WASHINGTON — Ingenious new devices able to see things faster and smaller than ever before are providing scientists with striking, 3-D color movies of atoms, molecules and living cells in action.
"We can watch the brain think, develop, age, deal with disease. We can see neurons grow inside the living brain," said Dr. Jeff Lichtman, a neurobiologist at the Washington University School of Medicine in St. Louis. "It's like a movie camera."
While biologists use their new instruments to observe cells, chemists use another new technology to track the motions of the infinitesimal particles — electrons, protons and neutrons — that make up an atom. To do so, they use an advanced laser strobe light that slices time into the shortest bits yet achieved —"attoseconds": a billionth of a billionth of a second.
The technology is like the familiar stop-action photography, freezing a speeding bullet or baseball in flight, but billions of times faster. There are more attoseconds in a minute than there have been minutes since the birth of the universe.
"In attoseconds, we can see electrons move," said Richard Loomis, a Washington University chemistry professor.
Robert Shull, an expert at the National Institute of Standards and Technology in Gaithersburg, Md., said, "We can count electrons one by one."
On a somewhat larger — but still microscopic — scale, biologists can peer into the nucleus of a living cell and spy on the interaction of proteins, the basic building blocks of every organism.
"We're watching the dance of the proteins in action," said molecular biologist David Piwnica-Worms, also at Washington University.
For example, Douglass Forbes, a biologist at the University of California, San Diego, has made movies of proteins shuttling cargo in and out of the nucleus of a cell through miniature, doughnut-shaped pores.
"They're like small spaceships for nuclear transport," Forbes said.
Scientists hope these sensitive new technologies will help detect disease in its earliest stages and develop more effective drugs and treatments.
"We can directly map where a drug goes in the body," Piwnica-Worms said. "We can determine if a patient is drug-resistant or not and tailor his or her therapy to that."
|Time's tiniest units
Here are the names of time's smallest units:
- Millisecond - 1/1,000 of a second
- Microsecond - 1/1,000 of a millisecond
- Nanosecond - 1/1,000 of a microseconds
- Picosecond - 1/1,000 of a nanosecond
- Femtosecond - 1/1,000 of a picosecond
- Attosecond - 1/1,000 of a femtosecond
- Zeptosecond - 1/1000 of an attosecond
In the past, he said, doctors treated different kinds of cancer tumors with the same kind of chemical poisons, hoping that 20 percent of them would respond. In the new "tailored therapy" approach, drugs can be targeted at specific cancer-causing genes in an individual.
Lichtman's movies of nerve fibers growing in mice reveal a furious competition among several neurons to connect to a target cell. One neuron wins the race and establishes a connection; the others weaken and disconnect.
"These are phenomena that have never been seen before. We are quite excited," he said.
In an e-mail message, Lichtman said his images show how a brain changes as it learns from experience.
"The nervous system of animals like us is not pre-ordained to do particular tasks," he explained. "We need to learn how to talk, play hopscotch, the violin, etc. The way we do this is by selecting among an initial large repertoire of connections. The selection causes some connections to get stronger and the rest to wither away."
Because of its practical as well as scientific value, the federal government plans to invest $850 million this year in the "quest for smallness and speed," said Mihail Roco, head of the administration's National Nanotechnology Initiative. Nanotechnology refers to work with objects ranging in size from one billionth to about 100 billionths of a meter — the realm of atoms and molecules.
These faster, smaller imaging techniques are challenging standard textbook descriptions of how cells work, said Andrew Belmont, a cell biologist at the University of Illinois, Urbana-Champaign.
"Our view has changed the last few years because of our ability to look at living cells," he said. "In the past, we had to tear up cells to study them."
Belmont noted that biologists used to think that the nucleus of a cell was relatively static. Now they can see that its components are constantly moving and shifting in response to signals from its environment. This turbulence might be a clue to the causes of cancer and aging, he said.
On the Web
For more information about nanotechnology: www.nano.gov
For more information about attosecond laser technology: http://physicsweb.org/article/world/13/02/5.
Copyright © 2003 Knight Ridder/Tribune Information Services. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.