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Frontiers

March-April 2020

A Disruptor, Decoded

A chemical plasticizer, produced by the millions of tons annually for use in clothing, shampoo, carpets, adhesives, printing inks, and even makeup, has long been linked to birth defects and male infertility. Now a team of researchers led by Harvard Medical School professor of genetics Monica Colaiácovo has shown why. Diethylhexyl phthalate (DEHP)—which softens plastics— disrupts the production of eggs and sperm, causes changes in chromosome structure, and alters early embryogenesis in C. elegans. (The team used female roundworms to study these effects because their molecular processes of reproduction are largely conserved in mammals.) DEHP, they found, causes breaks in DNA, and then impairs natural processes of repair. Federal and state regulations already limit the amount of DEHP and other phthalates in drinking water, food packaging, and children’s toys, but even small amounts, including levels recently measured in U.S. and Dutch women, can harm DNA involved in reproduction—and exposure can occur through inhalation, ingestion, or absorption through the skin.

The Two Faces of Sugar

All sugars are not alike. High levels of fructose, consumed in conjunction with a high-fat diet (HFD), inhibit the liver’s ability to burn fat, researchers at the Joslin Diabetes Center write in Cell Metabolism. Professor of medicine C. Ronald Kahn, chief academic officer at Joslin and senior author, found that in rats on a HFD, those fed water sweetened with fructose developed smaller liver mitochondria (the cells’ energy-producing organelles), and were less able to eliminate small and damaged mitochondria. Their livers therefore had a diminished ability to oxidize fat, and increasingly synthesized and stored it instead. Glucose had the opposite effect, improving overall metabolism. Said Kahn, consuming fructose “is almost like adding more fat to the diet.”

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