Differential expression of proteins in tibetan sheep ovary and relation to litter size traits at diff erent follicular development stages

Abstract

Reproductive performance of Tibetan sheep is the most important factor aff ecting the sheep industry"s production effi ciency in Qinghai-Tibet Plateau. To identify differences in lambing traits of Tibetan ewes and the ovarian proteome at different stages of follicular development during the reproductive cycle, the ovarian proteome of Tibetan sheep with clear lambing records and different litter sizes were screened and analyzed using label-free mass spectrometry. The results showed that of 2508 proteins detected, there were 57 differentially expressed proteins during the anestrus season, and compared with single ewes, in twin lambing ewes expression was up-regulated in 43 proteins and down-regulated in 14 proteins; 2664 proteins, with 69 differentially expressed proteins, were detected on the 1st day of the ewe estrus period. Expression of 39 proteins in twin ewes was up-regulated and down-regulated in 30 proteins when compared with single ewes; 2704 proteins and 96 differentially expressed proteins were detected in 11th day of the ewe estrus period. Expression of 16 proteins in twin ewes was up-regulated and expression of 80 proteins was down-regulated compared with single ewes. The pathways in twin sheep that were significantly up-regulated were oxidative phosphorylation (phagosome and endocytosis), oocyte meiosis, extracellular matrix receptor interaction, and cell adhesion. Th e amino acids (lysine, valine, leucine, isoleucine) and fatty acid degradation, TGF-β signal and GnRH signal pathways were significantly down-regulated in twin sheep. GDF9, BMPR-1B, MTHFR and Cu/Zn-SOD were relatively active in diff erent stages of follicular development during the reproductive cycle. This study contributes to the research of twin production in Tibetan sheep, the in-depth study of Tibetan sheep fertility, and promotes the development of animal husbandry in the Qinghai-Tibet Plateau.

Keywords

• tibetan sheep
• twin trait
• reproductive cycles
• follicular development
• label-free mass spectrometry