Homozygosity for nAChRα7[PΔEY6] causes a decrease in spontaneous excitatory post-synaptic current (sEPSC) frequency in primary cultures of neurons, isolated at the embryonic stage, at 5 or 9 days in vitro.
Mutant flies do not show increased resistance to the nAChRα6 agonist spinosad compared to wild type.
gfAPΔEY6 mutant vertical system neurons are still responsive to cholinergic input from columnar neurons.
gfAPΔEY6 flies perform no differently to wild-type flies in terms of flight, olfactory behavior, and in visual tests. However, in contrast to wild-type flies, these flies fail to jump in response to a lights-off stimulus.
gfAPΔEY6/+ flies have a defect in the jump circuit between the peripherally synapsing interneuron (PSI) branch of the giant fiber and the dorsal lateral muscle (DLM) motor neuron. This is demonstrated by intracellular recordings of DLMs following giant fiber stimulation; while the DLMs of wild-type flies can follow stimulation frequencies of up to 100 Hz, the majority of gfAPΔEY6 DLMs fail to show any response, even at 1 Hz. The defects are specific to the synapses between the PSI and DLM motor neurons as the tergotrochanteral muscles are able to follow the giant fiber stimulation at 100 Hz without any problem. This phenotype can also be seen in gfA1/gfAPΔEY6 transheterozygotes.
The tergotrochanteral muscle of gfAPΔEY6 flies responds to low-strength electrical stimulation, which activates the elements presynaptic to the giant fiber, which in turn activate the giant fiber, with the short-latency response seen in wild-type flies, but fails to show the long-latency response.
nAChRα7PΔEY6 is rescued by nAChRα7UAS.cMa/Scer\GAL4shot-OK307
nAChRα7PΔEY6 is partially rescued by nAChRα7D77T.L117Q.I196P.UAS/Scer\GAL4shot-OK307
nAChRα7PΔEY6 is partially rescued by nAChRα7D197A.UAS/Scer\GAL4shot-OK307
nAChRα7PΔEY6 is not rescued by nAChRα7Y195T.UAS/Scer\GAL4shot-OK307
Expression of gfAScer\UAS.cMa under the control of Scer\GAL4OK307 rescues the responses of the dorsal longitudinal muscle to stimulation of the giant fiber to wild type (the refractory period and maximum following frequency are normal).
Expression of gfAD77T.L117Q.I196P.Scer\UAS under the control of Scer\GAL4OK307 rescues an electrophysiological response of the dorsal longitudinal muscle (DLM) to stimulation of the giant fiber. However, the refractory period is nearly twice as long as in wild type. In addition, the DLMs are only able to follow 10 pulses given at 100Hz with 67.6% reliability and the maximum frequency to follow 10 stimuli (58 +/- 16 Hz) is reduced by almost half compared to wild type.
Expression of gfAD197A.Scer\UAS under the control of Scer\GAL4OK307 rescues an electrophysiological response of the dorsal longitudinal muscle (DLM) to stimulation of the giant fiber. However, the DLMs are only able to follow 10 pulses given at 100Hz with 17.3% reliability and the maximum frequency to follow 10 stimuli (13 +/- 7 Hz) is severely reduced compared to wild type.
Expression of gfAY195T.Scer\UAS under the control of Scer\GAL4OK307 fails to rescue an electrophysiological response of the dorsal longitudinal muscle to stimulation of the giant fiber.
Based on the extent of the jump circuit defect in gfA flies, the following alleles can be ranked from strongest to weakest as follows: gfAPΔ5 = gfAPΔEY6 > gfAPΔ41 > gfAPΔ14G.