Please read this delicious description of epigenetics! (From www.edge.org)

JILL NEIMARK
Science Journalist; Co-author, Why Good Things Happen To Good People

The Human Epigenome Project
There are maps, and then there are maps. We're embarking on a kind of
mapmaking that will usher in new ways of understanding ourselves-a map that
can explain why identical twins are not truly identical, so that one
succumbs to schizophrenia while the other remains cognitively intact; why
what your mom ate can save or sabotage your health (as well as that of your
children and your children's children); and how our genetic fates can be
tuned by such simple universals as love or vitamins.
It's The Human Epigenome Project (HEP). It's the next step after the Human
Genome Project, which in itself was as audacious as the Apollo space program
or the Manhattan Project, mapping 25,000 genes and the 3 billion pairs of
bases in our DNA. And yet, what The Human Genome Project mapped is like land
without borders, roads without names, a map without movement. Genes are
silent unless activated. To have them is not necessarily to be under their
influence.
"Land lies in water, it is shadowed green," begins Elizabeth Bishop's
classic early poem, "The Map." The double helix lies in the epigenome like
land lies in water. The epigenome is a flute playing a tune that charms the
snake-coiled snake that is the code of life-and the snake spirals upward in
response. A long bundle of biochemical markers all along the genome, the
epigenome responds to environmental signals and then switches genes off or
on, upregulates or downregulates their activity. And in that change lies a
great part of our destiny.
In 2003, in a widely discussed experiment, scientist Randy Jirtle of Duke
University Medical Center in Durham, North Carolina, showed that he could
change the activity of a mouse's genes by giving supplements to its mom
prior to, or during, very early pregnancy. A mouse with yellow fur, whose
offspring would normally also be yellow, will give birth to brown-furred
babies if fed a diet supplemented with vitamin B12, folic acid, betaine and
choline. Even the offspring of the mom's offspring will be born with brown
fur. The genes themselves have not changed at all, but their expression has,
and that lasts for at least two generations. And a fungicide used on fruits
led to sperm abnormalities in rats-abnormalities passed down at least four
generations. This gives us insight into nature's ways: apparently she
figures any change in the food supply will last a while, and isn't just a
seasonal fling.
Then, in 2004, Moshe Szyf, Michael Meaney and their colleagues at McGill
University in Montreal, Canada, showed that love can work in a similar way.
If mothers don't lick, groom and nurse their babies enough, a molecular tag
known as a methyl group-a tiny molecule made of three hydrogen atoms bound
to a single carbon atom-is added to a gene that helps regulate an animal's
response to stress. In pups that aren't nurtured properly, the methyl group
downregulates the genes' activity for life. The pups have higher levels of
stress hormones and are more afraid to explore new environments. What is
nature saying? If a mom didn't attend to her newborn much, it's probably
because the environment was hostile and stressful. Better to be vigilant and
cautious, even afraid. Later, Meany and his colleagues showed that a common
food supplement could do exactly the same thing to the genes of well-licked
and nurtured rats. Once the pups were three months old, researchers injected
a common amino acid, L-methionine, into their brains. This methylated the
same gene, downregulated it, and turned the rats into anxious wallflowers.
Last June, the European Human Epigenome Project published its first findings
on the methylation profiles, or epigenetics, of three chromosomes. The push
to map the epigenome is on. In the last few weeks alone I've seen very
different epigenetic stories coming across the science wires. From the
University of Texas Medical Branch at Galveston came the news that
breastfeeding protects children who are genetically susceptible to repeated
ear infections because of common variants in their genes. The tendency
toward ear infections runs in families, and researchers found the culprit in
two gene variants that increase inflammatory signaling molecules in the
immune system. Remarkably, breast milk seemed to permanently quiet the
genes, so that even later in childhood, long after the children had stopped
breastfeeding, they were protected from recurrent infections.
In research from the Universidad Nacional Autonoma de Mexico and the
Instituto Nacional de Cancerologia, Mexico, epigenetic drugs are now being
studied in breast, ovarian and cervical cancer. These drugs affect genes
that, when reactivated, help regulate cell proliferation, cell death, cell
differentiation, and drug resistance. They're cheaper than designer-name
cancer drugs, and might help increase survival rates.
Even water fleas are joining the epigenetic act. In a December study from
the University of California at Berkeley expression of genes in water fleas
changed in response to common contaminants. Water fleas are regularly used
to monitor freshwater toxicity, usually with a "kill 'em and count 'em"
approach. Researchers found that copper, cadmium and zinc decreased
expression of genes involved in digestion and infection. Screening like this
might help industry assess and avoid particularly toxic contaminants.
Epigenetics offers us a different kind of map. One where we can zoom in and
zoom out. A map of many colors, with street signs so we can navigate, routes
that we can choose, destinations that we can change. Maybe the gene isn't
selfish. Maybe it's actually sensitive. "More delicate than the historian's
are the mapmaker's colors." So concludes Elizabeth Bishop's poem, and the
epigenome may prove to be one of the more beautiful, delicate, subtle maps
of all time.


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