Sequences of the 1.672 g/cm3 satellite DNA of Drosophila melanogaster

Brutlag, D.; Peacock, W.J.

Journal of Molecular Biology 135(3): 565-580


ISSN/ISBN: 0022-2836
PMID: 119871
DOI: 10.1016/0022-2836(79)90164-5
Accession: 068521117

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The 1.672 g/cm3 satellite DNA of D. melanogaster was purified by successive equilibrium centrifugations in a CsCl gradient, an actinomycin D/CsCl gradient, and a netropsin sulfate/CsCl gradient. The resulting DNA was homogeneous by the physical criteria of thermal denaturation, renaturation kinetics and equilibrium banding in each of the gradients listed above. The complementary strands could be separated in an alkaline CsCl gradient. Despite this rigorous purification procedure, nucleotide sequence analysis indicates the presence of 2 different DNA species in this satellite .**GRAPHIC**. and .**GRAPHIC**. Further physical, chemical and template properties of the isolated complementary strands demonstrate that these 2 repeating sequences are not interspersed with each other. This result has biological significance since sequences of this particular satellite are known to be located primarily on 2 different chromosomes, Y and 2. The sequence heterogeneity observed in satellite DNA of higher eukaryotes may result from mixtures of very closely related but molecularly homogeneous repeated sequences each restricted to a particular chromosome or chromosomal region.