Identification of Potential Disease Biomarkers in the Ovaries of Dolang Sheep from Xinjiang using Transcriptomics and Bioinformatics Approaches

Background: The Dolang sheep is a well-known indigenous breed from the Xinjiang region of China. The most important characteristics of these sheep are a year-round estrus and a strong resistance to a variety of diseases. Although the molecular regulatory mechanisms governing the year-round estrus and adaptability in health and disease are well studied in various animals, the related information is limited for sheep, particularly, the Dolang variety. Methods: To identify differentially expressed genes (DEGs) that might be responsible for the year-round estrus and that are expressed under different physiological conditions in Dolang sheep, samples from ovaries collected at different reproductive periods were analyzed using high-throughput sequencing and subsequent transcriptomics and bioinformatics analyses. Result: We identified 28,717 expressed genes by RNA-Seq analysis and from a list of 987 candidate genes, we identified 308 that were differentially expressed in the ovaries of non-pregnant Dolang sheep in estrus and anestrus phases and those in the gestation phase. The genes DQA, DQB and LOC101106374 were upregulated during the gestation period. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that these three genes may improve immunity and prevent the occurrence of abortion, brucellosis, toxoplasmosis and globidiosis and can be used to monitor sheep health during pregnancy. Thus, DQA, DQB and LOC101106374 may serve as potential biomarkers for monitoring disease progression as well as abortion risk during pregnancy in sheep.