Figure 2

Ingestion of Ecc15 results in the delamination of enterocytes and anoikis. (a) A scheme describing the mechanism by which delamination of enterocytes could account for the shortening and widening of the gut. W, width; L, length. (b) Infection results in an intense multilayering (arrows) and the blebbing (stars) and delamination of enterocytes following ingestion of Ecc15. Representative images of UC and Ecc15 infected (t = 4 and 8 hours) guts are shown. Histological sections of the anterior midgut region were analyzed by light microscopy at ×63 original magnification. (c) Localization of the septate junction marker Discs large (dlgGFP) reveals a regular pattern in UC WT flies. Cross section of the gut shows that Dlg is located apically between enterocytes. Infection with Ecc15 disrupts Dlg localization in the gut. Cell blebbing (white arrows) occurs apically to the Dlg compartment. (d) Immunostaining of guts expressing the c-Jun N-terminal kinase (JNK)-responsive reporter gene puc-lacZ revealed that ingestion of Ecc15 results in the activation of the JNK pathway in most enterocytes and all delaminating cells. Additionally, immunostaining of sections of guts from WT flies with antibodies directed against the phospho-form of JNK (red) reveals continued JNK activation in delaminating enterocytes (4 to 16 hours postinfection with Ecc15). Fragmented nuclei were observed in some of these JNK-positive cells (inset). (e) Immunostaining of histological sections of WT flies with antibodies directed against the cleaved form of caspase 3 shows that cells undergo apoptosis only after they have detached from the epithelium. This signal was detected during the duration of the infectious process in cells at varying stages of delamination and anoikis.