Morpholino antisense targeting of SpRunt. (A) Schematic of SpRunt, showing the relative locations of sequences targeted by each of the five morpholinos used in this study. Exons 1–3 are depicted as boxes, with coding regions shaded. The Runt domain is black. Horizontal arrows indicate the positions of primers used for the RT-PCR shown in (C). (B) Immunoblots of protein translated in vivo from injected SpRunt mRNA co-injected with control morpholino (mC), m1, m2, or m3. As a loading control, the same blots were probed with an antibody to the sea urchin stem-loop binding protein (SLBP). (C) RT-PCR of SpRunt from total RNA extracted from early blastula stage embryos injected with mC, m4 or m5 (two separate experiments). RT-PCR of ubiquitin was used to control for RNA levels.