Figure 6.—

flam controls the expression of both gypsy and ZAM retroelements. The parental FM7c(R) allele is restrictive, stable for ZAM expression (S), and female fertile (see Table 2). It represses the β-galactosidase expression driven by gypsy as well as ZAM LTRs. The flam female-sterile mutant allele, py+(P), caused by insertion of the P{lyB} element into the flam locus of the FM7c chromosome, no longer represses the gypsy and ZAM reporters. In contrast, repression and fertility are restored in females carrying the revertant allele FM7c,679-5b(R), generated by excision of the P{lyB} element.