birds with teeth: one step closer to rats with wings

Birds with teeth turn the clock back 70m years

A batch of chicken embryos raised at a French laboratory have been coaxed into growing rudimentary teeth, after researchers managed to re-awaken a gene that has lain dormant in birds for at least 70 million years. [...]

Although no modern birds have teeth, their ancestors once boasted beaks bristling with incisors. The teeth sported 147 million years ago by the Archaeopteryx, the first bird known to science, disappeared from its descendants between 70 and 80 million years ago. The DNA that triggers tooth growth did not disappear completely, but instead lingered uselessly in the avian genetic blueprint.

A team led by Josiane Fontaine-Perus, of the University of Nantes, has managed to switch this genetic signal back on. In the experiment, which also involved Paul Sharpe, Professor of Craniofacial Development at King's College London, and other French researchers, a few mouse cells were transplanted into chicken embryos to create hybrids known as chimeras. Whereas chicken cells are incapable of deciphering genetic messages telling them to turn into teeth, mouse cells are receptive to them. They migrated to the correct place in the jaw, and the chicken embryos, which were otherwise normal, began to develop teeth.

"The tissue transplant produces cells that contribute to tooth formation," Professor Sharpe said. "Basically, this tells you that the bird still has the genetic information required to initiate tooth development, if there are cells capable of responding to it." [...]

His research team has also managed to grow mouse teeth from stem cells in the laboratory, and he hopes to begin human trials of replacement teeth within five years. [...]

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