FIGURE 5:

Increased global transcription preferentially occurs in small myofibers during hypertrophic growth. Myofibers were binned based on their cross-sectional area to determine the effect of cell size on EU-RNA integrated density levels. (A) Representative image of EU-RNA labeling intensity under Sham conditions. Scale bar, 50 μm. (B) No significant difference in EU-RNA per fiber with across cell size under sham conditions. (C) Representative image for increased EU-RNA labeling in small myofibers at SA3. Yellow/red arrowhead indicates a nucleus in a cell <1000 μm², and green/red arrow indicates a nucleus in a cell >2000 μm². Note the difference in EU-RNA staining intensity in the fibers <1000 μm². Scale bar, 50 μm. (D) Progressive decrease in EU-RNA integrated density with increasing cell size. *Significant difference between cell sizes (n = 5 for each cell size bin). (E) Mechanical overload results in a rightward shift in the relative frequency of large fibers (>2000 μm²) at SA7 (n = 5 or 6 mice per time point). All data are presented as mean ± SEM.