Fig. 3. Three ced-3 promoter elements act redundantly and specifically to regulate cell death and ced-3 expression in the tail-spike cell. (A) Alignment of the A, B and C promoter regions from the nematodes C. elegans and C. briggsae. Conserved nucleotides are shaded; boxed nucleotides are deleted in B and C; consensus nucleotides of caudal/Cdx2-binding sites are indicated by asterisks above the relevant nucleotides; numbers indicate the positions relative to the ced-3 start codon. (B,C) Regions A, B and C are required for GFP reporter expression and for the rescue of the ced-3(n717) cell death defect in the tail-spike cell. All experiments were performed in ced-3(n717) mutants. Regions A, B or C were deleted in the context of the conserved 349 bp C. elegans ced-3 promoter (B), the 1.5 kb C. elegans ced-3 promoter (C, left data column), or of pJ40, a plasmid containing C. elegans ced-3 genomic DNA (C, middle and right data columns). Reporter expression and cell death rescue were assessed as described in the Materials and methods section. x, deleted region; % Tail-spike cells expressing GFP, average±s.e.m. (number of transgenic lines examined); % Tail-spike cells surviving, average±s.e.m. (2-3 transgenic lines); No. extra cells in anterior pharynx, average±s.d. (2-3 transgenic lines); N.A., not applicable.