Biologists find gene network that gave rise to first tooth

February 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/perlserv/?request=get-document&doi=10.1371/journal.pbio.1000031

Source: Public Library of Science

Explore further: Lab-grown organoids hold promise for patient treatments

Related Stories

Lab-grown organoids hold promise for patient treatments

June 7, 2017

Ophir Klein is growing teeth, which is just slightly less odd than what Jeffrey Bush is growing – tissues that make up the face. Jason Pomerantz is growing muscle; Sarah Knox is growing salivary glands; and Edward Hsiao ...

Baleen whales' ancestors were toothy suction feeders

May 11, 2017

Modern whales' ancestors probably hunted and chased down prey, but somehow, those fish-eating hunters evolved into filter-feeding leviathans. An analysis of a 36.4-million-year-old whale fossil suggests that before baleen ...

Recommended for you

Scientists uncover origins of the Sun's swirling spicules

June 22, 2017

At any given moment, as many as 10 million wild jets of solar material burst from the sun's surface. They erupt as fast as 60 miles per second, and can reach lengths of 6,000 miles before collapsing. These are spicules, and ...

Quantum thermometer or optical refrigerator?

June 22, 2017

In an arranged marriage of optics and mechanics, physicists have created microscopic structural beams that have a variety of powerful uses when light strikes them. Able to operate in ordinary, room-temperature environments, ...

0 comments

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.