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  • 1
    Electronic Resource
    Electronic Resource
    Tetracycline uptake by susceptible Escherichia coli cells (1985)
    Springer
    Archives of microbiology 141 (1985), S. 260-265 
    Details
    ISSN: 1432-072X
    Keywords: (3H) Tetracycline purification ; Initial uptake kinetics ; Monophasic tetracycline uptake ; Tetracycline binding ; Temperature effect on tetracycline uptake ; Escherichia coli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments measuring the initial uptake of commercial (3H) tetracycline exhibit two distinct kinetic phases: a rapid phase followed by a slow phase. (3H) tetracycline purified by chromatography on a Dowex 50WX2 column exhibited only monophasic rapid uptake when tested with susceptible Escherichia coli cells. Cyanide inhibited the uptake of purified (3H) tetracycline only partially while transport of proline and maltose was entirely abolished. Energy independent accumulation of tetracycline may be accounted for by binding to cellular constituents. Uptake of tetracycline-as measured by inhibition of β-galactosidase synthesis-was strongly affected by a shift in temperature from 37°C to 21°C while carrier-mediated transport systems revealed only minor reductions. Taken together with the non-saturability of tetracycline uptake and the evidence for diffusion of tetracycline through phospholipid bilayers [Argast and Beck (1984) Antimicrob Agents Chemother 26:263–265] these data support the hypothesis that tetracycline enters the cytoplasm by diffusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00408069
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  • 2
    Electronic Resource
    Electronic Resource
    Gametic differentiation in Chlamydomonas reinhardtii: light dependence and gene expression patterns (1989)
    Springer
    Archives of microbiology 152 (1989), S. 572-577 
    Details
    ISSN: 1432-072X
    Keywords: Chlamydomonas reinhardtii ; Gametic differentiation ; Light requirement ; Light-pulse-studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gametes of Chlamydomonas reinhardtii synthesize numerous proteins not observed in vegetative cells and vice versa. Gametogenesis induced changes in gene expression were confirmed by SDS-PAGE of in vitro translation products using total RNA from gametes and vegetative cells. Vegetative cells and gametes thus represent two cell types with distinct patterns of gene expression. The generation of mature gametes from liquid cultures of asynchronously growing vegetative cells was dependent on light. This light requirement could not be substituted for by an organic source of energy and carbon, indicating that light serves as a signal in gametogenesis. The light signal was shown to become effective only after preincubation in nitrogen-free medium. This delayed competence for light indicates that the two external signals — nitrogen-starvation and light —may function in sequence. Execution of the light dependent step in gamete formation required cytoplasmic protein synthesis and RNA synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425489
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a Chlamydomonas gene that encodes a putative blue-light photoreceptor of the phototropin family (2002)
    Oxford, UK : Blackwell Science, Ltd
    Physiologia plantarum 115 (2002), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the search for a Chlamydomonas reinhardtii photoreceptor that may mediate blue-light-induced responses we identified a gene that encodes a protein with a structure typical for that of members of the phototropin family, i.e. two LOV domains that may function in flavin mononucleotide binding and a ser/thr kinase domain. The amino acid sequences of these domains are closely related to those of higher plant phototropins. This single-copy gene (Phot) encodes a protein with a calculated molecular mass of 81.4 kDa which is distinctly smaller than the homologous proteins of higher plants that exhibit molecular masses around 120 kDa. Expression analyses revealed rather constant levels of Phot mRNA and Phot protein in vegetative cells incubated in the dark and in cells undergoing gametogenesis. Only vegetative cells in the light showed a reduced expression of the Phot gene. Cell fractionation studies revealed that the protein is membrane-associated. In higher plants, phototropins were shown to be bound to the plasma membrane. However, the expression of a Phot-GFP gene fusion in tobacco protoplasts revealed an association of the fusion protein with the endogenous membrane network of the cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1399-3054.2002.1150416.x
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  • 4
    Electronic Resource
    Electronic Resource
    Changes in gene expression patterns during the sexual life cycle of Chlamydomonas reinhardtii (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Physiologia plantarum 83 (1991), S. 0 
    Details
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In the sexual life cycle of Chlamydomonas reinhardtii, three types of cells can be distinguished: vegetative cells, gametes, and zygotes. Using is vivo pulse labelling of proteins with 35S-sulfate, followed by two-dimensional separation of the polypeptides on polyacrylamide gels, we analyzed the patterns of protein synthesis typical for each cell type. Approximately 20% of the proteins detected were synthesized at very different rates when the pattern from vegetative cells was compared to that of gametes or zygotes. Gamete formation from vegetative cells is a two-step process controlled by two extrinsic signals: first, nitrogen-starvation induces the differentiation of vegetative cells to pregaroetes, which are then competent for a light–induced differentiation to mature gametes. The majority of the changes in rate of synthesis of different proteins during the switch from vegetative cells to gametes was observed already in pregametes. Between the stages of pregametes and gametes, changes in the rates of synthesis of four proteins were detected. Induction of zygote germination resulted in complex changes in the patterns of gene expression. Evidence is presented for three groups of proteins whose synthesis is turned on or turned off during zygote germination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1399-3054.1991.tb02480.x
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  • 5
    Electronic Resource
    Electronic Resource
    Functional in vivo verification in E. coli of promoter activities from the rDNA/tDNAVal(GAC) leader region of Zea mays chloroplasts (1987)
    Springer
    Current genetics 12 (1987), S. 241-246 
    Details
    ISSN: 1432-0983
    Keywords: rRNA promoters ; Maize chloroplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Restriction fragments containing upstream sequences of the rRNA operon from Zea mays chloroplasts were tested for promoter activity in vivo by insertion into an E. coli promoter-probe vector. The expression of this vector's reporter gene, which codes for alkaline phosphatase, was stimulated more than 1,500-fold upon linkage with the chloroplast rRNA promoter. Site specific mutagenesis of the invariant T of the −10 sequence of this promoter reduced the expression of the reporter gene to 2% of the wild type. This indicates that the chloroplast rRNA promoter, which directs transcriptional initiation 117 by upstream of the 16S rRNA gene, is also active in the bacterial system. A restriction fragment further upstream containing the gene for tRNAVal (GAC) also showed strong promoter activity (29% as compared with the rRNA promoter). This promoter activity probably reflects the chloroplast promoter directing the synthesis of the tRNAVal (GAC) primary transcript. Surprisingly, this restriction fragment also displayed promoter activity (13% compared with the rRNA promoter) in reverse orientation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00435284
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  • 6
    Electronic Resource
    Electronic Resource
    The negative effect of nitrate on gametogenesis is independent of nitrate assimilation in Chlamydomonas reinhardtii (2000)
    Springer
    Planta 211 (2000), S. 287-292 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Chlamydomonas ; Gametogenesis ; Nitrate reductase mutants ; Nitrate signal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract.  The effect of nitrate on gamete differentiation as well as on the expression of genes involved in gametogenesis, nitrogen scavenging, and nitrate assimilation has been analyzed in wild-type and mutant strains of Chlamydomonas reinhardtii. Nitrate prevented gamete formation from wild-type strains and caused a strong reduction in the number of zygotes recovered in genetic crosses between nitrate-assimilation-deficient mutants, thus suggesting that nitrate by itself is providing a negative regulatory signal for the sexual differentiation of the alga. Addition of nitrate at low concentrations to wild-type cells, after an initial period of nitrogen starvation, resulted in a drastic decrease in transcript levels of both nitrate-assimilation genes (NIA1 and NRT2;1) and genes induced after N-starvation (NCG2 and NCG4). This strong effect of nitrate was due to its assimilation products since it was not evident in nitrate-assimilation mutants. A slight negative effect of nitrate on NCG4 expression was only observed in the mutant. Nitrate by itself was also found to provide a negative signal for the expression of gamete-specific genes (GAS3 and GAS18) in mutants incapable of assimilating nitrate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250000291
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  • 7
    Electronic Resource
    Electronic Resource
    Identification of novel genes specifically expressed in Chlamydomonas reinhardtii zygotes (1991)
    Springer
    Plant molecular biology 16 (1991), S. 937-946 
    Details
    ISSN: 1573-5028
    Keywords: Chlamydomonas ; zygote germination ; zygote maturation ; zygote specific genes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The maturation of zygotes formed by the fusion of two gametes is the essential part of the diploid phase of the Chlamydomonas reinhardtii sexual life cycle and results in mature zygotes competent to germinate. To understand the molecular mechanisms underlying zygote maturation and the attainment of competence for germination we isolated genomic clones representing three different genes that are specifically expressed in Chlamydomonas reinhardtii zygotes. Accumulation of the RNAs started more than 24 h after mating, setting these genes apart from genes expressed in young zygotes [9]. Upon light-induced germination of zygotes, the mRNAs disappeared. The patterns of RNA accumulation and disappearance were gene-specific and suggested a function of these genes in maturation and/or in initial steps of germination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00016066
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  • 8
    Electronic Resource
    Electronic Resource
    Light-inducible geneHSP70B encodes a chloroplast-localized heat shock protein inChlamydomonas reinhardtii (1996)
    Springer
    Plant molecular biology 31 (1996), S. 1185-1194 
    Details
    ISSN: 1573-5028
    Keywords: chloroplast HSP70 ; chloroplast-specific sequence motifs ; heat shock gene ; light induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The nuclear heat shock geneHSP70B ofChlamydomonas reinhardtii is inducible by heat stress and light. Induction by either environmental cue resulted in a transient elevation in HSP70B protein. Here we describe the organization and nucleotide sequence of theHSP70B gene. The deduced protein exhibits a distinctly higher homology to prokaryotic HSP70s than to those of eukaryotes, including the cytosolic HSP70A ofChlamydomonas reinhardtii. The HSP70B protein, as previously demonstrated by in vitro translation, is synthesized with a cleavable presequence. Using an HSP70B-specific antibody, this heat shock protein was localized to the chloroplast by cell fractionation experiments. A stromal location was suggested by the presence of a conserved sequence motif used for cleavage of presequences by a signal peptidase of the stroma. Amino acid alignments of HSP70 proteins from various organisms and different cellular compartments allowed the identification of sequence motifs, which are diagnostic for HSP70s of chloroplasts and cyanobacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00040835
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  • 9
    Electronic Resource
    Electronic Resource
    Two GC-rich DNA elements ofChlamydomonas reinhardtii with complex arrangements of directly repeated sequence motifs (1992)
    Springer
    Plant molecular biology 18 (1992), S. 143-146 
    Details
    ISSN: 1573-5028
    Keywords: Chlamydomonas reinhardtii ; direct repeats ; GC-rich sequences ; molecular evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00018468
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  • 10
    Electronic Resource
    Electronic Resource
    Location on the chromosome ofSalmonella typhimurium of genes governing pyrimidine metabolism (1971)
    Springer
    Molecular genetics and genomics 111 (1971), S. 303-316 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genes encoding the enzymes cytidine deaminase (cdd), uridine monophosphate pyrophosphorylase (upp), cytidine triphosphate synthetase (pyrG), and uridine phosphorylase (udp) were located on theSalmonella typhimurium chromosome at 68, 77, 90 and 122 min, respectively. Strains carrying mutations inpyrG must also carry mutations incdd in order for cytidine to be sufficiently stable metabolically to supply the cell's requirement for CTP1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00569782
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