Generally, DNA is only good for preserving and passing on blueprints for making organisms. However, scientists at MIT and Boston University have altered E. coli DNA to perform another function within the cell, like basic computing. Essentially, they’ve taught E. coli to count.
As reported in the latest issue of the journal Science, researchers have created circuits within the E. coli genome that can do simple computing like incremental counting. But rather than trying to replace regular electric circuits, the scientists want to use the modified cells as a biological clock that could do everything from measure the levels of toxicity in an environment to putting a definitive lifespan on a genetically modified organism.
The circuits work by creating a cascade of enzyme production. The genome is programmed to react to stimuli like the division of the cell or the presence of a chemical in the environment. Each time the cell engages the stimulus, the programmed gene creates the enzyme to unlock the next gene in the cascade. As long as the stimulus keeps occurring, the cascade continues.
The genes are programed to run for a certain number of stimuli, and at the end, the final gene creates a new enzyme that performs the program’s function, like killing the cell or producing a signal to the researchers.
Right now, the genetic circuits can only count up to 100, but researchers hope to expand the count number, the possible end functions, and the timing between each tick of the genetic clock.