Flies expressing en45.T:Ivir\HA1 in a homozygous en54 mutant background are fertile with no phenotypic defects aside from minor defects in the wing veins in the posterior compartment in some flies.
30% of Df(2R)enΔ530/en54 wings exhibit split veins in the posterior compartment.
Homozygous en54 mutant embryos display a highly disturbed ventral nerve cord architecture. The commissures are fused, or posterior commissures are thinner than normal or absent, suggesting that axons are either misrouted or missing. Longitudinal tracts are globally less affected than commissures in these mutants.
Hindgut boundary cell rows and rings form normally in mutant embryos.
Occasional adult escapers are seen for enAdv-1/en54. enAdv-1/en54 escapers have en-type wing phenotypes, including transformation of posterior wing margin to an anterior fate, in addition to the additional vein phenotype seen in In(2R)Adv/+ flies.
The development of the border cells of the hindgut (which normally form an anterior and posterior ring at the ends of the hindgut and bilateral strands that connect the two rings) is not affected in mutant embryos.
Embryos develop merged denticle belts.
5% of en1/en54 flies have a gap in the fourth wing vein at 25oC.
Homozygous embryos do not show duplications of the RP2 neuron.
Mutants exhibit pairwise fusion of the abdominal segments, failure of head involution and extensive cell death causing a shortened cuticle.
Pair-rule defects in the naked cuticle of T1, T3, A2, A4, A6 and A8 result in the pair-wise fusion of adjacent segments. Spacing of apodemes is almost completely irregular and pattern of the somatic muscles is also extremely disturbed. Cells derived from the anterior segment border present signals essential for muscle guidance.
Larvae show no proventricular defects.
No reduction in rate of germ band extension, in wg, ptc, en triple mutants.
Defects in posterior compartments of each segment.
en54/en1 flies have wild-type shape wings and a wild-type scutellum. Vein III appears thickened and tends to have a posteriorwards bulge about halfway along its length. The anterior crossvein (ACV) is often reduced or absent. Small plexae of vein tissue tend to occur close to the ACV and the posterior crossvein. Vein IV is frequently interrupted and often carries campaniform sensilla. Bristles are occasionally seen in the posterior row, but they never have the characteristics of the middle triple row.