Supplemental Figures

This article contains the following supporting material:

• Supplemental Figure 1 - SUB localization and function during mitosis in embryos. SUB staining is in red, tubulin in green and DNA in blue. A) SUB is localized in the center of the spindle at metaphase of the mitotic divisions. B) During anaphase, SUB remains in the middle of the spindle. C) In embryos from sub mutant mothers, some embryos progress past pronuclear fusion. In these embryos, there is evidence of abnormal spindle formation, such as disorganized spindles (marked with arrow heads) and variability in DNA content. The scale bars are 5 μm.
• Supplemental Figure 2 - The intensity of tubulin fluorescence in different parts of the meiotic spindle was measured using the Leica confocal software “Profile” function. A Region of Interest was generated by drawing a line starting from one pole, continuing through the central spindle region, and ending at the other pole. In a tripolar spindle, the line was drawn between two of the poles. In a monopolar spindle, the line was drawn from the one pole to the central spindle region. The graphs show the tubulin fluorescence as a function of distance from one pole. Spindles with the profile shown in A) were common in wild-type but rare in sub mutants. In these spindles, the tubulin staining remained strong along the length of the spindle. In some cases, the tubulin fluorescence was strongest in the central region, resulting in a peak of fluorescence in the region near the karyosome. The profile in B) is typical of sub mutants and some wild-type spindles. The dip in the graph is in the region of the karyosome and reflects the drop in tubulin staining due to a weak or absent midzone. Some profiles from wild-type spindles, especially the shorter ones, had this shape even though it was clear from inspecting the images that a central region had formed. The relatively low central spindle intensity was not due to lack of a antiparallel microtubules, only they were not as developed as the longer spindles and therefore, did not have as much microtubule staining intensity as the kinetochore microtubules.