Carol Clemmer stared, mystified, at the computer images captured by her super-powered microscope.
The more Clemmer, a University of Utah graduate student in chemistry, studied the images, the more characteristics she viewed of what appeared to be the double-helix structure of DNA.But Clemmer, 24, knew she hadn't put a molecule on the graphite, the surface researchers routinely use as a background for microscope images of DNA, the master molecule of life.
It was a puzzle. Imagine getting some film developed and seeing a long-dead relative among the family members in the photos of your last reunion. You know they couldn't have been there slurping the Jell-O salad - but it's hard to argue with photographic evidence.
Clemmer's ghost was DNA. She hadn't taken a picture of it, as this was supposed to be a control slide, but the repeating spiraled pattern was hard to dispute.
After examining the images, she figured the spirals must be characteristics - or artifacts - of the graphite surface itself. It was a light-bulb-over-the-head moment that prompted her to show the computer pictures to her research instructor, assistant U. chemistry professor, Thomas Beebe, Jr.
Beebe was part of a team of San Francisco researchers who gained attention two years ago by being the first to use the scanning tunneling microscope to produce direct pictures of DNA. He was the lead writer on an article detailing the work published in November 1988 in Science, a prestigious journal.
"Wow, those are beautiful," was Beebe's first reaction when Clemmer showed him her images. "That looks better than anything I've ever seen published as DNA."
Then Clemmer delivered the kicker. "By the way, I didn't put any biomolecules on the surface."
Because of Clemmer's discovery, she and Beebe combined to write a new Science paper, published last week, suggesting that graphite isn't the best backdrop for DNA photographs. The paper is titled: "Graphite: A Mimic for DNA and other Biomolecules in Scanning Tunneling Microscope Studies."
Beebe said the new paper isn't meant to contradict his group's previous work, or the research of others, but to recommend other surfaces for DNA studies that don't have the imaging complications of graphite. In current research, he is exploring gold and other surfaces.
The handful of specialized researchers who work in the field are aware of the characteristics of graphite surfaces, Beebe said, but other scientists might not be. "We have to be more critical of things that are being published on graphite. I do think it's going to be a very powerful technique on other surfaces."
Gene research, especially studying the mysteries of genetic diseases, is currently one of the Holy Grail quests of science. And DNA is a concept that has captured the imagination of the public, as well.
It's only been in the past two years that researchers have been able to view direct images of DNA, the master molecules that determine the body's hereditary patterns.
The new images have come thanks to a scanning tunneling microscope, a super-powered instrument with a sharp stylus that traces the shape of a surface as it moves across it, similar to the way a phonograph needle reads a record. Measurements from the instrument, which uses electrons to "see" instead of light, are then compiled into a computerized image.
Researchers hope to use the super microscope to eventually unlock structural information about genes, about how traits are passed from one generation to the next.