nej^EP1179/nej^TA57 or nej^EP1149/nej^TA57 transheterozygotes are semi-viable as third instar larvae. These larvae are developmentally delayed by approximately 1 day and are sluggish. nej^EP1179/nej^TA57 larvae show an approximately 50% decrease in quantal content without any change in quantal size at the neuromuscular junction. No change in the average muscle resting potential or in the average muscle input resistance is seen. There is a significant (although moderate) increase in the number of boutons at the neuromuscular junction of muscles 4, 6 and 7 compared to wild type in nej^TA57/nej^EP1179 or nej^TA57/nej^EP1149 larvae. No alteration in axon guidance in the embryonic central nervous system is seen.

Transheterozygotes of nej^Q7 with nej^TA57 die in the embryonic stages. Embryonic cuticles of nej^TA57/nej^Q7 or nej^Q7/Y show maxillary and antennal sense organs often have a slight pattern deformation, mouth hooks and median tooth are reduced and the proventriculus is sclerotinized.