Centrioles no longer duplicate in endocycling cells prior to their elimination.

<p>(<b>A</b>) SPD-2::GFP signal can be seen throughout the germ line until oogenesis in (a), while in (b) it is undetectable in the intestinal cells in adult hermaphrodites. a′ and b′ are high magnification images of the GFP signal in the field identified by the two white rectangles a and b. (<b>B–F</b>) and (<b>G–I</b>) SPD-2 and SAS-4 foci are detectable up to the L1/L2 transition. The signal is no longer detectable by the L3 stage. The nuclear localized SPD-2 is absent following <i>spd-2</i>(<i>RNAi</i>) in (F). Animals were stained with DAPI (red) and anti-SPD-2 (green) in (B–F) or anti-SAS-4 (green) in (G–I). Arrowheads indicate centrioles, while asterisks indicate intestinal nuclei. The insets represent magnified SPD-2 or SAS-4 signal of the highlighted regions (white rectangles). The circles in (E) and (I) highlight the germ cells with either SPD-2 foci or SAS-4 foci. (<b>J</b>) Quantification of centriole numbers and described in (B–E) and (G–I) based on SPD-2 or SAS-4 detection. n≥56 for each stage. (<b>K</b>) Centriole duplication is uncoupled from the endocycles in the lateral hypodermal V cells in the late L1 stage. The centriole appears to be uncoupled from S-phase in the anterior endoreduplicating daughter cell but remains coupled to DNA replication in the mitotic posterior daughter. The square brackets indicate the daughter cells from a common mother V cell, while arrowheads indicate the centrioles. The inset is a magnified view of the region delineated by the white rectangle. A, anterior; P, posterior. hyp7 marks the hyp7 nucleus. (<b>L</b> and <b>M</b>) Supernumerary centrioles are detected in HU-treated L1 animals (M) but not in the control (L). The inset is a magnified SPD-2 signal of the region delineated by the white rectangle. Arrowheads indicate centrioles, while asterisks indicate intestinal nuclei. (<b>N</b> and <b>O</b>) Centriole duplication occurs once in response to S phase, but centrioles do not overduplicate and are not eliminated during un-quantized DNA re-replication. Heterozygous in (N) and homozygous <i>cul-4</i> (<i>gk434</i>) mutants in (O) were stained with DAPI (red) and SPD-2 (green) respectively. The insets show the SPD-2 signal in the regions outlined by the white rectangles. Arrowheads indicate centrioles. Scale bar, 5 µm.