Key Laboratory of Qinghai-Tibetan Plateau Animal Genetic Resource Reservation and Utilization, Sichuan Province and Ministry of Education, Southwest Minzu University, Chengdu, China.
School of Life Science and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan, China.
PLoS One. 2020 Feb 24;15(2):e0229503. doi: 10.1371/journal.pone.0229503. eCollection 2020.
Cattleyak are the hybrid offspring between cattle and yak and combine yak hardiness with cattle productivity. Much attempt has been made to examine the mechanisms of male sterility caused by spermatogenic arrest, but yet there is no research systematically and precisely elucidated testis gene expression profiling between cattleyak and yak.
To explore the higher resolution comparative transcriptome map between the testes of yak and cattleyak, and further analyze the mRNA expression dynamics of spermatogenic arrest in cattleyak. We characterized the comparative transcriptome profile from the testes of yak and cattleyak using high-throughput sequencing. Then we used quantitative analysis to validate several differentially expressed genes (DEGs) in testicular tissue and spermatogenic cells.
Testis transcriptome profiling identified 6477 DEGs (2919 upregulated and 3558 downregulated) between cattleyak and yak. Further analysis revealed that the marker genes and apoptosis regulatory genes for undifferentiated spermatogonia were upregulated, while the genes for differentiation maintenance were downregulated in cattleyak. A majority of DEGs associated with mitotic checkpoint, and cell cycle progression were downregulated in cattleyak during spermatogonial mitosis. Furthermore, almost all DEGs related to synaptonemal complex assembly, and meiotic progression presented no sign of expression in cattleyak. Even worse, dozens of genes involved in acrosome formation, and flagellar development were dominantly downregulated in cattleyak.
DEGs indicated that spermatogenic arrest of cattleyak may originate from the differentiation stage of spermatogonial stem cells and be aggravated during spermatogonial mitosis and spermatocyte meiosis, which contributes to the scarcely presented sperms in cattleyak.
犏牛是黄牛与牦牛的杂交后代，兼具牦牛的抗寒能力和黄牛的生产性能。人们已经尝试了很多方法来研究由精子发生阻滞引起的雄性不育的机制，但目前还没有系统和精确地研究犏牛和牦牛睾丸基因表达谱的相关研究。
为了探索牦牛和犏牛睾丸之间更精确的比较转录组图谱，并进一步分析犏牛精子发生阻滞的mRNA 表达动态，我们利用高通量测序技术对犏牛和牦牛睾丸的比较转录组图谱进行了特征描述。然后，我们使用定量分析方法验证了睾丸组织和精子发生细胞中几个差异表达基因（DEGs）。
睾丸转录组谱分析鉴定出 6477 个 DEGs（2919 个上调和 3558 个下调）在犏牛和牦牛之间存在差异表达。进一步分析表明，未分化精原细胞的标记基因和凋亡调控基因上调，而维持分化的基因下调。在犏牛的精原细胞有丝分裂过程中，大多数与有丝分裂检查点和细胞周期进展相关的 DEGs 下调。此外，与联会复合体组装和减数分裂进展相关的几乎所有 DEGs 在犏牛中都没有表达迹象。更糟糕的是，数十个参与顶体形成和鞭毛发育的基因在犏牛中明显下调。
DEGs 表明，犏牛的精子发生阻滞可能起源于精原干细胞的分化阶段，并在精原细胞有丝分裂和精母细胞减数分裂过程中加重，这导致犏牛中精子的数量很少。
