______________________________________________________________________________
|  File Name      : CROCAIR.ASC      |  Online Date     :  03/10/95          |
|  Contributed by : Bert Pool        |  Dir Category    :  BIOLOGY           |
|  From           : KeelyNet BBS     |  DataLine        :  (214) 324-3501    |
|           KeelyNet * PO BOX 870716 * Mesquite, Texas * USA * 75187         |
|        A FREE Alternative Sciences BBS sponsored by Vanguard Sciences      |
|----------------------------------------------------------------------------|
                           q1-19-1995 09:40 [ 1799]

           Scientists find key to long breath-holding in crocodiles

                               By Malcolm Ritter
                               AP Science Writer

NEW YORK (AP) -- Scientists have identified a quirk in crocodile blood that
lets the beasts hold their breath for more than an hour, and they've
reproduced it in a human blood protein.

Crocodiles, which often use their breath-holding ability to drown their prey,
have an unusual form of hemoglobin, the stuff that carries oxygen in blood.

When they hold their breath, their tissues give off a chemical signal that
makes their hemoglobin give up more of its oxygen than usual. So the croc can
use that oxygen for a while without gulping in any more air.

People's bodies make the chemical signal too, but their hemoglobin isn't set
up to respond to it.

In the new study, researchers from Japan and England identified the piece of
the hemoglobin molecule that receives the signal.  Then they built it into
human hemoglobin, and showed that this altered version acted like crocodile
hemoglobin in a test tube.

So does this mean that people might someday be able to linger for an hour
underwater without oxygen?

Don't hold your breath, says Harvard hemoglobin expert Dr. H. Franklin Bunn.

"My guess would be if you gave this sort of modified human hemoglobin to
somebody, that they would not be able to hold their breath for an hour," he
said Wednesday.

That's because hemoglobin is probably not the total explanation for how the
croc does its underwater act, Bunn said.

But the new research, reported in today's issue of the journal Nature, is
"important work and very well done," Bunn said. It may pay off someday for
medicine, perhaps in designing artificial blood, he said.

END -- SCIENCE51
------------------------------------------------------------------------------