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  • 1985-1989  (4)
  • 1930-1934
  • Cyanobacteria  (2)
  • Life and Medical Sciences  (2)
  • 1
    ISSN: 1432-072X
    Keywords: Cyanobacteria ; DNA restriction and cloning ; Gene fusions ; Leucine biosynthesis ; Mutant complementation ; Nostoc ; Transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Genomic DNA extracted from the symbiotically-competent, heterocyst-forming cyanobacterium Nostoc sp. strain 7801 was resistant to cleavage by a number of restriction endonucleases. A cosmid library of Nostoc DNA was prepared and maintained in the modification-limited Escherichia coli strain HB101. Analysis of cloned Nostoc DNA fragments indicated infrequent occurrence of restriction endonuclease recognition sites in the Nostoc genome. The Nostoc genomic library was screened for sequences complementing mutations in the E. coli leucine and proline biosynthetic operons. Two cosmids complementing leuB were isolated but none for leuA, leuC, leuD, or proA were detected in 1000 cosmids. A 3.0 kb fragment subcloned from one of the cosmids complemented mutations in leuB when inserted into the HindIII site of pBR322 in either orientation, demonstrating that transcription of leuB originated within the cloned fragment. The cloned fragment also carries a second site capable of initiating transcription of fused antibiotic resistance genes. While transcription of Nostoc DNA sequences did occur in E. coli, unknown barriers must also exist that prevented additional biological complementation of specific E. coli mutations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1617-4623
    Keywords: Cyanobacteria ; Nitrate reductase mutants ; Nitrite reductase mutants ; Regulatory mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Eighteen mutant strains of the unicellular cyanobacterium Anacystis nidulans R2 that are unable to assimilate nitrate have been isolated after transposon Tn901 mutagenesis. Characterization of phenotypes and transformation tests have allowed the distinction of five different mutant types. The mutants exhibiting a nitrate reductase-less phenotype were identified as being affected in previously defined loci, as they could be transformed to the wild type by one of the plasmids pNR12, pNR63 or pNR193, which contain cloned genes of A. nidulans R2 involved in nitrate reduction. The mutations in strains FM2 and FM16 appear to affect two other genes involved in nitrate assimilation. Strain FM2 apparently bears a single mutation which results in both lack of nitrite reductase activity and loss of ammonium-promoted repression of nitrate reductase synthesis. FM16 has a low but significant level of nitrate reductase that is also freed from repression by ammonium, and an increased level of nitrite reductase activity. FM16 exhibited properties which indicate that this mutant strain might also be affected in the transport of nitrate into the cell.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 138 (1989), S. 115-120 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The basic fibroblast growth factor (FGF) is a potent mitogen that has vascular endothelium as one of its principle target cells. Recent work has provided both the complete amino acid sequence of basic FGF and the nucleotide sequence of the genes for both human and bovine basic FGF. Although capillary endothelial cells have been shown to produce basic FGF in vitro and to deposit basic FGF in their extracellular matrix in vitro as well, no direct evidence yet exists for the distribution of basic FGF in vivo. Antipeptide antibodies were prepared against a 15-amino-acid sequence from the amino terminus of basic FGF in order to avoid cross-reactivity with acidic FGF, a protein with 55% overall homology to basic FGF. After affinity purification, these antisera were used to localize the basic fibroblast growth factor in the fetal and adult bovine retina. Immunoreactive material was found in capillaries of the inner nuclear layer, a capillary network undergoing development during the third trimester in the fetal bovine eye. Although the resolution of the technique does not permit a unique assignment of cellular localization, the presence of stain immediately adjacent to the lumen of capillaries suggests that capillary endothelial cells may produce the basic fibroblast growth factor in vivo during vascular development.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 6 (1985), S. 177-188 
    ISSN: 0197-8462
    Keywords: microwave irradiation ; specular microscopy ; monkey ; corneal endothelium ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Both eyes of anesthetized cynomolgus monkeys (Macaca fascicularis) were irradiated with 2.45-GHz microwaves, either pulsed or continuous wave. In vivo corneal endothelial abnormalities were observed by specular microscopy and confirmed through histologic techniques after a 16- to 48-hour postexposure period. Pulsed microwaves with an average power density of 10 mW/cm2 (equivalent to a specific absorption rate (SAR) = 2.6 W/kg) produced these effects, while levels of 20-30 mW/cm2 (equivalent to a SAR = 5.3 to 7.8 W/kg) with continuous wave irradiation were required to produce similar changes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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