Focus on mammalian embryogenomics

Abstract

The term ‘embryogenomics’ was coined by Minoru Ko (2001) in his pioneering studies on the profiling of gene expression during mouse embryonic development. It refers to the area of research that combines embryological approaches and large-scale genomics analysis to provide an integrated examination of the morphogenetic processes that lead to the first patterning events at the onset of embryonic development. The term was rapidly adopted by those of us contributing to the development of embryo biotechnologies in domestic mammalian species and therefore interested in studying the extensive regulative properties of early mammalian embryos grown in vitro prior to their transfer to surrogate females. This was because the global analysis of the expressed genome (RNA, proteins) proposed by Minoru Ko appeared to be a valuable means of deriving key information from those expensive embryos. At that time dedicated molecular resources formed by cDNA or SAGE libraries and arrays, already accessible in both the mouse and human, were still under construction in domestic species (reviewed in Ko 2004). Since then, the tiny amount of biological material accessible from relatively few preimplantation embryos has become amenable to molecular analysis with the first techniques of RNA amplification (Brady et al. 1995, Kacharmina et al. 1999). However, the fidelity of the amplification procedures was still disputed when used in academic embryonic models (see for instance Baugh et al. 2001) or with samples of human tissues (Wang et al. 2000, Iscove et al. 2002). It was to discuss these issues in the context of research conducted with embryos from domestic species that Marc-Andre Sirard (University of Laval) together with Andrew Watson (University Western Ontario) and Allan King (University of Guelph) launched the first ‘Embryogenomics’ meeting that took place in Quebec City in July 2002. This Canadian initiative was a marked success. It addressed recent progress and questions on cDNA library subtraction, SAGE analysis, use of heterospecific arrays, or RNA amplification procedures on oocytes or embryos from domestic species (see OECD proceedings, 2003). In the five intervening years, however, the landscape has