Figure 5. The exercise endurance of Abl2 null and Abl2 muscle-conditional mutant mice is impaired.

(A) During a twenty-hour period, Abl2^−/− and Abl2^f/−; Myod^iCre conditionally mutant mice run less than wild type (wt) mice. (B) The limb strength of Abl2^−/−, Abl2^f/−; Myod^iCre and wild type mice are similar. The graph and scatter plot show the values for individual mice and the mean values together with the SEMs. All Abl2 null and conditional Abl2 mutant mice were tested at 18 weeks with littermate controls. (C) Cross-sections of the diaphragm muscle were stained with Laminin and myosin heavy chain Type I (MHC-slow) to identify slow-twitch muscle fibers. The number of slow-twitch fibers is normal in Abl2 mutant mice. The scatter plot shows the percentage of myofibers in cross-sections of muscle that were stained by antibodies to MHC-I. The mean values and SEMs from three control (Abl2^f/+) and four muscle-conditional Abl2 mutant mice (Abl2^f/−; Myod^iCre) are shown. Scale bar is 50 µm.

Figure 5—figure supplement 1. Ultrastructural appearance of muscle-tendon junctions and muscle fibers is normal in Abl2 mutant mice.

(A) Deep muscle membrane specializations form at the myotendinous junction in wild type and Abl2^−/− mice. (B) The scatter plot shows the sarcomere lengths for 12 fibers from two wild type and two Abl2^−/− mice. The mean ±SEMs are also shown.