Syt1^AD4 homozygotes are partially lethal and the rate of their lethality is further increased by Scer\GAL4^elav.PU-driven expression of Syt1^P-L.Scer\UAS.

Syt1^AD4 heterozygotes expressing Syt1^P-L.Scer\UAS (with Scer\GAL4^elav.PU) have reduced adult lifespan (compared to flies expressing Syt1^Scer\UAS.cSb), at third instar larval stage the neural transmission at neuromuscular junction is impaired: the excitatory junction potential (EJP) amplitude is decreased but the amplitude as well as frequency of miniature EJP is unaffected as is the size of readily releasable pool of synaptic vesicles. However, the Syt1^P-L.Scer\UAS-expressing larvae also display significant decrease in the Ca[2+] affinity of release and larger paired pulse ratio, indicating a reduction in release probability, following either 10Hz or 50Hz train stimulation for 2sec, a significant decrease in synaptic depression is observed relative to controls but when a single stimulus is applied again 1 minute after the end of the stimulus train this effect is no longer evident. Syt1^AD4,Scer\GAL4^elav.PU/+;Syt1^P-L.Scer\UAS adults show reduced locomotor activity compared to age- and sex-matched controls but the circadian pattern of their activity is comparable to the Syt1^Scer\UAS.cSb-expressing controls, the mutants also show faster rate of muscle fatigue (measured in a modified climbing assay).