Comparative RNA-Seq Transcriptome Analysis In The Epididymides Of Yak And Cattleyak

Cattleyak are the Fl hybrids between(♀)yak(Bos grunniens)and(♂)cattle(Bos taurus).The cattleyak are females fertile but males sterile.Cattleyak exhibit higher capability in adaptability to harsh environment and display much higher performances in production than the yak and cattle.All previous studies greatly focused on testes tissues to study the mech anism of male infertility in cattleyak.However,so far,no transcriptomic study has been conducted on the epididymides of yak and cattleyak.Our objective was to perform comparative transcriptome analysis between the epididymides of yak and cattleyak and predict the etiology of male infertility in cattleyak.We performed comparative transcriptome profiles analysis by m RNA sequencing in the epididymides of yak and cattleyak.In total 3008 di fferentially expressed genes(DEGs)were identified in which 1645 DEGs were up-regulated and 1363 DEGs were down-regulated in cattleyak.Thirteen DEGs were validated by quantitative real-time PCR.DEGs included certain genes that were associated with spermatozoal maturation,motility,male fertility,water and ion channe ls,and beta-defensins(LCN9,SPINT4,CES5 A,CD52,CST11,SERPINA1,CTSK,FABP4,CCR5,GRIA2,ENTPD3,LOC523530 and DEFB129,DEFB124,DEFB122 A,DEFB122,DEFB119)were all downregulated,whereas NRIP1 and TMEM212 among top 30 DEGs were upregulated.Furtherm ore,protein processing in endoplasmic reticulum pathway was ranked at top-listed three significantly enriched KEGG pathways,and all the DEGs enriched in this pathway were downregulated except NEF.That as a consequence of abnormal expression of ER-associated genes in the entire ER protein processing pathway might have been disrupted in male cattleyak which resulted in downregulation of several important genes.Taken together,our findings revealed that there were marked differences in the epididymal transcriptomic profiles of yak and cattleyak.The DEGs were involved in spermatozoal maturation,motility,male fertility,water and ion channels,and beta-defensins.However,abnormal expression of ER-associated genes in the entire protein processing in endopl asmic reticulum pathway might have been disrupted in male cattleyak that resulted in downregulation of several important genes involved in sperm maturation,motility,and defense.