EMBRYO GROWTH
What allows embryos to develop such complex structures? We speak with Dr Megan Davey to find out
Davey is a group leader at the Roslin Institute, where she researches chicken embryos to study limb development
The development of an embryo is an amazingly complex phenomenon. Can you outline some of the major proteins involved in driving this process?
One of the main proteins responsible for limb patterns and growth is known as the Sonic hedgehog (SHH) protein. For SHH to work correctly, it has to come on for exactly the right amount of time and have exactly the right amount of activity. If you lose the activity of this protein, embryos develop with unusual differences. Too much can cause too many fingers to form; too little and things like cyclopia, where the eyes don’t part and the nose doesn’t develop properly, can occur. Another important protein is TALPID3, which affects the activity of centrosomes, cellular structures that are important for cell division. When the cell is not dividing, the centrosome migrates up to the cell surface and docks onto the cell membrane. Cells use centrosomes as their compass, but cells that lack the TALPID3 protein lose their spatial awareness. Centrosomes in these cells continue to migrate, but they don’t migrate in the right direction. Instead they move all over. This means that cells can end up growing the wrong way.
Could investigating stem cell activity lead to any medical applications?
We currently don’t know how to regenerate fingers, and we don’t know if there’s a stem cell for regenerating fingers. My hypothesis is that embryos may have stem cells at the tips of their growing digits. We’re currently investigating useful genetic tools in chickens, and one that we’re developing is called the Brainbow chicken, which allows us to visually mark cells and see where they go during development. We can use this to label the cells found at the end of the digits and see if they behave like stem cells, allowing us to learn more about how to regenerate fingers.