At room temperature, cacTS2 mutants have normal feeding, grooming, mating, activity levels, giant fiber electrophysiology and are not bang sensitive.
At room temperature, cacTS2 flies are seizure-resistant, with a higher seizure threshold (in response to high frequency stimulation) than wild type; at higher restrictive temperatures (38C), flies become seizure-sensitive (display spontaneous seizure-like dorsal longitudinal muscle activity) and display behavioural paralysis.
cacTS2 flies are paralysed rapidly at 38[o]C but exhibit only mild motor defects at 36[o]C.
Synaptic transmission is normal at the permissive temperature of 20[o]C, but a marked reduction in the excitatory postsynaptic current amplitude is seen at 36[o]C.
cacTS2 mutants are paralyzed at 38[o]c but resistant to paralysis at 36[o]C.
At 22[o]C, EJP amplitudes of cacTS2 are significantly reduced compared with controls.
cacTS2 larvae grown at 25[o]C exhibit reduced nerve-terminal morphology. There is no change at 22[o]C.
At 37[o]C, EJP amplitudes in cacTS2 mutants are significantly reduced compared to controls.
Heterozygous, homozygous and cacS/cacTS2 P1 stage pupae have a significantly increased heart rate and an increased strength of heart beat rhythmicity compared to controls.
In mutants exocytosis is decreased at non-permissive temperatures in presynaptic boutons (apparently not caused by a decrease in Ca2+ at the nonpermissive temperature). The evoked synaptic potentials (ESPs) in cytochalasin D-treated mutant preparations is reduced either at 1Hz or 10 Hz during incubation at 36oC for 20 minutes compared with that at 22oC, this is characteristic of a inhibition of exocytosis, but not endocytosis. No effect is seen on endocytosis at either permissive or non-permissive temperatures.
At 37oC, cacTS2 flies have severe motor defects. At 36oC, the flies are not paralysed. At 38oC, cacTS2 flies (reared at 20oC) paralyse, with a time for 50% paralysis of 0.28 +/- 0.04 minutes. cacTS2 flies reared at 23oC show paralysis at 38oC, with a time for 50% paralysis of 0.33 +/- 0.02 minutes. cacTS2/cacE(TS2)1 females (reared at 20oC) paralyse at 36oC, with a time for 50% paralysis of 0.31 +/- 0.03 minutes. At 38oC, cacTS2/cacsu(TS2)1 flies (reared at 20oC) show a time for 50% paralysis of 0.43 +/- 0.06 minutes. cacTS2/cacsu(TS2)2 flies reared at 23oC show paralysis at 38oC, with a time for 50% paralysis of 0.39 +/- 0.02 minutes. cacTS2 have a wild-type synaptic current at the dorsal longitudinal flight muscle neuromuscular synapse at 20oC, and a marked reduction in excitatory postsynaptic current amplitude at 36oC.
Intact cacTS2 males have a slightly lower than normal mating success. Mating success of cacTS2 males which have had their wings removed (compared to control flies with their wings removed) is more markedly impaired. Mutant males show higher than normal numbers of intrapulse cycles (CPP) among their song sounds. This mutant phenotype increases with increasing temperature. The pulse amplitudes are also heat sensitive, showing a steady increase as the temperature is raised. Intrapulse frequency tends to be lower than normal in mutant males. The interpulse interval (IPI) is significantly different from that of wild-type males at 30oC. Analysis of the average numbers of intrapulse cycles (CPP) per song bout of reasonable length indicates that at 30oC (but not at 20oC) mutant males generate song pulses containing larger than normal numbers of cycles. Mutant flies do not show defects in phototaxis. Room temperature ERG recordings from mutant flies appear normal looking with regard to the shapes of light-on transient spikes, light-coincident photoreceptor potentials, light-off transients and repolarisation times. At high temperature, repolarisation times are prolonged. Mutant males exposed to 29oC and then tested at 25oC are approximately 1/4 to 1/3 as active as wild-type flies. This locomotion defect is somewhat improved at 22-23oC. Mutant flies take longer to recover from mechanical shock than normal.
Homozygotes show rapid paralysis at 38oC. At 36oC, flies show spinning behaviour and a lack of coordination.
At 20oC, cacTS2 homozygotes show wild-type synaptic currents at the dorsal longitudinal flight muscle (DLM) neuromuscular synapses. Exposure to higher temperatures produces a marked reduction in the amplitude of the synaptic current compared to wild type. This phenotype is reversible, showing full recovery to wild type upon return to 20oC. The extent of the synaptic current reduction is dependent on temperature. A conditional reduction in the evoked synaptic current is also seen at the intracoxal lateral levator muscle synapse. Despite a marked reduction in the evoked synaptic current at 36oC, cacTS2 synapses show wild-type mEPSP amplitudes under the same conditions. Heterozygotes show wild-type synaptic currents at the DLM neuromuscular synapse at the restrictive temperature.
cacTS2 mutants show a conditional reduction in the excitatory postsynaptic current at neuromuscular synapses.