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 fertilization.
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 was published in Cell Stem Cell.
Using a method called RNA-sequencing, the team revealed that hundreds of genes awaken in human one-cell embryos. Because the gene activity starts small, previous techniques had not been sensitive enough to detect it. But state-of-the art RNA-sequencing used in this study was able to reveal even small changes.
“This is the first good look at the beginning of a biological process that we all go through — the transit through the one-cell embryo stage,” said Professor Tony Perry, the study’s co-leader, from the Department of Biology and Biochemistry at the University of Bath, England. “Without genome awakening, development fails, so it’s a fundamental step.”
Understanding the process of genome awakening is a key piece of the jigsaw of development that promises a better understanding of disease, inheritance and infertility. The scientists found some activated genes that might be expected to play roles in early embryos, but the roles of others were unknown and could point to embryonic events that we don’t yet understand.