REFERENCES AND NOTES

submitted for publication, a preprint has been posted on the bioRxiv web server showing that a split Cas9-gRNA gene drive system efficiently biases inheritance in yeast (6). The split system was used to avoid accidental escape of the gene drives. The use of a similar strategy in future MCRorganismswould reduce, but not eliminate, risks associated with accidental release. We therefore concur with others (7, 8) that a dia-logue on this topic should become an immediate high-priority issue. Perhaps, by analogy to the fa-mous Asilomar meeting of 1975 that assessed the risks of recombinant DNA technology, a sim-ilar conference could be convened to consider biosafety measures and institutional policies ap-propriate for limiting the risk of engaging in MCR research while affording workable oppor-tunities for positive applications of this concept