J Mol Biol 112: 31-47 (1977)[77230460]
A major fraction (80%) of the highly repeated DNA sequences from
the Drosophila melanogaster genome has been isolated as well-defined
satellites by buoyant density centrifugation in CsCl gradients
containing DNA-binding antibiotics. Four major satellites of
densities 1-672 g/cm3, 1.686 g/cm3, 1-68S g/cm3 and 1-705 g/cm3 (in
CsCI) were purified and characterized with regard to their amounts in
the genome, denaturation-renaturation characteristics and their mode
of organization. Several minor satellites were found with one (1-699
g/cm3} apparently representing linkage molecules resulting from
covalent joining of large blocks of the major satellites.
Analysis of yields of the 1.705 g/cm3 satellite from DNA of different
molecular weights suggested a mean segment length of approximately
100 million bases. Since this satellite accounts for between 4 and 5%
of the genome, we deduced it to have approximately eight major sites
in chromosomes. These data taken together with the existence of
"linkage" molecules are discussed in relation to the possibility of a
chromosome-specific arrangement of satellite DNA.
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