Xue and colleagues report efficient knock-out and knock-in manipulations of the Drosophila genome with a Cas9 transgenic system. Others have made similar observations. Xue et al. report the germline mutational rate ranging from 14% to 95%. They also demonstrated the targeted insertion of a large piece of heterologous DNA (2 kb in total) aided by the use of a visible marker. Xue et al recovered homologous recombination-based knock-in of a fluorescent marker at a rate of 4.5% by co-injecting gRNA with a circular DNA donor.
Efficient Gene Knock-out and Knock-in with Transgenic Cas9 in Drosophila. Zhaoyu Xue, Mengda Ren, Menghua Wu, Junbiao Dai, Yikang S. Rong and Guanjun Gao. G3 May 2014 4:925-929; Early Online March 21, 2014, doi:10.1534/g3.114.010496