Color Blindness Research Today is a free monthly online journal that collates and summarizes the latest research about Color Blindness, including details on causes, classification, red-green and blue-yellow color blindness, diagnosis. | ||||||||
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Identification of a zebrafish cone photoreceptor-specific promoter and genetic rescue of achromatopsia in the nof mutant.Kennedy BN, Alvarez Y, Brockerhoff SE, Stearns GW, Sapetto-Rebow B, Taylor MR, Hurley JB UCD Conway Institute and UCD School of Biomolecular and Biomedical Sciences, University College Dublin, Dublin, Ireland. brendan.kennedy@ucd.ie PURPOSE: To identify in vivo a promoter fragment that specifically directs transgene expression in all zebrafish cone photoreceptors. This promoter subsequently enables GFP labeling of cones for facile morphologic analysis and purification and genetic rescue of achromatopsia. METHODS: Promoter fragments of the zebrafish cone transducin alpha (TalphaC) gene were subcloned upstream of EGFP and microinjected into one- to two-cell-stage embryos. Promoter activity was assessed by fluorescence microscopy in wholemounts and retinal cryosections, and cone photoreceptors were purified by flow cytometry. Visual physiology was assessed by the optokinetic response (OKR) assay. RESULTS: A 3.2-kb promoter fragment from zebrafish TalphaC specifically directed robust transgene expression in retinal cone photoreceptors and pineal photoreceptors. With this promoter, a stable transgenic line expressing EGFP in all zebrafish cone photoreceptors types was generated, and populations of cones were purified. Achromatopsia in the nof mutant was rescued using the identified promoter fragment to direct transgenic expression of wild-type cone transducin in mutant cones. CONCLUSIONS: A 3.2-kb TalphaC promoter fragment replicates the temporal and spatial pattern of endogenous TalphaC expression. The integrity of cones can be readily assessed in an EGFP transgenic line generated with this promoter, enabling downstream genetic and chemical screens for cone determinants. Published 25 January 2007 in Invest Ophthalmol Vis Sci, 48(2): 522-9.
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