500-Million-Year-Old Gene May Show if Evolution Can Repeat Itself




Biologists have long wondered whether life would evolve the same way again if we could rewind Earth's tape. Eric Gaucher and Betül Arslan at Georgia Tech University in Atlanta synthesised an ancient gene –EF-Tu, a gene in Escherichia coli, that plays a crucial role in protein synthesis– and inserted it into E. coli in place of the modern version. Gaucher had previously worked out what this gene's DNA sequence must have been 500 million years ago.

The bacteria with the old gene grew less than half as fast as usual. Arslan then let eight bacterial lines evolve independently for 1000 generations. The experiment may help biologists understand the extent to which evolution is predictable.

All eight lineages eventually grew faster – a sign that evolution had occurred. When Arslan sequenced their genomes, though, she found that EF-Tu was unchanged. What had evolved – differently in each lineage – were the genes that interact with EF-Tu, she announced at NASA's Astrobiology Science Conference 2012 in Atlanta.

The sheer number of interacting genes in protein synthesis means that random mutations are more likely to hit one of EF-Tu's partners than EF-Tu itself. Eventually, though, EF-Tu may begin to evolve – either following the same path it began 500 million years ago or not. We'll have to wait for the final results.

Daily Galaxy via newscientist.com

Image credit: publicdomainpictures.net

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