"For any institution or university with a core facility, we think this will be the way they will start making mice carrying specific mutations because it's a lot faster and so efficient," says Shivalila, one of Jaenisch's graduate students. "We were surprised that we could get two genes 'knocked out' at four loci very, very efficiently, about 80% efficiency. If we used TALENs, a more recent and complicated development in genetic engineering, we got 30% efficiency for just one gene."
Because the CRISPR/Cas technique can generate mutant mice even without using ES cells, a limitation of the conventional method for making models, genetic research may no longer be confined to a limited list of model organismsthose for which ES cells exist.
"This breaks down the definition of model organism," says Wang, a postdoctoral researcher in Jaenisch's lab. "So now, even with limited resources, any animal with established embryo manipulation procedures could be the subject of genome engineering. With many of the animals' genomes that have been sequenced, we could use this technology to establish efficient genetic manipulations in more species, to study the unique biology of each, and to learn more about evolution."
Thus, Wang, Yang, and Shivalila have used CRISPR/Cas to create mouse models only, but the team is excited broaden its application to other animals.
"We also need to see if the CRISPR/Cas system has any unexpected, undesired off-target effects, changes to the genome that we don't want," says Yang, a postdoctoral researcher in the Jaenisch lab. "So we need study this further to establish the fidelity of the system. But I think this will be the way to go."
|Contact: Nicole Rura|
Whitehead Institute for Biomedical Research