title: Position-effect variegation in Drosophila melanogaster X chromosome inversion with a breakpoint in a satellite block and its suppression in a secondary rearrangement.
abstract: In(1LR)pn2a is a pericentric inversion with a euchromatic breakpoint in the 2E polytene region and a heterochromatic breakpoint in the right arm of the X chromosome. It is associated with position-effect variegation (PEV) of the pn, wapl, Pgd and other vital loci of the 2E region, which are relocated near the bulk of the X heterochromatin. Cytological analysis showed that the rearrangement brings the 1A-2E euchromatic segment directly into contact with a major portion of the h34 block, a heterochromatic region that is positively stained by the N-banding technique and contains the AAGAG satellite sequences. Molecular cloning revealed the presence of a new junction between euchromatin and AAGAG satellite sequences and demonstrated that the euchromatic breakpoint of In(1LR)pn2a lies in the vinculin gene. In the X ray-induced secondary rearrangement In(1LR)r30, consisting of a pericentric inversion superimposed on In(1LR)pn2a, the h34 material remains associated with the 2E region but is separated from the rest of the X heterochromatin. In this case, the pn, wapl and Pgd loci no longer variegate, suggesting that the satellite-containing h34 region is not able per se to induce detectable PEV on the adjacent euchromatic genes.
authors.affiliation: Institute of Molecular Genetics, Moscow 123182, Russia.
authors.forename: E V
authors.initials: EV
authors.lastname: Tolchkov
authors.forename: I A
authors.initials: IA
authors.lastname: Kramerova
authors.forename: S A
authors.initials: SA
authors.lastname: Lavrov
authors.forename: V I
authors.initials: VI
authors.lastname: Rasheva
authors.forename: S
authors.initials: S
authors.lastname: Bonaccorsi
authors.forename: V E
authors.initials: VE
authors.lastname: Alatortsev
authors.forename: V A
authors.initials: VA
authors.lastname: Gvozdev
mesh_terms: D000818:Animals; D019457:Chromosome Breakage; D007446:Chromosome Inversion; D004276:DNA, Satellite / Q000235:genetics*; D004303:Dosage Compensation, Genetic; D004331:Drosophila melanogaster / Q000235:genetics*; D006570:Heterochromatin / Q000737:chemistry / Q000235:genetics; D013489:Suppression, Genetic; D014960:X Chromosome / Q000235:genetics*
chemical_list: D004276:DNA, Satellite; D006570:Heterochromatin