300. Differential expression patterns of genes with immune and developmental relevance in individual bovine preimplantation embryos produced by nuclear transfer

Abstract

The overall efficiency of cloning by somatic cell nuclear transfer (NT) remains low when compared to in-vitro fertilisation (IVF). Inefficient reprogramming of the donor nucleus and epigenetic effects are hypothesized to lead to aberrant gene expression in cloned embryos. In this work differences in gene expression, between blastocysts from IVF and NT derived pre-implantation bovine embryos, were explored using a bovine cDNA array. 439 array elements were identified as being differentially expressed. 102 elements showing upregulation and 337 elements downregulation in NT blastocysts in a pairwise comparison to IVF-derived blastocysts. A major subset (65 elements) of differentially expressed elements comprised immune-related genes, possibly a reflection of the immune-focused cDNA microarray used in this study. For example, several cytokine genes, as well as elements of the innate immune system, were showing elevated expression in NT blastocysts. In addition, two regulatory elements of the same endocrine pathway exhibited a remarkable expression pattern, where the gene for one inhibitor showed upregulation and the gene for another inhibitor showed downregulation in NT blastocysts. Of specific interest is the observation that genes belonging to two growth factor pathways are upregulated in NT embryos. These results suggest an important role for immune-related genes during embryogenesis and indicate that specific cell growth and differentiation factors are of significant interest as targets in defining the abnormalities of preimplantation NT embryo development.