Third instar larvae expressing ShalDN.Scer\UAS.T:Ivir\HA1 pan-neuronally under the control of Scer\GAL4elav.PU exhibit learning defects in odor-association learning assays. Learning defects are also seen when ShalDN.Scer\UAS.T:Ivir\HA1 is specifically expressed in mushroom body neurons under the control of Scer\GAL4Tab2-201Y. Naive preference for fructose and odors and chemotaxis towards known attractants are similar to controls.
Flies expressing ShalDN.Scer\UAS.T:Ivir\HA1 pan-neuronally throughout development under the control of Scer\GAL4elav.PU are short lived. A reduction in lifespan is also seen when expression of ShalDN.Scer\UAS.T:Ivir\HA1 expression is restricted to the adult stages only (by expressing Scer\GAL80ts.αTub84B and shifting to the restrictive temperature at eclosion).
Expression of ShalDN.Scer\UAS.T:Ivir\HA1 under the control of Scer\GAL4eve.RRa blocks Shal K[+] function. However, mEPSC amplitudes increase after curare treatment as in wild-type motor neurons. Synaptic potentials are not stabilised as they are in wild-type motor neurons. mEPSP amplitudes are significantly larger after synaptic inhibition in the absence of Shal function, indicating that Shal channels are indeed required for stabilising synaptic potentials.
The I[[A]] current is completely abolished in embryonic neurons in culture derived from animals expressing ShalDN.Scer\UAS.T:Ivir\HA1 under the control of Scer\GAL4elav.PU. No compensatory current is expressed in these neurons: no transient A-type current is seen and there are no differences between the delayed rectifier currents of the mutant and wild-type cultured neurons. The mutant cultured neurons have much broader action potentials with little to no afterhyperpolarisations, compared to wild type. The mutant neurons have a decreased latency to action potential firing and have a lower threshold for inducing repetitive firing compared to wild type. During prolonged current injections, the first action potential in the mutant neurons consistently has a larger amplitude, and the interspike interval between the first and second action potential of the mutant neurons is reduced compared to wild type. After firing one or two initial action potentials in response to a 500ms stimulus, the subsequent depolarising peaks have decreasing amplitude in the mutant neurons, in contrast to wild-type neurons which fire repeatedly with no decrease in action potential size.
The I[[A]] current is completely abolished in embryonic motoneurons in culture derived from animals expressing ShalDN.Scer\UAS.T:Ivir\HA1 under the control of Scer\GAL4eve.RRa. The delayed rectifier current is unaffected in these neurons. Repetitive firing in the mutant neurons is induced with a lower current stimulus than wild-type motoneurons. The mutant motoneurons show a loss of excitability during prolonged stimuli.
Larvae expressing ShalDN.Scer\UAS.T:Ivir\HA1 under the control of either Scer\GAL4C164, Scer\GAL4109(2)80 or Scer\GAL4elav.PU crawl at a significantly lower speed than normal.
Adults expressing ShalDN.Scer\UAS.T:Ivir\HA1 under the control of either Scer\GAL4C164 or Scer\GAL4elav.PU have reduced climbing ability compared to controls.
Adults expressing ShalDN.Scer\UAS.T:Ivir\HA1 under the control of Scer\GAL4elav.PU show defects in grooming.
Expression of ShalDN.UAS.Tag:HA under the control of Scer\GAL4NP6024, significantly reduces reaction times of FoxP5-SZ-3955 mutant adult males discriminating between different concentrations of an odor, with no effect on accuracy, compared to controls.
