Figure 3.

Kinase activity at OCs and rearrangement of the nuclear envelope of meiotic nuclei. (A) Activation of the MAPK pathway and phosphorylation of meiotic substrates occurs at OCs, analogous to MTOCs (gamma-tubulin staining), as indicated by pERK1/2 and MPM-2 stainings, respectively. MeN, meiotic nucleus; NN, nurse nucleus. (B) OCs are positioned toward the vegetal pole of pro-oocytes, opposite clustered nuclear pore complexes (NPCs) at the animal pole in P3.⁷ In selected pro-oocyte meiotic nuclei (S-MeN), NPCs form clusters at the OC-nucleus interface at P4. Non-selected meiotic nuclei (N-MeN) associate with nurse nuclei, along with OCs which localize within a large invagination of the nurse nuclear envelope. (C) Nurse nuclei and selected meiotic nuclei of P4 ovaries are bounded by O. dioica lamin1,⁴⁴ whereas no odLamin1 was observed surrounding non-selected meiotic nuclei. D) Schematic representation of events in the coenocyst during P3 and P4, illustrating NPC, OC, and lamin dynamics from pre- to post-selection of meiotic nuclei. (A-C) Scale bars = 5 μm.