Cambridge, Mass. -- U.S. scientists have discovered that in certain DNA sequences, both strands of a DNA segment can perform useful functions.

Massachusetts Institute of Technology Professor Manolis Kellis and postdoctoral researcher Alexander Stark said they determined each DNA strand encodes a distinct molecule that helps control cell functions.

The discovery builds on a similar finding about microRNA regulation. In December, Stark and Kellis reported both arms of a single microRNA hairpin can also produce distinct, functional microRNAs, with distinct targets. The researchers said the two findings suggest a single gene can encode as many as four different functions -- one hairpin from each of the two DNA strands and one microRNA from each of the two arms of each hairpin.

The scientists said their findings are the latest example of the power of using computational tools to investigate the genomes of multiple species, known as comparative genomics.

"This represents a new phase in genomics-making biological discoveries sitting not at the lab bench, but at the computer terminal," Kellis said.

The research was reported in the Jan. 1 issue of the journal Genes & Development.

Copyright 2008 by United Press International.