Fig. 3. Ectopically patterned Engrailed uses exd to repress slp in vivo. Embryos collected as in Fig. 2 were double stained for a balancer marker (hb-lacZ, in brown in C,D, indicating absence of the prd-Gal4 driver transgene; all others are lacZ negative, indicating that they carry the driver) and for slp RNA by in situ hybridization. Notice that, in exd wild-type embryos (A,B), slp is progressively repressed by the ectopic En expression within alternate stripes; in heterozygous exd embryos, which lack a maternal exd contribution (E,F), the repression is delayed and reduced; in embryos that lack all exd function both maternally and zygotically (G,H), this effect is stronger. Because repression is progressive, mutant embryos are shown that are at least as old as the corresponding wild-type controls.

Return to article