Fig. 4: Deletion of SSNA-1 results in excess centrioles.

A Time-lapse images of the first four rounds of division of either wild-type or ssna-1(Δ) embryos expressing GFP::histone, mCherry::β-tubulin, and GFP::SPD-2. While wild-type embryos form only bipolar spindles, ssna-1(Δ) embryos form multipolar spindles beginning around the four-cell stage. During the third round of division in the ssna-1(Δ) embryo (t = 27:00), multiple centrosomes highlighted by cyan, yellow, and white arrowheads appear. These form a multipolar spindle in the EMS cell (t = 33:00). Each centrosome is capable of duplication as shown in the subsequent daughter cells E (white arrowheads) and MS (cyan and yellow arrowheads). Scale bar = 10. B Percent of embryos displaying a multipolar spindle or detached centrosome defect. (n = number of embryos scored). C Percent of embryos at each cell stage displaying at least one multipolar spindle or a detached centrosome defect. The percent of embryos displaying no defect (bipolar spindles only) are represented by black bars. (n = number of embryos scored). D Percentage of tripolar and tetrapolar spindles among all multipolar spindles (n = spindles scored). E Percentage of cells with a bi-, tri- or tetrapolar spindle at each embryonic cell stage (n = number of cells scored). F An immunofluorescent image of a four-cell stage ssna-1(Δ) embryo with a multipolar spindle in both the ABp (1–3) and EMS (4–6) cells. Note that all spindle poles are positive for both ZYG-1::SPOT and SAS-4 indicating the extra spindle poles contain centrioles. Scale bar = 10 μm. Nineteen embryos with multipolar spindles were examined with all poles of all multipolar spindles staining positive for each marker. Source data are provided as a Source Data file.