Long-range correlations in genomic DNA: A signature of the nucleosomal structure

We use the "wavelet transform microscope" to carry out a comparative statis tical analysis of DNA bending profiles and of the corresponding DNA texts. In the three kingdoms, one reveals on both signals a characteristic scale o f 100-200 bp that separates two different regimes of power-law correlations (PLC). In the small-scale regime, PLC are observed in eukaryotic, in doubl e-strand DNA viral, and in archaeal genomes, which contrasts with their tot al absence in the genomes of eubacteria and their viruses. This strongly su ggests that small-scale PLC are related to the mechanisms underlying the wr apping of DNA in the nucleosomal structure. We further speculate that the l arge scale PLC are the signature of the higher-order structure and dynamics of chromatin.