Scientists typically study cells in real-time by introducing glowing reporter proteins into cultured cells and then watching the action unfold under the microscope. But, these probes, introduced at random throughout the genome and expressed at high levels, can interfere with cellular systems and introduce unwanted toxicity.

Now, using enzymes called zinc finger endonucleases that can be engineered to insert glowing probes at specific points in the genome, researchers can more accurately capture cells in action.

“You want [your probe] to report on a process accurately. You don’t want your probe mucking up the process,” says cell biologist David Drubin of the University of California-Berkeley. “So you have to find the right compromise.”

Previous studies indicated that the absorption of proteins at the cell surface is much slower and less efficient in humans than in simpler systems such as yeast. But last month, using cells engineered with zinc finger enzymes, Drubin’s team demonstrated that this type of absorption is actually rapid and efficient, suggesting that the glowing probes previously used threw a wrench in the works.

In future, scientists anticipate that glowing cells such as these could be used to discover new drugs or to assess drug toxicities.

Here, watch two dividing bone cancer cells expressing a green glowing chromosomal protein.

Video: Courtesy of Sigma Aldrich