Position-effect variegation in Drosophila melanogaster X chromosome inversion with a breakpoint in a satellite block and its suppression in a secondary rearrangement.
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.
Tolchkov
E V
EV
Institute of Molecular Genetics, Moscow 123182, Russia.
Kramerova
I A
IA
Lavrov
S A
SA
Rasheva
V I
VI
Bonaccorsi
S
S
Alatortsev
V E
VE
Gvozdev
V A
VA
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*
D004276:DNA, Satellite; D006570:Heterochromatin