Expressing EcRB1-ΔC655.W650A.UAS under the control of Scer\GAL4CCAP.PP leads to the progressive loss of most CCAP neurons starting from late 2nd instar through to wandering third instar larval stage. This results in a severely defective pupal development, characterized by a failure in head eversion and shortened wings and legs.
Expressing EcRB1-ΔC655.W650A.UAS under the control of Scer\GAL4Crz.PU completely suppresses the death of vCrz peptidergic neurons at 6-7 hours after puparium formation.
Expressing EcRB1-ΔC655.W650A.UAS under the control of Scer\GAL4A9 results in the formation of melanotic spots in the digestive system of dying larvae.
Expressing EcRB1-ΔC655.W650A.UAS under the control of Scer\GAL4Burs.PL results in the loss of most CCAP neurons in third instar larvae.
Expression of EcRB1-ΔC655.W650A.Scer\UAS in astrocytes, under the control of Scer\GAL4alrm.PD, does not affect astrocyte morphology in 3rd instar larvae. However, EcRB1-ΔC655.W650A.Scer\UAS expression completely blocks their morphological transformation into the highly vacuolated morphology apparent in controls at 6 hours after pupal formation.
Astrocyte morphological transformation can be suppressed when EcRB1-ΔC655.W650A.Scer\UAS is expressed in one to two astrocytes, using MARCM, rather than the entire population. EcRB1-ΔC655.W650A.Scer\UAS expression blocks the induction of phagolysomal activity.
Blockage of EcR signaling in astrocytes, through expression of EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4alrm.PD, suppresses the clearance of brp[+] synapses from multiple brain regions at 18 hours after pupal formation and vCrz[+] neuronal debris, with neurite debris lingering until 18 hours after pupal formation.
Astrocytic EcRB1-ΔC655.W650A.Scer\UAS expression, under the control of Scer\GAL4alrm.PD, blocks the transformation of these astrocytes into phagocytes.
While the dorsal and medial lobes of mushroom body γ neurons are largely pruned by 18 hours after pupal formation in controls, pruning of these axonal branches is strongly inhibited by astrocytic EcRB1-ΔC655.W650A.Scer\UAS expression.
Severing of the dendrites of ddaC neurons occurs in animals expressing EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4repo does occur, albeit with some delay. However, the glial membranes that wrap the proximal dendrites as part of this dendrite pruning process show very little sign of retraction or disintegration by 16 hours after puparium formation and the wrapped dendrite segments remain intact. This defect persist until the death of the neurons during metamorphosis.
Expression of EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4twi.PG results in embryos with arrested midgut morphogenesis (midgut constriction and folding is impeded), while tracheal development, head involution and dorsal closure are unaffected.
Expression of EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4btl.PS at 20[o]C results in embryos with bloated dorsal tracheal trunks. If the temperature is raised to 29[o]C at the time of the 20-hydroxy-ecdysone pulse, the phenotype is more severe, with impaired tracheal branch growth.
Embryos expressing EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL469B show incomplete head involution and dorsal closure, as well as a reduced head skeleton and denticle belts.
Neuroblasts are found 24hr after puparium formation in 18 out of 101 MARCM clones expressing EcRB1-ΔC655.W650A.Scer\UAS, in contrast to controls which show no neuroblasts at this stage.
Motorneuron clones of a laterally located lineage (identified as lineage 15) expressing EcRB1-ΔC655.W650A.Scer\UAS show abnormally clumped and reduced dendritic arbors that leave large spaces devoid of dendrites. The axons of these clones generally show missing arbors in the adult femur and tibia, misaligned and clumped neuromuscular junctions, and about half the number of femoral endplates of controls. In all seven clones examined, proximal femoral branches were clumped or misaligned showing a star-shaped morphology projecting away from the primary tract. In approximately half the clones examined, the distal femoral arbors are completely missing, but of those still present most are misaligned. In a second, more medially located neuroblast clone (identified as lineage 7), similar phenotypes are seen with clumping and severe reduction in the extent of the dendritic arbor.
In the larval first thoracic neuromere, 9 of 11 clones of the neuroblast lineage identified as lineage 7, expressing EcRB1-ΔC655.W650A.Scer\UAS, the ipsilateral arbors of the secondary projections clump together to produce dense strands interspersed with areas containing no bundles. The midline crossing primary bundle also defasciculated in five out of the 11 clones, and the contralateral arbor shows clumping. Lineage 7 neuroblast clones of the larval third thoracic neuromere overexpressing EcRB1-ΔC655.W650A.Scer\UAS shows some abnormal fasciculation of ipsilateral and contralateral arbors.
Of five clones of lineage 6 neuroblast in the first or the third larval thoracic neuromere, expressing EcRB1-ΔC655.W650A.Scer\UAS, one had a clumped ipsilateral arbor, and two showed dorsal projecting neurons with both reduced and clumped ipsilateral arbors.
Three of four dorsally located lineage 18 neuroblast clones expressing EcRB1-ΔC655.W650A.Scer\UAS show a reduced ipsilateral arbor, with two of these showing clumping together of the terminal branching.
Seven of fourteen clones of lineage 9 neuroblast clones expressing expressing EcRB1-ΔC655.W650A.Scer\UAS show defasciculation of the primary bundle as it curves ventrally around the leg neuropil, compared to one out of six control clones.
Expression of EcRB1-ΔC655.W650A.Scer\UAS in ddaC neurons under the control of Scer\GAL4109(2)80 restricts ddaC dendritic pruning resulting in excess primary and secondary dendrites remaining attached to soma at 18h APF.
There is no sign of microtubule disruption in the dendrites of ddaC neurons at 6 hours after puparium formation (APF) in animals expressing EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4ppk.PG (microtubules in the dendrites of wild-type ddaC neurons show breakage at this stage).
Scer\GAL4da.G32-mediated expression of EcRB1-ΔC655.W650A.Scer\UAS results in a mild persistent amnioserosa phenotype. Development of the midgut is also inhibited, but a coherent amnioserosa tissue is evident in innervated and contractile embryos, suggesting amnioserosa degeneration is indeed delayed.
Expression of EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4da.Switch.PT in the presence of 1μg ml[-1] RU486 in male flies results in a 10% increase in the median lifespan compared to controls. Higher levels of EcRB1-ΔC655.W650A.Scer\UAS expression (using increasing concentrations of RU486) abolish this positive effect and even result in a decrease in median lifespan (14% decreased compared to controls at a concentration of 50μg ml[-1] RU486).
Expression of EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4da.Switch.PT in the presence of RU486 in female flies decreases lifespan in a RU486 dose-dependent manner.
Expression of EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4ppk.1.9 results in a significant reduction in the mean density of the dendrites of the ddaC dendritic arborisation neurons compared to controls. The higher order dendritic branches are primarily affected.
Thoracic ventral neurosecretory cells that express EcRB1-ΔC655.W650A.Scer\UAS under the control of Scer\GAL4Fmrf.PS are of normal size and larval morphology at the start of metamorphosis. However, these mutants show defective neuronal remodelling during metamorphosis. The axons show much lower levels of pruning compared to wild-type cells and show no filopodia during the pruning phase. Scer\GAL4Fmrf.PS>EcRB1-ΔC655.W650A.Scer\UAS neurons fail to extend filopodia during the outgrowth phase. The rare filopodial-like structures that form are very short, stubby and less active than those seen on control cells. Effects on adult axon outgrowth are severe, with arbors significantly reduced in size.
When expression is governed by Scer\GAL4Lsp2.PH in the larval fat body early autophagosomal structures are able to form but do not acidify, perhaps due to a failure to fuse with lysosomes. At the wandering third instar stage the cytoplasm lacks the usual autophagosomes and large 2-5 micron autolysosomes, and instead contain many small structures - probably autolysosome related. Autophagic area is markedly reduced. Autophagy has been inhibited. In clones, smaller and fewer acidic structures are evident than in wild type, and fat droplets appear distinct.