Scientists Resurrect 500-Million-Year-Old Gene Inside Modern Organism 135
An anonymous reader writes with news that researchers at the Georgia Institute of Technology have taken a gene from 500-million-year-old bacteria and inserted it into modern E. coli bacteria. They then allowed the bacteria to evolve over the course of a thousand generations to see whether it would resemble its original 'evolutionary trajectory.' From the article:
"After achieving the difficult task of placing the ancient gene in the correct chromosomal order and position in place of the modern gene within E. coli, Kaçar produced eight identical bacterial strains and allowed 'ancient life' to re-evolve. This chimeric bacteria composed of both modern and ancient genes survived, but grew about two times slower than its counterpart composed of only modern genes. '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."
Re:they damaged a gene meant to encode a protein (Score:5, Informative)
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.
Not really repair the damage, but work around it.
Re:Genius! (Score:5, Informative)
E. coli is absolutely everywhere. Some strains are dangerous, but other strains are beneficial; like the ones living in your gut.
Re:What about Horizontal Gene Transfer? (Score:3, Informative)
It appears the experiment already has proven that evolution can take many tracks, as the bacteria adapted to the ancient gene, and did not mutate the ancient gene at all as of yet. Sounds to me like the evolutionary track has already altered, and if the bacteria is as healthy or more so than its unaltered cousins, then this bacteria would already be in better shape on the evolutionary ladder and would push evolution in a different direction.
Honestly, I don't know why this is a surprise, since evolution is very much about reaction to outside pressures. A slight change in those pressures can change the outcome of the system, as it's not exactly a stable system.
Did they apply selective pressure? (Score:0, Informative)
Evolution is just the process of adapting to selective pressure. How things evolve depends on the best responses to that pressure.
If you just kind of let them go, with no pressure at all, then you probably won't see much evolution.
If you apply pressure, one would expect the end-results to be a natural response to that pressure.
I am not sure what this "trajectory" business is all about. Evolution does not have momentum.
Apparently Not Yet Peer Reviewed (Score:5, Informative)
Arslan BK and Gaucher EA Replaying the Tape of Life Through Experimental Evolution of Ancient EF-Tu proteins Astrobiology Science Conference 2010: Evolution and Life: Surviving Catastrophes and Extremes on Earth and Beyond, held April 26-20, 2010 in League City, Texas. LPI Contribution No. 1538
Which I think was just a presentation that provides very little information given all I can find is this PDF [usra.edu]:
Whether evolution would ‘replay the tape of life’ if given the opportunity has long fascinated biologists. Paleogenetics via laboratory resurrected ancient genes not only reveals information regarding ancestral phenotypes and environments but also provides an opportunity to ‘replay’ the molecular tape of life. Recent work has demonstrated that ancestral sequences can be computationally determined and experimentally resurrected. The ideal paleoexperimental evolution system requires an organism with a short generation time and a protein whose ancestral genotype and phenotype used to replace the modern gene and causes the modern host to be less fit. The research described here focuses on Elongation Factor Tu (EF-Tu) involved in the protein synthesis machinery of both eukaryotic and prokaryotic organisms. The optimal thermostability of EF-Tus correlates with the optimal thermostability of their host organisms and are ideal for these types of experiments. Previously we have resurrected ancient EF-Tus and showed that these ancient proteins display a range of thermostability profiles. We will replace the modern EF-Tu sequences with ancient EF-Tus and observe their adaptation through experimental evolution. Results from this work will help us identify whether evolution is repetitive for this experimental system.
I don't think that really answers your question and I think this research has only been presented at conferences, published in conference proceedings and not yet peer reviewed in a journal (if it has there is no mention of it on Kacar's CV). I also find it odd that on her site she's using the phrase "tree of life" and not "web of life" which I thought was a more modern way of looking at evolution -- especially in prokaryotes.
I will say that it is probably within line to chide the researcher for putting this little blurb on her research page [gatech.edu]:
Experimental Evolution of Ancient Proteins
To assess the role of contingency in evolution, I construct an experimental time machine in the lab by inserting previously resurrected genes into a modern bacterial genomes, then subjecting them to experimental evolution. Observing the real-time evolution of ancient genes as they adapt to the conditions of modern bacteria allows us to analyze evolution in action.
"Experimental time machine?" Please, leave the hype and sensationalism to the "science" reporters.
Re:Two words. (Score:4, Informative)
Re:As a microbiologist... (Score:5, Informative)