We have analyzed third position in codons and have observed strong long-ran
ge correlations along DNA sequence. We have shown that the correlations are
caused mostly by asymmetric replication. In the analysis, we have used a D
NA walk (spider analysis Cebrat et al., Microbial Comparative Genomics 2(4)
(1997) 259-268) in two-dimensional space [A-T,G-C]. The particular case of
the E. coli sequence has been studied in detail. (C) 1999 Elsevier Science
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