Early biochemical experiments established that the set of dinucleotide odds 
ratios or 'general design' is a remarkably stable property of the DNA of an 
organism, which is essentially the same in protein-coding DNA, bulk genomic DNA, 
and in different renaturation rate and density gradient fractions of genomic DNA 
in many organisms. Analysis of currently available genomic sequence data has 
extended these earlier results, showing that the general designs of disjoint 
samples of a genome are substantially more similar to each other than to those 
of sequences from other organisms and that closely related organisms have 
similar general designs. From this perspective, the set of dinucleotide odds 
ratio (relative abundance) values constitute a signature of each DNA genome, 
which can discriminate between sequences from different organisms. 
Dinucleotide-odds ratio values appear to reflect not only the chemistry of 
dinucleotide stacking energies and base-step conformational preferences, but 
also the species-specific properties of DNA modification, replication and repair 
mechanisms.