DOSDNA OCCURS ALONG YEAST CHROMOSOMES, RE GARDLESS OF FUNCTIONAL-SIGNIFICANCE OF THE SEQUENCE

Complex genomes contain numerous simple sequence repeats, the biologic al significance of which remains obscure. Recently it has been shown t hat several human diseases are the result of changes in such sequences . Thus it has become urgent to undertake a systematic study of their p roperties. We have set the task of describing as completely as possibl e the set of sequences which contain bases organized according to symm etrical elements, the dosDNA: defined ordered sequence. Examination of local anomalies in dinucleotide composition serves to identify dosDNA zones in the genome. The study of chromosomes II, III, VIII and XI of Saccharomyces cerevisiae reveals these dosDNA zones comprise about 2% of the genome. They are regularly distributed along the chromosomes, regardless of the functional significance of the sequence. A more deta iled analysis of dosDNA segments seems to indicate that simple repeats are the consequence of local properties of the chromosome and not due to any motif in particular.