A Systems-Genetics Analysis of Bovine Skeletal Muscle Iron Level

Beef is a nutrient-rich food source.  Therefore, we sought to identify genetic mechanisms that control nutrient content of beef. To determine the genetic architecture of the nutrient content of skeletal muscle, we performed whole genome association analyses utilizing data collected on 268 traits from 2285 head of Angus-sired cattle.  Significant amounts of genetic variation could be accounted for, for almost all of the nutrients analysed.  To investigate the transcriptional control of skeletal muscle iron, we used RNA-seq to contrast mRNA levels in five high and five low (N=10) Longissimus dorsi samples. Differential expression and wiring were detected.  Additional pathway analyses identified potential novel regulatory mechanisms. For example, interestingly, our initial results indicate that many of the same genes involved in human hemochromatosis may also regulate bovine skeletal muscle total iron content. However, many other regions of the genome contain no obvious candidate genes. Furthermore, genome-resequencing and variant detection from RNA-seq data are being used to identify potential causal variants.  The results from this project highlight the potential to use beef cattle as a model organism to elucidate genetic mechanism controlling tissue iron content.