FIG. 2.

Variegation and maintenance activities. (A) Top, S2 Ubx-lacZ construct and the insertion site for PRE fragments; bottom, expression patterns of the S2 enhancer construct in embryos at (from left to right) early extension, extended, and retracted germ band stages. Arrowheads indicate PS6. (B) Representative eye variegation patterns of constructs AB×6, BP×6, and PF×4 are shown together with embryos containing the corresponding S2 Ubx-lacZ reporter constructs. The embryos are shown at the late germ band retraction stage. Maintenance of early repression was obtained only with the BP×6 construct, in which expression continued to be repressed anterior of parasegment 6 (arrowhead) and in which the pattern was arrested at the pair rule stage.