UASt regulatory sequences drive expression of Csp coding sequences where residues 17-82 are deleted, including the 'J-domain'.

Scer\GAL4^elav-C155-driven expression of Csp^ΔJ.Scer\UAS fails to suppress the temperature-sensitive lethality of Csp^R1 mutants at 25[o]C. Indeed, expression actually enhances the temperature-sensitive lethality of Csp^R1 mutants. Whereas Csp^R1 mutants are fully viable at 18[o]C, only 11% of Csp^R1 mutants expressing Csp^ΔJ.Scer\UAS survive till adulthood.

Expression of Csp^ΔJ.Scer\UAS (under the control of Scer\GAL4^D42) restores the thermo-tolerance of evoked release at Csp^R1 mutant neuromuscular junctions. No difference is observed in spontaneous quantal release compared to controls. Neither mEJP frequency nor mEJP amplitude are significantly different between 22[o]C and 32[o]C in Csp^R1 mutants expressing Csp^ΔJ.Scer\UAS (under the control of Scer\GAL4^D42).

Expression of Csp^ΔJ.Scer\UAS at Csp^R1 mutant neuromuscular junctions (under the control of Scer\GAL4^D42) has little effect on the abnormally increased frequency of asynchronous release shortly after the evoked EJP.

Motor neuron expression of Csp^ΔJ.Scer\UAS (under the control of Scer\GAL4^D42) has no significant effect on the elevated intraterminal '[Ca[2+]'] of Csp^R1 mutant neuromuscular junctions.

Presynaptic expression of Csp^ΔJ.Scer\UAS, under the control of Scer\GAL4^elav-C155 in Csp^R1 mutants rescues the loss of synaptic boutons, increasing their number to approximately 74% of wild-type levels.

Expression of Csp^ΔJ.Scer\UAS in Csp^R1 mutant motor terminals (under the control of Scer\GAL4^D42) has no significant effect on '[Ca[2+]'] levels before, during, and after stimulation at 20 and 30[o]C.

Expression of Csp^ΔJ.Scer\UAS in motor neurons (under the control of Scer\GAL4^D42) has no significant effect on Ca[2+] levels in Csp^R1 mutant motor terminals before, during, and after stimulation at 20 and 30[o]C.

Expression of Csp^ΔJ.Scer\UAS at Csp^R1 mutant neuromuscular junctions (under the control of Scer\GAL4^D42), restores the thermo-tolerance of release: at 32[o]C, the average EJP amplitude is slight reduced by 9% but is not significantly different to wild-type controls. Neither mEJP frequency nor mEJP amplitude is significantly different between the groups at 22 or 32[o]C.

Expression of Csp^ΔJ.Scer\UAS in motor neurons under the control of Scer\GAL4^D42 increases EJP amplitudes at Csp^R1 mutant neuromuscular junctions to 74% of control amplitudes at 22[o]C. However, normal function is not restored as the amplitudes of EJPs resulting from Csp^ΔJ.Scer\UAS expression are significantly different to wild-type controls.