Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| ultrastructural and electron spectroscopic analyses of cyanobacteria and bacteria. | the extracellular sheath material and some intracellular cell components of cyanobacteria and phosphate-accumulating sewage bacteria were analysed by electron spectroscopic imaging (esi) and electron energy-loss spectroscopy (eels). the specimens were embedded in water-soluble nanoplast resin without any previous fixation and ultrathin sections were examined in a zeiss cem 902 microscope. a high sulphur content was detected in the inner sheath of the cyanobacterium gloeothece. the elemental comp ... | 1991 | 1651393 |
| polypeptide composition of the photosystem i complex and the photosystem i core protein from synechococcus sp. pcc 6301. | the polypeptide composition of the photosystem i complex from synechococcus sp. pcc 6301 was determined by sodium-dodecyl sulfate polyacrylamide gel electrophoresis and n-terminal amino acid sequencing. the psaa, psab, psac, psad, psae, psaf, psak and psal proteins, as well as three polypeptides with apparent masses less than 8 kda and small amounts of the 12.6 kda glnb (pii) protein, wee present in the photosystem i complex. no proteins homologous to the psag and psah subunits of eukaryotic pho ... | 1991 | 1653017 |
| characterization of insertion sequence is892 and related elements from the cyanobacterium anabaena sp. strain pcc 7120. | is892, one of the several insertion sequence (is) elements discovered in anabaena sp. strain pcc 7120 (y. cai and c. p. wolk, j. bacteriol. 172:3138-3145, 1990), is 1,675 bp with 24-bp near-perfect inverted terminal repeats and has two open reading frames (orfs) that could code for proteins of 233 and 137 amino acids. upon insertion into target sites, this is generates an 8-bp directly repeated target duplication. a 32-bp sequence in the region between orf1 and orf2 is similar to the sequence of ... | 1991 | 1653218 |
| characterization of the is895 family of insertion sequences from the cyanobacterium anabaena sp. strain pcc 7120. | a family of repetitive elements from the cyanobacterium anabaena sp. strain pcc 7120 was identified through the proximity of one element to the psbai gene. four members of this seven-member family were isolated and shown to have structures characteristic of bacterial insertion sequences. each element is approximately 1,200 bp in length, is delimited by a 30-bp inverted repeat, and contains two open reading frames in tandem on the same dna strand. the four copies differ from each other by small i ... | 1991 | 1653219 |
| cyanobacterial nodularin is a potent inhibitor of type 1 and type 2a protein phosphatases. | the present study characterizes the inhibitory effects of nodularin, a recently isolated hepatotoxic compound from the cyanobacterium nodularia spumigena, on type 1 (pp1), type 2a, (pp2a), type 2b (pp2b), and type 2c (pp2c) protein phosphatases. both pp2a and pp1 were potently inhibited (ic50 = 0.026 and 1.8 nm, respectively) by nodularin, whereas pp2b was inhibited to a lesser extent (ic50 = 8.7 microm). nodularin had no apparent effect on pp2c, alkaline phosphatase, acid phosphatase, insulin r ... | 1991 | 1656193 |
| structure-function relationships of microcystins, liver tumor promoters, in interaction with protein phosphatase. | microcystins, isolated from toxic blue-green algae, are potent inhibitors of protein phosphatases 1 and 2a. recently, we have reported that microcystin lr has a potent tumor-promoting activity on rat liver initiated with diethylnitrosamine. the structure of microcystins is unique in having an unusual amino acid, 3-amino-9-methoxy-10-phenyl-2,6,8-trimethyl-deca-4(e),6(e)-dienoic acid (adda), which is thought to be significant for the activity. geometrical isomers at c-7 in the adda portion of mic ... | 1991 | 1657848 |
| unique modification of adenine in genomic dna of the marine cyanobacterium trichodesmium sp. strain nibb 1067. | the genomic dna of the marine nonheterocystous nitrogen-fixing cyanobacterium trichodesmium sp. strain nibb 1067 was found to be highly resistant to dna restriction endonucleases. the dna was digested extensively by the restriction enzyme dpni, which requires adenine methylation for activity. the dna composition, determined by high-performance liquid chromatography (hplc), was found to be 69% at. surprisingly, it was found that a modified adenine which was not methylated at the usual n6 position ... | 1991 | 1657876 |
| genetic systems in cyanobacteria. | 1991 | 1658567 | |
| the cytochrome c oxidase genes in blue-green algae and characteristics of the deduced protein sequence for subunit ii of the thermophilic cyanobacterium synechococcus vulcanus. | blue-green algae (cyanobacteria) contain both primitive photosynthetic and respiratory systems in their membranes. the controversial genes coding for an alpha alpha 3-type cytochrome oxidase in cyanobacteria were examined. the dna probe coding for the most conserved part of subunit i hybridized with dna fragments from four cyanobacterial species. we have cloned the genes coding for subunits i and ii from the genomic library of the thermophilic cyanobacterium synechococcus vulcanus and determined ... | 1991 | 1659815 |
| insertional inactivation of the psbo gene encoding the manganese stabilizing protein of photosystem ii in the cyanobacterium synechococcus pcc7942. effect on photosynthetic water oxidation and l-amino acid oxidase activity. | a synechococcus pcc7942 mutant in which the psbo gene was inactivated by insertion of a chloramphenicol interposon and which did not contain any detectable manganese stabilizing protein in immunoblot experiments, was constructed. such a synechococcus mutant was able to grow under photoautotrophic conditions. isolated thylakoid membranes from the mutant required addition of cacl2 and mncl2 for photosynthetic o2 evolution, and the detectable l-amino acid oxidase activity in the isolated thylakoid ... | 1991 | 1660410 |
| a residue substitution in phosphoribulokinase of synechocystis pcc 6803 renders the mutant light-sensitive. | we have isolated a light-sensitive mutant (brls) of the photosynthetic cyanobacterium synechocystis 6803 (s. 6803) that does not survive exposure to bright light: 70% of brls cells die upon exposure to light of greater than 3,000 lux for 2 h. a complementing dna fragment from wild-type cells and the corresponding dna from the brls cells have been cloned and sequenced. an open reading frame is found to encode phosphoribulokinase, a key enzyme in the enzyme system for photosynthetic carbon reducti ... | 1991 | 1660882 |
| 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 ... | 1991 | 1662761 |
| cytochrome c and c-554 oxidation by membranous anacystis nidulans cytochrome oxidase. | 1991 | 1664371 | |
| enzyme inhibitors from algae. | 1991 | 1665441 | |
| acidic cytochrome c6 of unicellular cyanobacteria is an indispensable and kinetically competent electron donor to cytochrome oxidase in plasma and thylakoid membranes. | cytochromes c6 from three cyanobacteria were tested as substrates for membranous cyt. c oxidase(aa3) of anacystis and synechocystis using intact spheroplasts or isolated plasma(cm) and thylakoid(icm) membranes. neither spheroplasts nor cm/icm gave significant o2 uptake rates with nadh without added cyt. c. horse cyt. c (at low ionic strength) or cyt. c6 from anacystis, synechocystis or microcystis (at high ionic strength) supported substantial hcn- & co-sensitive nadh oxidase activity, consisten ... | 1991 | 1665972 |
| preliminary results on the biosynthesis of [11c]phenylalanine using a photosynthetic bacterium. | 1991 | 1666735 | |
| health risks from exposure to algae. | 1991 | 1669779 | |
| molecular cloning of the genes encoding two chaperone proteins of the cyanobacterium synechocystis sp. pcc 6803. | molecular chaperones help other proteins in their correct folding and assembly. we have cloned the genes, cpn60 and dnak, which encode proteins belonging to the chaperonin-60 and the 70-kda heat shock protein families from the transformable cyanobacterium synechocystis sp. pcc 6803. these genes are present in single copies in the genome, and the major transcripts for each gene are monocistronic. comparison of deduced amino acid sequences reveals that cyanobacterial chaperonin-60 is equally homol ... | 1991 | 1670771 |
| regulation of glutamine synthetase activity in the unicellular cyanobacterium synechocystis sp. strain pcc 6803 by the nitrogen source: effect of ammonium. | glutamine synthetase activity from synechocystis sp. strain pcc 6803 is regulated as a function of the nitrogen source available in the medium. addition of 0.25 mm nh4cl to nitrate-grown cells promotes a clear short-term inactivation of glutamine synthetase, whose enzyme activity decreases to 5 to 10% of the initial value in 25 min. the intracellular levels of glutamine, determined under various conditions, taken together with the results obtained with azaserine (an inhibitor of transamidases), ... | 1991 | 1676397 |
| selection of cyanobacteria isolated from mosquito breeding sites as a potential food source for mosquito larvae. | one way to increase the persistence of larvicidal toxins in mosquito breeding sites is to clone the corresponding genes in microorganisms, such as cyanobacteria, which could serve as a source of food for the larvae. we isolated and cultured 10 strains of cyanobacteria from three mosquito breeding sites along the french mediterranean coast. most of the strains were tolerant to a relatively wide range of salt concentrations, and all of them were totally or partially resistant to at least four of t ... | 1991 | 1677241 |
| osmoregulatory role of alanine during salt stress in the nitrogen fixing cyanobacterium anabaena sp. 287. | the freshwater cyanobacterium, anabaena sp. 287 exhibited enhanced tolerance to nacl in the presence of ammonium, nitrate, and the amino acids, alanine, valine, proline, lysine, histidine, methionine and aspartic acid. apart from providing permanent protection to the growth during stress, like no3- and nh4+, alanine also relieved the initial salt mediated inhibition on enzymes involved in nitrogen fixation, photosynthesis and respiration. the accumulation of sugars was observed only during molec ... | 1991 | 1677806 |
| role of azolla in controlling mosquito breeding in ghaziabad district villages (u.p.). | a survey was carried out during post-monsoon period (1988-89) in villages of dhaulana primary health centre, distt. ghaziabad (u.p.) to evaluate the utility of azolla pinnata for the control of mosquito breeding in different habitats. results of the survey revealed that pools, ponds, wells, rice fields and drains were infested with azolla. infestation rate and intensity of infestation varied from habitat to habitat. maximum infestation (36.5%) was observed in pools and minimum (3.7%) in rice fie ... | 1991 | 1680758 |
| influence of different forms of nitrogen on uptake of ammonium, glutamate and glutamine in the cyanobacterium nostoc muscorum. | effect of various types of nitrogen nutrition was studied on the uptake of ammonium, glutamate and glutamine by nostoc muscorum and its het-nif- mutant. ammonium nitrogen acted as a potent inhibitor/repressor of ammonium, glutamate and glutamine transport. nitrate nitrogen was found to be a strong inhibitor/repressor of ammonium transport, a partial inhibitor/repressor of glutamate transport but, caused a partial stimulation of glutamine transport. | 1991 | 1684351 |
| in vitro reactivation of in vivo ammonium-inactivated glutamine synthetase from synechocystis sp. pcc 6803. | glutamine synthetase from synechocystis sp. strain pcc 6803 is inactivated by ammonium addition to cells growing with nitrate as the nitrogen source. the enzyme can be reactivated in vitro by different methods such as alkaline phosphatase treatment, but not phosphodiesterase, by raising the ph of the crude extract to values higher than 8, by increasing the ionic strength of the cell-free extract, or by preincubation with organic solvents, such as 2-propanol and ethanol. these results suggest tha ... | 1991 | 1684495 |
| identification of a common cyanobacterial symbiont associated with azolla spp. through molecular and morphological characterization of free-living and symbiotic cyanobacteria. | symbiotically associated cyanobacteria from azolla mexicana and azolla pinnata were isolated and cultured in a free-living state. morphological analyses revealed differences between the free-living isolates and their symbiotic counterparts, as did restriction fragment length polymorphism (rflp) analyses with both single-copy glna and rbcs gene probes and a multicopy psba gene probe. rflp analyses with anabaena sp. strain pcc 7120 nifd excision element probes, including an xisa gene probe, detect ... | 1991 | 1685078 |
| evidence for a role of glutamine synthetase in assimilation of amino acids as nitrogen source in the cyanobacterium nostoc muscorum. | methylammonium/ammonium ion, glutamine, glutamate, arginine and proline uptake, and their assimilation as nitrogen sources, was studied in nostoc muscorum and its glutamine synthetase-deficient mutant. glutamine served as nitrogen source independent of glutamine synthetase activity. glutamate was not metabolised as a nitrogen source but still inhibited nitrogenase activity and diazotrophic growth. glutamine synthetase activity was essential for the assimilation of n2, ammonia, arginine and proli ... | 1991 | 1687107 |
| microbial ecology. variation among the masses. | 1990 | 1691826 | |
| 16s rrna sequences reveal numerous uncultured microorganisms in a natural community. | microbiologists have been constrained in their efforts to describe the compositions of natural microbial communities using traditional methods. few microorganisms have sufficiently distinctive morphology to be recognized by microscopy. culture-dependent methods are biased, as a microorganism can be cultivated only after its physiological niche is perceived and duplicated experimentally. it is therefore widely believed that fewer than 20% of the extant microorganisms have been discovered, and tha ... | 1990 | 1691827 |
| bacterial rna isolation with one hour centrifugation in a table-top ultracentrifuge. | a procedure for the rapid preparation of cesium-chloride purified rna from e. coli and the cyanobacterium synechococcus sp. pcc7942 is described. cells are lysed in modified sucrose, triton x-100, edta, tris buffer with phenol/chloroform. the cleared lysate is extracted further with phenol/chloroform and rna is peleted by centrifugation through a 5.7 m cscl cushion. high quality rna can be prepared in three hours using this procedure. | 1990 | 1691916 |
| characterization of the light-regulated operon encoding the phycoerythrin-associated linker proteins from the cyanobacterium fremyella diplosiphon. | many biological processes in photosynthetic organisms can be regulated by light quantity or light quality or both. a unique example of the effect of specific wavelengths of light on the composition of the photosynthetic apparatus occurs in cyanobacteria that undergo complementary chromatic adaptation. these organisms alter the composition of their light-harvesting organelle, the phycobilisome, and exhibit distinct morphological features as a function of the wavelength of incident light. fremyell ... | 1990 | 1694529 |
| genomic integration system based on pbr322 sequences for the cyanobacterium synechococcus sp. pcc7942: transfer of genes encoding plastocyanin and ferredoxin. | synechococcus sp. pcc7942 recipient strains were constructed for the chromosomal integration of dna fragments cloned in any pbr322-derived vector, which carries the ampicillin resistance (apr) marker. the construction was based on the incorporation of specific recombination targets, the so-called 'integration platforms', into the chromosomal metf gene. these platforms consist of an incomplete bla gene (aps) and the pbr322 ori separated from each other by a gene encoding an antibiotic (streptomyc ... | 1990 | 1701408 |
| the ferredoxin-thioredoxin reductase variable subunit gene from anacystis nidulans. | the ferredoxin-thioredoxin reductase variable subunit gene of anacystis nidulans was cloned, and its nucleotide sequence was determined. a single-copy 219-bp open reading frame encoded a protein of 73 amino acid residues, with a calculated mr of 8,400. the monocistronic transcripts were represented in a 400-base and a less abundant 300-base mrna form. | 1991 | 1705544 |
| cotranscription, deduced primary structure, and expression of the chloroplast-encoded rbcl and rbcs genes of the marine diatom cylindrotheca sp. strain n1. | the primary structure of ribulose-1,5-bisphosphate carboxylase/oxygenase from the marine diatom cylindrotheca sp. strain n1 has been determined. unlike higher plants and green algae, the genes encoding the large and the small subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase are chloroplast-encoded and closely associated (hwang and tabita, 1989). the rbcl and rbcs genes in strain n1 are cotranscribed and are separated by an intergenic region of 46 nucleotide base pairs. ribosome bindin ... | 1991 | 1706714 |
| characterization and mutagenesis of sulfur-regulated genes in a cyanobacterium: evidence for function in sulfate transport. | a sulfur-regulated gene (cysa) that encodes the membrane-associated atp-binding protein of the sulfate transport system of the cyanobacterium synechococcus sp. strain pcc 7942 was recently isolated and sequenced. adjacent to cysa and transcribed in the opposite direction is a gene encoding the sulfate-binding protein (sbpa). two other genes, cyst and cysw, encode proteins that may form a channel for the transport of sulfate across the cytoplasmic membrane. a fourth gene, cysr, located between cy ... | 1991 | 1708375 |
| isolation and characterization of a sulfur-regulated gene encoding a periplasmically localized protein with sequence similarity to rhodanese. | during sulfur-limited growth, the cyanobacterium synechococcus sp. strain pcc 7942 loses most of its photosynthetic pigments and develops an increased capacity to acquire sulfate. sulfur deprivation also triggers the synthesis of several soluble polypeptides. we have isolated a prominent polypeptide of 33 kda that accumulates specifically under sulfur-limiting conditions. this polypeptide was localized to the periplasmic space. the gene for this protein (designated rhda) was isolated and discove ... | 1991 | 1708376 |
| propionigenium modestum: a separate line of descent within the eubacteria. | the complete nucleotide sequence of 16s rrna from propionigenium modestum was determined and compared with 380 16s rrna sequences from representatives of all eu- and archaebacterial phyla known so far. the phylogenetic analysis of this data set indicated p. modestum to represent a new separated line of descent within the radiation of eubacterial phyla moderately related to cyanobacteria and gram-positive bacteria with low dna gc content. | 1991 | 1709606 |
| identification of a genomic region that complements a temperature-sensitive, high co2-requiring mutant of the cyanobacterium, synechococcus sp. pcc7942. | in a temperature-sensitive, high co2-requiring mutant of synechococcus sp. pcc7942, the ability to fix intracellularly accumulated inorganic carbon was severely impaired at non-permissive temperature (41 degrees c). in contrast, inorganic carbon uptake and ribulose-1.5-bisphosphate carboxylase activity in the mutant were comparable to the respective values obtained with the wild-type strain. the mutant was transformed to the wild-type phenotype (ability to form colonies at non-permissive tempera ... | 1991 | 1710016 |
| morphologic and staining characteristics of a cyanobacterium-like organism associated with diarrhea. | a spherical organism 9-10 microns in diameter, seen in three outbreaks of diarrhea in southeast asia and the united states during the past 2 years, bore characteristics of a cyanobacterium when observed in formalin-preserved stool specimens and by electron microscopy. organisms in freshly passed stool specimens showed an internal morula of lipid-containing globules. in fresh water, the morula divided into two sausage-shaped structures resembling the sporocysts of an isosporid coccidian. after 7 ... | 1991 | 1711553 |
| 16s rrna sequences of uncultivated hot spring cyanobacterial mat inhabitants retrieved as randomly primed cdna. | cloning and analysis of cdnas synthesized from rrnas is one approach to assess the species composition of natural microbial communities. in some earlier attempts to synthesize cdna from 16s rrna (16s rcdna) from the octopus spring cyanobacterial mat, a dominance of short 16s rcdnas was observed, which appear to have originated only from certain organisms. priming of cdna synthesis from small ribosomal subunit rna with random deoxyhexanucleotides can retrieve longer sequences, more suitable for p ... | 1991 | 1711832 |
| directed chloroplast transformation in chlamydomonas reinhardtii: insertional inactivation of the psac gene encoding the iron sulfur protein destabilizes photosystem i. | the chloroplast gene psac encoding the iron sulfur protein of photosystem i (psi) from the green alga chlamydomonas reinhardtii has been cloned and characterized. the deduced amino acid sequence is highly related to that of higher plants and cyanobacteria. using a particle gun, wild type c. reinhardtii cells have been transformed with a plasmid carrying the psac gene disrupted by an aada gene cassette designed to express spectinomycin/streptomycin resistance in the chloroplast. transformants sel ... | 1991 | 1712288 |
| isolation, transcription, and inactivation of the gene for an atypical alkaline phosphatase of synechococcus sp. strain pcc 7942. | the alkaline phosphatase of synechococcus sp. strain pcc 7942 is 145 kda, which is larger than any alkaline phosphatase previously characterized and approximately three times the size of the analogous enzyme in escherichia coli. the gene for the alkaline phosphatase, phoa, was cloned and sequenced, and the protein that it encodes was found to have little similarity to other phosphatases. some sequence similarities were observed between the synechococcus sp. strain pcc 7942 alkaline phosphatase, ... | 1991 | 1712356 |
| construction and characterization of cyanobacterial mutants lacking the manganese-stabilizing polypeptide of photosystem ii. | mutants of the cyanobacterium synechocystis sp. pasteur culture collection (pcc) 6803 that specifically lack the extrinsic 33-kda manganese-stabilizing polypeptide of the photosystem ii oxygen-evolving complex have been constructed by two independent methods. cartridge mutagenesis was used to insertionally inactivate the psbo gene of one mutant and completely delete the psbo gene of the other mutant. these mutants have no detectable manganese-stabilizing polypeptide, but they do accumulate stead ... | 1991 | 1712783 |
| photosynthetic electron transport controls degradation but not production of psba transcripts in the cyanobacterium synechocystis 6803. | accumulation and stability of psba and rbcl-s transcripts in synechocystis 6803 was followed in the presence and absence of the photosynthesis inhibitors dcmu and methylviologen. our results demonstrate that both transcript production and transcript stability are important regulatory elements for psba gene expression in synechocystis 6803. the production of psba transcripts was stimulated by light in a process that operated independently of the photosynthetic electron transport. however, stabili ... | 1991 | 1713480 |
| targeted genetic inactivation of the photosystem i reaction center in the cyanobacterium synechocystis sp. pcc 6803. | we describe the first complete segregation of a targeted inactivation of psaa encoding one of the p700-chlorophyll a apoproteins of photosystem (ps) i. a kanamycin resistance gene was used to interrupt the psaa gene in the unicellular cyanobacterium synechocystis sp. pcc 6803. selection of a fully segregated mutant, adk9, was performed under light-activated heterotrophic growth (lahg) conditions; complete darkness except for 5 min of light every 24 h and 5 mm glucose. under these conditions, wil ... | 1991 | 1717264 |
| a mixed group ii/group iii twintron in the euglena gracilis chloroplast ribosomal protein s3 gene: evidence for intron insertion during gene evolution. | the splicing of a 409 nucleotide intron from the euglena gracilis chloroplast ribosomal protein s3 gene (rps3) was examined by cdna cloning and sequencing, and northern hybridization. based on the characterization of a partially spliced pre-mrna, the intron was characterized as a 'mixed' twintron, composed of a 311 nucleotide group ii intron internal to a 98 nucleotide group iii intron. twintron excision is via a 2-step sequential splicing pathway, with removal of the internal group ii intron pr ... | 1991 | 1721702 |
| purification and properties of nadp-isocitrate dehydrogenase from the unicellular cyanobacterium synechocystis sp. pcc 6803. | nadp-dependent isocitrate dehydrogenase activity has been screened in several cyanobacteria grown on different nitrogen sources; in all the strains tested isocitrate dehydrogenase activity levels were similar in cells grown either on ammonium or nitrate. the enzyme from the unicellular cyanobacterium synechocystis sp. pcc 6803 has been purified to electrophoretic homogeneity by a procedure that includes reactive-red-120-agarose affinity chromatography and phenyl-sepharose chromatography as main ... | 1992 | 1730247 |
| analysis of the structure of photosystem i in cyanobacterial thylakoid membranes. | using electron microscopy of negatively stained specimens, we have investigated the shape and degree of association of photosystem (ps) i complexes in cyanobacterial thylakoid membranes. when incubated at high concentrations of magnesium chloride (greater than 0.15 m), the psi complexes form small ordered arrays in the membrane composed of monomeric complexes in a p1 square lattice of dimensions a = b = 11 nm. averaged projections of the complex resemble those found for the purified psi reaction ... | 1992 | 1730288 |
| multiple evolutionary origins of prochlorophytes, the chlorophyll b-containing prokaryotes. | prochlorophytes are prokaryotes that carry out oxygenic photosynthesis using chlorophylls a and b, but lack phycobiliproteins as light-harvesting pigments. these characteristics distinguish them from cyanobacteria, which contain phycobiliproteins, but no chlorophyll b. three prochlorophyte genera have been described: prochloron, prochlorothrix and prochlorococcus. the prochlorophytes share their pigment characteristics with green plant and euglenoid chloroplasts, which has led to a debate on whe ... | 1992 | 1731224 |
| multiple evolutionary origins of prochlorophytes within the cyanobacterial radiation. | the taxonomic group prochlorales (lewin 1977) burger-wiersma, stal and mur 1989 was established to accommodate a set of prokaryotic oxygenic phototrophs which, like plant, green algal and euglenoid chloroplasts, contain chlorophyll b instead of phycobiliproteins. prochlorophytes were originally proposed (with concomitant scepticism) to be a monophyletic group sharing a common ancestry with these 'green' chloroplasts. results from molecular sequence phylogenies, however, have suggested that proch ... | 1992 | 1731225 |
| amino acid substitutions in the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase that influence catalytic activity of the holoenzyme. | four unique amino acid substitutions were introduced by site-directed mutagenesis into the third conserved region of the small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) from anacystis nidulans (synechococcus sp., pcc6301), resulting in the formation of four mutant enzymes, i87v, r88k, g91v, and f92l. wild-type and mutant proteins were purified after synthesis in escherichia coli. these single amino acid substitutions do not appear to perturb intersubunit interactions o ... | 1992 | 1731909 |
| aspartate 170 of the photosystem ii reaction center polypeptide d1 is involved in the assembly of the oxygen-evolving manganese cluster. | eleven site-directed mutations were constructed at aspartate 170 of the d1 polypeptide of the photosystem ii (psii) reaction center of the cyanobacterium synechocystis sp. pcc 6803. the light-saturated rates of o2 evolution (vo2) measured in whole cells range from close to that of wild-type for asp170glu to zero for asp170ser and ala. those mutant strains that are best able to evolve o2 are also those that show the lowest km in psii core complexes for the oxidation of mn2+ by oxidized tyr161, th ... | 1992 | 1731951 |
| nucleotide sequence and expression of the ndhh gene of the cyanobacterium synechocystis sp. pcc6803. | 1992 | 1731965 | |
| structural organization of the chloroplast genome of the chromophytic alga vaucheria bursata. | the chloroplast genome of the chromophytic alga vaucheria bursata has been characterized by restriction site and gene mapping analysis. it is represented by a circular molecule 124.6 kb in size. an inverted sequence duplication (ir) not larger than 5.85 kb carries the rrna genes and separates two single-copy regions of 64.6 kb and 48.3 kb from one another. the vaucheria plastid genome exists in two equimolar isomers which is due to intramolecular flip-flop recombination within the ir sequences. ... | 1992 | 1731981 |
| illness associated with blue-green algae. | 1992 | 1734199 | |
| identification of specific carboxyl groups on anabaena pcc 7119 flavodoxin which are involved in the interaction with ferredoxin-nadp+ reductase. | flavodoxin from the nitrogen-fixing cyanobacteria anabaena pcc 7119 forms an electron-transfer complex with ferredoxin--nadp+ reductase (fnr) from the same organism. the complex is mainly governed by electrostatic interactions between side-chain amino groups of the reductase and carboxyl residues of flavodoxin. in order to localize the binding site on flavodoxin, chemical modification of its carboxyl groups has been carried out. treatment of flavodoxin with a water-soluble carbodiimide, n-ethyl- ... | 1992 | 1735424 |
| insertion and assembly of the precursor of subunit ii into the photosystem i complex may precede its processing. | the biogenesis and assembly of subunit ii of photosystem i (psi) (psad gene product) were studied and characterized. the precursor and the mature form were produced in vitro and incubated with intact plastids or isolated thylakoids. following import of the precursor into isolated plastids, mostly the mature form of subunit ii was found in the thylakoids. however, when the processing activity was inhibited only the precursor form was present in the membranes. the precursor was processed by a stro ... | 1992 | 1740118 |
| proteolysis in protein import and export: signal peptide processing in eu- and prokaryotes. | numerous proteins in pro- and eukaryotes must cross cellular membranes in order to reach their site of function. many of these proteins carry signal sequences that are removed by specific signal peptidases during, or shortly after, membrane transport. signal peptidases have been identified in the rough endoplasmic reticulum, the matrix and inner membrane of mitochondria, the stroma and thylakoid membrane of chloroplasts, the bacterial plasma membrane and the thylakoid membrane of cyanobacteria. ... | 1992 | 1740185 |
| pami and pamii restriction endonucleases from phormidium ambiguum. | 1992 | 1741304 | |
| microalgae as food and supplement. | the microalgae chlorella spp., dunaliella spp., and scenedesmus spp., and the cyanobacteria spirulina spp., and aphanizomenon flos-aquae, are being used as nutrient-dense foods and sources of fine chemicals. they have significant amounts of lipid, protein, chlorophyll, carotenoids, vitamins, minerals, and unique pigments. they may also have potent probiotic compounds that enhance health. their historical and current use are reviewed in this article. | 1991 | 1741951 |
| additional algal toxicosis hazard. | 1991 | 1746123 | |
| glycinebetaine enhances and stabilizes the evolution of oxygen and the synthesis of atp by cyanobacterial thylakoid membranes. | glycinebetaine (betaine), an osmoregulant in halophilic plants, stabilized the evolution of oxygen and the synthesis of atp by thylakoid membranes from the cyanobacterium synechocystis pcc6803 when it was present during the preparation and incubation of the thylakoid membranes. moreover, betaine enhanced the evolution of oxygen and the synthesis of atp when present during assays. when betaine at 1.0 m was present during the preparation of thylakoid membranes and during the measurement of activit ... | 1991 | 1756870 |
| growth-phase-dependent induction of 6-phosphogluconate dehydrogenase and glucose 6-phosphate dehydrogenase in the cyanobacterium synechococcus sp. pcc7942. | in most cyanobacteria, the only known pathway for oxidation of stored carbohydrate in the dark or under energy-limiting conditions is the hexose monophosphate shunt. to determine whether the increased use of the shunt under these conditions derives from an increase in the activity level of the respective enzymes, we measured the effect of growth phase during the growth of batch cultures of synechococcus sp. strain pcc7942 on the specific activity of 6-phosphogluconate dehydrogenase (6pgd) and gl ... | 1991 | 1756984 |
| molecular evidence for the origin of plastids from a cyanobacterium-like ancestor. | the origin of plastids by either a single or multiple endosymbiotic event(s) and the nature of the progenitor(s) of plastids have been the subjects of much controversy. the sequence of the small subunit rrna (ssu rrna) from the plastid of the chlorophyll c-containing alga cryptomonas phi is presented, allowing for the first time a comparison of this molecule from all of the major land plant and algal lineages. using a distance matrix method, the phylogenetic relationships among representatives o ... | 1991 | 1757997 |
| metal pollution and its impact on algae in flowing waters in india. | metal pollution in the river godavari in india, due to discharges of liquid wastes from a paper mill, has been studied for a period of two years. at the discharge point and 1 km from the point of discharge, iron, manganese, and zinc were recorded in high concentrations, whereas cadmium and chromium were observed in low concentrations. no metal was in detectable concentration in water before the river receives the effluents. a considerable drop in ph values and an appreciable increase in organic ... | 1991 | 1759850 |
| comparative analysis of ribosomal protein l5 sequences from bacteria of the genus thermus. | the genes for the ribosomal 5s rrna binding protein l5 have been cloned from three extremely thermophilic eubacteria, thermus flavus, thermus thermophilus hb8 and thermus aquaticus (jahn et al, submitted). genes for protein l5 from the three thermus strains display 95% g/c in third positions of codons. amino acid sequences deduced from the dna sequence were shown to be identical for t flavus and t thermophilus, although the corresponding dna sequences differed by two t to c transitions in the t ... | 1991 | 1764514 |
| characterization of glutamate-1-semialdehyde aminotransferase of synechococcus. steady-state kinetic analysis. | synechococcus glutamate-1-semialdehyde aminotransferase was expressed in large amounts in transformed cells of escherichia coli. the resulting purified enzyme has an absorption spectrum characteristic of b6-containing enzymes and could be converted to the pyridoxal-phosphate form with excess dioxovalerate (o2val), and back to the pyridoxamine-phosphate form with diaminovalerate (a2val). both enzyme forms are similarly active in the conversion of glutamate 1-semialdehyde (gsa) to 5-aminolevulinat ... | 1991 | 1765090 |
| disappearance of trichlorfon from cultures with different cyanobacteria. | 1991 | 1768954 | |
| association of microcystin-lr and its biotransformation product with a hepatic-cytosolic protein. | microcystin-lr (mcyst-lr), a cyclic peptide hepatotoxin, associates with high-molecular-weight, liver cytosolic components. repetitive cycles of heat denaturation and pronase digestion released 80 +/- 6% of the bound radiolabel from these components, parent toxin (22%), and two biotransformation products, with high-performance liquid chromatography (hplc) retention times of 6.7 (52%) and 5.6 (13%) min. both parent and the biotransformed (6.7 min) toxin appeared to be covalently bound to a monome ... | 1991 | 1770501 |
| anatoxin-a(s), a naturally occurring organophosphate, is an irreversible active site-directed inhibitor of acetylcholinesterase (ec 3.1.1.7). | anatoxin-a(s) is a guanidine methyl phosphate ester (unprotonated molecular ion equals 252 daltons) isolated from the freshwater cyanobacterium (blue-green alga) anabaena flos-aquae strain nrc 525-17. previous work has shown anatoxin-a(s) to be a potent irreversible inhibitor of electric eel acetylcholinesterase (ec 3.1.1.7, ache). in the present study the interaction of anatoxin-a(s) with ache was investigated by protection studies and since similarities have been noted between anatoxin-a(s) an ... | 1991 | 1770503 |
| waterborne-disease outbreaks, 1989-1990. | for the 2-year period 1989-1990, 16 states reported 26 outbreaks due to water intended for drinking; an estimated total of 4,288 persons became ill in these outbreaks. giardia lamblia was implicated as the etiologic agent for seven of the 12 outbreaks in which an agent was identified. the outbreaks of giardiasis were all associated with ingestion of unfiltered surface water or surface-influenced groundwater. an outbreak with four deaths was attributed to escherichia coli o157:h7, the only bacter ... | 1991 | 1770924 |
| mutagenesis of the cyanobacterium spirulina platensis by uv and nitrosoguanidine treatment. | the production of spirulina platensis cells resistant to 8-azaguanine or beta-(2-thienyl)-dl-alanine following mutagenesis with n-methyl-n'-nitro-n-nitrosoguanidine (mnng) and uv-irradiation is described. the conditions for the mutagenesis were determined by monitoring cell viability and the appearance of the two types of mutants as a function of the stage of growth of the tricomes and the length and the conditions of the treatment. the optimal conditions for uv and mnng mutagenesis were found t ... | 1991 | 1778426 |
| purification of prokaryotic metallothioneins. | 1991 | 1779788 | |
| use of a mutant strain of the cyanobacterium synechococcus r2 for the determination of nitrate. | a sensitive procedure for the determination of nitrate within the 1- to 50-microm range is described. the method is based on the photoreduction of nitrate to nitrite by whole cells of a nitrite reductase-less mutant strain of the unicellular cyanobacterium synechococcus r2. cell suspensions of this cyanobacterium retain high levels of nitrate photoreduction activity for at least 2 months when maintained in the presence of dimethyl sulfoxide at -70 degrees c. | 1991 | 1789426 |
| studies on a toxin produced by the cyanobacterium phormidium persicinum. | 1991 | 1794548 | |
| the composition and organization of photosystem i. | photosystem i, extensively studied in the past decade, was shown to be homologous in all photosynthetic organisms of the higher plants type. its core complex was found to be highly conserved through evolution from cyanobacteria to higher plants. the genes coding for the subunits of cci were isolated and the resulting sequences provided information about secondary structural elements. these suggested secondary structures enabled the prediction of the topology of these subunits in the photosynthet ... | 1991 | 1797091 |
| [substances from cyanobacteria--potential virostatics?]. | 1991 | 1798723 | |
| [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 ... | 1991 | 1798852 |
| [investigations of the immunomodulatory effect of cyanobacterial extracts]. | resulting from the knowledge that cyanobacteria (blue-green algae) are able to produce pharmacologically active substances the aqueous extracts from several cyanobacteria species and strains (microcystis aeruginosa, synechocystis aquatilis, oscillatoria redekei, anabaena flos-aque, aphanizomenon flos-aquae, oscillatoria rubescens, oscillatoria tenuis) were tested for their immunomodulating activity. extracts from oscillatoria redekei 051, oscillatoria tenuis 01 and synechocystis aquatilis 428 ca ... | 1991 | 1801597 |
| studies on glycolipids. iii. glyceroglycolipids from an axenically cultured cyanobacterium, phormidium tenue. | seven new monogalactosyl diacylglycerols (1-7) and six new digalactosyl diacylglycerols (11-16) were isolated from an axenically cultured cyanobacterium, p. tenue. their structures were elucidated on the basis of physicochemical evidence and the results of enzymatic hydrolysis using a lipase (from rhizopus arrhizus). comparison of antialgal activity for p. tenue between monogalactosyl diacylglycerols (1-8) and digalactosyl diacylglycerols (11-19) revealed that the former showed more potent activ ... | 1991 | 1804541 |
| evidence for energy-dependent copper efflux as a mechanism of cu2+ resistance in the cyanobacterium nostoc calcicola. | wild-type nostoc calcicola carried out oxygenic photosynthesis extremely sensitive to copper. a cu(2+)-resistant mutant (cu-r1) of the cyanobacterium grew normally at high concentrations of cu2+. its ability to grow under such conditions was found to be due to mutational acquisition of an energy-dependent efficient system of cu(2+)-efflux, which rendered cu(2+)-inhibited oxygenic photosynthesis fully reversible. | 1991 | 1804762 |
| plastid genomes of the rhodophyta and chromophyta constitute a distinct lineage which differs from that of the chlorophyta and have a composite phylogenetic origin, perhaps like that of the euglenophyta. | a phylogenetic tree has been constructed from comparisons of entire 16s rrna gene sequences from different prokaryotes and from several algal plastids. according to this study, and to previous work on the ribulose-1,5-bisphosphate carboxylase oxygenase (rubisco) large and small subunit genes, we postulate that: (1) rhodophyte and chromophyte plastid genomes have a common, composite phylogenetic origin which implies at least two different ancestors, a cyanobacterial and a beta-proteobacterial anc ... | 1991 | 1807834 |
| 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 ... | 1991 | 1809846 |
| amino acid sequence of the 8-kda protein in photosystem i reaction center complex from a thermophilic cyanobacterium, synechococcus elongatus. | the 8-kda protein in photosystem i (ps i) reaction center complex was isolated from a thermophilic cyanobacterium, synechococcus elongatus, by sds-polyacrylamide gel electrophoresis using tris-tricine buffer system. the complete amino acid sequence of the protein was determined. the 8-kda protein consisted of 73 amino acid residues giving a calculated molecular weight of 7,472. no significant sequence homology were observed with the known other small subunits in ps i reaction center complex, exc ... | 1991 | 1812486 |
| effects of dimethoate on n2-fixing cyanobacterium anabaena pcc 7119. | 1991 | 1813092 | |
| effect of lead on nitrogenase and enzymes of nitrogen assimilation in a cyanobacterium nostoc muscorum. | lead decreased the growth rates, total cell mass, heterocyst frequency, total cell protein, nitrogenase activity, glutamine synthetase (gs) and glutamate synthase (gogat) activities in n:muscorum. however, lead at 0.01 and 10 micrograms ml-1 conc. enhanced nitrogenase as well as gs activity of the cells. on transfer to excess lead (100 micrograms ml-1), nitrogenase and gs activities ceased almost after 24 hr in the cyanobacterium. it is deduced that lead has a two step effect on stimulation and ... | 1991 | 1816095 |
| functional complementation in escherichia coli of different phytoene desaturase genes and analysis of accumulated carotenes. | three different phytoene desaturase genes, from rhodobacter capsulatus, erwinia uredovora, and synechococcus pcc 7942, have been functionally complemented with a gene construct from e. uredovora which encodes all enzymes responsible for formation of 15-cis phytoene in escherichia coli. as indicated by the contrasting reaction products detected in the pigmented e. coli cells after co-transformation, a wide functional diversity of these three different types of phytoene desaturases can be conclude ... | 1991 | 1817513 |
| [production of the antibiotic-algicide cyanobacterin lu-2 by a filamentous cyanobacterium nostoc sp]. | a strain of cyanobacterium of nostoc has been isolated, and found to produce a new antibiotic cyanobacterin lu-2. the antibiotic is synthesized by the cyanobnacterium under intensive cultivation conditions in a liquid mineral medium. cyanobacterin lu-2 is an exometabolite; its maximum accumulation in the medium is achieved at 34 degrees. cyanobacterin lu-2 is active against many cyanobacteria tested, including those of microcystis and aphanizomenon which are principals to give rise to blooms in ... | 1991 | 1819038 |
| the antiquity of group i introns. | the recent discovery of self-splicing introns in cyanobacteria has given renewed interest to the question of whether introns may have been present in the ancestor of all living things. the properties of introns in genes of bacteria and bacteriophages are discussed in the context of their possible origin and biological function. | 1991 | 1822280 |
| the delta subunit of the chloroplast atpase is plastid-encoded in the diatom odontella sinensis. | a 5.2 kb psti restriction fragment containing the atpa gene cluster of the plastic genome of the centric diatom odontella sinensis was cloned. sequencing revealed a reading frame of 561 bp separating the genes atpf and atpa, which is preceded by a putative ribosome binding site. the third nucleotide of the codon for the last amino acid of atpf is the first nucleotide of the initiation codon of the 561 bp reading frame. the amino acid sequence deduced from the nucleotide sequence of this gene (at ... | 1991 | 1826484 |
| the atp1 and atp2 operons of the cyanobacterium synechocystis sp. pcc 6803. | the two operons atp1 and atp2, encoding the subunits of the f0f1 atp-synthase, have been cloned and sequenced from the cyanobacterium synechocystis sp. pcc 6803. the organization of the different genes in the operons have been found to resemble that of the cyanobacteria synechococcus sp. pcc 6301 and anabaena sp. pcc 7120. the synechocystis f0f1 atp-synthase has nine subunits. a tenth open reading frame with unknown function was detected at the 5' end of atp1, coding for a putative gene product ... | 1991 | 1832989 |
| sequence-specific endonucleases from the cyanobacterium nostoc sp. atcc 29132. | the nitrogen-fixing cyanobacterium nostoc sp. atcc 29132 was shown to contain two sequence-specific endonucleases. nsp(29132) i was an isoschizomer of asuii, and nsp(29132) ii was an isoschizomer of bamhi. nsp(29132) ii was shown to generate ends that could be ligated to those generated by bamhi. | 1991 | 1840140 |
| characterization of a gene controlling heterocyst differentiation in the cyanobacterium anabaena 7120. | anabaena 7120 mutant 216 fails to differentiate heterocyst. we previously identified a 2.4-kb wild-type dna fragment able to complement this mutant. we show here that the sequence of this fragment contains a single open reading frame (hetr), encoding a 299-amino-acid protein. conjugation of deletion subclones of this fragment into strain 216 showed that the hetr-coding region is both necessary and sufficient for complementation of the het- phenotype. the mutation in 216 is located at nucleotide ... | 1991 | 1840555 |
| genetic analysis of cyanobacterial development. | filamentous cyanobacteria, the only prokaryotes that form linear patterns of differentiated cells, can be genetically manipulated by the conjugative transfer of plasmids from escherichia coli. it has become possible to determine the cellular localization of genetic transcription, including transcription of developmentally critical genes before morphological differentiation takes place, by using luciferase as a reporter. these techniques are facilitating developmental analysis. | 1991 | 1840890 |
| expression of a higher plant psba gene in synechocystis 6803 yields a functional hybrid photosystem ii reaction center complex. | the psba gene codes for the d1 polypeptide of the photosystem ii reaction center complex and is found in all photosynthetic organisms that carry out oxygenic photosynthesis. here we describe the construction and characterization of a strain of the cyanobacterium synechocystis sp pcc 6803 in which the three endogenous psba genes are replaced by a single psba gene from the chloroplast genome of the higher plant poa annua. the resulting chimeric strain, kwpas, grows photoautotrophically with a doub ... | 1991 | 1840918 |
| a guide to electron paramagnetic resonance spectroscopy of photosystem ii membranes. | this guide is intended to aid in the detection and identification of paramagnetic species in photosystem ii membranes, by electron paramagnetic resonance spectroscopy. the spectral features and occurrence of each of the electron paramagnetic resonance signals from photosystem ii are discussed, in relation to the nature of the moiety giving rise to the signal and the role of that species in photosynthetic electron transport. examples of most of the signals discussed are shown. the electron parama ... | 1991 | 1845842 |
| nitrogen ligation to manganese in the photosynthetic oxygen-evolving complex: continuous-wave and pulsed epr studies of photosystem ii particles containing 14n or 15n. | the possibility of nitrogen ligation to the mn in the oxygen-evolving complex from photosystem ii was investigated with electron paramagnetic resonance (epr) and electron spin echo envelope modulation (eseem) spectroscopies using 14n- and 15n-labeled preparations. oxygen-evolving preparations were isolated from a thermophilic cyanobacterium, synechococcus sp., grown on a medium containing either 14no3- or 15no3- as the sole source of nitrogen. the substructure on the "multiline" epr signal, whic ... | 1991 | 1846751 |
| epr characterization of an oxygen-evolving photosystem ii preparation from the transformable cyanobacterium synechocystis 6803. | the transformable cyanobacterium synechocystis 6803 has a photosynthetic apparatus that is similar to that of plants. because of the ease with which this organism can be genetically manipulated and isotopically labeled, synechocystis has been used extensively in recent studies of electron transfer in the water-splitting complex, photosystem ii. here, we present the first epr characterization of a highly active oxygen-evolving preparation from this organism. this preparation shows oxygen-evolutio ... | 1991 | 1850295 |
| blooming algae. | 1991 | 1850634 | |
| sulfide-induced sulfide-quinone reductase activity in thylakoids of oscillatoria limnetica. | sulfide-dependent partial electron-transport reactions were studied in thylakoids isolated from cells of the cyanobacterium oscillatoria limnetica, which had been induced to perform sulfide-driven anoxygenic photosynthesis. it was found that these thylakoids have the capacity to catalyze electron transfer, from sulfide to externally added quinones, in the dark. assay conditions were developed to measure the reaction either as quinone-dependent sulfide oxidation (colorimetrically) or as sulfide-d ... | 1991 | 1898723 |
| self-splicing introns in prokaryotes: migrant fossils? | 1991 | 1898872 |