Fig. 2. Transient expression and assembly of GFP-myosin in embryonic cardiomyocytes. (A) In this live cardiomyocyte imaged 26 hours post-transfection the GFP-myosin is found assembled in striated myofibrils, in non-striated myofilaments, and in scattered thick filaments (white arrowheads) and non-aligned A-bands. (B) The same cell was examined 18 hours later (44 hours post-transfection). The organization and number of myofibrils in the cell have increased with a concomitant decrease in the non-striated fluorescence. (C) A cardiomyocyte expressing GFP-myosin (green) was fixed 72 hours post-transfection and stained with mAb RT11 (red) that labels the titin PEVK domain at the A-I junction (Moncman and Wang, 1996). The boxed region is enlarged (inset) to show the ordered myofibril structure. (D) A DIC image overlaid in green with the fluorescent image of GFP-myosin. Two adjacent cells are expressing GFP-myosin and a third neighboring cell is not. The GFP-myosin-expressing cells have formed a prominent intercalated disk (white arrowheads) and the myofibrils are arranged co-linearly across the disk. The magnification in A-C is the same.

Return to article