Breakthrough technology may shed new light on the functions of individual genes. How? By shining a light on them.

For some time, researchers studying individual gene expression have been forced to work within short timeframes, as the cells they monitor constantly toggle between different sets of genes. Although each cell contains the organism's entire genome, only a fraction is expressed at any given time, and just a minute later, the set of genes expressed at that moment may be radically different.

Now, scientists are finally able to study properly these fleeting genes. A new technology developed at Massachusetts Institute of Technology (MIT) and the Broad Institute can perturb individual gene expression by shining a light on the cell.

The new research tool, which originates in a technique called "optogenetics," uses light-sensitive proteins to manipulate RNA instructions within the cell. This allows scientists to activate or suppress specific genes almost instantly.

"Cells have very dynamic gene expression happening on a fairly short timescale, but so far the methods that are used to perturb gene expression don't even get close to those dynamics," says Silvana Konerman, a graduate student at MIT.

"To understand the functional impact of those gene-expression changes better, we have to be able to match the naturally occurring dynamics as closely as possible," she continued.

By approximating these dynamics, the new technology could prove indispensable in future efforts to link genes to specific functions, especially those relevant to cognitive functions like memory and learning. In addition, the system will help researchers study "epigenetic modifications," or chemical alterations to proteins surrounding DNA.

To test the technology, scientists targeted around 30 different genes in neurons and live animals. By emitting a single pulse of light, the system set off a tremendously intricate biological process, whereby various components reacted to initiate DNA copying within the cell. The team found that by shining the light once every minute, they could maintain this transcription for the desired period, thus circumventing previous time limits.

Professor Karl Deisseroth, of Stanford University's Department of Bioengineering, noted that the system's most important innovation is its capacity to control the transcription of naturally occurring genes, as opposed to scientifically engineered ones.

"You could control, at precise times, a particular genetic locus and see how everything responds to that, with high temporal precision," he said.

The technology thus promises a reliable method to approximate the dynamics of particular genes, and subsequently study the individual functions our genome is programmed to express. However, with 20,000 genes in the human cell, a rather long road may lie ahead.