Figure 2

Spectrum analysis by Fast Fourier transformation. Spectra of distributions of SNP density (A, C, and E) and nucleotide divergence between humans and chimpanzees (B, D, and F) of three TSS categories; all TSS (A and B), CGI-TSSs (C and D) and nonCGI-TSSs (E and F). The side view and sectional view at the periodicity 146 nucleotides of the FFT diagrams are shown on the left and top of the diagram panels, respectively. The magenta and red lines are the means and the 99 % confidence intervals of the power values. The number of sequences analyzed are 10,171 (A), 6,329 (C), and 3,842 (E). The diagrams and their side views of SNP density (A, C and E) are dynamically colored according to the Z-scores, while those of divergence (B, D and F) are colored according to the power in arbitrary units, which are the square of coefficients for the polynomials of the trigonometric functions in the FFT. The color range for SNP density goes from blue to red, corresponding to 0 to 25 in Z-score. Those for divergence correspond to 0 to 3, respectively, in power value (a.u.).