Biologists find gene network that gave rise to first tooth

Feb 10, 2009

A paper in this week's PLoS Biology reports that a common gene regulatory circuit controls the development of all dentitions, from the first teeth in the throats of jawless fishes that lived half a billion years ago, to the incisors and molars of modern vertebrates, including you and me.

"It's likely that every tooth made throughout the evolution of vertebrates has used this core set of genes," said Gareth Fraser, postdoctoral fellow at Georgia Tech's School of Biology.

The first vertebrates to have teeth were a group of eel-like jawless fish known as the conodonts that had teeth not in their mouth, but lining the throat. This particular group is long since extinct, but some modern fish retain teeth in the throat (pharynx). Dr. Fraser and colleagues studied tooth formation in a group of fish known for their rapid rate of evolution, the cichlids of Africa's Lake Malawi. The cichlids have teeth both in their oral jaws, like humans, and deep in their throats on a pharyngeal jaw. A co-author of the paper, Darrin Hulsey, first identified a surprising positive correlation between the number of teeth in the oral jaw and in the throat in these fish.

"Originally, I thought there wouldn't be a correlation due to the developmental differences and the evolutionary distinction between the two jaw regions, but it turns out there is," explained Fraser. "So fish that have fewer oral teeth also have fewer pharyngeal teeth. This shows that on some level there's a genetic control that governs the number of teeth in both regions."

The team investigated what this control might be by using a technique localizing gene expression in the cells during tooth development, known as in situ hybridization, and found that a common genetic network governs teeth in the two locations.

"So seemingly, regardless of where you grow a tooth, whether it's in the jaw or the pharynx, you use the same core set of genes to do it," said co-author J. Todd Streelman. "We also think it's probable that this network is not just acting in teeth, but also in other similarly patterned structures like hair and feathers."

Citation: Fraser GJ, Hulsey CD, Bloomquist RF, Uyesugi K, Manley NR, et al. (2009) An ancient gene network is co-opted for teeth on old and new jaws. PLoS Biol 7(2): e1000031. doi:10.1371/journal.pbio.1000031
biology.plosjournals.org/perls… journal.pbio.1000031

Source: Public Library of Science

Explore further: New class of insecticides offers safer, more targeted mosquito control

Related Stories

Early herders' grassy route through Africa

Mar 09, 2015

A University of Utah study of nearly 2,000-year-old livestock teeth show that early herders from northern Africa could have traveled past Kenya's Lake Victoria on their way to southern Africa because the ...

International team maps 'big bang' of bird evolution

Dec 11, 2014

The genomes of modern birds tell a story of how they emerged and evolved after the mass extinction that wiped out dinosaurs and almost everything else 66 million years ago. That story is now coming to light, ...

Recommended for you

Scientists discover new 'transformer frog' in Ecuador

4 hours ago

It doesn't turn into Prince Charming, but a new species of frog discovered in Ecuador has earned the nickname "transformer frog" for its ability to change its skin from spiny to smooth in five minutes.

Longer DNA fragments reveal rare species diversity

4 hours ago

A challenge in metagenomics is that the more commonly used sequencing machines generate data in short lengths, while short-read assemblers may not be able to distinguish among multiple occurrences of the ...

Scientists say polar bears won't thrive on land food

4 hours ago

A group of researchers say polar bears forced off melting sea ice will not find enough food to replace their current diet of fat-laden marine mammals such as seals, a conclusion that contradicts studies indicating ...

The vital question: Why is life the way it is?

6 hours ago

The Vital Question: Why is life the way it is? is a new book by Nick Lane that is due out on April 23rd. His question is not one for a static answer but rather one for a series of ever sharper explanations—explanations that a ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.