usp3/usp3 somatic clones of vCrz peptidergic neurons display larval features in both cell body and neural projections at 6 hours after puparium formation indicating that, unlike wild-type controls, they have bypassed cell death.
Homozygous ddaC dendritic arborisation neuron MARCM clones do not show dendrite branching defects.
usp3 somatic C4da neuron clones fail to prune their larval dendrites at 20 hours after pupal formation, with approximately 90% of large dendritic branches being retained after head eversion.
At the the wandering third instar stage, persistent olfactory projection neurons (PPNs) exhibit normal morphology. However, 8 hours APF significant defects in dendrite and axon pruning are observed. In the majority of cases, both dendritic densities in the location of the larval antennal lobe and exon branches in the mushroom body (MB) calyx are retained. In the adult fly mutant PPNs generally appear to target appropriate glomeruli in the adult antennal lobe (AL); however ectopic processes in additional areas of the AL, which may be persisting larval dendrites, are often present. In a few cases mutant PPN dendrites are sparser and less specifically targetted to particular glomeruli, but still remain somewhat confined to certain regions of the AL. About 40% of mutant PPNs retain larval-like boutons directly on their main trunks in the mushroom body calyx; however they always have side branches with terminal branches as well. In addition the main axon trunk often diverts from the inner antennocerebral tract in the MB calyx. Nearly all mutant PPN axons exhibit grossly wild-type morphologies in the adult lateral horn (LH).
The disappearance of varicosities and the increase in axon disconnections which are seen in wild-type γ mushroom body neurons during early pupal stages are significantly suppressed in usp3 animals.
In larval brains usp3 homozygous mutant γ neurons acquire axonal and dendritic projections indistinguishable from wild-type. However during metamorphosis, pruning of larval dendrites and axons is not observed in usp3 mutant single cell or two cell clones. All mutant γ neurons retain their larval-type bifurcation of axons into the adult stage.
usp3/Y larvae arrested during the first larval instar stage have both first and second larval instar mouth hooks.
Homozygous clones in the margin region of the wing disc show precocious differentiation of neurons.
Heterozygotes are viable and fertile. Ovaries of heterozygous females develop almost normally. The number of ovarioles, the number of terminal filament (TF) cells/stack and ovary size are normal and epithelial sheath morphogenesis occurs normally. There is a significant increase in the number of TF cells formed at 24 hours after ecdysis to the third instar relative to control flies. Large homozygous clones in the ovary result in regions lacking TFs which appear undifferentiated. Smaller clones in the anterior of the ovary result in abnormal TF formation either when several contiguous cells within a TF stack are homozygous for usp3 or when TF stacks are surrounded by predominantly homozygous usp3 cells. Mosaic ovaries have fewer TF stacks formed at the onset of metamorphosis than control flies.
Homozygous clones in the eye imaginal disc that lie posterior to the morphogenetic furrow have an abnormal arrangement of developing photoreceptor clusters. The clusters are irregularly spaced and differentiate prematurely, although they contain the normal number of cells. Movement of the morphogenetic furrow is accelerated where it passes through a homozygous clone. This displacement of the furrow is not caused by excess proliferation of usp3 cells in the clone.
Heterozygotes display thoracic defects ranging from mild, slight separation of the microchaetes and macrochaetes along the dorsal midline, to severe, a cleft extending through both the notum and scutellum. Flies also have bent and misshapen sensory bristles and develop severely knarled legs.
usp3 clones in the head show two distinct morphological abnormalities: usp3 retinas contain enlarged, split rhabdomeres, which wrap around the cell body. They only extend into the outside 20% of the retina. The ventral third of the retina is often atrophic and thinner than the dorsal part of the retina in eyes with usp3 clones. This phenotype is correlated with the presence of a usp3 clone in the eye-antennal disc, but not with the presence of a usp3 clone in the retina, and is a non-autonomous phenotype. Most of the eggs laid by usp3 mosaic females mutant in the germline are fertilised.
Phenotype of homozygous germ line clones is maternal effect lethal.
Homozygous usp3 germline generates misshapen eggs that are unfertilized with fused filaments.