Fig. 5. Induction of apoptosis activates PO in vivo in a Spn27A-dependent way. (A) Expression of the apoptotic inducer Grim together with GFP in hemocytes (he-GAL4 UAS-GFP.nls>UAS-grim) leads to formation of melanotic aggregates. Note that he is not expressed in all hemocytes, leaving some cells unaffected. (B) In a spn27a mutant background both the number and severity of the melanotic spots after expressing Grim in hemocytes is increased. (C) Spn27A co-expression with Grim in hemocytes (using the same driver but without UAS-GFPnls to compensate for GAL4 dosage in A and B) abolishes melanotic spot formation almost completely. (D,E) A preparation of an aggregate dissected from a larva such as those shown in A shows the presence of hemocytes which were labeled with GFP. Bar, 10 µm. Note that adults emerging from the cross in Fig. 5A show defects in wing morphology and co-expression of Grim and viral p35 protein abolishes the phenotypes attributable to Grim (not shown).