- Person
- Walter Gilbert
- Lived
- b. 1932
- Field
- Molecular biology
- From
- American
The story
Walter Gilbert was born in Boston in 1932 into a Jewish family. Trained as a theoretical physicist, he switched to molecular biology at Harvard in the early 1960s after James Watson invited him to join an experiment on messenger RNA. By the mid-1970s he was one of the leading figures in the young science of how genes work.
At that time, scientists knew that the instructions in a gene are written in a four-letter chemical code, the bases A, C, G and T strung along the DNA molecule. But reading that code was extremely slow. Working out even a short stretch of sequence could take a laboratory months or years.
In the mid-1970s Gilbert and his graduate student Allan Maxam developed a faster, chemical approach. A piece of DNA is labelled at one end with a radioactive tag. It is then divided into four portions, and each portion is treated with chemicals that break the DNA next to one or two particular bases (G, A or G, C, and C or T). The fragments from the four reactions are run side by side on a gel that separates them by size. Because every labelled fragment starts at the tagged end and stops at a known kind of base, reading the ladders of bands from the shortest to the longest spells out the sequence. Their paper, A new method for sequencing DNA, appeared in the Proceedings of the National Academy of Sciences in 1977.
At almost the same time, Frederick Sanger in Cambridge developed a different method that worked by copying DNA. In 1980 Gilbert and Sanger shared half of the Nobel Prize in Chemistry for their contributions concerning the determination of base sequences in nucleic acids. The Maxam–Gilbert method became the first widely adopted way to sequence DNA, because purified DNA could be used directly, before Sanger's approach, which was easier to automate, became the standard. In 2017 the American Chemical Society honoured the 1977 paper with a Citation for Chemical Breakthrough.
Gilbert went on to become one of the first scientists to argue, in 1986, that the entire human genome should be sequenced, a goal achieved by the international Human Genome Project in 2003. The ability to read DNA that he and Sanger pioneered is the foundation on which that project, and all of modern genomics, was built.
Why it matters
DNA sequencing, which Gilbert helped make practical, is now used every day to diagnose inherited diseases, guide cancer treatment, solve crimes and track new viruses.
About Walter Gilbert
Harvard physicist turned biologist who co-invented an early way to read DNA, co-founded the biotech company Biogen and was among the first to call for sequencing the human genome. Nobel Prize 1980.
Sources
- Walter Gilbert, Biographical NobelPrize.org
- Press release: The Nobel Prize in Chemistry 1980 NobelPrize.org
- Maxam–Gilbert sequencing Wikipedia
- Walter Gilbert Wikipedia
Another act of tikkun olam. This is part of tikkun olam, the Jewish idea of repairing the world, and every one of us can add to it.