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  • 1975-1979  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Genome structure and divergence of nucleotide sequences in echinodermata (1979)
    Springer
    Chromosoma 74 (1979), S. 105-124 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The arrangement of repetitive and single-copy DNA sequences has been studied in DNA of some species of Echinodermata — sea urchin, starfishes and sea-cucumber. Comparison of the reassociation kinetics of short and long DNA fragments indicates that the pattern of DNA sequence organization of all these species is similar to the so called “Xenopus pattern” characteristic of the genomes of most animals and plants. However, substantional variations have been found in the amount of repetitive nucleotide sequences in DNA of different species and in the length of DNA regions containing adjacent single-copy and repetitive sequences. Measurements of the size of S1-nuclease resistant reassociated repetitive DNA sequences show a variability of ratios between long and short repetitive DNA sequences of different species. — The degree of divergence of short and long repetitive DNA sequences and single-copy DNA was studied by molecular hybridization of the sea urchin Strongylocentrotus intermedius 3H-DNA with the DNA of other species and by determination of the thermostability of the hybridized molecules so obtained. All three fractions of S. intermedius DNA contain sequences homologous to DNA of the other echinoderm species studied. The results obtained suggest that short repetitive DNA sequences are those which have been most highly conserved throughout the evolution of Echinodermata. A new hypothesis is proposed to explain the nature of the evolutionary changes in DNA sequence interspersion patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00344486
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Genome structure of Tetrahymena pyriformiis (1978)
    Springer
    Chromosoma 69 (1978), S. 275-289 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Reassociation kinetics of DNA from the macronucleus of the ciliate, Tetrahymena pyriformis GL, has been studied. The genome size determined by the kinetic complexity of DNA was found to be 2.0×108 base pairs (or 1.2×1011 daltons). About 90% of the macronuclear DNA fragments 200–300 nucleotides in length reassociate at a rate corresponding to single-copy nucleotide sequences, and 7–9% at a rate corresponding to moderate repetitive sequences; 3–4% of such DNA fragments reassociate at C0t practically equal to zero. To investigate the linear distribution of repetitive sequences, DNA fragments of high molecular weight were reassociated and reassociation products were treated with Sl-nuclease. DNA double-stranded fragments were then fractionated by size. It has been established that in the Tetrahymena genome long regions containing more than 2000 nucleotides make up about half of the DNA repetitive sequences. Another half of the DNA repetitive sequences (short DNA regions about 200–300 nucleotides long) intersperse with single-copy sequences about 1,000 nucleotides long. Thus, no more than 15% of the Tetrahymena genome is patterned on the principle of interspersing single-copy and short repetitive sequences. Most of the so called “zero time binding” or “foldback” DNA seem to be represented by inverted self-complementary (palindromic) nucleotide sequences. The conclusion has been drawn from the analysis of this fraction isolated preparatively by chromatography. About 75% of the foldback DNA is resistant to Sl-nuclease treatment. The Sl-nuclease resistance is independent of the original DNA concentration. Heat denaturation and renaturation are reversible and show both hyper and hypochromic effects. The majority of the inverted sequences are unique and about 20% are repeated tens of times. According to the equilibrium distribution in CsCl density gradients the average nucleotide content of the palindromic fraction does not differ significantly from that of total macronuclear DNA. It was shown that the largest part of this fraction of the Tetrahymena genome are not fragments of ribosomal genes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00332132
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of the character of the cathode surface on the growth kinetics of dispersed copper deposits (1978)
    Springer
    Powder metallurgy and metal ceramics 17 (1978), S. 1-5 
    Details
    ISSN: 1573-9066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Conclusions 1. The number of simultaneously growing dendrites determined by plotting profilometer records of basis metal surfaces is in good agreement with the value obtained with an electron microscope, which is of the order of 106 per 1 cm2 of cathode surface [5]. 2. The character of growth of a dispersed deposit is largely determined by the conditions under which hydrogen evolution takes place on the electrode surface. The magnitude of hydrogen evolution polarization, which is determined by the nature of the basis material and the true surface of the electrode (its profile), controls the character of current density variation on the tips of dendrites, i.e., the rate of their growth. The greater the hydrogen overvoltage on a given material (vitreous carbon) and the smaller the active surface of the material (a gauze electrode) the higher is the rate of growth of dendrites, resulting in the formation of finer powders.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00795127
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Statistical analysis of conditions of preparation of copper powder (1978)
    Springer
    Powder metallurgy and metal ceramics 17 (1978), S. 899-900 
    Details
    ISSN: 1573-9066
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Conclusions 1. Statistical mathematical models have been obtained describing the dependence of the particle size (amount of the+0.045-mm fraction) and apparent density of copper powders on the basic parameters of the electrodeposition process. 2. The mathematical models provide a close approximation to the real industrial process within the process parameter ranges for which they were obtained. 3. The properties of electrodeposited copper powders can be controlled, and a suitable method has been developed for the selection of process parameters enabling copper powders of predetermined properties to be obtained. The method has been tested under pilot-plant conditions and adopted at the Uralélektromed' Combine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00792575
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Studies on deoxyribonucleoprotein structure. Small-angle X-ray scattering in solutions of various ionic strengths (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1133-1142 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cross-sectional radius of gyration of the deoxyribonucleoprotein (DNP) threads was measured by small-angle X-ray scattering in a wide range of ionic strengths (from 0.0005 to 2 M NaCl). For DNP in a solution of low ionic strength, this value is 30 Å. The increase of ionic strength results in partial deproteinization of DNP, while the cross-sectional radius of gyration varies from 25 Å for DNP in 0.7 M NaCl to 10 Å for DNP in 2 M NaCl. It is suggested that gradual deproteinization by the increase of NaCl concentration causes conformational changes, which are associated with the alteration of the DNP superstructure. The data are interpreted on the basis of the superhelical model of DNA packing in DNP; however, the coexistence of superhelical and unfolded regions in the DNP structure is also a possibility.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140603
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    Paper (German National Licenses)
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