Fig. 2

Atrogin-1 deficiency results in impaired membrane integrity and apoptosis. Live images of methyl cellulose–treated 6 dpf atrogin-1+/+ (A–C) and atrogin-1–/– (D–F) on the (Tg(actc1b:Lifeact-GFP);Tg(actc1b:CAAX-mCherry) background, whereby the actin filaments within the muscle fibers are labeled with GFP and membrane and t-tubules with mCherry. While muscle cells in the atrogin-1+/+ wild-type larvae span the entire length of the somite, with the sarcolemma fully surrounding each cell, atrogin-1–/– mutants display detached muscle fibers that are surrounded with irregular sections of sarcolemma, along with presence of abnormal sarcolemma vacuoles. Live images of methyl cellulose–treated 6 dpf atrogin-1+/+ (G–I) and atrogin-1–/– (J–L) larvae injected with Evans blue dye. atrogin-1–/– mutants displayed an accumulation of the dye, which is absent in atrogin-1+/+ larvae. TUNEL staining on 3 dpf methyl cellulose–treated atrogin-1+/+ (M–O) and atrogin-1–/– (P–R) larvae, with the latter displaying TUNEL in areas where the muscle cell had detached. Scale bar: 100 μm (A–F); 300 μm (G–R).