An Unusual Genomic Position Effect on Drosophila White Gene Expression: Pairing Dependence, Interactions with Zeste, and Molecular Analysis of Revertants

摘要: The white gene in the AR4-24 P[white,rosy] insertion on chromosome 2 has a novel expression pattern, which it is repressed dorsal half of eye. X-ray mutagenesis led to isolation six revertants mapping 2, are wild type zeste+ background, and three extreme derivatives, ventral regions eye as well. By Southern blot analyses breakpoints five one derivatives were mapped flanking DNA bordering each side insertion. show some repression presence z1, by this criterion only partial revertant. act not cis, but also trans repress its various derivatives. We provide evidence that these effects proximity-dependent effects, possibly mediated pairing copies, they do extend copies located elsewhere genome. derivative, E1, small deletion spanning site at 5' end gene, propose distance between negative regulatory element promoter influences degree repression.