Generation of endo-siRNAs in Xenopus laevis oocytes

Endogenous siRNAs (endo-siRNAs) are well documented and characterized in C. elegans and Drosophila. Endo-siRNAs can also be found in vertebrates; however, their biology is much less clear. They are thought to be produced by Dicer and to contribute to transposon silencing. Because of their generally low abundance and their similarity with miRNAs and products of physiological RNA turn-over, endo-siRNAs are difficult to investigate. Here, we report a system, oocytes from Xenopus laevis, that allows for the generation and analysis of endo-siRNAs from double-stranded RNA precursors.