The evoked excitatory junctional potential amplitude at the Csp^X1/Csp^U1 mutant third larval instar neuromuscular junction is reduced compared to controls at 23^oC and severely reduced compared to controls at 30^oC.

Spontaneous central nervous system generated bursts of electrical activity can occur at nonpermissive temperatures (35^oC) in muscle 6 of mutant larvae. EJP amplitudes evoked by low-frequency nerve stimulation are reduced at room temperature (21^oC) in mutant larvae (compared to wild type) and are completely absent at 32^oC. High stimulation frequencies at the nonpermissive temperature can partially rescue the block in synaptic transmission. The ability of the central nervous system to generate motor rhythms at any temperature is compromised in mutant larvae. The motor rhythms are reduced in frequency in the mutants and the rate at which rhythm frequency changes with temperature is most affected in the mutant at low temperatures.

The EJP amplitudes recorded from mutant neuromuscular junctions (NMJs) are reduced to about 3/4 of control amplitudes.

Mutant neuromuscular junctions show facilitation of transmission as measured by EJC amplitude. Despite this, neurotransmitter release in mutants was significantly reduced after repetitive stimulation in 1mM Ca²⁺. High Ca²⁺ restores the loss of evoked release at mutant neuromuscular junctions. An aberrant time course of Ca²⁺ signal is observed at 34^oC. Ca²⁺ clearance after stimulation is deficient, and this effect is exacerbated at higher temperatures.

Homozygotes show electroretinogram defects at 18.5^oC; the on transient is generally smaller than in wild-type flies and impairment increases at high stimulus frequencies, and the off transient disappears entirely at high and intermediate luminance levels when the light pulse frequency is increased, but is less severely affected at low light intensities.

Homozygous males seem too feeble to show any sign of courtship behaviour. The courtship song parameter interpulse interval is normal in heterozygous males at 25^oC, but the number of cycles per pulse and amplitude of sound are significantly higher than in wild-type males at 25^oC, and the interpulse frequency is significantly lower than in wild-type males at 25^oC.

Black widow spider venom or calcimycin stimulate a dramatic increase in quantal release at homozygous larval neuromuscular junctions, which is similar to the response seen in wild-type larvae.

Nerve-impulse evoked transmitter release is completely lost in larval muscles at the restrictive temperature of 32^oC. This transmission block develops slowly (over 10-20 minutes) and is reversible with cooling to the permissive temperature. The toxin α-latrotoxin or the calcium ionophore ionomycin can trigger a sustained discharge of quanta at the neuromuscular junctions of Csp^X1 mutant larvae at the nonpermissive temperature.

At room temperature mutant larvae have sluggish movement. Nerve evoked excitatory junction potentials (EJPs) of larvae are reduced to half the level of wild type. EJP can be rescued to wild type levels by P{Csp12.3}. Mutation does not affect the number of calcium binding sites needed to release a single quantum so there must have been a change in the number or properties of the calcium channel/transmitter release assemblies that led to a reduction of quantal output in response to nerve stimulation. Action potential propagation and postsynaptic events in receptor function are unaffected at high temperatures, so cannot explain the temperature- dependent loss of EJPs. Evoked neuromuscular transmission is blocked at high temperatures (30^oC), the block is reversible when the temperature is reduced from 30^oC to 22^oC.

At 29^oC flies become paralysed and die. Semilethal embryonic phenotype, adult escapers die within 4-5 days, there are no adult escapers at 29^oC. At 29^oC mutant ERG shows loss of on-off transients, these are restored at lower temperatures.

Csp^X1 has axon | larval stage phenotype, enhanceable by Hsc70-4^Δ356

Csp^X1 has axon | larval stage phenotype, enhanceable by Hsc70-4^Δ11

Csp^X1 is an enhancer of axon | larval stage phenotype of Hsc70-4^Δ356

Csp^X1 is an enhancer of axon | larval stage phenotype of Hsc70-4^Δ11