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K. Alvarez–Delfin, A.C. Morris, A. Millet, J.M. Fadool; Genetic Screening For Defects Of Photoreceptor Development And Patterning In Chemically Mutagenized Zebrafish . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4178.
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© ARVO (1962-2015); The Authors (2016-present)
The zebrafish (Danio rerio) has become a valuable model organism for the genetic analysis of patterning and development of the vertebrate embryo including the visual system. We have undertaken a large–scale genetics screen to identify mutations affecting the visual system of free–swimming larvae and adult zebrafish. In this study we have used the mosaic arrangement of the rod photoreceptors as a model to identify and characterize recessive mutations that alter retinal development.
Inbred larvae of chemically mutagenized zebrafish were provided by Drs. Mary Mullins and Michael Granato at the University of Pennsylvania. In our laboratory, the larvae were screened at 3–5 days post fertilization (dpf) to identify morphologic alterations in the eye. At 5 dpf, the larvae were fixed and immunolabeled with a rod–specific antibody to uncover recessive mutations that affect the rod pattern in the retina. The mutagenesis strategy incorporated a mapping panel to facilitate linkage analysis of the mutated loci.
In the initial screen of 300 genomes, we have identified numerous recessive mutations affecting the development and survival of the rod photoreceptors. An allele of laminin α–1 resulting in ectopic photoreceptors at the optic nerve was isolated. Interestingly we identified a locus (lots–of–rods; lor) that shows an increased number of rod photoreceptors in the retina compared with wildtype larvae without any other evidence of morphologic alterations. The frequency of the phenotype and complementation testing together suggest that the lor allele may have been present within the original zebrafish population.
This study demonstrates the utility of genetic screening to identify recessive mutations in the photoreceptor patterning in the zebrafish retina.
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