Fig. 2.

Nuclear deformation pattern is rescued by transfection of desmin-null muscles with GFP–desmin. Serial confocal images of single myonuclei within a muscle cell being imaged while the cell is stretched. The nuclear aspect ratio is measured after each stretch. (A–C) Represent double labels of nuclei (shown in blue with DRAQ5) and striations (shown with α-actinin in red; GFP–desmin in is green) to obtain sarcomere length (shown in each image). The variable measured to quantify nuclear ‘deformability’ is change in aspect ratio as a function of sarcomere length (Shah et al., 2004). Values for change in normalized aspect ratio as a function of sarcomere length for each sample are: (A) WT nucleus, 1.25 µm⁻¹, (B) desmin-null nucleus, 0.268 µm⁻¹, (C) GFP-desmin transfected nucleus, 1.27 µm⁻¹. (D) Sample aspect ratio change data obtained from each of the experimental groups. Note the similarity in slopes between the WT (1.25 µm⁻¹) and the transfected desmin-null muscles (+GFP-desmin, (1.27 µm⁻¹) compared to desmin-null muscles (No Tx, 0.268 µm⁻¹). The curve for transfected desmin-null muscle has been displaced vertically by about 0.1 units for clarity. (E) Average normalized aspect ratio change for all specimens. Note that the change in aspect ratio for the GFP-desmin transfected desmin-null fibers is not significantly different from WT nuclei (P>0.5) but both are significantly different compared to the other three experimental groups *P<0.001 (Student's t-test). Data represent mean±s.e.m., n = 15–20 nuclei/muscle for n = 4–6 muscles/group.