Mapping QTL for ocular component dimensions in chicken

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The eye requires exquisite co-ordination of the growth of its component parts to function as an effective optical system. Empirical evidence has shown that ocular component dimensions are under both genetic and environmental control. Two quantitative trait loci (QTL) for eye weight have been mapped in mouse. We propose to extend this work by identifying QTL for the following ocular component dimensions: radius of corneal curvature, anterior chamber depth, lens thickness and vitreous chamber depth. We will use the chicken as a model: chicks have large eyes that facilitate accurate phenotypic measurements, the chicken genome project is nearing completion, and excellent QTL-mapping resources exist for the chicken. In a preliminary study, we found that ocular component dimensions differed markedly between chicks of two different, well-characterised strains (a broiler line and a layer line, respectively). One of the applicants has successfully mapped QTL for body weight from a cross between these two strains. Keratometry, high-resolution A-scan ultrasonography, and eye weight measurements will be carried out on F8 chicks from a broiler x layer advanced intercross line (AIL). DNA samples from these chicks will be genotyped for a panel of 600 informative SNP markers spanning the chicken genome. QTL controlling each trait will be identified using established statistical methods. Fine-mapping of 2-4 of the QTL will be accomplished by genotyping additional markers in regions of interest. As well as providing fundamental insight into the regulation of ocular development, the QTL identified will be targets for modulating eye growth to prevent the progression of refractive errors. Joint with BB/C514482/1