Expression of TER94E375Q.E575Q.Scer\UAS under the control of Scer\GAL4ppk.PG leads to strong dendrite pruning defects with approx. 80% of class IV dendrite arborizing neurons still having dendrites attached to the cell body at 18h after puparium formation.
Expression of TER94E375Q.E575Q.Scer\UAS in class IV neurons (ddaC) under the control of Scer\GAL4ppk.PG causes a reduction in dendrite arborization, while major branches stay intact. These defects in class IV neurons mostly affect higher-order branches containing filamentous actin, but not primary dendrite branches rich in microtubules.
Expression of TER94E375Q.E575Q.Scer\UAS in class III neurons (ddaA and ddaF) under the control of Scer\GAL419-12 affects the length of class III dendrites, although spike appearance is normal. An additional copy of TER94E375Q.E575Q.Scer\UAS increases the severity of the phenotype, with approximately 64% of all neurons displaying strong defects.
A high proportion of class IV neurons (ddaC) expressing TER94E375Q.E575Q.Scer\UAS under the control of Scer\GAL4ppk.PG retain long, attached dendrites (with 63% not severed).
Addition of 100υM RU486 to Scer\GAL4ppk.Switch.PR/TER94E375Q.E575Q.Scer\UAS larvae 24 hours before the onset of metamorphosis does not visibly change the morphology of the larval neurons; however, a high proportion of class IV neurons (ddaC) in these drug-treated animals retina their dendrites at 18 hours after pupal formation (defects occur in approximately 70% of neurons). indicating that the phenotypes observed during metamorphosis can be disassociated from the defects at the larval stage.
Class III neurons overexpressing TER94E375Q.E575Q.Scer\UAS under the control of Scer\GAL419-12 do not undergo apoptosis and are still present by 18 hours after puparium formation. In these flies, the ddaF neuron is more prone to survive than ddaA.
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has abnormal neuroanatomy | pupal stage phenotype, non-enhanceable by Mfap1GD5122, Scer\GAL4ppk.PG
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has abnormal neuroanatomy | pupal stage phenotype, non-enhanceable by Mfap1[+]/Mfap1DsRed
Scer\GAL419-12, TER94E375Q.E575Q.UAS has decreased cell death | pupal stage phenotype, suppressible by Diap14/th[+]
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has abnormal neuroanatomy phenotype, suppressible | partially by Diap14/th[+]
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has larval multidendritic class IV neuron | pupal stage phenotype, non-enhanceable by Mfap1GD5122, Scer\GAL4ppk.PG
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has larval multidendritic class IV neuron | pupal stage phenotype, non-enhanceable by Mfap1[+]/Mfap1DsRed
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has larval multidendritic class IV neuron phenotype, suppressible by Diap14/th[+]
Scer\GAL4ppk.PG, TER94E375Q.E575Q.UAS has dendrite phenotype, suppressible by Diap14/th[+]
The dendrite pruning defects in class IV dendrite arborizing neurons observed in pupae expressing TER94E375Q.E575Q.Scer\UAS under the control of Scer\GAL4ppk.PG is not significantly affected by co-expression of Mfap1GD5122 or by combination with a single copy of Mfap1DsRed.
A th4 heterozygous mutant background suppresses the class IV pruning defects seen upon expression of TER94E375Q.E575Q.Scer\UAS under the control of Scer\GAL4ppk.PG. Lowering th levels also sensitises cells to stress-induced apoptosis, and a high proportion of TER94E375Q.E575Q.Scer\UAS-expressing neurons in a th4 heterozygous background undergo apoptosis during early metamorphosis (approximately 60% at 15 hours after pupal formation).