Characterization of Transcriptional Complexity during Adipose Tissue Development in Bovines of Different Ages and Sexes

BACKGROUND: Adipose tissue has long been recognized to play an extremely important role in development. In bovines, it not only serves a fundamental function but also plays a key role in the quality of beef and, consequently, has drawn much public attention. Age and sex are two key factors that affect the development of adipose tissue, and there has not yet been a global study detailing the effects of these two factors on expressional differences of adipose tissues. RESULTS: In this study, total RNA from the back fat of fetal bovines, adult bulls, adult heifers and adult steers were used to construct libraries for Illumina next-generation sequencing. We detected the expression levels of 12,233 genes, with over 3,000 differently expressed genes when comparing fetal and adult patterns and an average of 1000 differently expressed genes when comparing adult patterns. Multiple Gene Ontology terms and pathways were found to be significantly enriched for these differentially expressed genes. Of the 12,233 detected genes, a total of 4,753 genes (38.85%) underwent alternative splicing events, and over 50% were specifically expressed in each library. Over 4,000 novel transcript units were discovered for one library, whereas only approximately 30% were considered to have coding ability, which supplied a large amount of information for the lncRNA study. Additionally, we detected 56,564 (fetal bovine), 65,154 (adult bull), 78,061 (adult heifer) and 86,965 (adult steer) putative single nucleotide polymorphisms located in coding regions of the four pooled libraries. CONCLUSION: Here, we present, for the first time, a complete dataset involving the spatial and temporal transcriptome of bovine adipose tissue using RNA-seq. These data will facilitate the understanding of the effects of age and sex on the development of adipose tissue and supply essential information towards further studies on the genomes of beef cattle and other related mammals.