Posted on 01/27/2003 9:53:22 AM PST by Junior
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: The 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 (news - web sites)'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 (news - web sites) 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 UC 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 explained.)
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 explained. "Meanwhile, it's kind of fun to address these age-old questions" of evolution.
And creationists say evolution has no practical applications...
I wonder if you have bothered to contemplate just how absurd that claim is...
Actually, I think this should have been an important part of the experiment. Would they really not know how to use them? Or would the changes induced be extended into the brain itself?
I don't think that any of this should be surprising. During the embryonic phase, the separate parts of the developing body are running independently. I can imagine that, in the future when genetic control is figured out, you would be able to grow a new arm by resetting the clock on a section of tissue. Feedback from the developing arm would stimulate blood vessel growth, etc. Of course, the bone development at the shoulder would be problematic...
I didn't even contemplate the spelling of "disproven" adequately. But the real question is whether gore3K has contemplated much of anything, ever.
If done properly, the fish would just swim in circles.
When someone hired me, I always knew where the fish were.
I guess I needed a "</sarcasm>" on that post. I'm extremely unimpressed with gore's arguments.
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What?! "Species-specific programming"?! Where did the programming come from? How did it get there?
So Dick and Jill monkey around with the birds only to tell us what we already knew. Big news! Human medicine has only to gain from this incredible experiment. As if their evolutionary assumptions added something to science. If only all the birds throughout history had folks like Dick and Jill to play with their embryos this world would be a better place, to be sure.
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