FIG. 1.

CMM function of bxd and Mcp. GAL4 was expressed during embryogenesis (A and C) by transferring embryos to a 37°C water bath for 1 h. Afterwards, heat-shocked lines were raised at 18°C until adulthood, like their control siblings (B and D), which were kept at 18°C constantly. Activated flies showed derepression of the mini-white gene. (E) The bxd, Mcp, and Fab7 subfragments were cloned into the pUZ transformation vector in both orientations (d, distal; p, proximal). From these constructs, transgenic flies were generated. The bxd and Mcp strains inherit the activated state of the two reporter genes, whereas flies carrying the Fab7 subfragments do not, as illustrated. The boundary and the PRE region depicted in the Mcp element are based on information published by Karch et al. (18) and Strutt et al. (36). The separation between boundary and PRE is arbitrary and not based on functional analysis. Constructs which displayed pairing-sensitive silencing or showed CMM function are marked with +; otherwise, a − is indicated.