Cell Stem Cell challenges the traditional view: some genes have been turned on from the very beginning

The discovery that some genes are active from the beginning challenges the traditional view that genes are only active in human embryos when they are composed of 4 to 8 cells two to three days after fertilization

This newly discovered activity begins at the single-cell stage-much earlier than previously thought-and promises to change our view of the origin of our own development

The research was published today in the journal Cell Stem Cells and was co-led by Professor Tony Perry from the University of Bath, Dr Giles Yeo and Dr.

The research team used a method called RNA sequencing to accurately analyze individual human eggs and single-cell embryos, detailing signs of gene activity, that is, RNA transcripts

Professor Perry said: "This is the first good observation of the beginning of the biological process that all of us have gone through-the transition through the single-cell embryo stage

The research team also found that many genes activated in single-cell embryos remain on until the four to eight cell stage, at which point they are turned off

"There seems to be a kind of genetic transformation work in early embryos: the first transformation begins shortly after fertilization, and in single-cell embryos, the second transformation takes over at the eight-cell stage

What the human genome awakening tells us

At the moment humans are fertilized, the genomes of sperm and eggs (the collection of all genes) are inactive: sperm and eggs rely on the transcripts they produce when they are formed to obtain instructions that regulate their characteristics

Transcripts provide basic instructions for all cells, and embryonic cells are no exception

Understanding the process of genomic awakening is important: it is a key part of the developmental puzzle and helps to better understand diseases, genetics and infertility

The team’s findings also revealed how genes are activated

Link to cancer

It is worth noting that candidate factors that may trigger gene activation include factors commonly associated with cancer, such as some well-known oncogenes

These findings also have clinical implications for the inheritance of acquired traits, such as obesity: Parents who gain weight seem to pass this trait on to their children

As Dr.

The team also studied unhealthy single-cell embryos that could not continue to develop and found that many of their genes failed to activate
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Aberrant embryos have been used to evaluate methods for human heritable genome editing, but new findings suggest that they may not be suitable as a reliable test system
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Article title

Human embryonic genome activation initiates at the one-cell stage