Methionine Requirements for the Preimplantation Bovine Embryo

Abstract

Abstract. The early embryo's nutritional environment plays an important role in establishing its developmental potential. However, little is known about the specific nutrient requirements of the embryo. The objective of the present study was to determine requirements of the in vitro produced bovine embryo for the essential amino acid methionine. In addition to serving as a precursor for polypeptides, methionine plays roles in regulation of translation, DNA methylation, and antioxidant balance. In the first experiment, embryos were cultured in potassium simplex optimized medium -bovine embryo modification 2 containing 0, 35, 50, 100, 200 or 400 μmol/l L-methionine for 8 days. There was no effect of methionine concentration on cleavage rate. The percent of oocytes that developed to blastocyst was lower for embryos without methionine at Day 7 and 8 than other groups but was similar for embryos cultured with 35-400 μmol/l. Neither total cell number, allocation of cells to trophectoderm or inner cell mass, or frequency of apoptosis was affected by methionine concentration. In the second experiment, embryos were cultured with 0, 7, 14, 21, 28 or 35 μmol/ l methionine. There was no effect of methionine concentration on cleavage rate. The percent of oocytes that developed to blastocyst was lower for embryos without methionine at Day 7 and 8 but was not different between embryos cultured with 7-35 μmol/l methionine. However, the proportion of blastocysts that were expanded, hatching or hatched on Day 7 was reduced at lower concentrations of methionine (7 and 14). DNA methylation of blastocyst nuclei was unaffected by methionine concentration but intracellular glutathione content was higher for embryos cultured without methionine.In conclusion, the methionine requirement for preimplantation development is between 14 and 21 μmol/l. These concentrations are lower or similar to those found in the reproductive tract and suggest that methionine deficiency is not a common cause of embryonic mortality.

Association between methylation potential and nutrient metabolism throughout the reproductive cycle of sows

“…The high conversion rate of SAM into SAH suggests a high level of methylation reactions in this period. Since SAM is derived from methionine (Bonilla, Luchini, Devillard, & Hansen, ), it seems logical that in our study methionine and SAM and SAH were positively correlated. Despite the high conversion rate of SAM into SAH, enough methionine seemed to be available for the production of SAM, because a distinct increase in plasma methionine was noted as well.…”

Importance of Methionine Metabolism in Morula-to-blastocyst Transition in Bovine Preimplantation Embryos

“…SAM is also known to affect the activity of Na/K-ATPase [37,38]. Thus, we cannot exclude the possibility that methionine, through the conversion to SAM, regulates Na/K-ATPase-mediated blastocoelic cavitation, as suggested by Bonilla et al [9]. Furthermore, the impaired blastocyst development induced by ethionine was not completely recovered by SAM, suggesting that SAM-independent roles of methionine such as a source of protein synthesis are also important in bovine blastocyst development [1,2].…”

“…In addition, to exclude the possibility that the consequences of the ethionine treatment did not arise from nonspecific toxicity (such as the effects of osmolality) associated with the high concentration (10 mM) used, the effects of 10 mM methionine on embryonic development were also evaluated. Thus, the concentration of methionine used in this experiment was supraphysiological and not intended for the investigation of physiological effects of methionine, which have been studied by Bonilla et al [9]. Bovine embryos that had developed to the 5-cell stage or more at 72 h after the commencement of IVF were further cultured in IVCM, either not supplemented with additive (control) or supplemented with 10 mM of ethionine or methionine.…”

“…Recently, Bonilla et al [9] examined the effects of methionine added to cultured bovine zygotes and reported that the yields of advanced staged (expanded) blastocysts were increased in a dosedependent manner with 7, 14 and 21 μM of methionine, reaching a plateau at 21 μM. From these results, the authors concluded that the methionine requirement for bovine preimplantation development lies between 14 and 21 μM; this range is lower or similar to the concentrations in the bovine reproductive tract.…”

Increase of essential amino acids in the bovine uterine lumen during preimplantation development

“…Depletion or an insufficient supply of essential as well as non-essential AAs resulted in altered development of bovine embryos in vitro (Steeves & Gardner 1999). For instance, a reduction of L-methionine (Met) decreased intracellular concentrations of glutathione in in vitro produced bovine embryos, although this did not affect apoptosis, methylation status, or cleavage rate (Bonilla et al 2010). Whereas non-essential AAs seem to be crucial for cleavage of the zygote, blastocoel formation, and blastocyst hatching, essential AAs are particularly important for the complex development of the inner cell mass of murine embryos (Lane & Gardner 1997).…”