Chromatin structure at the 44D larval cuticle gene locus in Drosophila: the effect of a transposable element insertion.
The chromatin structure of the larval cuticle gene cluster at 44D was characterized in embryos from wild-type (Oregon R) and a variant line (2/3) of Drosophila melanogaster. A major DNase I hypersensitive (DH) site was found between genes II and III in the chromatin, in a position 5' to the transcriptional start of the genes in the cluster. The introduction of a 7.3 kilobase transposable element into the cluster in the 2/3 variant enhanced the sensitivity of the major site in 2/3 chromatin but had no other effect upon the pattern of DH sites associated with the wild-type sequences. The wild-type sequences were packaged into an ordered nucleosome-like array in embryos, as revealed by digestion with the chemical cleavage reagent (methidiumpropyl-EDTA) iron (II) [MPE . Fe(II)]. Nucleolytic cleavage within the transposable element chromatin shows it to be organized in an ordered array punctuated by several DH sites. While the patterns of DNase I hypersensitivity are similar in the vicinity of the direct terminal repeats, the patterns revealed by micrococcal nuclease and MPE . Fe(II) are not, indicating a different chromatin organization of these two identical sequences.
D000818:Animals; D002843:Chromatin / Q000032:analysis* / Q000648:ultrastructure; D004247:DNA / Q000302:isolation & purification; D004262:DNA Restriction Enzymes; D004251:DNA Transposable Elements; D003850:Deoxyribonuclease I; D004331:Drosophila melanogaster / Q000235:genetics*; D005796:Genes; D014644:Genetic Variation; D007814:Larva / Q000502:physiology; D009707:Nucleosomes / Q000648:ultrastructure
D002843:Chromatin; D004251:DNA Transposable Elements; D009707:Nucleosomes; D004247:DNA; D004262:DNA Restriction Enzymes; D003850:Deoxyribonuclease I