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Intragenomic DNA sequence homologies in the chicken and other members of the classAves: DNA re-association under reduced stringency conditions (1980)

Burr, Henry E. ; Schimke, Robert T.

Springer

Journal of molecular evolution 15 (1980), S. 291-307

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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

URL: http://dx.doi.org/10.1007/BF01733136

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Real-time measurement of RFR energy distribution in the macaca mulatta head (1980)

Burr, John G. ; Krupp, Jerome H.

New York, NY [u.a.] : Wiley-Blackwell

Bioelectromagnetics 1 (1980), S. 21-34

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ISSN: 0197-8462

Keywords: radiofrequency radiation ; microwaves ; rhesus monkey dosimetry ; microwave dosimetry ; cranial structures ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology , Physics

Notes: Temperature increases due to absorption of 1.2 GHz, CW, 70 mW/cm2, radio frequency (RF) energy, were measured in 3.3-cm-radius homogeneous muscle-equivalent spheres, M. mulatta cadaver heads (both detached from and attached to the body) and living, anesthetized M. mulatta heads. Temperatures were measured with a Vitek, Model 101 Electrothermia Monitor and temperature distributions were compared to theoretical predictions from a thermal-response model of a simulated cranial structure. The results show that the thermal response model accurately predicts the temperature distribution in muscle-equivalent spheres, the distribution of temperature in detached M. mulatta heads when exposed from the back of the head, and the distribution of temperature in attached M. mulatta cadaver heads for animals oriented with body parallel to the H-field. The temperature distribution in the detached M. mulatta heads varies markedly with exposure orientation, ie, facing forward, backward, or to the side. The orientation of the M. mulatta cadaver body significantly affects the temperature distribution in the head - with H-field orientation showing high, nonuniform values, and E-field orientation showing low, uniform values. In live animals blood flow produces a significant short-term effect on the temperature distribution in the midbrain, but not the cortex. Midbrain temperatures are both significantly higher and lower than the comparable cadaver measurements, depending on location.

Additional Material: 10 Ill.