Locus Affecting Retinal Lamination and Synaptic Formation in Danio Rerio

The structure and function of the eye is conserved across vertebrates. Mutagenesis screens of zebrafish have led to the discovery of many genes essential for retinal development and function. In one such screen, a recessive allele on the zvm9 locus was identified due to the lack of an optokinetic reflex in larvae of otherwise normal appearance. Preliminary histology indicated a lack of lamination in the zvm9 mutant retina and immunohistochemistry confirmed phenotypic defects in all layers of the retina. These included thin or absent plexiform layers, disorganization of cells within laminae, and the loss of specific retinal cell types. Additionally, cell death in both the retina and forebrain was identified by TUNEL. The presence of ectopic mitoses during retinal development and the later observation of ectopic cones suggests that the zvm9 product is a crucial component of a complex regulating cell-cell junctions or apical-basal polarity. The notable absence of synaptic structures in cone photoreceptors is consistent with my hypothesis that this complex is also required for proper cell-cell interactions.