A new paper in PLoS Biology outlines a study that found that a common gene regulatory circuit controls the development of all dentitions (from the teeth in the throats of now-extinct jawless fishes, to the incisors and molars of modern vertebrates).
"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.
Fraser and colleagues studied tooth formation in a group of 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. Darrin Hulsey, a co-author of the paper, 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," said 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 used a technique localizing gene expression in the cells during tooth development (known as in situ hybridization) to investigate what might control this, 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."
[Source: ScienceDaily]