Third instar larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4VGlut-OK371 show no significant increase in quantal content at the neuromuscular junction in the presence of the glutamate receptor antagonist philanthotoxin-433 (10μM), indicating a defect in synaptic homeostasis. In the absence of philanthotoxin-433, the larvae show a small increase in evoked excitatory postsynaptic potential (EPSP) amplitude, a small decrease in miniature mEPSP amplitude and a small increase in quantal content compared to controls.
Larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu fail to distinguish between 10mM NaCl and water in a taste assay, in contrast to wild-type larvae, which prefer 10mM NaCl. At high NaCl concentrations (500 and 1000mM), larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu reject NaCl, as do wild-type larvae. Larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4GH86 show defective salt-taste behaviour (a reduced preference for 10mM NaCl). Like wild-type larvae, larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu do not show a preference for 20mM mannitol versus water in a taste assay. Wild-type larvae prefer 10mM Kcl to water and to 10mM NaCl in a taste assay, but these preferences are disrupted in larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu. Larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu show similar responses to acid (pH3), butanol and propionic acid as wild-type larvae in a taste assay. Larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu show a normal preference for 500mM sucrose versus water in a taste assay. The terminal organ of larvae expressing ppk11DN.Scer\UAS under the control of Scer\GAL4elav.PLu shows a reduction in the frequency of action potentials produced in response to salt compared to wild type.
