Apoptosis analysis in CED-1::GFP transgenic nematode strain CU1546.

<p>Visualization of GFP apoptosis marker inside the nematodes exposed to the violacein deficient mutant clones (20G8<i>vioA</i>⁻ panels A and B; 20G8<i>vioC⁻</i> panels C and D) or violacein producing clone (20G8, panels E and F and G and H). Images show a section of the intestine and the gonads of <i>C. elegans</i> by DIC (panels A, C, E, G) and by epifluorescence microscopy (panels B, D, F, H). A ring-shaped GFP signal was detected in somatic cells of CU1546 nematodes exposed to 20G8 clone (two white arrows in panel F and white arrow in panel H) but not to 20G8<i>vioA</i>⁻ and 20G8<i>vioC⁻</i> mutants (panel B and D). The ring-shaped GFP signal is associated with the expression of CED-1 receptor on the cell wall of engulfing cells only when phagocytosis of apoptotic cells is taking place. The ring-shaped GFP signal is apoptosis-specific and is visible in somatic cells of the nematodes (white arrows in E and G), the germ line (gonad) of the nematode is shown in panel G (black arrow). A non-specific fluorescence signal is visible in panels B and D.