November 28, 2001
Lewis at 'Berg -- a force to reckoned with
By Cathy Willoughby
Staff Writer
Gravity is the most powerful force natural in the universe.
The effects of gravity, or the lack of it, on living organisms was shared by biologist Marian Lewis at Heidelberg College Tuesday morning.
Her work in microbiology have resulted in her experiments being conducted on 14 NASA space flights, including the Discovery flight manned by John Glenn.
The talk by Lewis, a research professor in the department of biological sciences at the University of Alabama in Huntsville, was sponsored by the Honors Program and the Religious and Cultural Life Committee.
She began by taking the students and faculty gathered in Rickly Chapel on a "flight to the moon.''
"Welcome to Moonbase,'' she said. "You will be here for one year. How will we adjust?''
"Will sleep patterns change?'' she asked them. "Will our interactions with other people change? Would we be able to grow our own food?''
The moon, which is one fourth the size of Earth, has only one sixth the gravitational force. A 100-pound person would weigh 16 pounds on the moon and be able to jump much higher.
"My research is conducted in the absence of gravity,'' Lewis said. "Gravity is always attracting. It binds the surface of the earth. It weakens with distance, yet is still a dominant force in the universe.''
The space shuttle is really on a "low earth orbit'' 150 to 300 miles above the earth's surface, Lewis said, using gravity to keep it in a constant freefall around the earth.
At liftoff, a space shuttle astronaut feels a backwards force of 300 pounds. Astronaut's bodies face physiological adaptations due to the loss of gravitational force.
"There is bone demineralization,'' Lewis said. "You lose mineral from your bone, and it happens very rapidly. Immune systems are impaired. There is a decreased blood cell count and cardiac and muscle deterioration.''
"What if you lived in space?'' she added. "Our bodies have a way of dealing with the absence of gravity. And they re-adapt when they come back.''
Lewis questioned how gravity affected the various elements in the structure of cells.
"The nucleus, with the genetic material,'' she said. "The cell wall and cell membrane with microtubules that are part of the cytoskeleton. How do they change in microgravity?''
Cells have aqueous, lipid and colloidal phases, which in combination help a cell adapt to its environment, Lewis explained.
"Cells also have a skeleton,'' she said. In a normal cell, the cytoskeleton has filaments and microtubules that radiate outward.
"In space, you don't see the filaments,'' she said of her research. "You don't see the radiation out to the cell membrane. In a normal cell, there is a web of cytoskeleton. On a space flight, it is absent.''
In a space-grown cell, the cell has lost its ability to separate its filaments, Lewis found.
"They don't extend clearly to the membrane of the cell,'' she said. "All terrestrial life has evolved in gravity. How did gravity influence the growth and structure of cells?''
Using the availability of the shuttle launches, Lewis sought to investigate the basic mechanisms for cell response in flight. "Cell growth and cell death,'' she said. "The cells seemed to age differently in space.''
Using a bar graph, Lewis illustrated that cells in space did not appear to grow. The cytoskeleton is affected by zero gravity, she hypothesized, with growth of the cell arrested because the cytoskeleton was disorganized.
Her experiment was on board the Oct. 29, 1998, Discovery shuttle mission. Returning astronaut Glenn received training from Lewis on how to operate the hardware for the experiments before launch.
After evaluating genes extracted from cells on the flight, Lewis said, she had more questions than answers. The genes that control gene growth were changed, yet further study may be able to discover the physiological changes and how to prevent them if space travel is in our future.