fu1 heterozygotes carrying one copy of Su(fu)+ display a partially suppressed wing phenotype, the presence of P{SUFU100} produces viable males with a fu1 wing phenotype (the transposon fully compensates the decreased amount of Su(fu)+ product). fu41 heterozygotes carrying one copy of Su(fu)+ are pharate adult lethal and display a cos wing phenotype, the presence of P{SUFU100} produces viable males with a fu41 wing phenotype (the transposon fully compensates the decreased amount of Su(fu)+ product). When the number of Su(fu)+ doses in fu1 or fu41 males is greater than two viability decreases, the decrease in viability is correlated with an enhancement of the fu wing phenotype. Decrease in viability is more pronounced when the transgene is provided by the mother. Viability of fu41 males, not fu1 males is also affected when the Su(fu)+ activity decreases, the decrease in viability is associated with an anterior wing duplication phenotype (similar to cos mutant phenotype).
