Pregnancy in mammals evolved with help from roving DNA | Science News

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Pregnancy in mammals evolved with help from roving DNA

'Jumping genes' changed uterus to stop laying eggs

By
12:10pm, January 29, 2015
Puppies

HOLD THE EGGS  Roving DNA helped program mammals like this dog to give birth to live young instead of laying eggs.

Roving pieces of DNA helped early mammals ditch egg-laying in favor of giving birth to live young. These “jumping genes,” or transposable elements, flipped the switch on thousands of genes, turning off ones that build hard eggshells and turning on ones that allow a fetus to develop in the uterus. Researchers report the finding in the Feb. 3 Cell Reports.

“Transposable elements … rewired when and where genes are expressed by giving them new regulatory information,” says study coauthor Vincent Lynch, an evolutionary biologist at the University of Chicago.

In early mammals, traveling DNA moved to new spots in the genome and carried machinery that allowed certain genes to be activated in the presence of a hormone called progesterone, which controls many aspects of pregnancy. These moves flipped on or off genes in the uterus. 

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