Genetics and evolution in a test tube
In 1901, the field of genetics was still young. For decades, people had been interested in the concept of heredity, but the early 1900s ushered in a new era of genetics—one fueled by the desire to understand how genes affect humans. 1901 was also the year in which the first Nobel Prize was awarded. Since that time, more than 530 Nobel Prizes have been awarded, many of which were presented to scientists whose work involved genetics.
This year’s ceremony was no different. Earlier this week, Dr. Frances H. Arnold, Dr. George P. Smith, and Sir Gregory P. Winter were awarded the Nobel Prize in Chemistry for the development and use of “evolution in a test tube.”
In 1859, Charles Darwin published On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. In it, Darwin put forth the idea of evolution through natural selection. He reasoned that animals had natural variations in their traits—feather color, beak length, petal shape—which could be either helpful, or harmful. If the variation was helpful, the animal was more likely to reproduce and successfully pass on its helpful trait to future generations. If it was harmful, the animal was not likely to survive long enough to pass on its harmful trait. This process, carried out over long periods of time, could cause a population to evolve.
More than a century later, Dr. Frances Arnold used Darwin’s theory of evolution to revolutionize synthetic biology. All living things have enzymes—proteins that help catalyze chemical reactions. Long ago, we realized that enzymes could be used to help produce valuable chemicals like biofuels and pharmaceutical drugs. However, the enzymes we needed either didn’t exist, or weren’t capable of working in the way we needed them too. That’s when Dr. Arnold came along.
Dr. Arnold took advantage of a long-used research tool: bacteria. Her research team inserted a gene in the bacteria coding for an enzyme they wanted to modify. They then used special techniques to cause random mutations in the bacteria, that resulted in each bacterial cell containing a potentially unique mutation that could affect how the enzyme was made. After testing the mutated enzymes, they selected the bacteria which produced a better enzyme. They then repeated the process until they had optimized the enzyme. To put it another way, Dr. Arnold and her team were selecting for the best enzymes and causing rapid evolution. This method has led to a boom in our ability to produce biofuels, pharmaceutical drugs, and much more.
In a similar way, Dr. Smith and Sir Winter applied evolution to the development of immunotherapies. Cells in our immune system produce a type of protein known as an antibody. These proteins help the body recognize the “self” from the “non-self.” That is, these proteins help identify bacteria or other objects that are foreign to the body. Once detected, our immune system can begin to eliminate them. Antibodies can thus serve as a powerful way to activate the immune system against particular targets. Dr. Smith and Sir Winter developed a method using viruses in the same way that Dr. Arnold used bacteria. By inserting antibody-producing genes into viruses, they could selectively grow viruses that made the antibodies they wanted. This method has since been used to produce antibodies that help fight arthritis, anthrax, and cancer.
The Nobel Prize reminds us to look back into history and see how far we’ve come. We look forward to seeing what next year has in store!