Figure 1.

Annulate Lamellae Are Maternally Synthesized

(A) Scheme of the Drosophila egg chamber: anterior nurse cells and the posterior oocyte form the germline, both are surrounded by somatic follicle cells. In all further images, anterior is to the left, posterior to the right and an accompanying scheme highlights the image content relative to the egg chamber.

(B and B’) RFP::Nup107 enriches at AL-NPCs. Correlative light and electron microscopy (CLEM) of a stage 9 oocyte dissected from a RFP::Nup107 expressing fly. RFP fluorescence concentrates at densely packed NPCs at stacked ER sheets in the oocyte, representing AL (arrowheads in B’).

(C–G) AL accumulate during oogenesis. Confocal images of living RFP::Nup107-expressing egg chambers (C–F) during stage 5 (C), 7 (D), 10 (E), and 14 (F). RFP::Nup107-labeled foci accumulate in the cytoplasm of oocytes (red arrowheads in C–F). AL are rare in nurse cells and absent in follicle cells (cyan arrowheads in E and F). In (G) is quantification of raw RFP::Nup107 fluorescence (integrated ± STDV) in either nurse cells (circles) or oocytes (squares) of z projections acquired from images as in (C)–(F) (n = 23 egg chambers). RFP::Nup107 fluorescence stays constant in nurse cells but increases in the ooplasm. Nurse cells have disappeared by stage 14. Abbreviation is as follows: a.u., arbitrary units.

(H–L) Nup107 is maternally contributed. Confocal images from fixed syncytial blastoderm (H and K), gastrulation (I and L) and late stage (J) embryos obtained from RFP::Nup107 mothers fertilized by GFP::Nup107 (H–J) or sqh-GFP::Kuk (K and L) fathers. Nuclei contain only maternal protein prior to zygotic induction (H and K). Nuclei in gastrulation embryos contain zygotic GFP::Kuk (L) but not GFP::Nup107 (I), which is only expressed in later embryo stages (J).

See also Video S1.