How Epigenetic Heredity works
Scientists have understood how the father's bad habits affect the work of children's DNA
Scientists have uncovered the mechanisms that determine the transmission of so–called epigenetic memory, thanks to which plants adapt to droughts, and children sometimes become genetic "hostages" of bad habits and poor living conditions of their father and even grandfathers, according to an article published in the journal Science (Siklenka et al., Disruption of histone methylation in developing sperm impairs offspring health transgenerationally).
The genetic material of humans and all other living beings with a separate cell nucleus is packed in special proteins-histones, which hold the folded DNA in place and affect the "readability" of individual genes.
In recent years, geneticists have found more and more hints that this "wrapper" of DNA is involved in the transmission of information between generations and allows animals and plants to adapt more quickly to new environmental conditions, and problems with "overwriting" special marks on its surface have been associated with a predisposition to homosexuality and suicide among people.
Sarah Kimmins from McGill University in Montreal (Canada) and her colleagues have found out how such tags, which scientists call epigenetic memory, are transmitted from a father to his sons and daughters.
To do this, the scientists raised a population of mice in which the KDM1A gene was specially modified, which was responsible for removing epigenetic marks on histones during the growth of future sperm and eggs. Kimmins and her colleagues changed the structure of this section of DNA in such a way that its activity could be controlled by forcing the protein produced by it to more actively clean the surface of histones from labels.
Using similar mice, the scientists tested what would happen to their offspring if almost all such tags were removed from the sperm. The results of the experiment turned out to be extremely clear – the mice conceived with the help of such germ cells almost universally suffered from the most serious developmental defects, anomalies in the structure of the skeleton, and many of them did not even live to be born. All this happened for the reason that the work of more than two thousand genes was drastically changed due to the absence of labels on their surface.
Interestingly, similar effects were also present among the offspring of the surviving mice from the first generation, whose KDM1A genes were not activated by chemical signals. This means that the breakdown of epigenetic tags in their "grandfathers" affected the health of two subsequent generations of rodents at once.
Such large-scale consequences of the "purification" of DNA from epigenetic memory, according to Kimmins and her colleagues, indicate that this form of information transmission plays a critical role in the continuation of the genus, the evolution of humans and animals, and the development of various diseases, including predisposition to cancer, diabetes and other diseases.
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09.10.2015