title: High-resolution analysis of Drosophila heterochromatin organization using SuUR Su(var)3-9 double mutants.
abstract: The structural and functional analyses of heterochromatin are essential to understanding how heterochromatic genes are regulated and how centromeric chromatin is formed. Because the repetitive nature of heterochromatin hampers its genome analysis, new approaches need to be developed. Here, we describe how, in double mutants for Su(var)3-9 and SuUR genes encoding two structural proteins of heterochromatin, new banded heterochromatic segments appear in all polytene chromosomes due to the strong suppression of under-replication in pericentric regions. FISH on salivary gland polytene chromosomes from these double mutant larvae allows high resolution of heterochromatin mapping. In addition, immunostaining experiments with a set of antibodies against euchromatic and heterochromatic proteins reveal their unusual combinations in the newly appeared segments: binding patterns for HP1 and HP2 are coincident, but both are distinct from H3diMetK9 and H4triMetK20. In several regions, partial overlapping staining is observed for the proteins characteristic of active chromatin RNA Pol II, H3triMetK4, Z4, and JIL1, the boundary protein BEAF, and the heterochromatin-enriched proteins HP1, HP2, and SU(VAR)3-7. The exact cytological position of the centromere of chromosome 3 was visualized on salivary gland polytene chromosomes by using the centromeric dodeca satellite and the centromeric protein CID. This region is enriched in H3diMetK9 and H4triMetK20 but is devoid of other proteins analyzed.
authors.affiliation: Laboratory of Molecular Cytogenetics, Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Lavrentyev Avenue 10, Novosibirsk 630090, Russia.
authors.forename: Eugenia N
authors.initials: EN
authors.lastname: Andreyeva
authors.forename: Tatyana D
authors.initials: TD
authors.lastname: Kolesnikova
authors.forename: Olga V
authors.initials: OV
authors.lastname: Demakova
authors.forename: Maria
authors.initials: M
authors.lastname: Mendez-Lago
authors.forename: Galina V
authors.initials: GV
authors.lastname: Pokholkova
authors.forename: Elena S
authors.initials: ES
authors.lastname: Belyaeva
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Rossi
authors.forename: Patrizio
authors.initials: P
authors.lastname: Dimitri
authors.forename: Alfredo
authors.initials: A
authors.lastname: Villasante
authors.forename: Igor F
authors.initials: IF
authors.lastname: Zhimulev
mesh_terms: D000818:Animals; D001483:Base Sequence; D002503:Centromere / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D006570:Heterochromatin / Q000235:genetics*; D007150:Immunohistochemistry; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D012469:Salivary Glands / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D006570:Heterochromatin; C464850:SuUR protein, Drosophila; D008780:Methyltransferases; C445404:SU(VAR)3-9