Class II fu allele, affects the carboxy domain of the protein by changing the open reading frame in the 5' region.
strong wing phenotype - veins L3 and L4 fused all along length; weak viability phenotype - ratio of the number of fused flies to wild type in fu/+ X fu/Y is 0.75-1.0; weak fecundity phenotype - ratio of eggs laid by fu/fu versus fu/+ sisters is 0.5-1.0; strong maternal effect on segmentation - percent of embryos with all segments entirely duplicated is 70-100%.
Su(fu)LP, fu53 has wing blade anterior compartment phenotype
Su(fu)LP, fu53 has leg anterior compartment phenotype
Su(fu)LP, fu53 has haltere anterior compartment phenotype
When in combination with Su(fu)LP heterozygotes individuals die as pupae. Adult escapers display wings, halteres and legs that have duplication of structures in the anterior compartment and shortening along the proximal-distal axis. Embryos derived from heterozygotes with Su(fu) mutants display a segment polarity phenotype: thoracic denticle belts are absent, last two rows of abdominal denticle belts are absent and a mirror image duplication of anterior rows of abdominal denticle belts.