| FORT WORTH -- In a laboratory at the University of
North Texas Health Science Center, tiny zebra fish are swimming upside down,
twirling in circles and just plain acting weird.
Why?
They developed in a world without gravity.
As eggs, they spent the 72 hours or less it took to go from fertilization
to hatching inside a cylindrical gadget called a Rotating Wall Perfused
Vessel.
Let North Side High School senior Joshua Slater explain.
"The point of all of this," Slater said during yesterday's Research
Appreciation Day at the Health Science Center, "is to see if the vestibular
system of the fish develops normally in the microgravity of outer space."
The what system?
Vestibular.
It's the anatomical system in the inner ear that helps coordinate
balance and equilibrium.
It is also linked to otoliths, tiny growths that send nerve signals
to tell an animal's eyes to rotate when the animal tilts its head.
Zebra fish have a vestibular system amazingly similar to the one
in humans.
So, if one were wondering whether human embryos nurtured with no
gravity would develop a normal vestibular system, what better animal to
use than the zebra fish?
And someone was wondering about just that: Slater and his colleagues.
"There's still many, many things that we do not know, so many things
we take for granted, and we don't ask why," Slater said.
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"You have to ask why," said Charlotte Burress, a
North Side junior. People at the National Institutes of Health and the National
Aeronautics and Space Administration are asking the same questions. Apparently,
they've studied other sensory systems in space, but not the vestibular.
The research at the Health Science Center by Slater, Burress and
North Side senior Rudy Cordova formed the basis of a three-year grant request
from the National Institutes of Health for which faculty member Stephen Moorman
expects to receive final approval soon.
NASA is also considering funding further zebra fish and vestibular
system research by Moorman, who will probably be aided by other high school
students through a federally funded sciences internship program.
But about those fish.
Those in the experimental groups often showed no sense of gravity.
They would point their topsides in any direction from which light originated,
even if it was below them. Normal zebra fish wouldn't fall for such a trick,
Moorman said.
Microscopic investigation showed that, physically, they were generally
a bobber shy of a full tackle box.
Most had abnormally small otoliths. Some were missing them altogether.
When made to list slightly, microscopic techniques showed that an
experimental fish's eyes did not rotate to compensate for the new angle.
"Now," Moorman said, "we ask why that is."
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