97-10-28 Moss Experiment Headed for Space

MOSS EXPERIMENT MAY HELP ANSWER LONG-STANDING BIOLOGICAL MYSTERY

     COLUMBUS, Ohio -- Ohio State University biologists will send
a crop of green moss into space aboard the Nov. 19 NASA space
shuttle to determine how the moss grows in zero gravity.

     The experiment, called SPM-A -- a shortened and scrambled
version of “Space Moss”, may reveal vital clues as to how plant
cells evolved and how plants grow.

     According to Fred Sack, professor of plant biology and SPM-A
project leader, scientists don’t really understand how plants
“know” to grow away from the earth and toward the sun.

     “How plants sense the direction of gravity is a still a
basic question in biology,” said Sack. “It’s a puzzle that people
have been studying long and hard for many years.”

     Sack has taken a stand on the issue. He’s suggested for the
last decade that gravity pulls tiny starch particles inside plant
cells to the bottom, and thus prompts plant shoots to grow in the
opposite direction. To test his idea, Sack looked to moss, a
plant in which all growth initiates from a single, simple cell.

     Sack said the simplicity of the moss makes it a good
starting point for scientists to learn about how more complex
plants sense gravity.

     “The thing I love about this project is that in a single
moss cell that is only 200 micrometers long, the trigger for
growth occurs only at the tip of the cell, and that tip is
exquisitely sensitive to the environment,” said Sack. “The tip
holds many secrets, like how it integrates signals from light and
gravity and causes the plant to grow.”

     Sack and Ohio State colleagues Volker Kern, a postdoctoral
researcher, and Nathan White, an undergraduate plant biology
student, will send two kinds of moss into space: a wild variety
that on Earth grows upward even in the dark, and a mutant variety
that grows downward. Both kinds of moss will travel in sealed
containers lined with gelatin, water, and sugar to help the moss
grow. The containers are similar to laboratory petri dishes.

     A Ukrainian cosmonaut will provide some of the moss plants
with light during the two-week mission and leave others in the
dark, then preserve them all for the trip home with a chemical
fixative similar to formaldehyde. To keep the poisonous fixative
from contaminating the air inside the shuttle, the researchers
asked NASA to modify the petri dishes so the cosmonaut may
conduct the experiment by flipping switches outside the
container.

     Once the moss returns to Earth, researchers will compare it
to moss they grew in their laboratory during the same period.
Sack said that moss growth in the laboratory will depend on
whether the plants are of the normal or mutant variety, and
whether they are exposed to light.

     “These moss cells can jump though a lot of hoops,” said
Sack. “In the dark they’ll normally grow straight up, but if you
give them light on one side, they’ll grow toward the light.”

     What will the plants in space do when kept in the dark? “The
filaments might grow randomly, or in a spiral,” said Sack. “When
moss is growing deep in the soil on Earth, its tendency to grow
away from gravity helps it find the light; without gravity to
help it, we think the moss might send out filaments in all
directions as if it is seeking the light. We won’t know until we
examine the moss. That’s how the experiment on the space shuttle
is going to help our work.”

     The researchers also plan to determine how the starch
particles are distributed in cells grown in space compared to on
the ground. They hope that this will tell them more about the
effect of mechanical forces inside these cells. This information,
in turn, may help scientists understand how all cells have
evolved to prevent their heavy interior components from sinking
to the bottom due to gravity.

     The researchers plan to take digital pictures of the moss
cells and locate the starch particles with image software from
the National Institute of Health. Sack said that the researchers
will then be better able to gauge the influence of the starch
particles on the direction of plant growth.

                             #

Contact: Fred Sack, (614) 292-0896; Sack.1@osu.edu
Written by Pam Frost, (614) 292-9475; Frost.18@osu.edu


[Submitted by: Von Vargas  (vargas.12@osu.edu)
               
Tue, 28 Oct 1997 10:47:54 -0500 (EST)]
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