SEGMENTED STRUCTURE OF SEPARATE AND TRANSPOSABLE DNA AND RNA ELEMENTSAS SUGGESTED BY THEIR SIZE DISTRIBUTIONS

A collection of about 1000 different eukaryotic and prokaryotic DNA mo bile and separate elements is compiled from literature - transposons, plasmids, extrachromosomal circular DNA, insertion sequences, as well as viral genomes and separate genome segments. Only small elements are collected, upto 2000 base pairs. Analysis of the sequence length dist ributions of the elements reveals that certain sizes are clearly prefe rred, namely those which correspond to multiples of about 345 bp in eu karyotes and multiples of about 210 bp in prokaryotes. This provides a dditional evidence in support of the theory (1) that segmented structu re is characteristic of not only protein-coding sequences (2) but rath er of genomes in general. In particular, it confirms the prediction (1 ) that mobile and separate elements would also be segmented.