Project description:Beef tenderness is a complex trait of economic importance for the beef industry. Understanding the genetic and epigenetic mechanisms underlying this trait may help improve the accuracy of breeding programs and deliver a better product quality to consumers. However, little is known about epigenetic effects in the muscle of Bos taurus and their implications in tenderness, and no studies have been conducted in Bos indicus. Therefore, we analyzed Reduced Representation Bisulfite Sequencing (RRBS) to search for differences in the methylation profile of Bos indicus skeletal muscle with extreme values for beef tenderness (tender = 6 animals, tough = 6 animals).
Project description:Satellite cells are myogenic precursor cells in adult skeletal muscle and play a crucial role in skeletal muscle repair, remodeling, and maintenance. Like myoblasts, satellite cells have the ability to proliferate, differentiate, and fuse to form multinucleated myofibers. In this study we aimed to identify the enhancers and the transcription factors binding to these enhancers that control gene expression in proliferating and differentiating bovine satellite cells. Using ChIP-seq, we identified 56,973 and 54,470 active enhancers, genomic regions marked with both H3K4me1 and H3K27ac, and 50,956 and 59,174 repressed enhancers, genomic regions marked with H3K27me3, in proliferating and differentiating bovine satellite cells, respectively. Motif enrichment analyses revealed many transcription factors including the AP-1 family transcription factors that regulate gene expression in proliferating bovine satellite cells and many transcription factors besides MyoG that regulate gene expression in differentiating bovine satellite cells.
Project description:BackgroundReference genomes are essential in the analysis of genomic data. As the cost of sequencing decreases, multiple reference genomes are being produced within species to alleviate problems such as low mapping accuracy and reference allele bias in variant calling that can be associated with the alignment of divergent samples to a single reference individual. The latest reference sequence adopted by the scientific community for the analysis of cattle data is ARS_UCD1.2, built from the DNA of a Hereford cow (Bos taurus taurus-B. taurus). A complementary genome assembly, UOA_Brahman_1, was recently built to represent the other cattle subspecies (Bos taurus indicus-B. indicus) from a Brahman cow haplotype to further support analysis of B. indicus data. In this study, we aligned the sequence data of 15 B. taurus and B. indicus breeds to each of these references.ResultsThe alignment of B. taurus individuals against UOA_Brahman_1 detected up to five million more single-nucleotide variants (SNVs) compared to that against ARS_UCD1.2. Similarly, the alignment of B. indicus individuals against ARS_UCD1.2 resulted in one and a half million more SNVs than that against UOA_Brahman_1. The number of SNVs with nearly fixed alternative alleles also increased in the alignments with cross-subspecies. Interestingly, the alignment of B. taurus cattle against UOA_Brahman_1 revealed regions with a smaller than expected number of counts of SNVs with nearly fixed alternative alleles. Since B. taurus introgression represents on average 10% of the genome of Brahman cattle, we suggest that these regions comprise taurine DNA as opposed to indicine DNA in the UOA_Brahman_1 reference genome. Principal component and admixture analyses using genotypes inferred from this region support these taurine-introgressed loci. Overall, the flagged taurine segments represent 13.7% of the UOA_Brahman_1 assembly. The genes located within these segments were previously reported to be under positive selection in Brahman cattle, and include functional candidate genes implicated in feed efficiency, development and immunity.ConclusionsWe report a list of taurine segments that are in the UOA_Brahman_1 assembly, which will be useful for the interpretation of interesting genomic features (e.g., signatures of selection, runs of homozygosity, increased mutation rate, etc.) that could appear in future re-sequencing analysis of indicine cattle.