Transcriptomic Study of Testicular Hypoxia Adaptation in Tibetan Sheep

The Tibetan sheep is a typical hypoxia-tolerant mammal, which lives on the plateau, at an altitude of between 2500 and 5000 m above sea level; the study of its hypoxic adaptation mechanism provides a reference for exploring the hypoxic adaptation mechanism of other animals. To grope for the genetic mechanism of adaptation to the hypoxic environment at the transcriptional level in Tibetan sheep testicular tissue, and to identify candidate genes and key pathways related to sheep adaptation, histological observation of testicular tissues from two sheep breeds was carried out using haematoxylin-eosin (HE) conventional staining. A total of 103 differentially expressed genes (DEGs) were authenticated in high altitude Tibetan sheep (ZYH) and low altitude Tibetan sheep (ZYM) by RNA sequencing technology (RNA-Seq), which included 50 up-regulated genes and 53 down-regulated genes. Functional analyses revealed several terms and pathways that were closely related to testis adaptation to the plateau. Several genes (including GGT5, AGTR2, EDN1, LPAR3, CYP2C19, IGFBP3, APOC3 and PKC1) were remarkably enriched in several pathways and terms, which may impact the Plateau adaptability of sheep by adjusting its reproductive activity and sexual maturation, and protecting Sertoli cells, various spermatocytes, and spermatogenesis processes. The results make a reasonable case for a better understanding of the molecular mechanisms of adaptation to altitude in sheep.