Fig. 2
Cell-death genes are expressed in B.al/rapaav. a GFP under the control of the egl-1 promoter is expressed brightly in B.al/rapaav in the tail of an early fourth larval stage “wild-type” male of genotype nIs343; him-8. Scale bar: 10 μm. b The average intensity of P egl-1 ::4xNLS::GFP in the nucleus is higher in the dying B.al/rapaav cell than in the surviving B.al/rapaav homolog in early fourth larval stage animals. The B.al/rapaav fate was assigned based on partial cytoplasmic refractility and/or nuclear position and distance from the midline of the animal. Average fluorescent intensity within the nucleus was measured for confocal images of B.alapaav, B.arapaav and P12.pa in each animal, and the average background intensity was subtracted from each. A.U., arbitrary units. All genotypes include nIs343, and some also contain †: him-5(e1490); ‡: him-8; °: nIs349. c–e Proapoptotic genes egl-1 and ced-3 are not highly expressed in the surviving B.al/rapaav homolog (c) but are highly expressed in the dying B.al/rapaav (d). These two images were taken from the same animal, approximately 1.6 μm apart. Anterior, left; dorsal, top. Scale bars: 10 μm. Full Z-stack of this animal is available as Additional file 2: Movie 2, and two more examples are available as Additional file 3: Movie 3, Additional file 4: Movie 4. These animals were of the genotype nIs343; him-5(e1490); nIs349. e Quantification of nuclear mRNA transcripts of egl-1 and ced-3 in B.al/rapaav and the B.al/rapaav homolog. Only nuclear transcripts were counted, because we could not unambiguously determine to which cell non-nuclear transcripts belonged. Condensed chromatin (as visualized by DAPI, which stains DNA and shows the chromatin in a dying cell to be slightly brighter and smaller in volume than that in a living cell), a position to the left or right of P12.pa, or expression of P egl-1 ::4xNLS::gfp was each interpreted as indicating the secondary cell fate. All animals were of the genotype nIs343, him-5(e1490), nIs349. *: P < 0.005, **: P < 5 × 10−4