Figure 1.

Four modes of nuclear envelope morphology during mitosis in eukaryotes. (A) In higher eukaryotes, both the nuclear membrane and the NPCs disassemble at the beginning of mitosis, and subsequently chromosomes are segregated by the mitotic spindle during mitosis. (B) In a filamentous fungus Aspergillus nidulans, the nuclear membrane does not disassemble, but the NPCs are partially disassembled and RanGAP1 enters into the nucleus. (C) In the fission yeast Schizosaccharomyces pombe, both the nuclear membrane and the NPCs remain intact but RanGAP1 enters into the nucleus, resulting in V-NE BD during meiosis II. In (B and C), the collapse of the Ran-GTP gradient results in scrambling of nuclear and cytoplasmic materials. (D) Many lower eukaryotes, like fungi, undergo closed mitosis. During closed mitosis both the nuclear membrane and the NPCs remain intact, RanGAP1 remains localized in the cytoplasm, and the Ran-GTP gradient across the NE remains intact.