Figure 3

Dazl TSS switching and f11r exon skipping switch. (a) A screenshot from Integrative Genomics Viewer shows that dazl has been transcribed from at least two TSS’s in the maternal transcriptome; grey arrows 1–3 at bottom indicate Ensembl annotated TSSs. Black arrows in the upper panel indicate reads supporting promoter 1 (rightmost black arrow) and promoter 2/3 (leftmost black arrow; our data cannot distinguish between TSS 2 and 3). A white arrow in the upper panel points at a splice junction ‘bridge’ (red), symbolizing the splice junction for the most distal first exon. The thickness of splice junction symbols is correlated with the number of reads supporting the junction. Post-ZGA transcripts lack the most 5’ exon as can be observed from the absence of reads supporting the splice junction originating from this exon (white arrow, bottom panel). (b) Pre-ZGA an f11r isoform with exon 8 included is present (white arrow, top panel). Post-ZGA a different f11r isoform, this one with exon 8 lacking, has been transcribed (white arrow, bottom panel). (c) The f11r exon skipping (red asterix) leads to a frame shift resulting in a 6 nt longer ORF, including the removal of two C-terminal valine residues. Two functional domains, immunoglobulin V-set domain (PF07686) and immunoglobulin domain (PF00047) (white bars) are intact in both splice isoforms.