Flies expressing fh^{dsRNA.IR.Scer\UAS} in the glia under the control of Scer\GAL4^repo.PU display a clear motor impairment and increased brain vacuolization compared with controls.

Only 3% of Scer\GAL4^da.G32 fh^{dsRNA.IR.Scer\UAS} larvae form pupae before 160h after egg deposition, and these pupae do not become viable adults. The developmental timing defect, but not viability, is rescued by feeding with 20-hydroxy-ecdysone.

At 23[o]C, Scer\GAL4^phm.PU fh^{dsRNA.IR.Scer\UAS} larvae present delayed pupariation and 32% of larvae fail to pupariate - at 26[o]C, all larvae fail to pupariate and they become giant larvae. The pupariation defect is rescued by feeding with 20-hydroxy-ecdysone, but is not significantly rescued by feeding with 7-dehydrocholesterol.

Delayed pupariation is not observed when fh^{dsRNA.IR.Scer\UAS} is expressed using Scer\GAL4^drl.PU, Scer\GAL4^ppl.PP, Scer\GAL4^elav-C155 or Scer\GAL4^repo.

Flies expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^{Hand.ΔVM.Switch} throughout life (initiated by feeding flies RU486 during development and adulthood) show striking cardiac defects. These defects are already present in two day old flies and remain stable over the first two weeks. Limiting expression of fh^{dsRNA.IR.Scer\UAS} to the third instar larval stage (by transferring larvae to RU486-containing medium at this stage) also produces cardiac defects, but no heart phenotypes are observed when expression is limited to adult stages. Treatment with a synthetic superoxide dismutase and catalase mimetic, EUK8, does not suppress these phenotypes, and no improvement is seen with idebenone, either when treated during development or continuously throughout development and adulthood. Treatment with methylene blue (MB), either solely in development of continuously throughout development and adulthood, is able to suppress heart defects. Post-symptomatic treatment during the adult stages, from two days old, also results in suppression of heart defects in a concentration-dependent manner. Treatment with the MB derivative toluidine blue suppresses the phenotypes, but less strongly than MB. Four other MB derivatives, Neutral Red, 2-chlorophenothiazine, chlorpromazine and promethazine, had no effect.

Expression via P{GAL4-tim.E}27 (in the presence of Dcr-2^Scer\UAS.cDa) results in a prolonged period.

Expression of fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^repo.PU results in age-progressive accumulation of lipid droplets in adult brain glial cells, brain vacuolization, decreased climbing ability in adults as well as reduced adult lifespan and severely impaired adult survival under hyperoxia conditions compared to controls.

Expression of fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^da.G32 results in long-lived larvae of which only a few are able to pupate.

Expression of fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42 in segmental nerves does not result in any morphological differences to wild-type in the second to early third instar, but pathology becomes apparent in the distal nerve late in development. At late third instar the cross sectional area of the distal nerve decline to 72% of wild-type at segment A6 and further to 61% at A8. The structure of the ventral ganglion of these larvae is indistinguishable from wild-type until late third instar, when the cortical area declines to 62% of that in wild-type, and the number of motor cell bodies per section is reduced to 61%, from the mean of just above 80 to just under 50.

Expression of fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42 results in nerves with a significantly lower inner mitochondrial membrane potential. In cell bodies of the ventral ganglion, the membrane potential is 25% lower in those expressing fh^{dsRNA.IR.Scer\UAS} at second instar and declines further by late instar. Mitochondria throughout the length of fh^{dsRNA.IR.Scer\UAS} axons show lower mitochondrial membrane potential than wild-type, a difference that becomes more pronounced with both larval age and position along the nerve. The most extreme mitochondrial membrane potential phenotype is found in neuromuscular junctions.

Segmental nerves expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42 exhibit wild-type mitochondrial transport at the second instar stage but begin to show small defects in transport in the distal axons at early third instar, rising significantly at late third instar. Specifically, anterograde and retrograde flux, duty cycle, and velocity all decline significantly in axons expressing fh^{dsRNA.IR.Scer\UAS}. The velocities of anterograde- and retrograde-moving mitochondria are almost equally affected, dropping to 77% and 73% of wild-type respectively. However, flux and duty cycle are more profoundly affected in the retrograde direction: anterograde flux drops to 81% of wild-type while retrograde flux drops to 70%, and anterograde duty cycles drops to 83% of wild-type while retrograde duty cycle drops to 70%.

The total area of neuromuscular junctions in flies expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42 increases during development as in wild-type. However, the NMJ mitochondrial content increases significantly more than in wild-type (by late third instar), resulting in a 1.3-fold higher mitochondrial density in these NMJs compared to wild-type. Thus, by late third instar, expression of fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42, leads to an accumulation of excess mitochondria in neuromuscular junctions, many of which are partially or completely depolarized.

The density of Synaptic vesicles in the neuromuscular junctions of flies expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42 rises similarly through development in both wild-type and mutant larvae, but by late third instar the mutant neuromuscular junctions accumulate synaptic vesicles to a 1.3-fold excess over wild-type,

No change in the levels of mitochondrial Reactive Oxygen Species (ROS) detected in cell bodies of the ventral ganglion expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42, relative to wild-type, at any stage of development. However, at late third instar stage, cell bodies expressing fh^{dsRNA.IR.Scer\UAS} do respond to a 100υM antimycin A challenge with a 40% greater increase in Reactive Oxygen Species than in wild-type. This pattern also occurs in axonal mitochondria: fh^{dsRNA.IR.Scer\UAS} axons show no greater ROS levels than wild-type at any region or stage of development, but in response to antimycin A, they show a significantly greater increase in mitochondrial Reactive Oxygen Species than in wild-type in the middle axons at late third instar and in distal axons at early and late third instar. fh^{dsRNA.IR.Scer\UAS}-expressing neuromuscular junctions do not show an increase in ROS until late third instar, when they show a much greater response to antimycin A challenge, compared to wild-type controls.

In unperturbed preparations, wild-type and fh^{dsRNA.IR.Scer\UAS}-expressing flies (under the control of Scer\GAL4^D42) do not exhibit detectably different Reactive Oxygen Species (ROS) levels at any stage of development or region of the neurons, but an antimycin challenge elicits higher ROS levels in the cytoplasm of fh^{dsRNA.IR.Scer\UAS} cell bodies (170%), distal axons (175%) and neuromuscular junctions (160%) at late third instar only.

Larvae expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^da.G32 show retarded development and reduced viability, enduring an extended larval phase which can last as long as 45 days, resulting in some individuals being 2-fold larger than normal when they initiate pupation.

Less than 0.5% of animals expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^da.G32 at 25^oC survive to adulthood. Female escapers are five times more prevalent than males. The survival of these escaping adults is short but biphasic; by day 3, survival of females is reduced to 40-60%, but the remaining cohort of survivors persists with relatively low mortality for up to 40 more days.

Larvae expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^da.G32 show a striking sensitivity to elevated iron concentration in food compared to controls.

Expression of fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^bbg-C96 or Scer\GAL4^D42 has no detectable effect on pre-adult development. Eclosing adults expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^bbg-C96 show a 40% reduction in adult lifespan, whereas adults expressing fh^{dsRNA.IR.Scer\UAS} under the control of Scer\GAL4^D42 have a normal lifespan.

Scer\GAL4^repo.PU, fh^RNAi.UAS.cAa has abnormal locomotor behavior phenotype, suppressible by mfrn^GD336/Scer\GAL4^repo.PU

Scer\GAL4^repo.PU, fh^RNAi.UAS.cAa has abnormal oxidative stress response | adult stage phenotype, suppressible | partially by GLaz^UAS.cWa, Scer\GAL4^repo.PU

Scer\GAL4^repo.PU, fh^RNAi.UAS.cAa has short lived phenotype, suppressible | partially by GLaz^UAS.cWa, Scer\GAL4^repo.PU

Scer\GAL4^repo.PU, fh^RNAi.UAS.cAa has abnormal locomotor behavior phenotype, suppressible | partially by GLaz^UAS.cWa, Scer\GAL4^repo.PU

Scer\GAL4^da.G32, fh^RNAi.UAS.cAa has lethal phenotype, non-suppressible by Sod1^UAS.cAa/Scer\GAL4^da.G32

Scer\GAL4^da.G32, fh^RNAi.UAS.cAa has lethal phenotype, non-suppressible by Cat^UAS.cAa, Scer\GAL4^da.G32

Scer\GAL4^da.G32, fh^RNAi.UAS.cAa has lethal phenotype, non-suppressible by Sod2^UAS.cMa/Scer\GAL4^da.G32