Fig. 1. spen dominantly suppresses a P[sev-wg^ts] eye bristle phenotype. Micrographs are SEMs of adult fly heads. (A,B) Flies contain the P[sev-wg^ts] transgene and are heterozygous for either the parental chromosome iso^5A1 (A) or spen^9C7 (B), both reared at 17.6°C. The spen heterozygotes display significant suppression of the P[sev-wg^ts] partial loss of interommatidial bristles. A similar suppression was also seen with spen^14C2 (data not shown).