Table 1.

PRE activities of subfragmentsa

ConstructbVarcNo. of variegating lines/no. of lines tested with heterozygous mutationd:PolyteneseMaintenancef
AB×6 S2 Ubx-lacZ4/80/6
BP×6 S2 Ubx-lacZ5/135/13
PF×4 S2 Ubx-lacZ4/80/5
  • a For each fragment, the ability to induce variegated expression of the miniwhite gene in the CaSpeR4 vector was tested.

  • b Oligomerization is indicated by the number following the multiplication sign.

  • c Number of lines that variegate or are repressed when homozygous for the transposon/number of lines tested.

  • d Mutations Pc 3,Psc 1, Su(z)2 1, andTrl R85 increased pigmentation, and mutationstrx E2 and E(z) 1 decreased it.

  • e Number of lines in which a PcG binding site on polytene chromosomes was created/number of lines tested. The determination was performed for selected lines in which the transposon was not inserted at an endogenous PcG site by staining with anti-PC antibodies and in some cases also with anti-PSC and anti-SU(Z)2 antibodies.

  • f Number of lines in which repression was maintained/number of lines tested. The maintenance of repression was determined in embryos of lines containing the PRE fragment in front of an S2 Ubx-lacZ reporter gene.

  • g —, not tested.