Man, Mouse or Just Plain Chicken?

At the embryo stage, humans, mice and chickens apparently have a lot in common. Their faces, at least, are similar enough to allow Joy Richman to study chicken embryos to learn more about the development of the human face. Richman is a pediatric dentist and development biologist. Her work will provide new understanding around facial abnormalities such as cleft palate, today affecting one in 700 babies born.

“The chicken embryo is ideal to unravel these mysteries,” says Richman, who literally cuts postage-stamp sized windows into eggs that allow her to peer inside to the developing embryos with a microscope.

Many animal faces start out as a rudimentary oral cavity surrounded by buds of tissue called prominences that develop into a face. Richman is trying to discover what it is that, at the molecular level, stimulates indistinct cells to form specific structures of the face. To help, she has been awarded $900,000 from the Canadian
Institutes of Health Research.

Prior to receiving her grant, Richman had established that jaw development is linked to the presence of retinoic acid, a vitamin A derivative and a protein linked to bone formation. She did this by inserting beads containing the acid into a chicken embryo, which subsequently developed bones that would become a beak, where
normally there would be cheek bones.

Now she is investigating the genes that play a role in forming the centre of the face. She has already discovered a gene of interest “because it makes a protein that is secreted outside the cell and as such could play a pivotal role. It may act as an orchestrator, directing nearby cells into required patterns.” The protein is strongly
turned on during beak development, and placing a gene for the protein in an embryo caused the growth of an extra beak. Ongoing research will further determine the protein’s role in forming face and limbs.

“Our work will shed light on inherited birth defects that affect the skeleton including cleft lip, jaw size and shape abnormalities, and disturbances in the bones of the hands and feet,” says Richman. “Our results may also one day help to improve healing after injuries to the skeleton.”

UBC Alumni Magazine Trek Summer 2010, p. 5