Figure 4.

Hydrogen peroxide accumulates in the digestive tubules of starving E. cornigera, but not E. timida. Confocal laser scanning micrographs of the kleptoplast-bearing digestive tubules that pervade the parapodia of 10 days starved, whole mount E. cornigera and E. timida stained with 100 µM dichlorofluorescin (DCF; blue) and MitoTracker Red (green); chlorophyll autofluorescence in red to yellow (a,e) or red only (b–d, f, g). Digestive tubules of E. cornigera (lined with autofluorescent kleptoplasts) show well-defined DCF staining within the lumen and epithelium (a–d). Details of single digestive tubules revealing readily H₂O₂ accumulators of equal size as kleptoplasts (b arrowheads), kleptoplasts displaying weak DCF staining (c; see arrowheads) and MitoTracker Red co-localizing with DCF staining (d). Digestive tubules of E. timida displaying no distinguishable DCF signal in epithelium or lumen (e). Details of single digestive tubules revealing accumulating weak levels of H₂O₂ (f, arrowheads), comparable to those seen in E. cornigera (c, arrowheads) and showing globular structures of unknown nature accumulating H₂O₂ (g, arrowhead).