Figure 3.

β1-integrin redistribution occurs very early in myofibrillogenesis to pattern membrane domains overlying new myofibrils. Zebrafish embryos at 20 (A) and 24 (B–G) hpf were immunolabeled for β1-integrin. Embryos demonstrated clustering of β1-integrin at new somite boundaries (arrows: A) with subsequent localization to membrane domains overlying new myofibrils in the more mature somites (arrowheads: A). (B,C) At the onset of myofibrillogenesis, β1-integrin localizes diffusely overlying the nascent myofibril before achieving a striated appearance with accumulation overlying the Z disk (arrowheads: D,E). Frequently a lower abundance and more diffuse accumulation of β1-integrin is noted at the mid A band (arrows: D,E). Line scans assessing pixel intensity notes a regular pattern of β1-integrin accumulation overlying the Z disks (black bars: F,G) with frequent smaller accumulations in the mid (A) band (grey bars: F,G). Note that, in general, the distance between Z disk accumulations of β1-integrin is less between Z disks without an intervening mid (A) band accumulation (F: far right; G: far left). Scale bars are 50 μm (A), 20 μm (B,C) and 5 μm (D,E).