Analysis of gene expression in mouse 2-cell embryos using fluorescein differential display: comparison of culture environments

The effect of the oviductal environment on gene expression in 2-cell mouse embryos was examined with mRNA differential display. Embryos used for experiments were cultured in modified Whitten medium with or without oviductal tissue until late 2-cell stage. The results of sequencing indicated that the genes for ATP synthase (ATPase 6), S-adenosylmethionine decarboxylase (S-AMDC) and nuclear autoantigenic sperm protein (NASP) were differentially expressed in embryos cultured in the oviduc-tal environment (nonblocking culture condition). The ATPase 6 gene is encoded by mitochondrial DNA and is essential for the production of ATP. This indicates that the expression of ATP syn-thesis-related genes at the 2-cell stage may be required to main-tain normal development in vitro. S-Adenosylmethionine decar-boxylase decarboxylates adenosylmethionine, which is a sub-strate of DNA methylation. The expression of S-AMDC may be responsible for the low level of methylation of preimplantation development. As NASP is a histone-binding protein that is thought to be testis and sperm specific, its function in embryos remains unclear. On the other hand, the Tcl1 gene and a novel gene, the c-1 gene, were strongly expressed in embryos cultured without oviductal tissue (blocking culture condition). The ex-pression patterns of these genes are quite similar. However, the detailed functions of these genes in embryos remain to be de-termined. gametogenesis, implantation/early developmen