Fig 4. SPD-1 and centralspindlin localize to anaphase spindle microtubules. (A and B) DNA (blue), tubulin (green) and ZEN-4 (top) or SPD-1(bottom) (red) in control (A) or
klp-15/16(RNAi) (B) oocytes. ZEN-4 does not localize to metaphase spindles in either case. In anaphase, ZEN-4localizes to a distinct region in the midzone of control spindles (A, top zoom), but is sometimes not seen on spindles with a short chromosomesegregation distance. Following
klp-15/16(RNAi), ZEN-4 localizes to the microtubule bundles but is not concentrated to as distinct a band as in thecontrol (B, top zoom). In both control and
klp-15/16(RNAi) oocytes, SPD-1 does not localize to metaphase spindles. In control oocytes, SPD-1localizes to the microtubules between the chromosomes in early anaphase and then becomes concentrated in a band on the microtubule bundles inthe center of the spindle (A, bottom zoom). Following
klp-15/16(RNAi), SPD-1 localizes to microtubule bundles between segregating chromosomes,even when bundles are not all oriented along the same axis (B, bottom zoom) (quantification in Materials and Methods). (C) DNA (blue), tubulin(green), ZEN-4 (red) and SPD-1 (green in final merge). In both control and
klp-15/16(RNAi) oocytes, ZEN-4 and SPD-1 have similar but distinctlocalization patterns. (D) Movie stills of oocytes expressing mCherry::histone and SPD-1::GFP in both control and
klp-15/16(RNAi). In controlspindles, SPD-1 localizes between chromosomes as they begin to segregate and continues to accumulate as anaphase progresses, consistent withprevious studies [19, 20]. Following
klp-15/16(RNAi), SPD-1 begins to load all over the microtubules, and as SPD-1 accumulates, long bundlesbegin to form that then orient along the same axis and the chromosomes segregate (4/4 movies analyzed). White dashed lines = cell cortex.Bars = 2.5 um.