| dc.description.abstract | The mammalian embryo must develop from a single cell (the oocyte fertilized by the sperm) to a multi-cellular fetal-placental unit. In particular, the conceptuses (embryo/fetus and associated placental membranes) of livestock species develop from a spherical structure into an elongated filamentous form. In order to achieve this significant increase in cellular growth and proliferation, the conceptus is entirely reliant upon the nutrients secreted from the uterine epithelia. It has been demonstrated that the secretion of these nutrients is regulated by progesterone (P4; the hormone of pregnancy) and/or interferon tau (IFNT; the signal for maternal recognition of pregnancy in ruminants). Of particular interest, agmatine and polyamines (putrescine, spermidine, and spermine) have important roles in the survival, growth, and development of mammalian conceptuses. The cationic polyamines are derived from arginine metabolism and bind anionic molecules to regulate DNA transcription, RNA translation, and protein expression. However, it is not known if P4 or IFNT regulate the endometrial mRNAs or proteins involved in polyamine biosynthesis or interconversion. While arginine and its products are important for embryonic growth, it is actually serine and glycine that are found in greater abundance in uterine flushings and fetal fluids of sheep. Both serine and glycine are utilized in one carbon (1C) metabolism, which is responsible for the production of formate required for synthesis of purines and thymidine for nucleic acid synthesis. This biochemical pathway is vital for mammalian conceptuses because the developing cells of the conceptus must increase the synthesis of nucleic acids to build DNA strands during cellular division. The findings from the studies described here revealed: 1) how P4 and IFNT work cooperatively and independently to affect expression of mRNAs and proteins involved in endometrial polyamine metabolism and transport during the peri-implantation period of pregnancy; and 2) the contributions of serine, glycine, glucose, and fructose for 1C metabolism by the ovine conceptus during the peri-implantation period of pregnancy. These novel findings are valuable in advancing our understanding of the importance of specific nutrients in the context of conceptus development during the peri-implantation period of pregnancy in sheep to ultimately improve pregnancy success in livestock species. | |
