title: Two distinct domains in Drosophila melanogaster telomeres.
abstract: Telomeres are generally considered heterochromatic. On the basis of DNA composition, the telomeric region of Drosophila melanogaster contains two distinct subdomains: a subtelomeric region of repetitive DNA, termed TAS, and a terminal array of retrotransposons, which perform the elongation function instead of telomerase. We have identified several P-element insertions into this retrotransposon array and compared expression levels of transgenes with similar integrations into TAS and euchromatic regions. In contrast to insertions in TAS, which are silenced, reporter genes in the terminal HeT-A, TAHRE, or TART retroelements did not exhibit repressed expression in comparison with the same transgene construct in euchromatin. These data, in combination with cytological studies, provide evidence that the subtelomeric TAS region exhibits features resembling heterochromatin, while the terminal retrotransposon array exhibits euchromatic characteristics.
authors.affiliation: Department of Biological Chemistry, University of California-Irvine, Irvine, CA 92697, USA.
authors.forename: Harald
authors.initials: H
authors.lastname: Biessmann
authors.forename: Sudha
authors.initials: S
authors.lastname: Prasad
authors.forename: Valery F
authors.initials: VF
authors.lastname: Semeshin
authors.forename: Eugenia N
authors.initials: EN
authors.lastname: Andreyeva
authors.forename: Quang
authors.initials: Q
authors.lastname: Nguyen
authors.forename: Marika F
authors.initials: MF
authors.lastname: Walter
authors.forename: James M
authors.initials: JM
authors.lastname: Mason
mesh_terms: D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D002875:Chromosomes / Q000235:genetics* / Q000648:ultrastructure; D019295:Computational Biology; D017931:DNA Primers; D004331:Drosophila melanogaster / Q000235:genetics*; D040461:Gene Components; D015698:Genomic Library; D006570:Heterochromatin / Q000235:genetics; D017403:In Situ Hybridization; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D018626:Retroelements / Q000235:genetics; D017422:Sequence Analysis, DNA; D016615:Telomere / Q000235:genetics*; D020079:Terminal Repeat Sequences / Q000235:genetics; D019076:Transgenes / Q000235:genetics
chemical_list: D017931:DNA Primers; D006570:Heterochromatin; D018626:Retroelements