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Y. F. Leung, P. Ma, B. A. Link, J. E. Dowling; Genomic Analysis of Zebrafish Retinal and Retinal Pigment Epithelium Development. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2915.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate zebrafish retinal and retinal pigment epithelium (RPE) development by two tissue-specific expression profiling methodologies and to characterize the roles of the identified candidate genes during zebrafish eye development.
For the retinal development study, embryonic retinas at 36 and 52 hours post-fertilization (hpf) were microdissected from wild type (WT) zebrafish and homozygous young (yng) mutants in which retinal lamination is disrupted due to a point mutation in a brahma-related gene (brg1). Their gene expression levels were measured using Affymetrix Zebrafish arrays (Leung et al., ARVO 2006). For the RPE development study, retinas with RPE attached at 52hpf were dissected and the expression values measured by Affymetrix arrays. The RPE specific gene expression values were estimated by comparing the dissected tissues with retinas without RPE at 52hpf using statistical analyses.
Seven hundred thirty one genes were inferred to be significantly related to retinal differentiation. For example, a few cell cycle genes (cyclin E, cdc25 & cdc27) were over-expressed in yng, which may cause a cell-cycle withdrawal problem. Many genes related to neurite outgrowth (e.g. p35 & p39, neuronal specific activators of cdk5) were under-expressed in yng, and knock-down of these genes in developing embryos phenocopied the lamination problem. Several signal transduction pathways including delta-notch were found to be down-regulated in yng. In the RPE expression study, 8810 probesets were found to be significantly expressed in the RPE at 52hpf, of which 1443 might have biologically meaningful expression levels. Further, 78 and 988 probesets were found to be significantly over- or under-expressed in RPE respectively compared to retina. Also, 79.2% (38/48) of the known over-expressed probesets have been independently validated as RPE-related transcripts.
This study has identified key genetic pathways and biological processes that control retinal development and differentiation. The over-expressed genes in the RPE during early photoreceptor differentiation are likely to play an important role in photoreceptor development. Combining the data from the two expression profiling investigations will give a comprehensive view on the genetic controls of zebrafish eye development.
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