Homozygotes die throughout larval and pupal development with 5-10% surviving until adulthood. Two electrode voltage clamp analysis of third instar larval muscle 6 nmjs shows a strong reduction in sEJC amplitude, and a large decrease in sEJC frequency. Although presynaptic morphology at the end of embryogenesis is normal, by the third larval instar presynaptic morphology is severely disrupted. Total nmj area is reduced by approximately one half, and the number of boutons is reduced to one third.