According to Sanes, developmental neurologists have long tried to identify different types of neural cells based on their function and anatomy -- how they appeared on the outside.
"But it's a huge limitation because it's essentially a qualitative assessment," he says. "We really need some way to reliably identify and track these cells if we ever hope to study their development. So the emergence of cell-specific molecular markers is a very big deal, because it will do just that. Already we've seen that it helps us identify new kinds of cells we didn't know existed before. Once we have a promising molecule, we can track down the cells that it corresponds to."
"The other important result," continues Sanes, "is that we're actually mimicking how the brain itself identifies its cells. The brain has to be able to reliably recognize and tell apart different kinds of cells, and that's going to happen on a molecular basis. In fact, its possible that some of the molecules we've identified are, in fact, the same molecules the brain uses to distinguish cell types."
By identifying molecules that are solely expressed by specific types of neurons, scientists hope to gain insights into how nerve cells form synapses, or connections, with other nerve cells -- in short, how the brain controls its development on a molecular basis.
For the moment, however, researchers are busy puzzling over the results of the JAM-B mouse retinal cells.
"Why in the world would mice need to develop cells to detect upward motion"" Sanes wonders. "It's a great mystery."
|Contact: Steve Bradt|