A University of
Florida science project that rocketed to the International Space Station on
April 18 aboard the SpaceX-3 Dragon is focused, literally, on what it takes for
biology to adapt and thrive in space.
The experiment by
plant molecular biologists Robert Ferl and Anna-Lisa Paul uses small plants as
models to understand cellular responses to spaceflight. This experiment, known
as CARA, is a follow-up to research they conducted on the ISS in 2010 which
found for the first time that roots display normal movements used to get around
rocks and obstacles even when there is no gravity.
The movements,
known as waving and skewing, were thought to be due to cellular responses to
gravity pulling on roots as they sample their growing surface with touch, Paul
said.
“But as the
images from our experiment started to come down from the International Space
Station in early 2010, it was clear that gravity was not required after all,”
she said.
Based on the 2010
results, Paul and Ferl wanted to see if, in the absence of gravity, perhaps the
plants were responding to another directional cue, such as the overhead light
source integrated into the plant growth hardware. Such alternate signal
processing by the plant cells would indicate that biology explores unique
adaptive strategies when in novel circumstances.
“We are intrigued
by the numerous light-sensing genes that are expressed specifically in roots in
orbit, and the SpaceX-3 experiment further explored the role of these genes in
orientation and cellular remodeling,” Paul said. “It is likely that light plays
a more important role in root growth in microgravity than it does on Earth.”
And that has big
implications for life somewhere other than Earth, Ferl said.
“This is telling
us that life utilizes special, potentially unique signals to adapt to living
off planet,” he said. “This has tremendous implications for the expansion of
human existence to other worlds, but also richly informs us about the potential
for plants to adapt to unusual environmental changes here on Earth.”
Ferl and Paul are
working with NASA engineers at Glenn Research Center (GRC) in Ohio to adapt the
Light Microscopy Module (LMM) for biological applications in order to focus the
analysis on the cells that normally sense gravity in plants.
The LMM is a
sophisticated fluorescent microscope facility housed on the ISS, with a
counterpart at GRC, that has historically been used for physics experiments.
The plants of the CARA experiment are grown in square petri plates on a
nutrient agar matrix, and in this experiment simply attached to the wall of the
US module of the ISS. During the course of the CARA experiment the plates are
being photographed in place with a standard camera.
In addition, the
plate containing plants engineered with fluorescent reporters are being
examined with the LMM to evaluate spaceflight-associated changes in the
cellular localization of selected genes.
An astronaut
inserts the plate into a specially adapted holder on the on-orbit LMM, then
Paul and Ferl work with the GRC engineers to control the use of the microscope
telemetrically from the ground.
The experiment is
sponsored as a research grant to Paul and Ferl by the Center for the
Advancement of Science in Space (CASIS), the Florida-based national organization
responsible for promoting science on the ISS.
