FIGURE 9:

Spectrin is required for production of prominent central actin bundles during ovulation. (A) Confocal maximum intensity projections of spermathecae expressing GFP::ACT-1 to label actin. Images are frames from first ovulation movies at 280-s intervals from oocyte entry (0 s) to after contraction (1120 s) colored to highlight differences in fluorescence intensity. In the WT cell before contraction (0 s), three prominent central bundles are seen (white arrows) that appear less bright than actin bundles at the cell periphery (asterisks). During contraction, central actin bundles become more prominent. After contraction (1120 s), at least five prominent central actin bundles are visible (white arrows) that are nearly as bright as actin bundles at the cell periphery (asterisks). In the unc-70(RNAi) cell before contraction (0 s), there are two prominent central actin bundles (white arrowheads). These central bundles diminish in intensity during contraction while peripheral bundles are maintained and slightly increase in intensity. After contraction (1120 s), the central bundles (white arrowheads) are less prominent than the bright actin bundles at the cell periphery (asterisks). (B) Quantification of fluorescence intensity of a line drawn across the WT cell and the unc-70(RNAi) cell indicated by dashed lines in A. Prominent central bundles are indicated by black arrows and peripheral actin bundles are indicated by black asterisks. Scale bar, 5 μm.