INTERACTIONS BETWEEN FUSED AND ENGRAILED, TWO MUTATIONS AFFECTING PATTERN FORMATION IN DROSOPHILA MELANOGASTER

In this paper we demonstrate that the severity of the engrailed phenotype is greatly increased when engrailed is combined with the X-linked mutation fused. The secondary sex combs of fu;en flies contain from two to four times more setae than do those of en siblings. The number of transverse rows of bristles on the metatarsus of the metathoracic leg is reduced by a factor of one and a half to two in fu;en flies when compared to their en siblings, while the frequency of reversed bract polarity, bristle abnormalities and misshapen metatarsi increases greatly. In addition, fu;en flies express the en wing phenotype more completely than their siblings and have a much higher frequency of wing vein abnormalities—some of which we have interpreted as triplications of the third and first longitudinal wing veins. We briefly discuss the significance of the fused-engrailed gene interaction.