[ExI] Inheritance - It's not just the DNA

[BillK]

The Toxins That Affected Your Great-Grandparents Could Be In Your Genes

<http://www.smithsonianmag.com/ideas-innovations/The-Toxins-That-Affected-Your-Great-Grandparents-Could-Be-In-Your-Genes-231152741.html>

Quote:
For half a century it has been common knowledge that the genetic
material DNA controls this process; the “letters” in the DNA strand
spell out messages that are passed from parent to offspring and so on.
The messages come in the form of genes, the molecular equivalent of
sentences, but they are not permanent. A change in a letter, a result
of a random mutation, for example, can alter a gene’s message. The
altered message can then be transmitted instead. The strange thing
about Skinner’s lab rats was that three generations after the pregnant
mothers were exposed to the fungicide, the animals had abnormally low
sperm counts—but not because of a change in their inherited DNA
sequence. Puzzled, Skinner and his team repeated the experiments—once,
twice, 15 times—and found the same sperm defects.

Skinner and his team found instead that as the toxins flooded in, they
altered the pattern of simple molecules called methyl groups that
latch onto DNA in the fetus’ germ-line cells, which would eventually
become its eggs or sperm. Like burrs stuck to a knit sweater, these
methyl molecules interfered with the functioning of the DNA and rode
it down through future generations, opening each new one to the same
diseases. These burrs, known to be involved in development, persisted
for generations. The phenomenon was so unexpected that it has given
rise to a new field, with Skinner an acknowledged leader, named
transgenerational epigenetics, or the study of inherited changes that
can’t be explained by traditional genetics.
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BillK