The results were published online Sept. 25 in the journal Nature Genetics describe in unprecedented detail the molecular changes that can bring their young mammals develop inside the uterus, rather than the safety of their nests, or to carry 'inside of the bag.
"Over the past two decades has been dramatic changes in our understanding of evolution operates," said Gunter Wagner, Alison Richard Professor of Ecology and Evolutionary Biology (EEB) and the senior author of the paper. "We used to believe that the only changes came about through a small mutation in the DNA that have accumulated over time. But in this case, we found a huge cut and paste function, which converts large areas of the genome to create a large change morphological scale. "
The Yale team study the evolutionary history of the cells examined pregnancy in the uterus associated with the development of the placenta. They compared the genetic makeup of these cells in opossums - marsupials give birth two weeks after conception - of the armadillos and humans, a distant relative of placental mammals that feed on highly developed development of the fetus for nine months.
They found over 1500 genes that were expressed in the uterus than in placental mammals. Interestingly, the researchers note, the expression of these genes in the uterus is coordinated by transposable elements - essentially selfish pieces of genetic material to replicate in the host genome and used to be called junk DNA .
"Transposons grow as parasites that have invaded the body, multiplying and taking place in the genome," said Vincent J. Lynch, a researcher in the BEE and lead author of the document.
But they also activate or repress genes associated with pregnancy, he said.
"These transposons are genes that have undergone small changes over long periods and eventually became their new role during pregnancy," said Lynch. "They are more like prefabricated units regulators, who settled in a host genome, which then recycles entirely new functions that facilitate communication Maternal-Fetal "Lynch said.
Robert Leclerc and Gemma May from Yale also contributed to the research.
