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  • 1
    Electronic Resource
    Electronic Resource
    NtcA represses transcription of gifA and gifB, genes that encode inhibitors of glutamine synthetase type I from Synechocystis sp. PCC 6803 (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 35 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Synechocystis sp. PCC 6803 glutamine synthetase type I (GS) activity is controlled by direct interaction with two inactivating factors (IF7 and IF17). IF7 and IF17 are homologous polypeptides encoded by the gifA and gifB genes respectively. We investigated the transcriptional regulation of these genes. Expression of both genes is maximum in the presence of ammonium, when GS is inactivated. Nitrogen starvation attenuates the ammonium-mediated induction of gifA and gifB as well as the ammonium-mediated inactivation of GS. Putative binding sites for the transcription factor NtcA were identified at −7.5 and −30.5 bp upstream of gifB and gifA transcription start points respectively. Synechocystis NtcA protein binding to both promoters was demonstrated by gel electrophoresis mobility shift assays. Constitutive high expression levels of both genes were found in a Synechocystis NtcA non-segregated mutant (SNC1), which showed a fourfold reduction in the ntcA expression. These experiments indicate a repressive role for NtcA on the transcription of gifA and gifB genes. Our results demonstrate that NtcA plays a central role in GS regulation in cyanobacteria, stimulating transcription of the glnA gene (GS structural gene) and suppressing transcription of the GS inactivating factor genes gifA and gifB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.01789.x
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  • 2
    Electronic Resource
    Electronic Resource
    A two-component signal transduction system involved in nickel sensing in the cyanobacterium Synechocystis sp. PCC 6803 (2002)
    Oxford, UK : Blackwell Science Ltd.
    Molecular microbiology 43 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In the cyanobacterium Synechocystis sp. PCC 6803, genes for Ni2+, Co2+, and Zn2+ resistance are grouped in a 12 kb gene cluster. The nrsBACD operon is composed of four genes, which encode proteins involved in Ni2+ resistance. Upstream from nrsBACD, and in opposite orientation, a transcription unit formed by the two genes rppA and rppB has been reported previously to encode a two-component signal transduction system involved in redox sensing. In this report, we demonstrate that rppA and rppB (here redesigned nrsR and nrsS respectively) control the Ni2+-dependent induction of the nrsBACD operon and are involved in Ni2+ sensing. Thus, expression of the nrsBACD operon was not induced by Ni2+ in a nrsRS mutant strain. Furthermore, nrsRS mutant cells showed reduced tolerance to Ni2+. Whereas the nrsBACD operon is transcribed from two different promoters, one constitutive and the other dependent on the presence of Ni2+ in the medium, the nrsRS operon is transcribed from a single Ni2+-inducible promoter. The nrsRS promoter is silent in a nrsRS mutant background suggesting that the system is autoregulated. Purified full length NrsR protein is unable to bind to the nrsBACD-nrsRS intergenic region; however, an amino-terminal truncated protein that contains the DNA binding domain of NrsR binds specifically to this region. Our nrsRS mutant, which carries a deletion of most of the nrsR gene and part of the nrsS gene, does not show redox imbalance or photosynthetic gene mis-expression, contrasting with the previously reported nrsR mutant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.02741.x
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrophilins from distant organisms can protect enzymatic activities from water limitation effects in vitro (2005)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 28 (2005), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Hydrophilins are a wide group of proteins whose defining characteristics are high hydrophilicity index (〉 1.0) and high glycine content (〉 6%). The transcripts of most hydrophilins accumulate in response to water deficit in organisms such as plants, fungi and bacteria. In plants, most of the known Late Embryogenesis Abundant (LEA) proteins belong to this group (Garay-Arroyo et al., Journal of Biological Chemistry 275, 5668–5674, 2000). To gain insight into the function of hydrophilins, an in vitro assay was developed in which the enzymes malate dehydrogenase (MDH) or lactate dehydrogenase (LDH) are subjected to controlled partial water removal. Subtle changes in conformation during partial water removal were detected using 1-anilinonaphtalene-8-sulphonate (ANS), a fluorescent probe, whose emission at 460 nm increases when bound to hydrophobic groups. The results show that water limitation conditions imposed in this in vitro assay induce changes in MDH or LDH protein structures, which correlate with enzyme inactivation. It is also shown that plant, fungal and bacterial hydrophilins are able to protect enzymatic activities from water-loss effects in this in vitro system, in a wide range of water potentials. In addition, the data in this work indicate that the presence of hydrophilins also avoids the MDH and LDH conformational modifications caused during the assay. These results show that hydrophilins are able to protect enzymatic activities from inactivation due to in vitro partial water limitation and thus suggest a function for these proteins in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2005.01317.x
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  • 4
    Electronic Resource
    Electronic Resource
    Ascorbate and plant cell growth (1994)
    Springer
    Journal of bioenergetics and biomembranes 26 (1994), S. 399-405 
    Details
    ISSN: 1573-6881
    Keywords: Ascorbate ; cell wall ; onion root elongation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract Ascorbate and related enzymes are involved in the control of several plant growth processes. Ascorbate modulates cell growth by controlling (i) the biosynthesis of hydroxyproline-rich proteins required for the progression of G1 and G2 phases of the cell cycle, (ii) the cross-linking of cell wall glycoproteins and other polymers, and (iii) redox reactions at the plasma membrane involved in elongation mechanisms. The effect of ascorbate on onion root elongation is reviewed here. The ascorbate free radical induces a high vacuolization responsible for elongation. This effect may be dependent on the activity of the redox system linked to the plasma membrane. Current data are discussed on the basis of the modulation of the plasma membrane energetic state derived from the ascorbate-induced hyperpolarization and the activity of an intrinsic transplasmalemma ascorbate-regenerating enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00762781
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of artificial microRNAs in transgenic Arabidopsis thaliana confers virus resistance (2006)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 24 (2006), S. 1420-1428 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Plant microRNAs (miRNAs) regulate the abundance of target mRNAs by guiding their cleavage at the sequence complementary region. We have modified an Arabidopsis thaliana miR159 precursor to express artificial miRNAs (amiRNAs) targeting viral mRNA sequences encoding two gene silencing suppressors, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt1255
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  • 6
    Electronic Resource
    Electronic Resource
    The NADP-glutamate dehydrogenase of the cyanobacterium Synechocystis 6803: cloning, transcriptional analysis and disruption of the gdhA gene (1995)
    Springer
    Plant molecular biology 28 (1995), S. 173-188 
    Details
    ISSN: 1573-5028
    Keywords: cyanobacteria ; gdhA mutant ; glutamate dehydrogenase ; nitrogen metabolism ; growth-phase-specific regulation ; Synechocystis PCC 6803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The gdhA gene of Synechocystis PCC 6803, which encodes an NADP-dependent glutamate dehydrogenase (NADP-GDH), has been cloned by complementation of an Escherichia coli glutamate auxotroph. This gene was found to code for a polypeptide of 428 amino acid residues, whose sequence shows high identity with those of archaebacteria (42–47%), some Gram-positive bacteria (40–44%) and mammals (37%). The minimal fragment of Synechocystis DNA required for complementation (2 kb) carries the gdhA gene preceded by an open reading frame (ORF2) encoding a polypeptide of 130 amino acids. ORF2 and gdhA are co-transcribed as a 1.9 kb mRNA, but shorter transcripts including only gdhA were also detected. Two promoter regions were identified upon transcriptional fusion to the cat reporter gene of a promoter probe plasmid. Transcription from the promoter upstream of ORF2 was found to be regulated depending on the growth phase of Synechocystis, in parallel to NADP-GDH activity. This promoter is expressed in Escherichia coli too, in contrast to the second promoter, located between ORF2 and gdhA, which was silent in E. coli and did not respond to the stage of growth in Synechocystis. Disruption of the cyanobacterial gdhA gene with a chloramphenicol resistance cassette yielded a mutant strain totally lacking NADP-GDH activity, demonstrating that this gene is not essential to Synechocystis 6803 under our laboratory conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042048
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  • 7
    Electronic Resource
    Electronic Resource
    Electron transport controls transcription of the glutamine synthetase gene (glnA) from the cyanobacterium Synechocystis sp. PCC 6803 (1995)
    Springer
    Plant molecular biology 27 (1995), S. 789-799 
    Details
    ISSN: 1573-5028
    Keywords: cyanobacteria ; glnA gene ; glutamine synthetase ; Synechocystis sp. PCC 6803 ; light regulation ; nitrogen assimilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The glnA gene, encoding type I glutamine synthetase (GS) in Synechocystis sp. PCC 6803, showed a high sequence similarity with other cyanobacterial glnA genes. A dramatic decrease in the amount of glnA mRNA, a single transcript of about 1.6 kb, was observed after transfer to darkness, or after incubation with the electron transport inhibitors DCMU or DBMIB. The levels of glnA transcript were fully recovered after 5 min of reillumination. The glnA mRNA was found to be equally stable both in the light and the dark (half-life about 2.5 min). Unlike the glnA messenger, the amount of GS protein was not reduced in the dark. Synthesis of the glnA transcript in the dark required the presence of glucose. In addition, glnA transcription in a Synechocystis psbE-psbF mutant lacking photosystem II required the presence of glucose even when grown in the light. These observations indicate that glnA transcription is under the control of the redox state of the cell. Finally, nitrogen starvation provoked a delay in the decrease of glnA transcript in darkness, suggesting a connection between nitrogen and redox controls of glnA transcript levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00020231
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  • 8
    Electronic Resource
    Electronic Resource
    Bacterial analysis of Chromobacterium sp. and Flavobacterium sp. in a waste stabilization pond system (1987)
    Springer
    Water, air & soil pollution 32 (1987), S. 397-406 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A survey on Chromobacterium sp. and Flavobacterium sp. was conducted in a waste stabilization pond system at Santo Tomas Atzingo, State of Mexico. For this purpose methods for the isolation and identification of Chromobacterium sp. and Flavobacterium sp. from wastewater were developed and proved to be efficient. Such methods are the result of combining and modifying a series of previously reported techniques for this genera strains, but for environments different from wastewater.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225124
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  • 9
    Electronic Resource
    Electronic Resource
    Immediate deterioration of rabbit colon preparations byEntamoeba histolytica trophozoite lysates (1992)
    Springer
    Parasitology research 78 (1992), S. 260-262 
    Details
    ISSN: 1432-1955
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00931737
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  • 10
    Electronic Resource
    Electronic Resource
    Differential morphometric values induced in Golgi apparatus of higher plant cells by aldehyde and permanganate fixation (1989)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 11 (1989), S. 1-8 
    Details
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Fixation methods ; Golgi apparatus morphometry ; Onion roots ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In order to determine the best conditions to carry out quantitative ultrastructural studies in plant specimens, five different fixation techniques, including some of the most reported electron microscopy fixatives (glutaraldehyde-paraformaldehyde, osmium tetroxide, potassium permanganate), were assayed in onion root meristems to check their ability to induce morphometric changes in Golgi apparatus ultrastructure. Although the parameters evaluated showed in all cases the same tendency, values obtained after permanganate fixation were always higher than those found after aldehyde techniques (especially aldehyde-osmium). Aldehyde followed by osmium fixation appears as the most indicated fixation method when accurate quantitative ultrastructural studies are to be developed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060110102
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