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J Cell Sci. 2015 May 1;128(9):1812-23. doi: 10.1242/jcs.167353. Epub 2015 Mar 18.

Biased assembly of the nuclear pore complex is required for somatic and germline nuclear differentiation in Tetrahymena.

Author information

1
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan.
2
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Japan Women's University, Tokyo 112-8681, Japan.
3
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan.
4
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan.
5
Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology (NICT), Kobe 651-2492, Japan Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan tokuko@nict.go.jp.

Abstract

Ciliates have two functionally distinct nuclei, a somatic macronucleus (MAC) and a germline micronucleus (MIC) that develop from daughter nuclei of the last postzygotic division (PZD) during the sexual process of conjugation. Understanding this nuclear dimorphism is a central issue in ciliate biology. We show, by live-cell imaging of Tetrahymena, that biased assembly of the nuclear pore complex (NPC) occurs immediately after the last PZD, which generates anterior-posterior polarized nuclei: MAC-specific NPCs assemble in anterior presumptive MACs but not in posterior presumptive MICs. MAC-specific NPC assembly in the anterior nuclei occurs much earlier than transport of Twi1p, which is required for MAC genome rearrangement. Correlative light-electron microscopy shows that addition of new nuclear envelope (NE) precursors occurs through the formation of domains of redundant NE, where the outer double membrane contains the newly assembled NPCs. Nocodazole inhibition of the second PZD results in assembly of MAC-specific NPCs in the division-failed zygotic nuclei, leading to failure of MIC differentiation. Our findings demonstrate that NPC type switching has a crucial role in the establishment of nuclear differentiation in ciliates.

KEYWORDS:

Ciliates; Live CLEM; Live cell imaging; Nuclear differentiation; Nuclear envelope; Nuclear pore complex

PMID:
25788697
PMCID:
PMC4432229
DOI:
10.1242/jcs.167353
[Indexed for MEDLINE]
Free PMC Article

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