> Finally, Siksnys showed that the system could also be reconstituted in a second way—by combining purified His-tagged Cas9, in-vitro-transcribed tracrRNA and crRNA, and RNase III—and that both RNAs were essential for Cas9 to cut DNA. (They would ultimately drop the second reconstitution from their revised paper, but they reported all of the work in their published U.S. patent application filed in March 2012 [Siksnys et al., 2012]).
> Siksnys submitted his paper to Cell on April 6, 2012. Six days later, the journal rejected the paper without external review. (In hindsight, Cell’s editor agrees the paper turned out to be very important.) Siksnys condensed the manuscript and sent it on May 21 to the Proceedings of the National Academy of Sciences, which published it online on September 4. Charpentier and Doudna’s paper fared better. Submitted to Science 2 months after Siksnys’s on June 8, it sailed through review and appeared online on June 28.
[1] -- https://www.cell.com/cell/fulltext/S0092-8674(15)01705-5