Fig. 3

Muscle fibres from Mtm1 knockout (KO) mice have increased density of myonuclei, and reduced force-generating capacity. Data obtained from healthy control mice (WT, N = 3 animals, n = total of 46 muscle fibres) and Mtm1 KO animals (N = 3 animals, n = total of 63 fibres). a Typical single myofibres from each group, stained for actin (rhodamine phalloidin; red) and nuclei (DAPI; green). Scale bar: 50 μm. b Proportion of muscle fibres containing internal or central nuclei. Each data point corresponds to the mean per animal. c Number of myonuclei per individual myofibre. d Myonuclear number was linearly related to fibre CSA for all the groups (P < 0.05). The regression lines were significantly more elevated for Mtm1 KO than WT (P < 0.05). e Myonuclear domain volume per individual muscle fibre. f Myonuclear domain size was linearly related to fibre CSA for all the groups (P < 0.05). g Order score (g). h Specific force defined as absolute (maximal) force divided by CSA. Individual data points for c–h correspond to individual muscle fibres. Column graphs show mean ± S.D. Scatter graphs show linear regression lines. Asterisks denote a significant difference compared with CTL (*P < 0.05; **P < 0.01; t-test)