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Environment Can Affect Which Genes Are Activated



(p. D5) In September 1944, trains in the Netherlands ground to a halt. Dutch railway workers were hoping that a strike could stop the transport of Nazi troops, helping the advancing Allied forces.

But the Allied campaign failed, and the Nazis punished the Netherlands by blocking food supplies, plunging much of the country into famine. By the time the Netherlands was liberated in May 1945, more than 20,000 people had died of starvation.

The Dutch Hunger Winter has proved unique in unexpected ways. Because it started and ended so abruptly, it has served as an unplanned experiment in human health. Pregnant women, it turns out, were uniquely vulnerable, and the children they gave birth to have been influenced by famine throughout their lives.

When they became adults, they ended up a few pounds heavier than average. In middle age, they had higher levels of triglycerides and LDL cholesterol. They also experienced higher rates of such conditions as obesity, diabetes and schizophrenia.


. . .


"How on earth can your body remember the environment it was exposed to in the womb -- and remember that decades later?" wondered Bas Heijmans, a geneticist at Leiden University Medical Center in the Netherlands.

Dr. Heijmans, Dr. Lumey and their colleagues published a possible answer, or part of one, on Wednesday in the journal Science Advances. Their study suggests that the Dutch Hunger Winter silenced certain genes in unborn children -- and that they've stayed quiet ever since.

While all cells in a person's body share the same genes, different ones are active or silent in different cells. That program largely is locked in place before birth.

But scientists have learned that later experiences -- say, exposure to a virus -- can cause cells to quiet a gene or boost its activity, sometimes permanently.

The study of this long-term gene control is called epigenetics. Researchers have identified molecules that cells use to program DNA, but how those tools work isn't entirely clear. One of the best studied is a molecular cap called a methyl group.

At millions of spots across our DNA, genes may carry a methyl group. They seem to silence genes -- at least, researchers have found that silenced genes often have a collection of methyl groups lurking nearby.



For the full story, see:

Zimmer, Carl. "Dutch Genes Still Bear Scars of a Famine." The New York Times (Tuesday, February 6, 2018): D5.

(Note: ellipsis added.)

(Note: the online version of the story has the date JAN. 31, 2018, and has the title "MATTER; The Famine Ended 70 Years Ago, but Dutch Genes Still Bear Scars.")






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