Last week, I wrote a piece about nanopore sequencing, a revolutionary technique that could one day allow anyone to sequence DNA anywhere, bringing the world of genetics into classrooms, living rooms, and space stations. In the piece, I noted that David Deamer reputedly came up with the idea for the technique while driving down California’s Interstate 5, and was so struck by it that he had to pull over to jot it down. Deamer got in touch to say that he liked the piece, and sent a scan of the very notebook entry in which he sketched out his idea. This is the first time that both pages have been published together, and they show how fully-formed the concept already was in Deamer’s head. As I wrote in my piece:
A nanopore is exactly what it sounds like: a small hole. Typically, it’s a tiny peg-shaped protein with a hollow tube at its core, just a few billionths of a meter wide. In Oxford Nanopore’s devices, the protein sits in a synthetic membrane, submerged in liquid. When a voltage is applied across the membrane, ions flow through the pore, creating an electric current. But if something blocks the pore—say, a strand of DNA—the ions are impeded and the current drops. The four building blocks (or bases) of DNA—A, C, G, and T—each change the current through the nanopore in different ways. By measuring that current, you can decipher the sequence of a DNA strand as it threads through the pore like a piece of ticker-tape.