ATHENS, Ga. -- Genes are the on-off switches in plants and animals, directing everything from growth to fighting disease. Until a mere 50 years ago, scientists thought all genes worked from a stable position along a chromosome. Then, a brilliant researcher named Barbara McClintock (who was to win the Nobel Prize) showed that some genes actually move around.
These genes, which scientists now call transposable elements or transposons, have been found in vast numbers in virtually every organism researchers have studied. And yet their role has been the subject of considerable discussion and even controversy. The question remains: Are transposable elements merely self-replicating "junk" DNA as some researchers suspect, or do they contribute to the function and evolution of the organisms in which they reside?
Now, a molecular biologist at the University of Georgia has proposed that transposons may play a crucial and central role in evolution and could be the "missing link" in our understanding of how multicellular and vertebrate organisms arose.
"The whole idea of transposons as purely selfish DNA is beginning to crumble," said John McDonald, a professor in the department of genetics at UGA, "It now appears that at least some transposable elements may be essential to the organisms in which they reside. Even more interesting is the growing likelihood that transposable elements have played an essential role in the evolution of higher organisms, including humans."
McDonald has studied and published papers on transposons for more than 10 years. His new theory was published in the March issue of the journal Trends in Ecology and Evolution, which will be released this week.
For years, researchers believed that transposable elements were simply
pieces of rogue DNA, barnstorming through the cellular world like petulant
children, causing the misexpression of other genes and, in general, looking out
for num
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Contact: John McDonald
mcdonald@bscr.uga.edu
706/542-8109
University of Georgia
9-Feb-1998