Gap junction proteins expressed during development are required for adult neural function in the Drosophila optic lamina.

We provide evidence that gap junction proteins, expressed during development, are necessary for the formation of normally functioning connections in the Drosophila optic lamina. Flies with mutations in the gap junction genes (innexins), shakingB, and ogre have normal photoreceptor potentials but a defective response of the postsynaptic cells in the optic lamina. This is indicated by a reduction in, or absence of, transients in the electroretinogram. Ogre is required in the presynaptic retinal photoreceptors. ShakingB(N) is, at a minimum, required in postsynaptic lamina neurons. Transgenic expression of the appropriate innexins during pupal development (but not later) rescues connection defects. Transient gap junctions have been observed to precede chemical synapse formation and have been hypothesized to play a role in connectivity and synaptogenesis; however, no causal role has been demonstrated. Here we show that developmental gap junction genes can be required for normally functioning neural connections to form.