U.S. researchers say they've created synthetic biological circuits from bacterial cells that not only perform logic functions but also remember the results.

Engineers at the Massachusetts Institute of Technology say the results of the functions are encoded in the cell's DNA and passed on for dozens of generations.

Synthetic biologists said they use interchangeable genetic parts to design circuits that perform a specific function, and such circuits could be used as long-term environmental sensors, in biomanufacturing or to program stem cells to differentiate into other cell types.

In most of the previously engineered cellular logic circuits, the MIT researchers said, the end product is generated only as long as the original stimuli are present; once they disappear, the circuit shuts off until another stimulus comes along.

Timothy Lu and his colleagues set out to design a circuit that would be irreversibly altered by the original stimulus, creating a permanent memory of the event.

"Almost all of the previous work in synthetic biology that we're aware of has either focused on logic components or on memory modules that just encode memory," Lu said. "We think complex computation will involve combining both logic and memory, and that's why we built this particular framework to do so."

The study has been reported in the journal Nature Biotechnology.