Subject: birds may reveal how human faces develop
Date: Feb 4 05:39:51 2003
From: Devorah A. N. Bennu - nyneve at amnh.org



hello again tweets,

and yet another cool story about how birds are helping scientists
better understand humans.

regards,

Devorah A. N. Bennu, PhD
email:nyneve at amnh.org or nyneve at myUW.net
work page http://research.amnh.org/ornithology/personnel/bennu.htm
personal pages http://research.amnh.org/users/nyneve/

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http://enn.com/news/wire-stories/2003/01/01242003/ap_49405.asp

Bird beaks may teach scientists how to read human faces

Friday, January 24, 2003
By The Associated Press

WASHINGTON -- Talk about funny-looking birds: The duck had a quail's
pointy beak and the quail a duck's flat bill.

But University of California scientists who switched birds' beaks
through a little egg tinkering had more than avian oddity in mind.
Their experiment uncovered some of the key cellular players in bird
evolution, and may even lead to better understanding of what causes
facial birth defects such as cleft palate.

"It connects back to some of the earliest roots of evolutionary
thought, but also connects to very real issues in human medicine,"
molecular evolutionist Michael Braun at Smithsonian Institution's
National Museum of Natural History said after reading the new
research.

Birds' amazing variety of beak styles is integral to the study of
evolution. One of Charles Darwin's most famous observations during
his 1835 visit to the Galapagos Islands was that finches were subtly
different -- including their beak size and type -- depending on where
they lived on the chain of pristine, volcanic islands. His analysis
of such differences later led to his theory of evolution through
natural selection.

But just what genes and cells drive those differences remained
mysterious.

Beaks all derive from similar-looking tissues in very early bird
embryos, said Jill Helms, an orthopedics researcher at the University
of California at San Francisco. To find out what makes them turn out
dramatically different, she and colleague Richard Schneider picked
two birds with unmistakable beaks -- ducks and quails -- and tried to
get them to grow each other's.

They took 36-hour-old duck and quail embryos from an incubator and
drilled small holes in the eggs encasing them. Using the tiniest of
needles, Schneider sucked out the cells that seemed to give rise
to beaks, called neural crest cells, from duck embryos and replaced
them with neural crest cells from quail embryos, and vice versa.

Taping over the egg hole, researchers let the eggs incubate until
they were about 11 days old, halfway to hatching but just large
enough to tell what the still-forming birds' beaks looked like.
Letting them survive to hatch with beaks they didn't know how to
use would have been unethical, Helms said.

Call the result "qucks" and "duails:" The ducks grew pointy
little quail beaks and the quails grew that distinctive flat, wide
duck bill, the researchers report in Friday's edition of the
journal Science.

That means neural crest cells carry species-specific programming for
beak growth, Paul Trainor of the Stowers Institute for Medical
Research in Kansas City said in an accompanying Science review.

The transplanted neural crest cells also altered how the bird's
natural tissues and even genes reacted in the presence of the
foreign beak, slightly modifying some surrounding facial features
and speeding some gene action, Trainor noted. Together, that makes
the cells crucial players in beak evolution.

It's an important study, narrowing down the specific pathway that
produces birds' amazing variety of beaks, agreed the Smithsonian's
Braun. But seeing how these cells direct the development of
surrounding tissue has implications far beyond birds, he said.

Indeed, understanding what causes a beak to develop the way it does
could shed light on human craniofacial development, Helms said. If
people harbor an equivalent to the birds' powerful neural crest
cells, perhaps surgeons one day could correct a cleft palate before
a baby was born with a transplant of the right mouth-growing cells,
she said.

Helms equates her experiment to eavesdropping on a conversation
between two tissues, as the transplanted cells altered the bird's
natural development.

"Once you understand the nature of the dialogue between the tissues,
then you can start to think about, when development goes awry, is
there a way to correct it," Helms said. "Meanwhile, it's kind of fun
to address these age-old questions" of evolution.

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