Fig. 5. Lmd protein expression is high in fusion-competent myoblasts and not exclusively nuclear. (A-D) Two segments of a representative rP298-lacZ embryo that was triple-stained with antibodies against Lmd, MEF2 and ß-gal, and analyzed by confocal microscopy. Different channel combinations of the same scan are shown. Co-expression of Lmd (green) and MEF2 (blue) is observed in lacZ-negative fusion-competent myoblasts (green/turquoise signals in A,B). Hollow arrowheads identify representative lacZ-positive (red) founders that express MEF2 (red/pink signals in C,D). A very low level of Lmd expression is observed in these founders (hollow arrowheads in A). (E-H) Three segments of a representative late stage 12 embryo that was triple-stained with antibodies against Lmd, MEF2 and nuclear lamin. Different channel combinations of the same scan are shown. Cy3-labeled lamin (red) demarcates the nuclear envelope. Lmd expression (green) is observed in both the cytoplasm and nucleus (arrowheads in E,G), whereas MEF2 expression (blue) is strictly nuclear (arrowheads in H); see also high magnification views in E₁-H₁. Co-expression of nuclear Lmd and MEF2 is observed in fusion-competent myoblasts (green/turquoise signals in F). Arrows identify representative myoblasts with exclusively cytoplasmic Lmd and no MEF2 expression; see also high magnification views in E₂-H₂. Hollow arrowheads identify MEF2-positive founder cells that lack Lmd expression.