Figure ED4. A small RNA library cloning approach that allows the recovery of longer piRNA species.

Drosophila total RNA contains large amounts of the 31-nt long 2S rRNA. Previous cloning approaches therefore typically restrict small RNA cloning to the 18-29 nt window by cutting these small RNA populations from a gel. We used the 2S rRNA depletion method published by Seitz et al. (2008), followed by extracting small RNAs ranging from 18-40 nt in length for library preparation.

Shown are size distributions of TE mapping small RNAs (obtained from w¹¹¹⁸ ovaries) comparing the standard small RNA cloning protocol (left) and the protocol using total RNA depleted of 2S rRNA (middle; see Methods). An overlay of the longer reads (>27 nt) is displayed to the right.