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Re: Bird embryo wing digits are 1, 2, 3



I quite don't get an idea of what they're talking about...(plus the paper is not free-access)
Does this refute digit shift theory?
Cheers,
Jean-Michel

Le 10/02/2011 12:04, bh480@scn.org a écrit :
From: Ben Creisler
bh480@scn.org

In case this new paper in Science has not been mentioned
yet:

Koji Tamura, Naoki Nomura, Ryohei Seki, Sayuri Yonei-
Tamura, and Hitoshi Yokoyama (2011)
Embryological Evidence Identifies Wing Digits in Birds as
Digits 1, 2, and 3.
Science 331(6018): 753-757 (11 February 2011)
DOI: 10.1126/science.1198229
http://www.sciencemag.org/content/331/6018/753.abstract

Abstract
The identities of the digits of the avian forelimb are
disputed. Whereas paleontological findings support the
position that the digits correspond to digits one, two,
and three, embryological evidence points to digit two,
three, and four identities. By using transplantation and
cell-labeling experiments, we found that the
posteriormost digit in the wing does not correspond to
digit four in the hindlimb; its progenitor segregates
early from the zone of polarizing activity, placing it in
the domain of digit three specification. We suggest that
an avian-specific shift uncouples the digit anlagen from
the molecular mechanisms that pattern them, resulting in
the imposition of digit one, two, and three identities on
the second, third, and fourth anlagens.