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. 2011 Apr 8;6(4):e18325. doi: 10.1371/journal.pone.0018325

Figure 1. LST-4 is required for efficient cell corpse clearance in the adult C. elegans germ line.

Figure 1

(A–D). DIC micrographs (A–D) or epifluorescence pictures (A′–D′) of C. elegans germlines. Dorsal is to the top and the germline bend is to right. Arrowheads indicate apoptotic germ cells or Acridine Orange (AO) staining of apoptotic corpses. In wild-type worms (A, D′) and in mutants with increased levels of germline apoptosis such as gla-3(op216) (B, B′), AO preferentially stains engulfed apoptotic cells present in acidic compartments. In worms mutant for genes required for efficient removal of apoptotic cells, here ced-12(k149), refractile cell corpses persist but do not stain with AO (C, C′). Similarly, lst-4(tm2423) worms show increased persistent cell corpses that fail to stain with AO (D, D′). Size bar, 10 µm. (E–G′) Transmission electron microscopy images of cell corpses and their neighboring cells (E–G) and corresponding camera lucida drawings (E′–G′); apoptotic cells are represented in dark grey, sheath cells in light grey and the germline syncytium in white. In lst-4(tm2423) animals (E, E′), apoptotic cells are fully internalized by the sheath cells, whereas in the ced-1(e1735); ced-5(n1812) double mutants apoptotic cells accumulate between germline syncytium and the sheath cells (F, F′). gla-3(op216) animals, which have increased germ cell apoptosis were used as a positive control (G, G′). Size bar, 2 µm. (H) Quantification of internalized apoptotic cells using TEM. For each genotype, two to three different animals 24 h post L4/adult molt were processed and analyzed as described by Zhou and coworkers [31]. (I) The domain structure of the SNX9 subfamily of sorting nexins is conserved through evolution. The percent aminoacid identity of each domain between LST-4 and human SNX18, mouse SNX33 and fly DSH3PX1 is indicated. SH3: Src- homology 3 domain; PX: Phagocytic oxidase domain; BAR: Bin/Amphiphysin/Rvs domain. The tm2423 deletion results in a frame shift and a premature stop. (J) Expression of C. elegans LST-4 or mouse SNX33 in engulfing cells rescues the cell corpse clearance defect of lst-4 mutants. Results shown are mean ± s.d. n>15 animals for each genotype.