title: Characteristics of the large (dA).(dT) homopolymer tracts in D. discoideum gene flanking and intron sequences.
abstract: D. discoideum, the slime mold, is one of the most AT rich eukaryotic genomes known. In this paper we examine this organism's database for overlapping N-tuples of high frequency and find A and T tracts possess among the highest frequencies in flanking sequences but not in coding sequences. We examined both overlapping and non-overlapping frequencies of the A, T, G and C homopolymer tracts of 2 < N < 6. Overlapping (dG).(dC) and (dA).(dT) tracts occur at greater frequencies than expected, based on random occurrence. Long (dA).(dT) tracts of N > 10 occur at well above expected frequencies in flanking and intron regions, while (dG).(dC) tracts above N = 5 are rarely found. Some of the implications of these findings for tract origins in slip-strand replication and for chromatin structure are discussed.
authors.affiliation: Department of Chemistry, University of Massachusetts Lowell 01854.
authors.forename: K A
authors.initials: KA
authors.lastname: Marx
authors.forename: S T
authors.initials: ST
authors.lastname: Hess
authors.forename: R D
authors.initials: RD
authors.lastname: Blake
mesh_terms: D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D004271:DNA, Fungal / Q000737:chemistry*; D004023:Dictyostelium / Q000737:chemistry / Q000235:genetics*; D005800:Genes, Fungal; D007438:Introns; D009838:Oligodeoxyribonucleotides / Q000032:analysis; D011067:Poly dA-dT / Q000032:analysis*
chemical_list: D004271:DNA, Fungal; D009838:Oligodeoxyribonucleotides; D011067:Poly dA-dT