Role for A Bidentate Ribonuclease in the Initiation Step of Rna Interference

NATURE | VOL 409 | 18 JANUARY 2001 | www.nature.com 363 22. Saitoh, S., Takahashi, K. & Yanagida, M. Mis6, a ®ssion yeast inner centromere protein, acts during G1/S and forms specialized chromatin required for equal segregation. Cell 90, 131±143 (1997). 23. Kelly, T. J. et al. The ®ssion yeast cdc18 gene product couples S-phase to start and mitosis. Cell 74, 371± 382 (1993). 24. Fernandez-Sarabia, M. J., McInery, C., Harris, P., Gordon, C. & Fantes, P. The cell cycle genes cdc22 and suc22 of the ®ssion yeast Schizosaccharomyces pombe encode the large and small subunits of ribonucleotide reductase. Mol. Gen. Genet. 238, 241±251 (1993). 25. Lin, L. & Smith, G. R. Transient, meiosis-induced expression of the rec6 and rec12 genes of Schizosaccharomyces pombe. Genetics 136, 769±779 (1994).