Searching for the Genome's Second Code

摘要

The genome has more than one code for specifying life. The hunt for the various types of noncoding DNA that control gene expression is heating up Molecular biologists may have sequenced the human genome, but it's going to take molecular cryptographers to crack its complex code. Genes, keystones to the development and functioning of all organisms, can't by themselves explain what makes cows cows and corn corn: The same genes have turned up in organisms as different as, say, mice and jellyfish. Instead, new findings from a variety of researchers have made clear that it's the genome's exquisite control of each gene's activity—and not the genes per se—that matters most. "The evolution of the genetic diversity of animal forms is really due to differences in gene regulation," says Michael Levine, an evolutionary biologist at the University of California (UC), Berkeley. Turning on a gene at a different time, or in a new place, or under new circumstances can cause variations in, say, size, coloration, or behavior. If the outcome of that new regulatory pattern improves an organism's mating success or ability to cope with harsh conditions, then it sets the stage for long-term changes and, possibly, the evolution of new species.