Fig. 1

Motif spectrum distributions of genome sequences. a Motif spectra of three representative genome sequences. Of human genome is shown to represent the tri-modal spectrum, of chicken genome is shown to represent quasi-di-modal and of yeast genome is shown to represent unimodal. The vertical bar is the center frequency of the corresponding random sequence. b The spectra of XY2, XY1 and XY0 motif subsets of human genome sequence (X, Y = A, C, G, T). c The spectra of CG2, CG1 and CG0 motif subsets in human, chicken and yeast genome sequences. d The normalized spectra of CG2, CG1 and CG0 motif subsets in which the motif frequencies are transformed by the square root transformation in human, chicken and yeast genome sequences. e The spectra of TA2, TA1 and TA0 motif subsets of three representative genome sequences. Tetrabaena socialis is green algae (left), Schizophyllum commune is fungus (middle) and Halomicrobium katesii is prokaryote (right). f The normalized spectra of TA2, TA1 and TA0 motif subsets in which the k-mer frequencies are transformed by the square root transformation in the three representative genome sequences