[Characteristics of nucleotide blocks in coding and non-coding DNA sequences from different organisms].

A statistical analysis of occurrence of particular nucleotide runs (1 divided by 10 nucleotides long) in DNA sequences of different species has been carried out. There are considerable differences in run distributions in DNA sequences of prokaryotes, invertebrates and vertebrates. Distribution of various types of runs has been found to be different in coding and non-coding sequences. There is an abundance of short runs 1 divided by 2 nucleotides long in coding sequences, and there is a deficiency of such runs in the non-coding regions. However, some interesting exceptions from this rule exist: for run distribution of adenine in prokaryotes and for distribution of purine-pyrimidine runs in eukaryotes. This may be stipulated by the fact that the distribution of runs are predetermined by structural peculiarities of the entire DNA molecule. Runs of guanine or cytosine of three to six nucleotides long occur predominantly in the non-coding DNA regions in eukaryotes, especially in vertebrates.