Figure 5.

The pro-apoptotic machinery is expressed in the male germ line during meiotic prophase, but CED-3 caspase is not activated. (A) Pathway of germ cell apoptosis in C. elegans [53]. (B) CED-9 inactivation does not induce apoptosis in the male germ line. Number of apoptotic nuclei per gonad arm measured by AO staining 24h post L4 stage (and 24h post IR). The number of germ lines scored for each genotype is in parenthesis. The data shown are means ± S.E.M. (C) CED-4 and SIR-2.1 are expressed in both hermaphrodite and male germ lines but no SIR-2.1 translocation occurs in male germ cells. Immunolocalization of CED-4 (green) and SIR-2.1 (red) counterstained with DAPI (blue) in pachytene nuclei from wild-type and zim-1(tm1813) hermaphrodite and male germ lines. Arrowheads point to nuclei with more intense CED-4 staining. Scale bars, 5μm. (D) CED-3 is expressed in hermaphrodite and male germ lines but levels do not increase under checkpoint-activating conditions in the male germ line. CED-3 immunolocalization (green) in pachytene nuclei stained with DAPI (blue) of adult worms (24h post L4). Arrowheads indicate apoptotic nuclei that lack CED-3 staining presumably because they have proceeded to a later stage. Scale bars, 5μm. (E) Males do not activate CED-3 caspase. Caspase activity was monitored by fluorescence microscopy following microinjection of SR-FLICA inhibitor in hermaphrodite and male germ lines of N2, zim-1(tm1813) and zim-1(tm1813);ced-3(RNAi) worms. Arrowheads mark some of the caspase-positive cells. Scale bars, 10μm.