Figure 2. SPD-2 Is a Component of the C. elegans Centrosome. (A) wt and
spd-2(RNAi) embryos were labeled for DNA (blue), MTs (green), and SPD-2. Labeling of SPD-2 in wt embryos was restricted to the centrosome and was two tiered; a bright, central spot was surrounded by a dimmer halo. No labeling could be detected in
spd-2(RNAi) embryos confirming the specificity of our antibody. Merged images of the DNA and MT labelings are shown. Bar is 10 um.(B) Immuno-EM of wt embryos using SPD-2 antibodies. Labeling was observed on the centrioles (see higher magnification of boxed region) and in the periphery of centrioles, in the region corresponding to the PCM (arrows). The density of gold labeling is plotted against the distance from the centriole (gold particles/100
nm2). The labeling density was highest within 100 nm of the centriole. Bar is 250 nm.(C) Mature sperms were labeled for DNA (blue), SAS-4 (green), and SPD-2 (red). Note that SPD-2 and SAS-4 are both found on the sperm centriole. Bar is 1 um.(D) Embryos shortly after fertilization (top), further into female meiosis (middle), and shortly after the completion of female meiosis (bottom) were labeled for DNA (blue), MTs (green), SPD-2, and SPD-5. Note that SPD-5 localizes to the centrosomes after SPD-2. Merged images of the DNA and MT labelings are shown. Bar is 10 um.