Resurrecting a 500 million year old gene
|July 11, 2012||Posted by News under Evolution, News|
From “Giving Ancient Life Another Chance to Evolve: Scientists Place 500-Million-Year-Old Gene in Modern Organism”(ScienceDaily, July 11, 2012), we learn,
Using a process called paleo-experimental evolution, Georgia Tech researchers have resurrected a 500-million-year-old gene from bacteria and inserted it into modern-day Escherichia coli (E. coli) bacteria. This bacterium has now been growing for more than 1,000 generations, giving the scientists a front row seat to observe evolution in action.
“This is as close as we can get to rewinding and replaying the molecular tape of life,” said scientist Betül Kaçar, a NASA astrobiology postdoctoral fellow in Georgia Tech’s NASA Center for Ribosomal Origins and Evolution. “The ability to observe an ancient gene in a modern organism as it evolves within a modern cell allows us to see whether the evolutionary trajectory once taken will repeat itself or whether a life will adapt following a different path.”
“The altered organism wasn’t as healthy or fit as its modern-day version, at least initially,” said Gaucher, “and this created a perfect scenario that would allow the altered organism to adapt and become more fit as it accumulated mutations with each passing day.”
The growth rate eventually increased and, after the first 500 generations, the scientists sequenced the genomes of all eight lineages to determine how the bacteria adapted. Not only did the fitness levels increase to nearly modern-day levels, but also some of the altered lineages actually became healthier than their modern counterpart.
When the researchers looked closer, they noticed that every EF-Tu gene did not accumulate mutations. Instead, the modern proteins that interact with the ancient EF-Tu inside of the bacteria had mutated and these mutations were responsible for the rapid adaptation that increased the bacteria’s fitness. In short, the ancient gene has not yet mutated to become more similar to its modern form, but rather, the bacteria found a new evolutionary trajectory to adapt.
In other words, it’s not clear that anything dramatic happened, but some people have been following bacteria for tens of thousands of generations, and that might be a next step here.
Surely they are on the right track in this respect: To develop possible scenarios for origin of life or the cell, researchers must attempt to create them in the lab. Arguing about whether montmorillonite or silica actually played a role in the origin of life way back when is arguing over subjects the truth of which may never be possible to know.