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Genetic analysis of homeotic gene silencing in Drosophila

Tuesday, October 25, 2011 — Poster Session II

Noon – 2:00 p.m.

Natcher Conference Center




  • M Mortin
  • M Cooper
  • J Kennison


Most transposon insertions selected using the white gene as a reporter show an intermediate phenotype between the wild-type red and loss-of function white eye colors. Homozygotes (with two copies of the transgene instead of one) usually become darker or more like the wild-type eye color. In studying cis-regulatory DNA for the Hox gene Sex combs reduced (Scr) we identified a number of elements that caused the homozygous insertion flies to have lighter eye colors instead of darker, a phenomenon called pairing-sensitive silencing. Pairing-sensitive silencing is postulated to reflect the endogenous functions of these cis-regulatory elements. To identify novel proteins that regulate these cis elements, we carried out a screen for recessive mutations that interfere with pairing-sensitive silencing. We isolated 73 mutations. Thirty-one are alleles of 7 known Polycomb group genes. These Polycomb group genes encode subunits of four different chromatin–associated complexes. The remaining mutations identify 18 genes not previously associated with pairing-sensitive silencing.

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