Stockholm, Sweden - American scientists Victor Ambros and Gary Ruvkun won the Nobel Prize in Medicine on Monday for their discovery of microRNA and its role in how genes are regulated.

Understanding the regulation of gene activity has been an important goal for decades, the Nobel jury said.

If gene regulation goes awry, it can lead to serious diseases such as cancer, diabetes, or autoimmunity.

"Their groundbreaking discovery revealed a completely new principle of gene regulation that turned out to be essential for multicellular organisms, including humans," the jury said.

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Collaborating but working separately, the pair conducted research on a 1 millimeter roundworm, C. elegans, to determine why cell mutations occurred and when.

They discovered microRNA, a new class of tiny RNA molecules that play a crucial role in gene regulation, which in turn allows each cell to select only relevant instructions.

Their findings were published in two articles in 1993.

"The seminal discovery of microRNA has introduced a new and unexpected mechanism of gene regulation," Thomas Perlmann, secretary general of the Nobel Assembly, told reporters.

"MicroRNAs are important for our understanding of embryological development, normal cell physiology and diseases such as cancer," he said.

Ambros (70) is a professor at the University of Massachusetts medical school while Ruvkun (72) is a professor at Harvard Medical School.

The pair will receive their Nobel prize, consisting of a diploma, a gold medal, and a $1-million check, from King Carl XVI Gustaf in Stockholm on December 10, the anniversary of the 1896 death of scientist Alfred Nobel who created the prizes in his last will and testament.

Last year, the medicine prize went to Katalin Kariko and Drew Weissman for work on messenger RNA (mRNA) technology that paved the way for Covid-19 vaccines.

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The Nobel season continues this week with the announcement of the winners of the physics prize on Tuesday and the chemistry prize on Wednesday.

They will be followed by the much-anticipated prizes for literature on Thursday and peace on Friday.

The economics prize winds things up on Monday, October 14.

Awarded since 1901, the Nobel Prizes honor those who have, in the words of Alfred Nobel, "conferred the greatest benefit on humankind."

For Tuesday's Nobel Prize in Physics, Swedish public radio SR's science experts suggested the honor could go to Swiss physicist Christoph Gerber, a pioneer in the development of the atomic force microscope.

"This is a microscope that gives 3D images on such an incredibly small scale that they sometimes are even atomic resolution," said SR science reporter Camilla Widebeck.

The tool has become indispensable in nanotechnology and nano research, she added.

The Clarivate analytics group also highlighted David Deutsch and Peter Shor for their work on quantum algorithms and quantum computing.

Speculation is also rife for the literature prize, to be announced on Thursday and perhaps the most highly anticipated Nobel after the peace prize.

Several pundits believe Chinese author Can Xue will be the Swedish Academy's choice this year – and she has the lowest odds on several betting sites. An avant-garde fiction writer often likened to Kafka, her experimental style flips between utopia and dystopia and transforms the mundane into the surreal.

"I think it will be a woman from a language zone outside Europe," Bjorn Wiman, culture editor at Sweden's newspaper of record, Dagens Nyheter, told AFP.

Others suggest it could go to Australian novelist Gerald Murnane, Britain's Salman Rushdie, or Kenya's Ngugi wa Thiong'o.

The climax of the week comes Friday when the Nobel Peace Prize laureate is announced, but experts say predictions are harder than ever this year due to the growing number of crises in the world.

The UN agency for Palestinian refugees UNRWA, the International Court of Justice, and Afghan women's rights activist Mahbouba Seraj have been mentioned as possibilities.

Given the existential risks to humanity posed by weapons systems that can operate autonomously without human control, several Nobel-watchers have also cited the Campaign to Stop Killer Robots as a potential laureate.