Amphibians migrated to land. Primates developed opposable thumbs. Hard-beaked Galapagos finches outlived their competition. But what if those animals’ evolutionary tracks had taken a different course?
We may never know the answer, but one group of Georgia Tech scientists hopes to gain some insight from experiments that mimic evolution. In a mash-up that would make Dr. Moreau proud, researchers under the direction of associate professor of biology Eric Gaucher have revived a 500-million-year-old protein and spliced it into bacteria.
In 2008, Gaucher determined the ancestral genetic sequence of Elongation Factor-Tu (EF-Tu)—the most abundant protein expressed in cells, without which bacteria would die. And this year, using genetic analysis and molecular biology techniques, researchers under Gaucher inserted this ancestor protein into Escherichia coli (E. coli), a bacteria known by most for its unpleasant associations with foodborne illness.
“We are replaying the tape for this protein and seeing whether we will obtain the same outcome in the laboratory as nature once did,” said Betül Kacar, a NASA astrobiology postdoctoral fellow in Tech’s NASA Center for Ribosomal Origins and Evolution. Kacar built on Gaucher’s findings by producing eight identical strains of the bacterial hybrid, which originally grew much slower than its modern counterpart.
E. coli divides into new generations every 20 to 25 minutes, making genetic changes easy to track. After the first 500 generations, fitness levels of the experimental strains increased. Observing its growth has led Kacar and her fellow scientists to new discoveries about how cellular machinery works.
The Paleozoic era protein could have changed and accumulated mutations, but so far it hasn’t. Instead, the modern proteins that interact with the ancient EF-Tu inside of the bacteria have mutated, causing rapid adaptation and giving the bacteria a new evolutionary path. “If we understand how evolution works,” Kacar says, “we can understand why things that we see right now happened that way in the first place. That’s the big question we are asking here.”
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