Transplantation experiments suggest that induction of

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Transplantation experiments suggest that
induction of neural tissue occurs during
gastrulation
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Holtfreter exogastrulation evidence suggests
principle of neural induction
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Rodents' Higher IQ The Washington Post January
29, 2001 Rick Weiss, Washington Post Staff Writer
It hurts to be smart. That's one conclusion
from the latest study of so-called Doogie mice --
"smart" rodents that are genetically engineered
to have enhanced memory and learning skills.
Along with those extra IQ points, researchers
have found, comes an added sensitivity to some
kinds of pain. The new work offers a sobering
lesson about the difficulty of enhancing certain
brain functions without simultaneously taking a
toll on others. It also may temper whatever
momentum there is to engineering genetic
enhancements into people. "Beware what you ask
for," said James L. McGaugh, a neuroscientist at
the University of California at Irvine. "And when
you get it, look carefully and see what else you
got."
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Wildtype mouse embryosA, B and C
Otx2 knockoutD, E and F
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Ventral ectoderm
Dorsal ectoderm
Early bias toward neural fate in dorsal ectoderm
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St. 10-
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HoxB1 expression in explants at different stages
a role for both planar and vertical signaling
Normal HoxB1 expression
From Poznanski and Keller (1997)
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Era of the Quest for the Neural
Inducer(s) EVERYTHING induces neural tissue
High pH, Low pH Divalent cations Nucleic
acids Dead tissues Organic chemicals Sterols Methy
lene Blue! Transfilter experiments suggest
diffusible molecule(s)
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Neural response programmed into dorsal
ectoderm? Suggests that neural induction is
permissive rather than instructive. So..what
is the neural inducer?
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(Planar)
BMP inhibitors (vertical)
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Looptail neural tube defect caused by
strabismus/van gogh mutation
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Holtfreter was wrong!!!!
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