Pectoral muscle transcriptome analyses reveal high-altitude adaptations in Tibetan chickens

The largest muscles in fowl are the pectorals, which provide the power required for birds to fly. Tibetan chickens show specific adaptations to high-altitude conditions, but changes in the muscle transcriptome associated with these adaptations have not been characterized yet. Therefore, in this study, we used next-generation sequencing technologies to generate eight libraries of mRNA sequences for four Tibetan chickens and four Beijing fatty chickens. A comprehensive transcriptome analysis was performed. In the eight samples, 12 333 annotated protein-coding genes were expressed. Among these, 48 differentially expressed genes were found; all of which were upregulated in Tibetan chickens. These differentially expressed genes were mainly involved in kidney morphogenesis, which indicates that hypoxia has an important effect on renal tubule development. Only nine genes were involved in Kyoto Encyclopedia of Genes and Genomes pathways, such as the endocytosis pathway, the MAPK signaling pathway, the calcium signaling pathway and the TGF-beta signaling pathway. The differentially expressed genes identified in this study will be used to facilitate future research into the Tibetan chicken.