Fig. 5

Distribution of FLNc and titin in myofibrillar lesions. a Longitudinal cryosections of soleus muscle from an adult Hom mouse stained for FLNc and titin. The upper panel shows an image with increased gain settings necessary to reveal localization of mutant FLNc in Z-discs. Macro- and microlesions are strongly stained. The middle panel shows the identical part of the section with a gain setting enabling localization of FLNc within lesions. The lower panel shows a second fiber with a macrolesion. Boxed areas are shown enlarged in panels b and c. Note the highly extended distance between Z-discs within lesions, and the localization of FLNc between Z-discs. b Line profile of the boxed area in a (middle panel) confirms increased signal intensity of FLNc in filamentous appearing structures between Z-discs, while FLNc signals are decreased exactly at the position of the Z-discs. The distance between individual Z-discs increased from 2 to 2.5 μm in normal myofibrils to approximately 7.2 μm (mean distance: 7.21 ± 0.73 μm) in lesions. c Line profile of the boxed area in a (lower panel). Note a single normal appearing sarcomere within the macrolesion (asterisk) and the absence of FLNc in this area, whereas the space between the titin signals within the lesion is completely filled with FLNc (arrows). RR90 antibody was used to detect FLNc in a (lower panel), b and c. Polyclonal rabbit antiserum against FLNc d16–20 was used in a (upper panels). Bars: 10 μm (a), 10 μm (b), 5 μm (c)