Human egg fertilization sparks a cascade of genetic activity. After 1 day, the single
cell becomes two, after 2 days there are four cells, after 3 days there are eight, and so it continues.
Now, for the first time, scientists have mapped the genetic activity that accompanies this early stage
of embryo growth.
The study shows that on the second day after fertilization, only 32 of the 23,000 human genes are switched on.
The international study, led by the Karolinska Institutet in Sweden, is published in the journal
“Our results provide novel insights into the regulation of early embryonic development in
humans,” reports senior author Outi Hovatta, a professor of clinical science,
intervention and technology.
The study is the first to map all the genes that are activated in the first few days of embryo
development from the point of fertilization; a discovery that is akin to finding the “ignition key” that switches on
human development, according to one of the researchers.
While there are approximately 23,000 human genes, the order in which genes are activated following fertilization has been a mystery until now.
Prof. Hovatta and colleagues hope the results will open a number of research avenues, such as
discovering new treatments for infertility and other diseases.
Researchers identify new genes activated shortly after fertilization
The team found that on the second day after fertilization, only 32 of the 23,000 human genes are switched
on. By the third day, the number of active genes rises to 129. Seven of these active genes had not been previously identified.
Most genes carry the instructions for making proteins. There are a number of repeated sequences
in our DNA that were initially thought to be “junk” DNA but were later discovered to be regulating the
genes that code for proteins.
The new genes the researchers found appear to interact with the so-called “junk” DNA, and this
interaction is essential for triggering early embryo development. Prof. Hovatta explains how this might
be useful for future research:
“We identified novel factors that might be used in reprogramming cells into so-called
pluripotent stem cells for possible treatment of a range of diseases, and potentially also in the
treatment of infertility.”
Meanwhile, Medical News Today has learned of a new IVF
approach that older women may find more successful. The researchers behind the new development
discovered that it is not aging of the eggs themselves but aging of their environment that appears to
reduce older women’s chances of conceiving through IVF (in vitro fertilization).
The researchers found that retrieving eggs from the ovaries earlier than in conventional IVF led to increased production of good quality embryos and higher success rates.
Written by Catharine Paddock PhD
Copyright: Medical News Today
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