Evaluation of caprine and ovine preimplantation embryo development, energy metabolism, and protein synthesis following in vitro fertilization and parthenogenetic activation
Abstract
The efficiency of nuclear transfer procedure requires effective species specific oocyte activation protocols. The first study evaluated the development of goat embryos developing from parthenogenetic activation of oocytes using different methods and the effect of overnight oocyte shipment on subsequent embryo development. Sequential activation of caprine oocytes using 5 μM ionomycin and 7% ethanol, both followed by exposure to 6-dimethylaminopurine (6-DMAP) resulted in cleavage and pre-implantation blastocyst development comparable to if not better than that of in vitro fertilized (IVF) oocytes. There was no significant difference (p < 0.05) in the number of blastocyst cells suggesting equivalent embryo viability. Although parthenogenetic embryos have morphologically normal preimplantation development, they are not viable. This deficit is thought to be due to aberrant gene expression. However, the genes that are incorrectly expressed are not known. The second study compared the metabolism of glucose and pyruvate between IVF and parthenogenetically developing blastocysts since energy metabolism may predict the viability of in vitro developing embryos after transfer to recipients. There were no significant differences in the utilization of glucose and pyruvate between IVF blastocysts and parthogenogenotes. Glucose utilization by all three categories of blastocysts was significantly higher (p < 0.05) than pyruvate utilization suggesting that glucose is a major source of energy at this stage of embryonic development. Proteins are important as structural components of embryos and as regulatory molecules. Protein synthesis patterns change during early embryonic development. The third study used one- and two-dimensional polyacrylamide gel electrophoresis to compare proteins present in IVF and parthenogenetically activated blastocysts. Several proteins present in parthenogentic blastocysts did not match those present in IVF blastocysts. Identification and function of these proteins should be investigated to help us understand the effects of genomic imprinting on protein synthesis and embryonic development. Although the composition of serum is undefined, it is a common supplement of in vitro oocyte maturation systems. The last study evaluated the effect of serum supplementation on protein synthesis of ovine oocytes matured in vitro. There were slight differences in the proteins present in oocytes matured in medium with and without serum, suggesting that serum may have a stimulatory effect on protein synthesis.
Degree
Ph.D.
Advisors
Krisher, Purdue University.
Subject Area
Anatomy & physiology|Animals
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