Fig. S6

Rbfox1l and Rbfox2 are both expressed in uninjured adult zebrafish skeletal muscle, with Rbfox2 expressed mainly in satellite-like cells and Rbfox1l expressed mainly in differentiated muscle cells. (A) Immunoblot detection of Rbfox1l and Rbfox2 in 24 hours post fertilization (hpf) embryo lysates (2 embryos per lane). The Rbfox1l protein band (between 46-58 kD) is depleted after rbfox1l morpholino (MO) injection and the Rbfox2 protein band (between 58-80 kD) is depleted after rbfox2 MO injection. Both bands are depleted after co-injection of rbfox1l and rbfox2 MOs (Double MO). Tubulin expression was used as a loading control. (B-B'') Rbfox2 is expressed in Pax7-positive cells (white arrowheads; inset shows enlarged view of boxed region), and in a few other cells throughout the muscle (gray arrowheads). (C-C'') Rbfox1l is expressed in a subset of Pax7- positive cells (white arrowheads, inset of boxed region), and more prominently in nuclei that are Pax7-negative (gray arrowheads). (D-D'') Rbfox1l expression in the myog:H2B-mRFP transgenic line indicates that myonuclei are consistently Rbfox1l-positive. (E-F) Rbfox2 and Rbfox1l expression together with DAPI in the adult zebrafish myotome. Rbfox2 is localized to nuclei of some cells and is cytoplasmic in others (E). Rbfox1l is localized to nuclei based on overlap with DAPI (F). Scale bar in in B'' and C'' is 30 μm, in D'' is 75 μm, and in E, F is 50 μm in the large panels and 5 μm in the small panels.