CONTINUOUS IN-VITRO EVOLUTION OF CATALYTIC FUNCTION

A population of RNA molecules that catalyze the template-directed liga tion of RNA substrates was made to evolve in a continuous manner in th e test tube. A simple serial transfer procedure was used to achieve ap proximately 300 successive rounds of catalysis and selective amplifica tion in 52 hours. During this time, the population size was maintained against an overall dilution of 3 x 10(298). Both the catalytic rate a nd amplification rate of the RNAs improved substantially as a conseque nce of mutations that accumulated during the evolution process. Contin uous in vitro evolution makes it possible to maintain laboratory ''cul tures'' of catalytic molecules that can be perpetuated indefinitely.