title: Insertion/deletion and nucleotide polymorphism data reveal constraints in Drosophila melanogaster introns and intergenic regions.
abstract: Our study of nucleotide sequence and insertion/deletion polymorphism in Drosophila melanogaster noncoding DNA provides evidence for selective pressures in both intergenic regions and introns (of the large size class). Intronic and intergenic sequences show a similar polymorphic deletion bias. Insertions have smaller sizes and higher frequencies than deletions, supporting the hypothesis that insertions are selected to compensate for the loss of DNA caused by deletion bias. Analysis of a simple model of selective constraints suggests that the blocks of functional elements located in intergenic sequences are on average larger than those in introns, while the length distribution of relatively unconstrained sequences interspaced between these blocks is similar in intronic and intergenic regions.
authors.affiliation: Section of Evolutionary Biology, Biocenter, University of Munich, Planegg-Martinsried, Germany.
authors.forename: Lino
authors.initials: L
authors.lastname: Ometto
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Stephan
authors.forename: David
authors.initials: D
authors.lastname: De Lorenzo
mesh_terms: D000818:Animals; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000235:genetics*; D007438:Introns; D008957:Models, Genetic; D011110:Polymorphism, Genetic; D017384:Sequence Deletion; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements