“ we will give a higher priority to those worlds that our colleagues tell us are not too warm and not too cold, but just right. ” — JILL TARTER, PAGE 11
In the News
Earth Kilauea can kill
Atom & Cosmos location isn’t everything
Life animal life’s lost years
Genes & Cells pituitary grows in a dish
Body & Brain rats help each other out
inbred bedbugs get by just fine
Matter & Energy diamonds entangled
Tiny voltage
grows eyes in
strange places
Fine-tuning electrical charge
produces eye in frog’s gut
STORY ONE
By Tina Hesman Saey
Scientists have created a tad- pole that can literally watch what it eats: The tadpole has an eye growing in its gut.
Led by developmental biologist
Michael Levin of Tufts University
in Medford, Mass., the researchers
manipulated cells in the tadpole’s gut to
take on a specific electrical state. Those
cells developed into a fully formed eye.
Inducing just the right electrical state
in cells can lead to eye growth anywhere
on the body, the team reports online
December 7 in Development.
Bizarre as the experiment sounds, it is
a major step toward regenerating complex organs and limbs. One day, Levin
says, someone who loses an arm or leg
might be able to slip on a special sleeve
that will electrically stimulate cells at the
wound site to regrow the missing limb.
sherry aw, vaibhav pai and m. levin
The study “opens up a huge door to new
therapies in regenerative medicine using
electricity,” says Jim Coffman, a developmental biologist at Mount Desert Island
Biological Lab in Salisbury Cove, Maine.
The work is “quite a ways outside the
box most developmental biologists think
in,” Coffman says. These scientists usually think about specific molecules in cells
building structures like eyes or limbs.
A tadpole has an eye growing in its gut (shown in red circle) thanks to scientists
who manipulated electrical signals in gut cells to spark eye development. The tech-
nique might lead to technologies that spur regrowth of limbs and complex organs.
“What’s surprising is that development
makes use of nonmolecular information”
to create body parts, he says.
Levin’s team previously regrew a tadpole’s tail by causing cells to take in salt,
which changed the electrical properties
of the cells. The new eye-growing work
shows that during development of an
animal, electrical signals tell cells what
to be when they grow up.
“Instead of a chemical factor, this is a
physical factor for telling cells what to
do,” Levin says.
All cells have an electrical state called
a membrane potential, created when
there is a different concentration of
electrically charged atoms called ions
outside and inside the cell. Cells have
molecular gates called ion channels that
can open or close to control the flow of
the ions — such as sodium, potassium
and calcium — across the membrane. For
cells other than nerves and muscles, the
potentials created by the flows of these
ions are tiny, just a few millivolts. But
Levin and his colleagues have found
that the voltage between cells is impor-
tant for cell migration and development,
and also plays a role in cancer.
