FIGURE 1:

Nuclear accumulation of actin is developmentally regulated. (A–D′) Maximum projections of two to four confocal slices of wild-type follicles. (A–D) Merged images of nuclear envelope (wheat germ agglutinin, WGA) in magenta and anti–actin C4 staining in green. (A′–D′) Anti–actin C4, white. Scale bars, 50 μm. The nurse cells during S5–9 exhibit varying levels of nuclear actin (A–B′), with some exhibiting structured actin (orange arrows) and others exhibiting a low haze of nuclear actin (unmarked). The germinal vesicles have very high levels of nuclear actin (A–C′, yellow arrowheads). In addition, actin is observed in the nuclei of a subset of the follicle cells during early oogenesis (B and B′, blue arrows). The actin C4 antibody also labels some F-actin structures, including the basal cortical actin of the follicle cells and the oocyte cortical actin during early oogenesis (B and B′, white arrows), the nurse cell cortical actin later in follicle development (>S10A; C–D′), ring canals (B and B′, white asterisks), and the muscle sheath (A–B′, blue asterisk). (E) Representative Western blots of subcellular fractionation with four independent samples, labeled 1–4, of whole ovary lysates from wild-type flies (total lysate, cytoplasmic fraction, nuclear fraction) blotted for actin (actin C4 and JLA20), Fascin (two exposures), Lamin Dm0 (nuclear marker), and α-Tubulin (cytoplasmic marker). bl, blank lane; Lad, ladder with molecular weight markers labeled. Actin and Fascin are found in the nuclear fraction of wild-type ovary lysates.