Studies of mammals have shown that various environmental effects such as ‘memories’ such as diet, weight and stress are passed down from father to offspring, although these states are not coded into sperm-driven DNA sequences. Now, we have a new understanding of how this is possible.
The story has a lot to do with epigenetics. The molecules that attach themselves to DNA can act like a D-swf switch that controls which parts of DNA are used – but we still don’t know which of these molecules can carry the settings marked by the father’s life experiences, including May contain. Fetus by sperm.
Sarah Kimmins, an epigenetist at McGill University, said: “The major breakthrough in this study is that it has identified non-DNA-based media by which semen remembers a father’s environment (diet) and transmits that information to the fetus.” Said Sarah Kimmins.
Using mice, epigeneticist Ariane Lismer and colleagues showed that the effect of folate-deficient diets can be passed on by modifying histone molecules in semen. Simply put, histones are actually the basic proteins that wind up for free storage of tangled DNA.
In mammals, when the male bodies produce sperm, they shed most of the histone spool to allow for harder packing.
But there is still a small percentage left (1 percent in mice and 15 percent in humans), providing scaffolding for DNA in the areas of sperm formation and function, metabolism and fetal development – cellular methods allow the use of these DNA instructions.
The chemical modification of these histones – the most common form is methylation – allows or prevents DNA from being ‘read’ so that it can be written into protein products. These histones can alter their methylation status due to poor diet.
That’s why we hear about the importance of folate for women during pregnancy: Mother’s folate helps stabilize DNA methylation in their infancy.
By feeding the male rat folate-deficient food during the weaning period, the researchers examined changes in male sperm and histones in the resulting fetus. And indeed, sperm histone changes were also present in the developing fetus.
No one has been able to figure out how those inherited environmental signatures are transmitted from semen to the fetus, Lismer said.
The team also found that these effects could be cumulative and increase the severity of the congenital defect.
Interestingly, folate-deficiency is well documented in the human population, including congenital defects found in mice, underdeveloped at birth, and spinal abnormalities.
Researchers hope that expanding our knowledge of inheritance methods will lead to new ways to treat and prevent such conditions. But much remains to be done.
“Our next steps will determine if these harmful changes induced in semen protein (histones) can be corrected. We have an exciting new function that suggests this is indeed the case,” Kimmins said.
This research was published Developmental cell.
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