Absence of short period interspersion of repetitive and non-repetitive sequences in the DNA of Drosophila melanogaster

Abstract

A sensitive search has been made in Drosophila melanogaster DNA for short repetitive sequences interspersed with single copy sequences. Five kinds of measurements all yield the conclusion that there are few short repetitive sequences in this genome: 1) Comparison of the kinetics of reassociation of short (360 nucleotide) and long (1,830 nucleotide) fragments of DNA; 2) reassociation kinetics of long fragments (2,200 nucleotide) with an excess of short (390 short nucleotide) fragments; 3) measurement of the size of S1 nuclease resistant reassociated repeated sequences; 4) measurement of the hyperchromicity of reassociated repetitive fragments as a function of length; 5) direct assay by kinetics of reassociation of the amount of single copy sequence present on 1,200 nucleotide long fragments which also contain repetitive sequences.