UBC Theses and Dissertations
Comparison of gene expression levels in embryo, endometrium and corpus luteum of dairy heifers and lactating dairy cows and manipulation of endometrial gene expression in-vitro Thavaneetharajah, Pretheeban
Fertility in high producing dairy cows has declined over the past sixty years. Even though, fertility has dropped in lactating dairy cows it remained high in dairy heifers. There is increasing evidence to suspect that embryo quality, corpus luteum (CL) function and endometrial environment are major factors affecting fertility in lactating dairy cows. The main objective of this study was to compare the quality of the embryo, endometrium and CL by examining selected genes at mRNA and/or protein levels between dairy heifers and lactating dairy cows. In embryos, interferon tau (IFNτ) and heat shock protein 70 (HSPA1A) were highly expressed in heifers compared to lactating dairy cows. Also, differences were observed in the expression levels of glucose transporter 5 (GLUT5) and sodium-potassium adenosine triphosphatase (Na/K-ATPase) between grade 1 and 2 embryos of lactating dairy cows. The CL studies revealed better maintenance, angiogenesis and steroidogenesis in terms of mRNA expression levels (interleukin 1 alpha: IL1A, insulin like growth factor 1: IGF1, fibroblast growth factor 2: FGF2, vascular endothelial growth factor: VEGF, b-cell lymphoma 2: BCL2 and 3-beta-hydroxy steroid dehydrogenase: 3βHSD) in the CL of heifers than lactating dairy cows. Endometrium of lactating dairy cows and heifers showed differences in the expression of candidate genes (BCL2, HSPA1A, IGF1, FGF2, IL1A, tumor necrosis factor alpha: TNF, and serpin peptidase inhibitor, clade A member 14: SERPINA14) on day 11 of the estrous cycle with more expression in heifers than lactating dairy cows. We further studied the effect of recombinant bovine IFNτ (rbIFNτ) on mid luteal phase endometrium in-vitro to manipulate the expression levels of above endometrial genes. Expression levels of genes (IGF binding protein 3: IGFBP3, TNF, SERPINA14, FGF2, oxytocin receptor: OXTR) and prostaglandin F2 alpha: (PGF2α) levels in the media were inhibited at higher concentrations of rbIFNτ. Collectively, differences observed in the candidate gene expression levels of embryo, CL and endometrium between dairy heifers and lactating dairy cows suggest that they may regulate reduced fertility observed in lactating dairy cows. Additionally, treatment of endometrium with IFNτ may potentially regulate the luteal survival mechanism and endometrial function during mid luteal phase in bovines.
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