A group of scientists from CalTech have developed a system that allows the visualization of specific embryonic cells as they begin to specialize and develop into parts of an organism, using a gene that codes for a fluorescent protein. 

After fertilization the number of cells in the embryo exponentially increases, and the initial unspecialized cells begin to assume specific identities, for example becoming cells that will eventually give rise to bones, parts of the nervous system, or organs such as the liver. Currently, however, there is limited information on exactly what happens during particular stages of development in organisms, especially with respect to which genes are switched on and involved in certain developmental phases. In a move hoping to be able to shed more light on this area, scientists used a system where they injected the gene which codes for a reporter, green fluorescent protein, into a fertilized egg. This gene then incorporates into the DNA of a particular cell type, and hey presto, you've got glowing cells. "You can do it with any cell type you desire," said Julius Barsi, one of the members of the team that developed this method using sea urchin embryos. 

Fluorescent cells aren't novel, but that's not what makes this research special. Although scientists have previously been able to isolate different cell types from tissue culture, they haven't been able to do this from a developing embryo before, and being able to choose which particular cell type you desire to isolate has been problematic. The scientists hope that this methodology could be used to demonstrate how particular organisms develop from a fertilized embryo into a whole animal, shedding an enormous amount of previously unknown information. 

It's hoped that this will allow scientists to be able to see which genes are switched on in specific cell types and why, and how this changes as the organism develops. "Now you can connect the genes to a given function," said Barsi. "You can see what specifies a cell to become a certain cell, what enables a cell to do what it does, what tells it to secrete hormones, to become a neuron." It is hoped that this could be eventually applied to decipher which genes are responsible for particular genetic diseases and abnormalities, which could aid in diagnostics. This research is very much still in its infancy, so it will be a long time before we see applications such as this. 

Of course, it isn't ethical to start doing this with human embryos, but the team hope to start investigating different animals to sea urchins, such as mice.