http://m.phys.org/news/2015-02-light...precisely.html

"This technology should allow a scientist to pick any gene on any chromosome and turn it on or off with light, which has the potential to transform what can be done with genetic engineering" said Lauren Polstein, a Duke PhD student and lead author on the work. "The advantage of doing this with light is we can quickly and easily control when the gene gets turned on or off and the level to which it is activated by varying the light's intensity. We can also target where the gene gets turned on by shining the light in specific patterns, for example by passing the light through a stencil."