Wednesday, October 29, 2003
The yeast and the cockroach -- a spy tale
Meet the future of biological and chemical espionage: yeast and cockroaches.
Odd as the combination sounds, it could be the building block of a new, inexpensive spy device -- one that could sneak into a building and sense chemicals or biological agents, said Jeff Brinker, a Sandia National Laboratories scientist and professor at the University of New Mexico.
"Cockroaches are robust -- they can go into environments that humans can't withstand," Brinker said. "You could attach a sensing device onto the back of a cockroach and send it into a place where you suspect they're making chemical weapons.
"If you can go in covertly, you can collect evidence without anyone getting spooked."
Who needs the CIA when you've got cockroaches? As for the sensing device, Brinker said, that would be made of yeast.
"Yeast functions like a canary in a coal mine," said Helen Baca, a doctoral student working with Brinker. "If yeast cells are exposed to dangerous chemicals, they change and die. You can actually genetically modify yeast cells so when something specific happens to them, they change color."
Brinker and Baca are creating genetically modified yeast cells that can stay alive for days attached to the back of a cockroach -- or a cockroach-sized robot.
"Inside each yeast cell is a marker that turns green if it is exposed to a particular chemical," Brinker said. "They have optical radar where you can shoot a beam at the cockroach, and if a chemical triggered any of the yeast cells, it would be able to see the green fluorescent marker."
Keeping the yeast sensors alive isn't all that easy. The cells need a constant supply of water and nutrients, which is hard to supply on the back of a cockroach.
"The Sol-Gel creates an environment like a tiny reservoir that can store an influx of nutrients," he said. "It maintains the hydrated environment, and to our surprise we found the yeast actually seems to develop a symbiotic relationship with the host material."
In other words, the yeast appears to eat a portion of the Sol-Gel, and the Sol-Gel keeps the yeast alive.
"We've had it survive for three days that way," Baca said. "It looks like there's the potential for them to last a lot longer than that."
And she means longer as in hundreds of years. That's because yeast becomes dormant when it is deprived of water and nutrients.
While it couldn't be used as a sensor in its dormant state, a quick drop of nutrients could suddenly bring the yeast back to life for its next mission, Brinker said.
"These yeast sensors can be applied to things by all kinds of interesting techniques," he said. "We've created an ink jet cartridge for a printer that can print out arrays of yeast in Sol-Gel droplets."
A printed page of yeast sensors could be taped or glued to the back of a cockroach or robot. It might even be used in unusual medical devices.
Say the yeast is engineered to detect human disease. Then a doctor could print up a yeast card, have a patient breathe on it and determine what illness the person has, Brinker said.
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