Late stage embryos exhibit incomplete fasciculation of the intersegmental and segmental nerve bundles and the longitudinal tracts. Also nonneural forms of secretion are impaired, secretory defects are intermediate between Syx1A⁰⁶⁷³⁷ and Syx1A^Δ229. Syx1A^Δ6/Syx1A^15ts transheterozygotes produce progeny that exhibit reduced viability, rough eyes (disrupted ommatidial array, ommatidia may be missing, fused, improperly rotated or misaligned) and notching along the posterior margin of the wing. Clones cannot be recovered in the eye as lack of Syx1A activity in cells of the developing eye causes lethality.