Fig. 2: SSNA-1 is a component of the centriole and centriole satellite-like structures.

A Immunofluorescence images of SSNA-1::SPOT and SAS-4::GFP during the first embryonic division. SSNA-1 is found only at centrioles from meiosis through anaphase of the first cell cycle. During first telophase, additional weaker SSNA-1::SPOT foci can be seen (arrowheads). Scale bar = 10 μm and applies to (A and B). Enlargements are 2× magnifications. Experiment was repeated three times with identical results. B During the second cell cycle SSNA-1::SPOT remains centriolar but beginning around nuclear envelope breakdown (NEBD), SSNA-1::SPOT assembles into satellite-like structures that surround the centriole. Enlargements are 2× magnifications. Experiment was repeated three times with identical results. C, D Immunofluorescence image showing co-localization of SSNA-1::SPOT relative to the PCM marker GFP::SPD-5. Twenty-six two-cell embryos were examined with identical results. C During anaphase, SSNA-1::SPOT satellite-like structures localize outside of the PCM marked by GFP::SPD-5. Scale bar = 10 μm and applies to (C and D). D During telophase when the PCM breaks up into packets, SSNA-1::SPOT satellite-like structures remain distinct from SPD-5 packets. However, a portion of both SSNA-1::SPOT and GFP::SPD-5 co-localize at the centriole (arrowheads in enlargements). E Frames from a time-lapse recording of an embryo expressing SSNA-1::wrmScarlet, γ-tubulin::GFP, and GFP::Histone H2B. First and last frame are at top. SSNA-1::wrmScarlet reorganizes during division of the ABpl cell (boxed). Time-lapse images reveals that the satellite-like structures disperse over the nucleus during interphase and accumulate at centrosomes as cells enter mitosis. Time is shown as mm:ss. Scale bar = 10 μm. A total of 40 embryos were imaged with similar results.