Lance
2006-02-22 20:36:12 UTC
Surprise: Chickens Can Grow Teeth
By Bjorn Carey
LiveScience Staff Writer
posted: 22 February 2006
11:06 am ET
http://www.livescience.com/animalworld/060222_chicken_teeth.html
Chicken will grow teeth when pigs can fly.
Well, better start searching the skies for flying pork-scientists
have discovered a mutant chicken with a full set of crocodile-like
chompers.
Researchers also tweaked the genes of normal chickens to grow teeth.
The mutant chick, called Talpid, also had severe limb defects and died
before hatching.
Although it was discovered 50 years ago, no one had ever examined its
mouth.
"What we discovered were teeth similar to those of crocodiles-not
surprising as birds are the closest living relatives of the reptile,"
said Mark Ferguson of the University of Manchester.
What happened
Around 300 million years ago, the ancestor of all modern vertebrates
gave rise to two lineages, the mammals and the reptiles/birds. The
oldest reptiles, such as crocodiles and alligators, had cone-shaped
teeth. So did the earliest birds, called archosaurs.
Then, around 80 million years ago, modern birds emerged without teeth.
"So what would you expect bird teeth to look like? You would expect
them to have teeth like their ancestors and their most closely related
living relative," study co-author John Fallon of the University of
Wisconsin told LiveScience.
Indeed, Talpid's teeth are conical, much like an archosaur's and
closely resembling the teeth of a baby alligator or crocodile, Fallon
said. If the chick survived, the teeth would most likely reabsorb into
the mouth.
The archosaurs had mouths similar in shape to a reptile's. It turns out
that developing a beak caused birds to lose their teeth.
"The reason that birds lost their teeth is that in forming a beak, the
two tissues that 'talk' to each other to make a tooth become
separated," Fallon said. "They can't have the conversation to make a
tooth. In the mutant, these tissues are brought back together."
Make more mutants
The finding made scientists curious whether healthy chickens still
possessed the 80-million-year-old genetic pathway for producing teeth.
By making a few changes to the expression of certain molecules in the
pathway, the researchers were able to induce tooth growth in normal
developing chickens. These teeth also looked like reptilian teeth and
shared many of the same genetic traits, supporting the scientists'
hypothesis. None of these chickens were allowed to hatch.
This is all good news for hockey players. A direct application of this
research, Ferguson said, could be re-growing teeth in people who have
lost them through accident or disease.
The research is detailed this week in the journal Current Biology
By Bjorn Carey
LiveScience Staff Writer
posted: 22 February 2006
11:06 am ET
http://www.livescience.com/animalworld/060222_chicken_teeth.html
Chicken will grow teeth when pigs can fly.
Well, better start searching the skies for flying pork-scientists
have discovered a mutant chicken with a full set of crocodile-like
chompers.
Researchers also tweaked the genes of normal chickens to grow teeth.
The mutant chick, called Talpid, also had severe limb defects and died
before hatching.
Although it was discovered 50 years ago, no one had ever examined its
mouth.
"What we discovered were teeth similar to those of crocodiles-not
surprising as birds are the closest living relatives of the reptile,"
said Mark Ferguson of the University of Manchester.
What happened
Around 300 million years ago, the ancestor of all modern vertebrates
gave rise to two lineages, the mammals and the reptiles/birds. The
oldest reptiles, such as crocodiles and alligators, had cone-shaped
teeth. So did the earliest birds, called archosaurs.
Then, around 80 million years ago, modern birds emerged without teeth.
"So what would you expect bird teeth to look like? You would expect
them to have teeth like their ancestors and their most closely related
living relative," study co-author John Fallon of the University of
Wisconsin told LiveScience.
Indeed, Talpid's teeth are conical, much like an archosaur's and
closely resembling the teeth of a baby alligator or crocodile, Fallon
said. If the chick survived, the teeth would most likely reabsorb into
the mouth.
The archosaurs had mouths similar in shape to a reptile's. It turns out
that developing a beak caused birds to lose their teeth.
"The reason that birds lost their teeth is that in forming a beak, the
two tissues that 'talk' to each other to make a tooth become
separated," Fallon said. "They can't have the conversation to make a
tooth. In the mutant, these tissues are brought back together."
Make more mutants
The finding made scientists curious whether healthy chickens still
possessed the 80-million-year-old genetic pathway for producing teeth.
By making a few changes to the expression of certain molecules in the
pathway, the researchers were able to induce tooth growth in normal
developing chickens. These teeth also looked like reptilian teeth and
shared many of the same genetic traits, supporting the scientists'
hypothesis. None of these chickens were allowed to hatch.
This is all good news for hockey players. A direct application of this
research, Ferguson said, could be re-growing teeth in people who have
lost them through accident or disease.
The research is detailed this week in the journal Current Biology