SOME PROPERTIES OF SINGLE STRANDS ISOLATED FROM DNA OF NUCLEAR SATELLITE OF MOUSE (MUS MUSCULUS)

It has already been shown that mouse satellite DNA is composed of a light and a heavy strand which can be resolved in alkaline gradients of caesium chloride. It is probable that each strand is composed of a number of repeats of a sequence 300 to 400 bases long. About 15% of the light and heavy strands form, in the absence of a complementary strand, light-light or heavy-heavy complexes which are stable at high temperatures. Several lines of evidence suggest that this is not due to contamination, but to a relatively small number of complementary sequences which are periodically reversed between the light and heavy strands. Main band DNA from the mouse also contains satellite sequences, which band at this position because they are integral parts of molecules of predominantly main band composition. Satellite sequences, while extremely common in the mouse, are, we find, rare or non-existant in the other rodents studied. It should be easy to detect RNA which is complementary to one or the other of the highly reiterated sequences in the light or heavy strands. We find however, less than 1 in 60,000 complementary molecules in RNA from liver, spleen or kidney cells. These sequences may not, therefore, be transcribed. © 1969.