Extended Data Figure 3. RT-PCR validations of Drosophila recursive splicing events.

RT-PCR validation of ratchet points (red dots) from the indicated genes using primers in the upstream constitutive exon and flanking the putative ratchet points. The RP primers are expected to yield RT-PCR products if the constitutive exon is spliced to the ratchet point. The URP primers, which are upstream of each ratchet point, serve as negative controls. The identity of all RT-PCR products were verified by Sanger sequencing. Though the URP control RT-PCR reactions yielded a product for hppy RP1 and pum RP2, we were not able to generate sequence from them and therefore consider them to be amplification artifacts.