dac3 neuroblast clones generated in first instar larvae contain similar numbers of neurons as wild-type controls.
dac3 neuroblast clones induced in early larvae (to mark &ygr; neurons), in late larvae (to mark α'β' neurons) and in pupae (to mark αβ neurons) all extend axons into the proper lobes. Axons lacking dac did exhibit some irregularities, with misrouting and over-extension of projections occurring in αβ and α'β neurons. Despite their relatively normal projection pattern, axons of all three types of mushroom body neurons are more extensively and variably branched in dac3 mutant single cell clones compared to controls, particularly mutant &ygr; axons.
In dac3 mutant first instar larval neuroblast clones the axons fail to contribute significantly to the α lobe and the medially projecting axons are unevenly distributed within the horizontal lobes. In mid-third instar larval neuroblast clones the clonal axons project primarily to the α' and β' loves, and only a few clonal axons contribute to the α and β lobes. Although axons of dac3 larval neuroblast clones fail to contribute normally to the α lobe, the axons of dac3 pupal neuroblast clones project essentially normally to the α and β lobes, with β axons occasionally crossing the midline.
dac3 mutant αβ neurons project to α' and β' lobes in larval neuroblast clones.
dac3 mutants have no eyes.
Tv neurons show normal innervation of the dorsal neurohemal organs in dac3/Df(2L)dac-4 mutant embryos.
dac3/dacGAL4 animals have almost no eyes, and those ommatidia that remain are severely disorganised. Homozygous mutant animals have eyes smaller than a third of wild-type size, and small fused legs.
In dac3/Df(2L)dac-4 transheterozygotes a fusion of the antennal segment 5 (a5) with the arista and a reduction in width of a5 are seen. However, no obvious reductions in length or loss of segments are seen in the mutant antenna.
Mutant animals rarely eclose due to their truncated legs. Mutant females still have two spermathecae (as in wild type) but the two ducts are fused into one branched duct that is shared by both spermathecae. Male mutant flies show a severe reduction of the clasper; the clasper is truncated, has a reduced number of clasper teeth bristles and lacks the long bristle at the "distal" end.
Homozygous clones in the leg result in segment fusions. Homozygous clones in the leg disc are a comparable size to wild-type clones.
The mushroom bodies of dac1/dac3 or dac3/Df(2L)dac-4 adults show a number of defects. The α lobes are reduced in size. Aberrant projections are often seen emanating from the calyx along the peduncle and in the direction of the tips of the α lobes. The medial (β, β' and γ) lobes appear grossly disorganised. Aberrant projections are often seen emanating from the γ lobe and projections from the heel are occasionally seen. The ellipsoid body is severely disorganised in dac1/dac3 adults. Only 3.2% of dac1/dac3 and 10.5% of dac3/Df(2L)dac-4 third instar larvae show a marked reduction in size of the α-type lobe and the defect is frequently unilateral. No aberrant projections are evident from the β-type lobe, the peduncle or the calyx. Homozygous mushroom body neuroblast clones generated just after hatching fail to contribute to the α lobes. This defect is not due to the death of α/β neurons. Cells of the clone do contribute to the α' lobes. In contrast to wild-type control clones, which fill the horizontal mushroom body lobes homogeneously, mutant axons fill these neuropils in a disorganised way, with a substantial variability between clones.
Mutants lack eyes because of a failure of morphogenetic furrow initiation.
Homozygous adults exhibit severely reduced or no eyes due to failure of the morphogenetic furrow to initiate.
Eyes of homozygotes are severely reduced and roughened, or absent. Morphogenetic furrow movement does not occur in about half mutant eye discs, and is dramatically reduced in the rest. Mutants have short, little legs. Femur, tibia and proximal three tarsi are severely condensed. Cell death is increased in mutant leg discs.