When Harvard Medical School professor Gary B. Ruvkun started researching the development of roundworms 20 years ago, he had no idea that the tiny genes of their ribonucleic acid—DNA’s chemical cousin—would map out a new field of biology.

It was this accidental discovery of the genes’ importance that led scientists to explore the previously unknown universe of what is known as micro-RNA (miRNA).

In recognition of his work on miRNA, Ruvkun won this year’s Lasker Award for Basic Medical Research—a prize he shares with his fellow researchers, Victor R. Ambros, a professor at the University of Massachusetts Medical School in Worcester, and David Baulcombe, who teaches at the University of Cambridge.

Japanese scientist Akira Endo received the clinical medical research prize and microbiologist Stanley Falkow of Stanford claimed the special achievement award.

The three Lasker Awards—known informally as the “American Nobel Prizes,” because 75 laureates have gone on to receive the Nobel Prize in Physiology or Medicine—will be presented at a ceremony featuring New York City Mayor Michael R. Bloomberg as the keynote speaker on Sept. 26. The prize in each category is $300,000.

Ruvkun and his co-recipients found that miRNAs—long regarded as far less versatile players in gene activity—play a significant role in governing growth and development in animals and plants. This discovery could have implications for diseases such as viral infections, heart failure, and cancer, as well as shed light on normal functions like muscle action.

“Who knew that such small RNAs would have such a critical role in regulating biological processes in animals and plants?” Lasker Foundation President Maria C. Freire said in a statement, adding that scientists had long believed that proteins—not RNAs—regulated gene activity in animal cells.

In light of the researchers’ work with miRNAs, Ruvkun, who received a Ph.D in biophysics from Harvard, said that scientists are now shifting their attention to smaller genes that otherwise might not have been studied. Recent research suggests an increasing awareness of the role of these genes, as over 500 miRNAs contained in the human genome may control a third of protein-coding genes.

“The most important thing is it sort of revealed a world of regulation that was mediated by smaller genes that we’ve never envisioned before,” Ruvkun said. “It’s sort of a lens through which one can view biology now.”

Previously, Ruvkun added, the smallest RNA known to be of importance in cells consisted of 75 nucleotide building blocks. The miRNA they worked with was composed of 22 nucleotides.

Twenty years ago, Ruvkun and Ambros, then fellows working in the laboratory of MIT professor H. Robert Horvitz, began studying the genes that control the development of the Caenorhabditis elegans, a 1 mm-long roundworm that biologists often use as a model organism, from newly-hatched larva to fully-grown adult.

Ruvkun said that it took approximately 10 years to “sniff around the whole thing” to unearth the genetic regulatory role of miRNAs in worms and another decade to confirm that these genes execute similar functions during growth and development of other creatures including humans, fruit flies, frogs, and sea urchins.

The next step for scientists in this new field, Ruvkun said, is figuring out exactly how the miRNAs work.

—Staff writer June Q. Wu can be reached at junewu@fas.harvard.edu.