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  • 1
    Electronic Resource
    Electronic Resource
    Substitutional bias confounds inference of cyanelle origins from sequence data (1992)
    Springer
    Journal of molecular evolution 34 (1992), S. 153-162 
    Details
    ISSN: 1432-1432
    Keywords: Phylogenetic inference ; Stationarity ; Substitutional Bias ; Compositional bias ; Cyanelle ; Cyanophora paradoxa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Available molecular and biochemical data offer conflicting evidence for the origin of the cyanelle of Cyanophora paradoxa. We show that the similarity of cyanelle and green chloroplast sequences is probably a result of these two lineages independently developing the same pattern of directional nucleotide change (substitutional bias). This finding suggests caution should be exercised in the interpretation of nucleotide sequence analyses that appear to favor the view of a common endosymbiont for the cyanelle and chlorophyll-b-containing chloroplasts. The data and approaches needed to resolve the issue of cyanelle origins are discussed. Our findings also have general implications for phylogenetic inference under conditions where the base compositions (compositional bias) of the sequences analyzed differ.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00182392
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  • 2
    Electronic Resource
    Electronic Resource
    Characterization of the group 1 and group 2 sigma factors of the green sulfur bacterium Chlorobium tepidum and the green non-sulfur bacterium Chloroflexus aurantiacus (1998)
    Springer
    Archives of microbiology 170 (1998), S. 285-296 
    Details
    ISSN: 1432-072X
    Keywords: Key words Chloroflexus aurantiacus ; Chlorobium tepidum ; Green non-sulfur bacteria ; Green sulfur ; bacteria ; Sigma factor ; RNA polymerase ; Phylogenetic studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The group 1 and group 2 σ70-type sigma factors of the green sulfur bacterium Chlorobium tepidum and of the green nonsulfur bacterium Chloroflexus aurantiacus were cloned and characterized. Cb. tepidum was found to contain one σ70-type sigma factor; the expression of the gene was analyzed by Northern blot hybridization and primer-extension mapping. Cf. aurantiacus has genes encoding four sigma factors of groups 1 and 2. The expression of these genes was examined in cells grown aerobically and anaerobically. The sigC gene was expressed at approximately equal levels under both conditions, resulting in its designation as the group 1 sigma factor of this organism. The only other detectable transcripts arose from the sigB gene, which was expressed at higher levels during aerobic growth. A phylogenetic tree was obtained using the group 1 sigma factors of Cb. tepidum, Cf. aurantiacus, and diverse eubacteria as the molecular marker. The resulting phylogenetic tree shows that Cb. tepidum and Cf. aurantiacus are related to each other and to the cyanobacteria. The relationship of the group 2 sigma factors of Cf. aurantiacus and the cyanobacteria was more specifically examined phylogenetically. The group 2 sigma factors of Cf. aurantiacus probably arose by gene duplication events after the split of the green nonsulfur bacteria from other photosynthetic eubacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050644
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  • 3
    Electronic Resource
    Electronic Resource
    Characterization of csmB genes, encoding a 7.5-kDa protein of the chlorosome envelope, from the green sulfur bacteria Chlorobium vibrioforme 8327D and Chlorobium tepidum (1996)
    Springer
    Archives of microbiology 166 (1996), S. 234-244 
    Details
    ISSN: 1432-072X
    Keywords: Key words Chlorobium tepidum ; Chlorobium ; vibrioforme ; Chlorosome ; csmB gene ; Light-harvesting complex ; DNA sequence ; Bacteriochlorophyll ; Protein overproduction ; Green sulfur bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The csmB gene, encoding the 7.5-kDa “Gerola-Olson” protein of chlorosomes, has been cloned and sequenced from the green sulfur bacteria Chlorobium vibrioforme strain 8327D and Chlorobium tepidum. Two potential start codons were identified, and the csmB gene may be translated into a preprotein with an amino-terminal extension. Two forms of the mature CsmB protein (74 or 75 amino acids in length) were identified that differ by the presence or absence of a methionine residue at the amino terminus. The csmB gene of Chl. tepidum is transcribed as an abundant monocistronic mRNA of approximately 350 nucleotides; primer extension mapping of the 5′ endpoint of the csmB mRNA suggests there is strong similarity between the csmB promoter and the σ70 promoters of Escherichia coli. The CsmB protein of Chl. tepidum was overproduced as a histidine-tagged fusion protein in E. coli, purified to homogeneity by Ni2+ chelation affinity chromatography, and used to raise polyclonal antibodies in rabbits. Protease susceptibility mapping and agglutination experiments with isolated chlorosomes using anti-CsmB antibodies indicate that the CsmB protein is a component of the chlorosome envelope.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050379
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  • 4
    Electronic Resource
    Electronic Resource
    Growth at low temperature causes nitrogen limitation in the cyanobacterium Synechococcus sp. PCC 7002 (1997)
    Springer
    Archives of microbiology 169 (1997), S. 10-19 
    Details
    ISSN: 1432-072X
    Keywords: Key words Chilling tolerance ; Chlorosis ; Cyanobacterium ; Low-temperature acclimation ; Nitrogen assimilation ; Phycobiliprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The coloration of cells of the cyanobacterium Synechococcus sp. PCC 7002 changed from normal blue-green to yellow-green when cells were grown at 15° C in a medium containing nitrate as the sole nitrogen source. This change of coloration was similar to a general response to nutrient deprivation (chlorosis). For the chlorotic cells at 15° C, the total amounts of phycobiliproteins and chlorophyll a decreased, high levels of glycogen accumulated, and growth was arithmetic rather than exponential. These changes in composition and growth occurred in cells grown at low (50 μE m–2 s–1) as well as high (250 μE m–2 s–1) light intensity. After a temperature shift-up to 38° C, chlorotic cells rapidly regained their normal blue-green coloration and normal exponential growth rate within 7 h. When cells were grown at 15° C in a medium containing urea as the reduced nitrogen source, cells grew exponentially and the symptoms of chlorosis were not observed. The decrease in photosynthetic oxygen evolution activity at low temperature was much smaller than the decrease in growth rate for cells grown on nitrate as the nitrogen source. These studies demonstrate that low-temperature-induced chlorosis of Synechococcus sp. PCC 7002 is caused by nitrogen limitation and is not the result of limited photosynthetic activity or photodamage to the photosynthetic apparatus, and that nitrogen assimilation is an important aspect of the low-temperature physiology of cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050535
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  • 5
    Electronic Resource
    Electronic Resource
    Alteration of low-temperature susceptibility of the cyanobacterium Synechococcus sp. PCC 7002 by genetic manipulation of membrane lipid unsaturation (1997)
    Springer
    Archives of microbiology 169 (1997), S. 20-28 
    Details
    ISSN: 1432-072X
    Keywords: Key words Chilling tolerance ; Cyanobacterium ; Fatty acid desaturase ; Low-temperature acclimation ; Membrane lipid ; Photosynthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cyanobacteria acclimate to low temperature by desaturating their membrane lipids. Mutant strains of Synechococcus sp. PCC 7002 containing insertionally inactivated desA (Δ12 acyl-lipid desaturase) and desB (ω3 acyl-lipid desaturase) genes were produced, and their low-temperature susceptibility was characterized. The desA mutant synthesized no linoleic acid or α-linolenic acid, and the desB mutant did not produce α-linolenic acid. The desA mutant grew more slowly than the wild-type at 22° C and could not grow at 15° C. The desB mutant could not continuously grow at 15° C, although no observable phenotype appeared at higher temperatures. It has been shown that expression of the desA gene occurs at 38° C and is up-regulated at 22° C, and that the desB gene is only expressed at 22° C. These results indicate that the expression of the desA and desB genes occurs at higher temperatures than those at which a significant decline in physiological activities is caused by the absence of their products. The temperature dependency of photosynthesis was not affected by these mutations. Since chlorosis and inability to grow at 15° C with nitrate was suppressed by the substitution of urea as a nitrogen source, it is very likely that the chilling susceptibility of the desaturase mutants is attributable to nutrient limitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050536
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  • 6
    Electronic Resource
    Electronic Resource
    Characterization of the alternative σ-factors SigD and SigE in Synechococcus sp. strain PCC 7002. SigE is implicated in transcription of post-exponential-phase-specific genes (1998)
    Springer
    Archives of microbiology 169 (1998), S. 211-219 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsSynechococcus sp. PCC 7002 ; Cyanobacterium ; σ-Factor ; RNA polymerase ; RpoS ; DpsA ; PexB ; Stationary phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sigD and sigE genes, which encode two alternative σ-factors from the unicellular marine cyanobacterium Synechococcus sp. PCC 7002, were cloned and characterized. Strains in which the sigD and sigE genes were insertionally inactivated were viable under standard laboratory conditions, indicating that SigD and SigE are group 2 σ-factors. When stationary-phase cells were diluted into fresh growth medium, it was observed that the sigE mutant strain required longer times to re-establish exponential growth than the wild-type strain. By monitoring the growth rates in such dilution experiments, it was observed that the lag times for the mutant strain became progressively longer as the original cultures progressed towards stationary phase. Transcripts for the sigE gene initially increased and subsequently decreased as cells grew further into stationary phase. It was determined that a functional SigE protein is required for the expression of the starvation-induced protein DpsA/PexB. The results suggest that SigE is involved in the transcription of genes specifically expressed in the post-exponential phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050563
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  • 7
    Electronic Resource
    Electronic Resource
    Allophycocyanin B (λmax 671, 618 nm) (1975)
    Springer
    Archives of microbiology 104 (1975), S. 15-22 
    Details
    ISSN: 1432-072X
    Keywords: Phycobiliprotein (λ 671, 618 nm) ; Allophycocyanin B ; Photosystem II ; Cyanobacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A hitherto undescribed red fluorescent phycobiliprotein (maximum emission at ∼ 680 nm), characterized by long wavelength absorption maxima in the visible region at 671 nm (ε=172000 M−1·cm−1 per monomer of mol. wt. 30600) and 618 nm, has been purified to homogeneity from a unicellular cyanobacterium, Synechococcus sp., and from a filamentous cyanobacterium, Anabaena variabilis. The name allophycocyanin B has been proposed for the new protein. A. variabilis allophycocyanin B is characterized by a native molecular weight of 89000 ± 5000 (in 0.05 M phosphate at pH 7.2), an isoelectric point of 5.09, and a subunit molecular weight, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, of 15300. The protein contains one phycocyanobilin chromophore per subunit. In common with allophycocyanin from the same organism, allophycocyanin B does not contain either histidine or tryptophan. In other respects, the amino acid compositions of the two proteins are significantly different. Synechococcus sp. (Anacystis nidulans) allophycocyanin B gives two components of 16000 and 17000 mol. wt., of equal staining intensity, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Allophycocyanins B from both organisms cross-react with rabbit antisera directed against either Synechococcus sp. or Anabaena sp. allophycocyanin, but not with antisera against the phycocyanins of the same organisms. It is suggested that allophycocyanin B occupies a position between allophycocyanin and chlorophyll a in the energy transfer path from the accessory pigments to species of chlorophyll a with absorption maxima at λ〉670 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00447294
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  • 8
    Electronic Resource
    Electronic Resource
    Cloning and characterization of the psaE gene of the cyanobacterium Synechococcus sp. PCC 7002: characterization of a psaE mutant and overproduction of the protein in Escherichia coli (1993)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 9 (1993), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: The psaE gene, encoding a 7.5 kDa peripheral protein of the photosystem I complex, has been cloned and characterized from the cyanobacterium Synechococcus sp. PCC 7002. The gene is transcribed as an abundant monocistronic transcript of approximately 325 nt. The PsaE protein has been overproduced in Escherichia coli, purified to homogeneity, and used to raise polyclonal antibodies. Mutant strains, in which the psaE gene was insertionally inactivated by interposon mutagenesis, were constructed and characterized. Although the PS I complexes of these strains were similar to those of the wild type, the strains grew more slowly under conditions which favour cyclic electron transport and could not grow at all under photoheterotrophic conditions. The results suggest that PsaE plays a role in cyclic electron transport in cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1993.tb01680.x
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  • 9
    Electronic Resource
    Electronic Resource
    Design and Construction of the New Bintulu Water Supply, Sarawak, Malaysia (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 5 (1991), S. 0 
    Details
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: The new Bintulu water supply was built in the early 1980s to serve a major development of the town of Bintulu in Sarawak, East Malaysia, arising from the extraction of natural gas from the South China Sea. The water supply was designed to supply 78 Ml/d. The works comprise earth dams forming a pumped storage reservoir, a river intake, pumping stations, pipelines, a water-treatment works, treated water storage and a distribution system. The treatment works and distribution system are being built in two phases. The first phase was completed in 1983, and the second phase is to be constructed in 1990–91.The paper describes the initial planning of the scheme, including water-demand forecasts, the design and construction of the Phase I works, and problems encountered during its operation. It also highlights the exceptionally rapid implementation programme and stability problems at the main earth dam.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1747-6593.1991.tb00600.x
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular cloning and transcriptional analysis of the cpeBA operon of the cyanobacterium Pseudanabaena species PCC 7409 (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 5 (1991), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: 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 Calothrix species PCC 7601 contain an activity which specifically binds a restriction fragment containing the Pseudanabanea species PCC 7409 cpeBA promoter. Green-light-dependent cpeBA transcription in Group II and III chromatically adapting cyanobacteria is suggested to be similarly controlled by a transcriptional activator.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1991.tb01867.x
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