Genetics of Global Gene Expression Patterns and Gene Networks Affecting Muscling in Sheep

The Sheep Genomics research program in Australia has undertaken a range of investigations to identify genes and DNA markers contributing to increase in size and altered distribution of muscling in sheep breeds (Oddy et al. 2007). The main objectives of this study were: (i) to discover key genes and pathways underlying muscling traits by expression profiling of skeletal muscle from sheep born to industry sires with high and low genetic merit (Estimated Breeding Values or EBVs) for eye muscle depth (EMD), and analysing the resulting expression data by advanced bioinformatics / systems genetics approaches, and; (ii) to link high throughput genetic information on these animals (single nucleotide polymorphisms or SNPs) with gene expression profiles of highly differentially expressed genes and highly connected regulatory (hub) genes identified in the first objective. With these approaches, we can generate a comprehensive understanding of the molecular mechanisms underpinning muscle hypertrophy phenotypes in sheep and identify potential candidate genes that can be used in breeding programs to improve meat quantity.