Variations in Base Bair Composition and Associated Long-range
Correlations in DNA Sequences - Computer Simulation Results
C.A. Chatzidimitriou-Dreismann, R.M. Streffer, D. Larhammar
Biochimica et Biophysica Acta - Gene Structure and Expression ,
1217, 181-187 (March 1, 1994)
Abstract
Recently, the possible occurrence of long-range correlations between nucleotides in DNA sequences
of living organisms has excited considerable interest. Of particular importance is the claim that only
intron-containing sequences exhibit these correlations. Different investigations, however, have disproved the
claimed difference between intron-containing and intron-less DNA sequences. Moreover, very recent
investigations pointed out that the long-range correlations appear only if relatively large variations in nucleotide
composition along the DNA sequence are present. Furthermore, some examples demonstrated that these
variations may have clear biological reasons. In this paper we investigate in detail, with the aid of computer
simulations, the connection between compositional heterogeneity of a DNA sequence and the appearance of
long-range correlations. As an explicit example, the DNA sequence of the lambda-phage is compared with
different artificial sequences of similar compositional heterogeneity. The results demonstrate that the variations of
the nucleotide composition along the sequence can fully account for all properties of the claimed long-range
correlations. New results of extensive computer simulations are presented which clearly demonstrate how the
apparent 'fractal' (or 'long-range-correlated') character of a sequence gradually evaporates, as the frequency of
the compositional variations of a simulated sequence continuously increases.
