Abstract
Culture systems promote development at rates lower than the in vivo environment. Here, we evaluated the embryo's transcriptome to determine what the embryo needs during development. A previous mRNA sequencing endeavour found upregulation of solute carrier family 7 (cationic amino acid transporter, y+ system), member 1 (SLC7A1), an arginine transporter, in in vitro- compared with in vivo-cultured embryos. In the present study, we added different concentrations of arginine to our culture medium to meet the needs of the porcine embryo. Increasing arginine from 0.12 to 1.69mM improved the number of embryos that developed to the blastocyst stage. These blastocysts also had more total nuclei compared with controls and, specifically, more trophectoderm nuclei. Embryos cultured in 1.69mM arginine had lower SLC7A1 levels and a higher abundance of messages involved with glycolysis (hexokinase 1, hexokinase 2 and glutamic pyruvate transaminase (alanine aminotransferase) 2) and decreased expression of genes involved with blocking the tricarboxylic acid cycle (pyruvate dehydrogenase kinase, isozyme 1) and the pentose phosphate pathway (transaldolase 1). Expression of the protein arginine methyltransferase (PRMT) genes PRMT1, PRMT3 and PRMT5 throughout development was not affected by arginine. However, the dimethylarginine dimethylaminohydrolase 1 (DDAH1) and DDAH2 message was found to be differentially regulated through development, and the DDAH2 protein was localised to the nuclei of blastocysts. Arginine has a positive effect on preimplantation development and may be affecting the nitric oxide-DDAH-PRMT axis.