Genes are switched on in the human embryo from the get-go

Mouse one-cell embryo showing two pronuclei - Scientists have discovered that genes in human embryos rapidly become active after fertilisation, opening a new window onto the start of human embryonic life. Scientists have discovered that genes in human embryos rapidly become active after fertilisation, opening a new window onto the start of human embryonic life. The finding that some genes are active from the get-go challenges the textbook view that genes don't become active in human embryos until they are made up of four-to-eight cells, two or three days after fertilisation. The newly discovered activity begins at the one-cell stage - far sooner than previously thought - promising to change the way we think about our developmental origins. The research , published today in Cell Stem Cell, was co-led by Professor Tony Perry at the University of Bath, Dr Giles Yeo at the University of Cambridge and Dr Matthew VerMilyea at Ovation Fertility, US. Using a method called RNA-sequencing, the team applied precision analysis to individual human eggs and one-cell embryos to make a detailed inventory of tell-tale products of gene activity, called RNA transcripts. It revealed that hundreds of genes awaken in human one-cell embryos.