The Biogenesis and Function of PIWI Proteins and piRNAs: Progress and Prospect

Annual Review of Cell and Developmental BiologyVol. 25: 355-376 (Volume publication date November 2009)

Bayesian phylogenetic analysis of Argonaute family proteins in the PIWI and AGO subfamilies

Meiosis genes in Daphnia pulex and the role of parthenogenesis in genome evolution

by Schurko, Andrew; Logsdon, John; Eads, BrianJournal: BMC Evolutionary Biology Vol. 9 Issue 1DOI: 10.1186/1471-2148-9-78Published: 2009-04-21

FIGURE | Two pathways for piRNA biogenesis.

PIWI-interacting small RNAs: the vanguard of genome defenceMikiko C. Siomi, Kaoru Sato, Dubravka Pezic & Alexei A. AravinNature Reviews Molecular Cell Biology 12, 246-258 (April 2011)

http://www.kyowa-kirin.co.jp/antibody/basics/structure.html