A breakthrough—sex is unnecessary!

When genes correct themselves, especially when they shouldn't March 23, 2005
The most misused word in science journalism is "breakthrough." I'’ve flunked papers in journalism classes that use the word because real breakthroughs in science are extremely rare, and the word ought to be reserved for findings that shift paradigms or something. We may, however, actually have one now. Researchers at Purdue University, reporting in Nature, have found plants with the ability to revert to a backup version of its genes in order to correct mutations. If this stands up, it would be a major exception to what everyone thought they knew about the rules of inheritance since Gregor Mendel. The plants, arabidopsis (the fruit-fly of plant biology), had parents both containing mutated genes, called hotheads, that produced clumped petals instead of normally formed ones. According to the rules, there would be no way those plants would not have clumped petals. But 10% did. And when Robert E. Pruitt and Susan J. Lolle and colleagues went back to look, they found no DNA copy of the correct genes. The plants had apparently stored a backup somewhere, possibly in RNA, and reverted to it rather than produce abnormal petals. No one has a clue how. Interestingly, other scientists had seen this happen before and simply assumed they had screwed up and the reversion was due to contamination or goofy procedures. But the Purdue scientists persisted. Now, if evolution depends on mutations to move ahead, here is a potential brake on the process, complicating things. Presumably, it is a rare event. And if it works on plants, how about humans? And does this really mean that sex is unnecessary (a line we’ve all heard at one time or another)? One rationale for sexual reproduction is that by combining two sets of genes, really bad mistakes are avoided. This should invoke yet another rule of science: the findings have to be replicated. Interestingly, neither Nick Wade in the New York Times nor Rick Weiss in the Washington Post, writing about the findings, reported any skeptics. They quoted researchers not involved with the work as saying they were surprised and amazed, and seemed thoroughly tickled by the findings, and they projected that it might be true in humans and might open all kinds of doors. An actual breakthrough?