to 1.9- and 1.75-a resolution, respectively. rcpa was found in phosphorylated and rcpb in nonphosphorylated form. both rrs are members of phytochrome-associated, light-sensing two-component signal transduction pathways, based on histidine kinase-mediated receptor autophosphorylation and phosphorelay to a rr. despite the overall folding similarity to chey-type rrs ((beta/alpha)(5) ...200415240481
synthesis, electrochemistry, and bioactivity of the cyanobacterial calothrixins and related quinones.the calothrixins are quinone-based natural products isolated from calothrix cyanobacteria which show potent antiproliferative properties against several cancer cell lines. preliminary mechanistic studies suggest that the biological mode of action of the calothrixins may be linked to their ability to undergo redox cycling. in this study we compare the bioactivities of the calothrixins with those of structurally related quinones in order to identify the structural features in the calothrixins esse ...200415369400
modulation of pigment profiles of calothrix elenkenii in response to environmental changes.cyanobacteria are versatile tetrapyrrole synthesizers that can regulate their tetrapyrrole content and composition in response to environmental signals. the present investigation analyses the interplay between light and dark regimes (continuous light, light-dark cycles (16:8) and continuous darkness) and aerobic, air-tight, and anaerobic environments (argon-enriched), on the relative composition of various pigments and growth attributes of calothrix elenkenii as a prelude to exploiting c. elenke ...200415535122
development of a universal microarray based on the ligation detection reaction and 16s rrna gene polymorphism to target diversity of cyanobacteria.the cyanobacteria are photosynthetic prokaryotes of significant ecological and biotechnological interest, since they strongly contribute to primary production and are a rich source of bioactive compounds. in eutrophic fresh and brackish waters, their mass occurrences (water blooms) are often toxic and constitute a high potential risk for human health. therefore, rapid and reliable identification of cyanobacterial species in complex environmental samples is important. here we describe the develop ...200415574913
a correlation matrix of alkaline phosphatase and sporulation in diazotrophic cyanobacteria and its thermo-tolerant mutant.alkaline phosphatase (phosphomonoesterase i.e. pmease) activity in heterocystous cyanobacteria anabaena flos-aquae, nostoc calcicola, calothrix brevissima, scytonema javanicum and hapalosiphon intricatus is known to be temperature and ph dependent. maximum level of enzyme activity was recorded at either 35 degrees c or 37.5 degrees c. also, the cell bound phosphomonoesterase enzyme was shown to exhibit ph optima of 10.0 or 10.2. a thermo-tolerant (tr) mutant isolated after mnng (n-methyl-n'-nitr ...200415790075
benthic cyanobacteria from the baltic sea contain cytotoxic anabaena, nodularia, and nostoc strains and an apoptosis-inducing phormidium strain.benthic cyanobacteria from aquatic environments have been reported to produce biologically active metabolites. however, the toxicity and other biological activities of benthic cyanobacteria from the baltic sea are not well known. we determined the biological activities of 21 anabaena, calothrix, nodularia, nostoc, and phormidium strains isolated from benthic littoral habitats of the baltic sea. we studied whether benthic cyanobacterial extracts caused cytotoxicity by necrosis or induced apoptosi ...200515892066
community phylogenetic analysis of moderately thermophilic cyanobacterial mats from china, the philippines and thailand.most community molecular studies of thermophilic cyanobacterial mats to date have focused on synechococcus occurring at temperatures of approximately 50-65 degrees c. these reveal that molecular diversity exceeds that indicated by morphology, and that phylogeographic lineages exist. the moderately thermophilic and generally filamentous cyanobacterial mat communities occurring at lower temperatures have not previously been investigated at the community molecular level. here we report community di ...200515970994
a high proportion of baltic sea benthic cyanobacterial isolates contain apoptogens able to induce rapid death of isolated rat assess the potential hepatotoxicity of benthic cyanobacteria, we isolated 41 strains from the baltic sea. the bacteria were differentially extracted with solvents of decreasing polarity. the extracts were tested for ability to induce death of primary rat hepatocytes in suspension culture. mainly morphological criteria were used to discriminate between cell death with apoptotic features (shrinkage, chromatin hypercondensation, budding) or necrotic features (swelling, loss of plasma membrane in ...200515990143
physiological and molecular diversity of feather moss associative n2-fixing cyanobacteria.cyanobacteria colonizing the feather moss pleurozium schreberi were isolated from moss samples collected in northern sweden and subjected to physiological and molecular characterization. morphological studies of isolated and moss-associated cyanobacteria were carried out by light microscopy. molecular tools were used for cyanobacteria identification, and a reconstitution experiment of the association between non-associative mosses and cyanobacteria was conducted. the influence of temperature on ...200516263908
characterization of nitrogen-fixing cyanobacteria in the brazilian amazon floodplain.the diversity of the free-living nitrogen-fixing cyanobacterial community in the floodplain sediments along the solimões and amazon rivers and some of their tributaries (japurá, negro and madeira) was investigated. five cyanobacterial genera were morphologically identified, four of which (nostoc, calothrix, cylindrospermum and fischerella) have not previously been isolated from the brazilian amazon floodplain. nostoc strains were the most commonly found heterocyst-forming cyanobacteria. five str ...200516289234
microcystin production in benthic mats of cyanobacteria in the nile river and irrigation canals, egypt.the present study describes for the first time the species composition and toxicity of benthic cyanobacteria forming mats on the nile river and irrigation canal sediments in egypt. a total of 19 species of cyanobacteria were isolated from these mats during this study. the toxicity of the extracts of these species was investigated using artemia salina assay, mouse bioassay and enzyme linked immunosorbent assay (elisa). the results showed that all the 19 benthic species isolated from cyanobacteria ...200616564062
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