Reorganization of microtubules in the amitotically dividing macronucleus ofTetrahymena

Fujiu, Kenta; Numata, Osamu

doi:10.1002/(sici)1097-0169(200005)46:1<17::aid-cm3>3.0.co;2-c

Cited by 34 publications

(26 citation statements)

References 25 publications

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“…In Tetrahymena, macronuclear chromosomes lack centromeres and the MAC divides amitotically without a typical spindle being assembled. However, intranuclear microtubules that organize perpendicularly to the cleavage region have been implicated in MAC division (Smith et al, 2004;Fujiu and Numata, 2000;Wunderlich and Speth, 1970;Tamura et al, 1969). These microtubules seem to be nucleated at a large number of sites inside of the nucleus (Fujiu and Numata, 2000).…”

Section: Tetrahymena Mob1 Depletion Leads To a Delay In Cilia Recoverymentioning

confidence: 99%

Mob1: defining cell polarity for proper cell division

Tavares

Gonçalves

Florindo

et al. 2012

Journal of Cell Science

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SummaryMob1 is a component of both the mitotic exit network and Hippo pathway, being required for cytokinesis, control of cell proliferation and apoptosis. Cell division accuracy is crucial in maintaining cell ploidy and genomic stability and relies on the correct establishment of the cell division axis, which is under the control of the cell's environment and its intrinsic polarity. The ciliate Tetrahymena thermophila possesses a permanent anterior-posterior axis, left-right asymmetry and divides symmetrically. These unique features of Tetrahymena prompted us to investigate the role of Tetrahymena Mob1. Unexpectedly, we found that Mob1 accumulated in basal bodies at the posterior pole of the cell, and is the first molecular polarity marker so far described in Tetrahymena. In addition, Mob1 depletion caused the abnormal establishment of the cell division plane, providing clear evidence that Mob1 is important for its definition. Furthermore, cytokinesis was arrested and ciliogenesis delayed in Tetrahymena cells depleted of Mob1. This is the first evidence for an involvement of Mob1 in cilia biology. In conclusion, we show that Mob1 is an important cell polarity marker that is crucial for correct division plane placement, for cytokinesis completion and for normal cilia growth rates.

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Section: Tetrahymena Mob1 Depletion Leads To a Delay In Cilia Recoverymentioning

confidence: 99%

Mob1: defining cell polarity for proper cell division

Tavares

Gonçalves

Florindo

et al. 2012

Journal of Cell Science

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“…In Tetrahymena, cytoplasmic microtubules appear to connect the nuclear envelope and the cell cortex during cell division, possibly pulling on the nuclear envelope in a manner resembling the action of astral microtubules. Intranuclear microtubules are nucleated within or around the chromatin, eventually reaching from the chromatin to the nuclear envelope, pushing the nuclear envelope in a manner resembling the action of spindle microtubules (17,40).…”

Section: Discussionmentioning

confidence: 99%

“…Coverslips were inverted onto 7 l of Vectashield (Vector Laboratories) with 1 g/ml DAPI. Immunofluorescence with antibodies against ␣-tubulin was done as described by Fujiu and Numata (17). Mating cells were prepared as described by Numata et al (34).…”

Section: Methodsmentioning

confidence: 99%

The Condensin Complex Is Essential for Amitotic Segregation of Bulk Chromosomes, but Not Nucleoli, in the Ciliate Tetrahymena thermophila

Cervantes

Coyne²,

et al. 2006

Molecular and Cellular Biology

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The macronucleus of the binucleate ciliate Tetrahymena thermophila contains fragmented and amplified chromosomes that do not have centromeres, eliminating the possibility of mitotic nuclear division. Instead, the macronucleus divides by amitosis with random segregation of these chromosomes without detectable chromatin condensation. This amitotic division provides a special opportunity for studying the roles of mitotic proteins in segregating acentric chromatin. The Smc4 protein is a core component of the condensin complex that plays a role in chromatin condensation and has also been associated with nucleolar segregation, DNA repair, and maintenance of the chromatin scaffold. Mutants of Tetrahymena SMC4 have remarkable characteristics during amitosis. They do not form microtubules inside the macronucleus as normal cells do, and there is little or no bulk DNA segregation during cell division. Nevertheless, segregation of nucleoli to daughter cells still occurs, indicating the independence of this process and bulk DNA segregation in ciliate amitosis.

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“…Double immunofluorescence staining for TCBP-25 and α-tubulin was performed by the method of Fujiu and Numata (2000), except for using protease inhibitors (50 μg/ml leupeptin, 0.02 mM N α -tosyl-L-lysyl chloromethylketone, 5 μg/ml pepstatin A), and PiEM (10 mM Pipes, 10 mM EGTA, 5 mM MgSO4, pH 6.9) instead of PEM buffer solution. At the end of the immunofluorescent staining procedure, the cells were washed with PiEM.…”

Section: Indirect Immunofluorescence Microscopymentioning

confidence: 99%

Involvement of a 25 kDa Tetrahymena Ca2+-binding Protein in Pronuclear Exchange

Nakagawa

Fujiu

Cole

et al. 2008

Cell Struct. Funct.

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ABSTRACT. The Tetrahymena Ca2+ -binding protein of 25 kDa (TCBP-25) is a calmodulin family protein containing four EF-hand type calcium-binding domains. TCBP-25 is localized in the whole cell cortex and around both the migratory and stationary pronuclei at the pronuclear exchange stage during conjugation. TCBP-25 is expected to play an important role in conjugation, though its function during sexual reproduction has not been elucidated. According to the localization of this protein and its timing, three possible roles of TCBP-25 are proposed. TCBP-25 may play a role in 1) differentiating the two functional pronuclei from the degenerative postmeiotic nuclei, 2) the process of pronuclear exchange and 3) pronuclear fusion. To test these hypotheses, the localization of TCBP-25 in conjugation mutants (cnj10, cnj7 and bcd2) was examined. The results ruled out the first and the third hypotheses and suggested that TCBP-25 may play a role in pronuclear exchange. In the next step we succeeded in reducing expression of the TCBP-25 gene using the antisense ribosome system, and we analyzed the phenotype of the transformants. The knock down of TCBP-25 function also suggests that TCBP-25 plays a role in the pronuclear exchange and in the maintenance of cell shape.

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Reorganization of microtubules in the amitotically dividing macronucleus ofTetrahymena

Cited by 34 publications

References 25 publications

Mob1: defining cell polarity for proper cell division

Mob1: defining cell polarity for proper cell division

The Condensin Complex Is Essential for Amitotic Segregation of Bulk Chromosomes, but Not Nucleoli, in the Ciliate Tetrahymena thermophila

Involvement of a 25 kDa Tetrahymena Ca2+-binding Protein in Pronuclear Exchange

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