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  • Avian genome evolution  (1)
  • Biochemistry and Biotechnology  (1)
  • 1980-1984  (2)
  • 1920-1924
  • 1
    ISSN: 1432-1432
    Keywords: Avian genome evolution ; Intragenomic DNA sequence homology Reduced-stringency DNA reassociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have investigated the intragenomic DNA sequence homologies of twelve species of birds representing five orders, and emphasizing Galliformes. This study differs in two important ways from the classical approaches taken in constructing and evaluating phylogenies based on DNA sequence similarities. Comparisons are made on the basis of sequence homologieswithin genomes of related birds, rather than between genomes. DNA is reassociated at 50°C in 0.5M phosphate buffer; these conditions allow formation and detection of duplexes containing more mismatch than would normally be permitted using more stringent conditions, affording an opportunity to observe more ancient sequence homologies. Thermal stability profiles of DNA duplexes formed under these conditions are the basis of comparison; three general patterns were observed. This approach emphasizes differences in sequence composition between genomes while the more traditional method of intergenomic tracer DNA hybridization at higher stringency emphasizes sequence similarities. No correlation was found between taxonomic position and intragenomic sequence composition, either within or between lineages. The thermal stability profiles of DNA duplexes formed within avian genomes did not reflect the biological similarities inferred from morphology, karyotype, and studies of interspecific hybridization. While all of the differences observed could have occurred over geological time, it was surprising that the genomes of the domestic chicken and the Red Jungle Fowl (Gallus gallus) differ in their sequence compositions. It appears that amplification/reduction events and/or positional changes occur rather often during evolution of a lineage.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 1122-1125 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Treatment of wheat straw with 1N trifluoroacetic acid (TFA) for 7 h at reflux temperature yielded 23% xylose based upon initial straw weight. This corresponds to about an 80% xylose yield based on the xylan content of the hemicellulose. The cellulose component of wheat straw was largely unaffected, as evidenced by low glucose yields. Decomposition of xylose by prolonged refluxing (23 h) was minimal in 1N TFA compared to 1N HCl. Treatment of wheat straw with refluxing 1N TFA converts about 10% of the lignin initially present in straw into water-soluble lignin fragments. Fermentation of the xylose-rich wheat straw hydrolyzate to ethanol with Pachysolen tannophilus was comparable to the fermentation of reagent grade xylose, indicating that furfural and toxic lignin by-products were not produced by 1N TFA in sufficient amounts to impair cell growth and ethanol production. Cellulase treatment of the wheat straw residue after TFA hydrolysis resulted in a 70-75% conversion of the cellulose into glucose.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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