The findings published online Sept. 25 in the journal Nature Genetics describe in unprecedented detail the molecular changes that allowed mammals to carry their developing young within the safety of the womb rather than laying them in nests or carrying them around in pouches.
"In the last two decades there have been dramatic changes in our understanding of how evolution works," said Gunter Wagner, the Alison Richard Professor of Ecology and Evolutionary Biology (EEB) and senior author of the paper. "We used to believe that changes only took place through small mutations in our DNA that accumulated over time. But in this case we found a huge cut-and-paste operation that altered wide areas of the genome to create large-scale morphological change."
The Yale team studying the evolutionary history of pregnancy looked at cells found in the uterus associated with placental development. They compared the genetic make-up of these cells in opossums — marsupials that give birth two weeks after conception — to armadillos and humans, distantly related mammals with highly developed placentas that nurture developing fetuses for nine months.
They found more than 1500 genes that were expressed in the uterus solely in the placental mammals. Intriguingly, note the researchers, the expression of these genes in the uterus is coordinated by transposons — essentially selfish pieces of genetic material that replicate within the host genome and used to be called junk DNA.
"Transposons grow like parasites that have invaded the body, multiplying and taking up space in the genome," said Vincent J. Lynch, research scientist in EEB and lead author of the paper.
But they also activate or repress genes related to pregnancy, he said.
"These transposons are not genes that underwent small changes over long periods of time and eventually grew into their new role during pregnancy," Lynch said. "They are more like prefabricated regulatory units that install themselves into a host genome, which then recycles them to carry out entirely new functions like facilitating maternal-fetal communication" Lynch said.
Robert LeClerc and Gemma May from Yale also contributed to the research.
The work was funded by the John Templeton Foundation.
Bill Hathaway | EurekAlert!
When Air is in Short Supply - Shedding light on plant stress reactions when oxygen runs short
23.03.2017 | Institut für Pflanzenbiochemie
WPI team grows heart tissue on spinach leaves
23.03.2017 | Worcester Polytechnic Institute
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
23.03.2017 | Life Sciences
23.03.2017 | Power and Electrical Engineering
23.03.2017 | Earth Sciences