Fig. 5
SC35-containing speckles in myotube nuclei were fewer in number but larger in size than those in myoblast nuclei. a, b Immunostaining for SC35 (red) was used to identify SC35 speckles and staining for myosin heavy chain (green) was used to identify myotubes and thus distinguish nuclei in myotubes from those in myoblasts. SC35 speckles in myotube nuclei typically appeared to be fewer in number and sometimes larger than those in myoblasts. c Quantitation of the number of SC35 speckles in myoblast nuclei (mb, light gray bars) and in myotube nuclei (mt, dark gray bars). As indicated, speckles were counted in healthy control, MDC1A, and LGMD2D myogenic cells, as well as in the DUX4-FL-negative nuclei of FSHD myogenic cells. In each type of cells, the average number of SC35 speckles was lower in myotube nuclei than in myoblast nuclei. Error bars = s.e.m. **P < 0.01 by t test. Speckles were counted in n = 50 nuclei. d Quantitation of the cross-sectional areas (μm2) of SC35 speckles in myoblasts (mb, light gray bars) and myotubes (mt, dark gray bars). As indicated, speckles were measured in healthy control, MDC1A, and LGMD2D myogenic cells, as well as in the DUX4-FL-negative nuclei of FSHD myogenic cells. In each type of cell, the average size of SC35 speckles was higher in myotube nuclei than in myoblast nuclei. Error bars = s.e.m. **P < 0.01 by t test. The number of speckles measured is indicated on each bar. Bar in a = 20 μm