Tiny molecules control life processes.

• Position: Microbiology

Researchers at Oregon State University, Corvallis, have made a very important advance in the understanding of "micro-RNA" molecules, which are tiny bits of genetic material that were literally unknown 10 years ago, but now represent one of the most-exciting fields of study in biology. They reveal for the first time a new mechanism by which micro-RNA can stop the function of messenger RNA by literally cutting it in half, thus interfering with the normal function of messenger RNAs in gene expression. This "expression" of genes that code for essential proteins is ultimately what controls whether a cell turns into a lung, liver, brain, or other cell. Understanding what activates this process--or stops it--is a key to understanding the biological process of life itself, and forms the foundation for advances in medicine, agriculture, and other fields.

On this frontier of biology, experts say, the most-intriguing new component is micro-RNA, a miniscule type of regulatory molecule that once had seemed quite insignificant even in the extraordinarily tiny, microscopic world of cell biology. The first micro-RNA, in fact, was just discovered in 1993 and at the time was thought to be a biological oddity in worms. A couple of hundred have since been found in plants and animals. Yet, it has only been in the past several months that scientists working in this area have come to understand the potentially profound importance of micro-RNA.

"For a long time, people really did not know that these micro-RNAs were even there," notes James Carrington, director of the university's Center for Gene Research and Biotechnology. "They were under the radar, and observations of them were limited by our technology. But as we learn more about these regulatory molecules, we're beginning to understand the scope of their biological importance. In molecular biology, micro-RNAs are clearly one of the top two or three discoveries of the past decade."

Every normal cell in complex organisms, such as plants, flies, and humans, has a complete copy of the DNA for the entire organism--some 15,000 to 35,000 genes that...