A set of transgenic constructs that each consist of a short guide RNA (sgRNA) targeting the coding sequence of a gene. The sgRNA is under the control of a U6:3 (ubiquitous) promoter. When crossed to a stock that contains a source of Cas9, cleavage and mutagenesis of the targeted gene is induced, resulting in a small deletion or insertion mutation.
pCFD3 and pCFD4 vectors described at [CRISPR fly design](http://www.crisprflydesign.org/plasmids/)
Many of the TRiP RNAi and sgRNA stocks generated at Harvard Medical School (HMS lines) and Tsinghua University (HMC lines), but not stocks generated at the National Institute of Genetics in Japan (HMJ lines), contain the sev21 allele as a result of introducing a mutated X chromosome from Bloomington stock 35781 (FBst0035781) or 32261 (FBst0032261) as the transgenes were being established in stock.