Abstract
Piwi-bound small RNAs induce programmed DNA elimination in the ciliated protozoan Tetrahymena. Using the phenomenon called codeletion, this process can be reprogrammed to induce ectopic DNA elimination at basically any given genomic location. Here, we describe the usage of codeletion for genetic studies in Tetrahymena and for investigations of the molecular mechanism of Piwi-directed programmed DNA elimination.