Fig. 6

Phenotypic characterization of candidate mammalian heart genes with severe cardiac-specific mortality in Drosophila. Cardiac RNAi against RpL14, RpS24, and Rpn8 does not affect embryo hatching rates (A) nor first instar heart rates (B) relative to sibling controls. ns, not significant. (C) Stitched confocal projection images of third instar larval heart tubes marked by Hand-GFP with aorta, heart proper (hp), and pericardial cells indicated, of representative RpL14, RpS24, and Rpn8 knockdown, and control (4 × Hand-Gal4/+) individuals. Note the diminished pericardial cell size in RpL14 and RpS24 knockdown larvae and cell size variability in Rpn8 knockdown larvae (yellow arrowhead indicates a normal sized cell). These larvae had no heartbeat. Scale bars are 400 μm. Yellow asterisk denotes non-cardiac tissue. Anteriors are to the left. D Heart tube structure and morphology in cardiac knockdown third instar larvae visualized by F-actin staining (top row) and anti-Pericardin immunostaining (bottom row) to show extracellular matrix (cardiac collagen). Knockdowns displayed partial (RpL14, Rpn8, arrowed) or complete heart tube atrophy (RpS24) and infiltration of cells (likely macrophages, asterisks). Pericardin is thickened and breaks are visible for RpS24 (arrowhead), while for RpL14 collagen appears thin and less dense. Dotted lines indicate the expected location of the heart tube filament. Scale bars are 100 μm