The fission yeast, Schizosaccharomyces pombe, unusually retains one pathway for this process, which it uses for heterochromatin formation, while this process has been completely lost by most budding yeast, including Saccharomyces cerevisiae. This process was discovered when increasing the level of chalcone synthase unexpectedly led to decreased, variegated pigmentation in petunias. (15[1])An early stage of this process includes the formation of the microprocessor complex when DGCR8 binds to (*) Drosha. This process is carried out by a complex known as RISC, in which Argonaute binds to the guide strand after this process is initiated by Dicer. A Nobel Prize was awarded to Craig Mello and Andrew Fire for their investigation of this process in C. elegans. For 10 points, name this process in which a namesake nucleic acid is used to induce post-transcriptional gene silencing. ■END■