Investigating the role of DCBLD2 in zebrafish visual system development and function

Our lab investigates the signaling pathways responsible for patterning the developing retina. As we uncover these pathways, we are always left wondering how the embryo can see with these retinal disruptions. An optokinetic response chamber is the most common method for quantitatively assessing the visual acuity of zebrafish (Danio rerio). For my summer research project, I built an effective and easy-to-use optokinetic response chamber used to observe eye movement in response to visual stimuli of the entire visual field. The chamber uses rotating black and white stripes as visual stimuli with varying cycles per degree (cpd), or thickness of the stripes. Zebrafish embryos will track the stripes, and their eyes will rotate in the socket to follow them. This response can be visualized and recorded easily from above. I have worked towards creating a comprehensive protocol for its use consisting of testing wild-type zebrafish embryos. Various factors have to be considered such as embryo age, light intensity, cpd, speed, and how the embryos are held in place. After various preliminary rounds of testing, I determined the best mode of testing to be the consistent use of a single cpd and increasing the rotations per minute until the visual tracking ceases. I am currently using this chamber to test zebrafish embryos lacking the orphan receptor DCBLD2. These mutants have normal retinas until 8 days postfertilization (dpf) where the back of the eye blows out and retinal neurons spill into the brain. I have not observed a significant difference in visual acuity between wildtype and mutant embryos at 4 and 5 dpf, however, I will continue to test older embryos up to when the phenotype becomes apparent at 8 dpf.