title: Induced transcription results in local changes in chromatin structure, replication timing, and DNA polytenization in a site of intercalary heterochromatin.
abstract: In salivary gland polytene chromosomes of Drosophila melanogaster, the regions of intercalary heterochromatin are characterized by late replication, under-replication, and genetic silencing. Using Gal4/UAS system, we induced transcription of sequences adjacent to transgene insertions in the band 11A6-9. This activation resulted in a loss of "silent" and appearance of "active" epigenetic marks, recruitment of RNA polymerase II, and formation of a puff. The activated region is now early replicating and shows increased level of DNA polytenization. Notably, all these changes are restricted to the area around the inserts, whereas the rest of the band remains inactive and late replicating. Although only a short area near the insertion site is transcribed, it results in an "open" chromatin conformation in a much broader region. We conclude that regions of intercalary heterochromatin do not form stand-alone units of late replication and under-replication. Every part of such regions can be activated and polytenized independently of other parts.
authors.affiliation: Institute of Molecular and Cellular Biology SB RAS, Novosibirsk 630090, Russia.
authors.forename: Dmitry E
authors.initials: DE
authors.lastname: Koryakov
authors.forename: Galina V
authors.initials: GV
authors.lastname: Pokholkova
authors.forename: Daniil A
authors.initials: DA
authors.lastname: Maksimov
authors.forename: Stepan N
authors.initials: SN
authors.lastname: Belyakin
authors.forename: Elena S
authors.initials: ES
authors.lastname: Belyaeva
authors.forename: Igor F
authors.initials: IF
authors.lastname: Zhimulev
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D002843:Chromatin / Q000378:metabolism / Q000648:ultrastructure*; D042522:DNA Replication Timing; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics*; D062951:Endoreduplication; D044127:Epigenesis, Genetic; D017930:Genes, Reporter; D006570:Heterochromatin / Q000378:metabolism*; D059007:Polytene Chromosomes; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D019076:Transgenes
chemical_list: D002843:Chromatin; D029721:Drosophila Proteins; D006570:Heterochromatin; D012319:RNA Polymerase II