Novel properties of satellite DNA from muskmelon.

The purified dense satellite of muskmelon (Cucumis melo L.) represents 30% of the total DNA and forms a sharp, unimodal peak in both neutral and alkaline CsCl gradients. Spectrophotometric melting and DNA reassociation analyses revealed that one-third of the satellite is high melting and has a complexity of about 2.5 x 10(5) daltons, while the remaining two-thirds of the satellite melts 8 degrees lower and has a complexity of about 5 x 10(8) daltons. The thermal stability of reassociated satellite DNA indicates that the multiple copies of the two melting fractions are essentially identical. The sharp, unimodal peak in Cs(2)SO(4) becomes two distinct peaks when either silver or mercuric ions are included in the Cs(2)SO(4) gradient