Despite continuous improvement of DNA FISH, a method that has been extensively used for years, it still requires harsh treatments to allow probe hybridization. Oligoprobes are also expansive, and the method is time consuming. Teams are thus looking for improvements. For this purpose, Deng et al. from the Transcription Imaging Consortium (Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147) have used the CRISPR/Cas9 system to allow highly specific and efficient labeling of DNA without global DNA denaturation, which is generated by heat or chemical treatments in DNA FISH protocols.
Let’s quote the significance they attach to their work:
We have derived a new technology for the detection of genes within undisturbed nuclei of fixed cells and tissues. Previous approaches have used fluorescent DNA probes to hybridize to genes of interest, requiring treatment of heat and disruptive chemicals that distort the natural organization of the nucleus. Instead, we have used a bacterial protein, CRISPR (clustered regularly interspaced short palindromic repeats), combined with an RNA sequence as probes to find the genes of interest in the intact genome. This approach preserves the spatial relationships of the genetic elements, which are important for understanding gene expression, and the process is remarkably rapid (15 min), convenient, and can be used directly on tissues for diagnosis of disease.