The discovery of a previously unknown type of genetic material and a new technique for taking three-dimensional pictures of cells promise to advance our understanding of biology and generate new treatments for disease. These are among the top scientific breakthroughs in 2002 as identified by the editors of the U.S. research journal Science.

Science magazine's choice for the top breakthrough of 2002 is the discovery that molecules called small RNAs control many of the genetic workings in cells. Scientists had believed that RNA, the genetic cousin of the better known DNA, did little more than execute DNA's commands to assemble proteins, which are needed to carry out life processes.

Science magazine senior editor Phillip Szuromi says the new understanding of RNA uncovers new leads for treating diseases caused by errors in genes.

"So this impacts on development, it impacts on things like cancer because this is a new mechanism for how cells regulate themselves," he said. "So this is one of those basic building block things that you really have to understand if you are going to understand biology and come up with medical advances."

Several recent studies have shown how small RNAs switch various genes on and off, trim away unwanted sections of DNA, and herd DNA into the right configuration during cell division.

The year's research suggests that certain diseases may occur when RNA processes go bad. The deputy life sciences editor for Science magazine, Katrina Kelner, says controlling these processes may become a new way to treat the illnesses.

"Potentially, it could be used therapeutically to turn off genes or other biochemical cellular processes that have gone awry in disease, as in cancer or inflammation," she said. "It has proven to be so useful in the laboratory it's my suspicion that it will prove to be very useful in the clinic as well."

Another biological breakthrough in 2002 involved a new technology for taking three-dimensional pictures of cells, providing added insights into how they carry out basic life processes. Phillip Szuromi says that, like a doctor's CT scan, a computer builds a 3D image of a cell from a series of image slices created by penetrating electron beams.

"Most of our techniques for looking at biomolecules tend to look at the isolated biomolecules," he said. "But that's not what it looks like in a cell. It's important not only to know what molecules are there, but how they interact with each other."

Other researchers using a different imaging technique caught a glimpse of electrons whizzing in their orbits around nuclei of atoms.

"It's just reassuring that they are doing what they are supposed to do," Mr. Szuromi said.

The high-speed imaging technique relies on ultra-short pulses of laser light, billionths of a billionth of a second, to freeze motion in a series of frames to make a movie of the whirling electrons.

In astronomy, telescopes used a technology called adaptive optics in 2002 to find the best evidence yet of a black hole in our Milky Way galaxy and a volcano on Jupiter's moon Io. The technology erases the blurring effect of Earth's atmosphere by flexing thousands of tiny, thin mirrors hundreds of times each second, countering the atmosphere's flux.

A telescope that views the universe in microwaves saw in greater detail than ever the faint afterglow of the Big Bang, the theoretical origin of the universe. It revealed the smallest structures yet seen in the forming universe, essentially hotspots where matter was gathering into what would become stars, galaxies, and other objects.

In solar physics, research in 2002 settled a mystery about neutrinos, some of the least understood particles in the universe. Scientists found that one of the three neutrino varieties, the electron neutrino, reaches Earth in smaller than expected quantities from the sun because they often change into the other types enroute.

"That might seem really arcane, but we don't really understand why the sun changes its output, how much energy it produces year to year," said Phillip Szuromi. "There's very good evidence that long term climate change depends on very short term, small changes in the output of the sun."

2002 also brought greater knowledge of how we sense things. Researchers found proteins in mouth and skin cells that make some spices feel hot and breath mints taste cool. The results might help us understand how the nervous system sends impulses to the brain.

Science editor Katrina Kelner tells of the discovery of a class of cell in the eye that does not see light but still reacts to light to send signals to our brain to set the body clock.

"It's the solution of a very longstanding problem, which is that blind people still respond to the light-dark cycle of 24 hours," he said. "That has been very, very mysterious."

As another top discovery of 2002, Science magazine cited the unearthing in West Africa of a six or seven million-year-old skull with both ape and human features. It pushed back the date of the earliest known human ancestor by more than three million years.

Part of VOA's Yearend Series