Gene-cutting system may play second role as a genetic dimmer switch In a series of experiments with laboratory-cultured bacteria, Johns Hopkins scientists have found evidence that there is a second role for the widely used gene-cutting system CRISPR-Cas9 -- as a genetic dimmer switch for CRISPR-Cas9 genes. Its role of dialing down or dimming CRISPR-Cas9 activity may help scientists develop new ways to genetically engineer cells for research purposes. A summary of the findings was published Jan. 8 in Cell. First identified in the genome of gut bacteria in 1987, CRISPR-Cas9 is a naturally occurring but unusual group of genes with a potential for cutting DNA sequences in other types of cells that was realized 25 years later. Its value in genetic engineering -- programmable gene alteration in living cells, including human cells -- was rapidly appreciated, and its widespread use as a genome "editor" in thousands of laboratories worldwide was recognized in the awarding of the Nobel Prize in Chemistry last year to its American and French co-developers.