FIGURE 10:

Fascin genetically interacts with Cofilin to regulate nuclear actin. (A–C) Maximum projections of two to four confocal slices of follicles stained for nuclear actin (anti–actin C4). (A) fascin^sn28/ +, (B) cofilin^tsr1/+, and (C) fascin^sn28/ +; cofilin^tsr1/+. Orange arrows indicate structured nuclear actin within the nurse cells. Scale bars, 50 μm. (D) Chart quantifying the percentage of nurse cells in S5–6, S7–8, and S9 of the indicated genotypes exhibiting unstructured or structured nuclear actin; the number of follicles (n) examined is indicated across the top of the chart. Each follicle within a confocal stack was scored, in a genotypically blinded manner, for the percentage of nurse cells exhibiting unstructured nuclear actin haze or low, medium or high levels of structured nuclear actin. Heterozygosity for a null allele of fascin has minimal effect on the frequency of nurse cells with structured nuclear actin levels, whereas heterozygosity for cofilin (Drosophila twinstar, tsr) exhibits reduced structured nuclear actin in S5/6 and S9 compared with fascin−/+ (A and B, quantified in D). Double heterozygotes for mutations in fascin and cofilin result in a striking reduction in the number of nurse cells with structured nuclear actin compared with either heterozygote alone (C vs. A and B; quantified in D); red asterisks indicate significant difference from both individual heterozygotes at the same stages. ***p < 0.001 and *p < 0.05; Fisher’s exact test.