Direct environmental changes in DNA after sperm and egg binding.

A team of scientists at the Helmholtz Center in Munich, Germany, showed direct environmental changes in DNA after sperm and eggs combine to form fertilized eggs.
this result explains why fertilized eggs can develop into all somtic cells.
months before the often-mentioned miracle of life occurred, there were many things that scientists could not fully understand.
, for example, how a single cell becomes the origin of all cells in an entire organism.
the answer to this question is that of Professor Maria-Elena Torres-Padilla, who heads the Institute of Oscic Genetics and Stem Cells at the Helmholtz Center in Munich.
We are particularly interested in how cells can divide so many times and in so many different ways, such as by dividing into skin cells, liver cells, and heart cells," the researchers explained.
current study, she and her team worked out the problem by testing chromatin, a complex of proteins in and around DNA.
we looked at how specific histoproteins change after fertilization, which allows us to explain a new mechanism," she said.
" image shows a normal mouse embryo (2 pictures above) and an extra expression of SUV4-20 mouse embryo (2 pictures below, methylation shown in red).
Although cells without histoprotein modification replicate DNA (a small number of yellow cells) and cell division, cells expressed by SUV4-20 are trapped in the replication state (a large number of yellow cells) and cannot be divided.
researchers found that the Suv4-20h2 molecule, a so-called histone methyl transferase, moved upstream of chromatin and caused methylation when the histone was connected to some methyl, and that cell division and development were inhibited when these chemical changes increased.
but once fertilization occurs, these attachments disappear and fertilized eggs become new organisms.
to confirm these results, the researchers used an experimental model to test the role of keeping SUV4-20h2 active in fertilized eggs.
, phD student and lead author of the paper, explains: "We can prove that methyl is still on histones in this case.
this inhibits further development of the fertilized egg and therefore stops after the first split.
in further experiments, the team found that the mechanism may be based on the fact that methyl on the hismoglobin surface causes defects in the replication of genetic material that cause replication "checkpoints" and therefore the cell cycle to stall.
Results allow us to understand the relationship between chromatin and the ability of cells to develop into other types of cells (cell omnipotence)," said Torres-Padilla, a professor of chroma.
"this is an important step in understanding human embryology and specific cancers, and in some cancers cells exhibit similar mechanisms that affect the rate at which cells grow.
study has been published in Genes and Development.
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