Selectively breeding an enzyme (V0355)
Evolution in the lab is called directed evolution, because it focuses on one gene. David Ackerley of Victoria University, Wellington, describes the process of directed evolution and compares it to selective breeding.
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Dogs have been selectively bred for particular traits for centuries. Directed evolution applies the same principles of dog breeding to individual genes. The gene is copied with lots of variations in the DNA sequence. Then, if the gene variants code for proteins with new or improved function, they are selected for further study.
Bonnie van den Born
David Ackerley (Victoria University, Wellington): Directed evolution is really nothing new; it’s actually been around as long as Darwin’s theory of evolution. He actually made a lot of his original observations on pigeons. He [Darwin] was a pigeon fancier, he bred pigeons, and he noted that, if you applied artificial selection, you select for very specific traits that you are interested in, you can achieve change in very rapid or very real time.
The dog’s a really good example, because people have originally selected dogs for hunting, but more recently over the last couple of hundred years as priorities have changed, people have picked dogs for companionship and celebrity accessories, you know all sorts of other reasons. You have seen an explosion in these weird and wonderful types of dogs over the last few hundred years, so just by changing selective pressure, you can get very rapid change in evolutionary terms.
Just by breeding individuals that have the traits that you like, you can retain those ones and get rid of ones that you don't.
What I would call directed evolution in the lab is exactly the same thing, but it’s at a molecular level. We can use the same tricks of introducing variation to just a single gene and selecting for improvements in the protein or enzyme that's encoded by that gene.
- 05 December 2008
- The University of Waikato