Fig. 3. kette and blow mutants form precursor cells with three or four nuclei. kette and blow mutants were analysed for founder/precursor cell status (using Eve and Kr) at (A-C) stage 15-16 and (D-G) stage 13. As a control for the Kr pattern of expression, we used mbc mutant embryos, which do not undergo any fusion step and arrest at the founder cell stage. It can be clearly seen that both kette and blow mutants build precursors that contain three or four nuclei, corresponding to what is seen in the wild type at stage 13. (A-C) Anti-Eve fluorescent staining in red (pc, pericardial cells). (A) Stage 16 wild-type embryo containing up to 14 Eve- and rP298-positive nuclei in DA1 muscle after fusion is completed. (B) Stage 15 kette^J4-48 null mutant embryo containing three or four Eve-positive nuclei in muscle DA1, corresponding to precursor cells. (C) Stage 15 blow² mutant with two or three nuclei in DA1 muscle, which also indicates the presence of precursor cells. (D-G) Anti-Kr fluorescent staining. (D) Stage 13 wild-type embryo displays precursor cells of muscles DA1 and DO1 with three or four nuclei after the first fusion step occurs. (E) Stage 13 mbc mutant embryo does not undergo the first fusion step, indicated by the single kr-expressing cells that correspond to the founder cells of the muscles. (F) Stage 13 kette^J4-48-null mutant embryo with three or four nuclei in precursors of muscles DA1 and DO1. (G) Stage 13 blow² mutant embryo with two or three nuclei in precursors of DA1 and DO1. Arrows in D-G indicate precursors of lateral muscles that are developing.