Figure 6. Mp activity is essential for proper heart contraction of adult fly hearts.

Cardiac cross sections through an adult heart stained with anti Mp (red, A,A′) and anti Laminin (green, A′). Empty white arrowheads in A and A′ indicate positive staining for Mp in the cardiac lumen. Filled white arrowheads show positive staining of Mp between the cardioblast layer and the ventral longitudinal muscles. B- Heart contractility is quantified as fractional shortening or the extent to which the heart walls come together during systole. Fractional shortening is significantly reduced in mp mutant flies. C- the reduction in fractional shortening is also evident in representative Mmode records from wild type (WT) or mp mutant hearts. Diastole and systole levels are indicated by red arrows.