Sequence relationship between long and short repetitive DNA of the rat: a preliminary report

Long and short repetitive sequences of rat DNA can be isolated and characterized. Long [greater than 1.5 kilobases (kb)] sequences can be separated from short (0.2-0.4 kb) sequences by exclusion chromatography after renaturation of 4-kb DNA fragments to a repetitive Cot and digestion with the single-strand-specific S1 nuclease. (Cot is the initial concentration of DNA in mol of nucleotides/liter multiplied by time in sec.) Long repetitive DNA can be driven by an excess of whole rat DNA can also be used to drive tracer quantities of either long (self-renaturation) or short repetitive DNA. Both the extent and the rate of the renaturations are found to be similar, suggesting that long and short DNA fragments share sequences. When long repetitive DNA is used to drive whole DNA tracers of various lengths, a 3.2-kb interspersion period is found. These data are consistent with the concept that short repetitive sequences are present within long repetitive DNA sequences in the rat genome.