Genetic Analysis of Vision in Zebrafish.

Dr. Brockerhoff and her colleagues are screening for novel zebrafish mutants with defects in visual behavioral responses. The goal of this research is to identify genes required for normal cone photoreceptor function. The behavioral assay, the optokinetic response (OKR), measures the ability of zebrafish larvae to use their vision to track rotating stripes. Zebrafish are mutagenized and F3 fish are screened for recessive mutations that cause abnormal optokinetic behavior. The mutants are initially analyzed by electroretinography and histology to localize the defects. The mutant genes are cloned by positional cloning and candidate gene analysis. Several of the mutations that affect cone function have now been cloned by Dr. Brockerhoff and her colleagues.

The following is a partial list of mutants that have been characterized and cloned. In addition, there are several new OKR defective mutants that are ready to be characterized.

pob	red cone degeneration	novel protein
nrc	abnormal cone synaptic terminal	synaptic vesicle regulatory protein
noa	abnormal synaptic transmission and light adaptation	metabolic enzyme
nof	no phototransduction	cone transducin

Dr. Brockerhoff's group makes up a medium-sized zebrafish lab that combines a variety of methods (cellular, biochemical, molecular, genetic and electrophysiological) to analyze zebrafish mutants to enhance the understanding of cone photoreceptor function and viability.