Tag Archives: Dr. Niles Lehman

The Selfish Gene by Richard Dawkins portrayed the genes as if they were acting selfishly. But is that really the whole story? Nature published on http://www.nature.com/nature/journal/vaop/ncurrent/full/nature11549.html the research of Chemistry Professor Dr. Niles Lehman and his student, Nilesh Vaidya, that may shed light on the origins of life on earth.

Cooperation may have been given an evolutionary advantage. Present in all living cells, most RNA today translates genetic information stored elsewhere in the cell, specifically in DNA. However, in early life, RNA was the principal material for storing and replicating genetic information.

Defining life as the ability to replicate oneself while maintaining and evolving biological information, the team showed how networks of cooperating RNA molecules would have had a competitive edge over self-replicating RNA. As the cooperative networks evolved, it highlighted the advantages of cooperative behavior even at the molecular stages of nascent life.

Niles Lehman and colleagues created three RNA molecules that could repair each other – A did B, B did C, and C did A. When the team put these broken molecules together in a test tube, the collective network worked well. When they pitted the cooperative network against a selfish, self-repairing molecule, the cooperators won out.

Although earlier studies showed that pairs of molecules can cooperate, Lehman is the first to create a network of 3, opening the door to much larger networks. “If you can go from 2 to 3, you can go from 3 to infinity,” he says. Lehman repeated the study with 48 different fragments of an RNA molecule. Sure enough, they assembled into a network that eventually included all 48.

Such cooperation may have arisen early in the RNA world and helped to build complexity, says Gerald Joyce of the Scripps Research Institute in San Diego. “It’s an experimental demonstration that real molecules can do this,” he says.

Cooperating RNA networks might have an even greater advantage if the component molecules could cluster together in space.

To show this, Philip Bevilacqua and colleagues at Penn State University in University Park studied an RNA called a “hammerhead ribozyme” that cuts itself into pieces. They helped the RNAs to cluster by putting them into a solution containing both dextran and polyethylene glycol. These two compounds separate instead of mixing, causing the ribozyme, which is more soluble in the dextran portion, to become more concentrated.

They found this increased the RNA’s reaction rate about 70-fold. Something similar – a pore on a rock surface, say, or a slime layer – could have given prebiotic molecules a boost as life got started, says Joyce.

Contrary to the notion that competition (Selfish Gene being one example) was the prevalent means by which life evolved, the study suggests that cooperation may have played a key role in the emergence of life.