Fig. 1.

Relative frequency distribution of GC content in duplicated and nonduplicated (unique) DNA. Base composition of segmental duplications (24) and of the remaining genomic DNA for segments >20 kb long. The corresponding mean GC content and the standard deviation are indicated. The percentage of GC content for nonredundant segmental duplications without any length limitations is: for chromosome X, 42.47 (39.13); Y, 39.98 (38.47); and autosomes, 42.57 (40.52). Numbers in parentheses indicate the corresponding genomic base composition after the duplicated segments were masked. Based on the two-tailed t test, all differences between base compositions are significant (P < 0.001).