Homozygous and VAChT1/VAChT2 larvae are inactive. Approximately 65% of homozygotes die as first instar larvae and 35% die as second instar larvae. Short-latency responses to a single stimulation of the giant fiber are observed in the dorsal longitudinal muscle (DLM) and tergotrochanteral muscle (TTM) of heterozygous flies. The refractory periods are not significantly different from wild type. After a high-frequency tetanic stimulation before the test stimulus, the response of the TTM remains intact but the none or only a few responses are detected in the DLM of heterozygous flies.
VAChT2/Df(3R)Cha5 has lethal phenotype, non-suppressible by ChATm7.4