Figure 3.

Frequency of occurrence of different ages and families of interspersed repeats in regions of different GC-content. The local GC-content (measured as the fraction of G or C in the surrounding 50 kb) was determined for each member of a repeat family, the number of repeats in intervals of GC-content was counted and then divided by the abundance of all genomic DNA in that interval to obtain the relative frequency of repeats. Repeats of different ages (measured by their divergence from the consensus) were examined for SINEs (A) and LINEs (B) for the rat (top), mouse (middle), and human (bottom) genomes.