scholarly journals All that is old does not wither: Conservation of outer kinetochore proteins across all eukaryotes?

2017 ◽  
Vol 216 (2) ◽  
pp. 291-293 ◽  
Author(s):  
Aruni P. Senaratne ◽  
Ines A. Drinnenberg
Keyword(s):  
Chromosome Segregation ◽  
Cell Biol

The kinetochore drives faithful chromosome segregation in all eukaryotes, yet the underlying machinery is diverse across species. D’Archivio and Wickstead (2017. J. Cell Biol. https://doi.org/10.1083/jcb.201608043) apply sensitive homology predictions to identify proteins in kinetoplastids with similarity to canonical outer kinetochore proteins, suggesting some degree of universality in the eukaryotic kinetochore.

scholarly journals Reductionism at the vertebrate kinetochore

2012 ◽  
Vol 200 (1) ◽  
pp. 7-8 ◽  
Author(s):  
Ana Stankovic ◽  
Lars E.T. Jansen
Keyword(s):  
Chromosome Segregation ◽  
Protein Interactions ◽  
Mitotic Spindle ◽  
De Novo ◽  
Large Structure ◽  
Cell Biol ◽  
Spindle Microtubules ◽  
The Creation

The kinetochore forms the site of attachment for mitotic spindle microtubules driving chromosome segregation. The interdependent protein interactions in this large structure have made it difficult to dissect the function of its components. In this issue, Hori et al. (2013. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201210106) present a novel and powerful methodology to address the sufficiency of individual proteins for the creation of a functional de novo centromere.

scholarly journals Concentrating on the mitotic spindle

2015 ◽  
Vol 210 (5) ◽  
pp. 691-693 ◽  
Author(s):  
Paul S. Maddox ◽  
Anne-Marie Ladouceur
Keyword(s):  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Molecular Crowding ◽  
Cell Biol ◽  
New Feature

In eukaryotes, the microtubule-based spindle drives chromosome segregation. In this issue, Schweizer et al. (2015; J. Cell Biol. http://dx.doi.org/10.1083/jcb.201506107) find that the spindle area is demarcated by a semipermeable organelle barrier. Molecular crowding, which is microtubule independent, causes the enrichment and/or retention of crucial factors in the spindle region. Their results add an important new feature to the models of how this structure assembles and is regulated.

scholarly journals A chemical tool box defines mitotic and interphase roles for Mps1 kinase

2010 ◽  
Vol 190 (1) ◽  
pp. 21-24 ◽  
Author(s):  
Weijie Lan ◽  
Don W. Cleveland
Keyword(s):  
Chromosome Segregation ◽  
Kinase Activity ◽  
Mitotic Checkpoint ◽  
Checkpoint Kinase ◽  
Checkpoint Proteins ◽  
Cell Biol ◽  
Chemical Inhibitors ◽  
Mitotic Inhibitors

In this issue, three groups (Hewitt et al. 2010. J. Cell Biol. doi:10.1083/jcb.201002133; Maciejowski et al. 2010. J. Cell Biol. doi:10.1083/jcb.201001050; Santaguida et al. 2010. J. Cell Biol. doi:10.1083/jcb.201001036) use chemical inhibitors to analyze the function of the mitotic checkpoint kinase Mps1. These studies demonstrate that Mps1 kinase activity ensures accurate chromosome segregation through its recruitment to kinetochores of mitotic checkpoint proteins, formation of interphase and mitotic inhibitors of Cdc20, and correction of faulty microtubule attachments.

scholarly journals ETAA1 ensures proper chromosome segregation: A matter of S phase or mitosis?

2019 ◽  
Vol 218 (12) ◽  
pp. 3883-3884
Author(s):  
Marina Alejandra González Besteiro ◽  
Vanesa Gottifredi
Keyword(s):  
Chromosome Segregation ◽  
S Phase ◽  
Chromosome Stability ◽  
Checkpoint Kinase ◽  
Cell Biol

ETAA1 activates the master checkpoint kinase ATR. Bass and Cortez (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201810058) recently reported an intra-mitotic function of ETAA1 that safeguards chromosome stability. In this issue, Achuthankutty et al. (2019. J. Cell Biol. https://doi.org/10.1083/jcb.201905064) describe a mechanism controlling the ATR-activating potential of ETAA1 in S phase to preserve chromosome stability.

scholarly journals A new piece in the kinetochore jigsaw puzzle

2014 ◽  
Vol 206 (4) ◽  
pp. 457-459
Author(s):  
Kevin D. Corbett ◽  
Arshad Desai
Keyword(s):  
Cell Division ◽  
Signaling Pathways ◽  
Chromosome Segregation ◽  
Budding Yeast ◽  
Eukaryotic Cell ◽  
Jigsaw Puzzle ◽  
New Model ◽  
Cell Biol ◽  
Chromosome Attachment ◽  
Spindle Microtubules

In eukaryotic cell division, the kinetochore mediates chromosome attachment to spindle microtubules and acts as a scaffold for signaling pathways, ensuring the accuracy of chromosome segregation. The architecture of the kinetochore underlies its function in mitosis. In this issue, Hornung et al. (2014. J. Cell Biol. http://dx.doi.org/201403081) identify an unexpected linkage between the inner and outer regions of the kinetochore in budding yeast that suggests a new model for the construction of this interface.

Freeze-Fracture Replication in the Ultrastructure of Blue-Green Algae

1967 ◽  
Vol 25 ◽  
pp. 74-75
Author(s):  
L. V. Leak
Keyword(s):  
Cell Wall ◽  
Electron Microscope ◽  
Green Algae ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Electron Microscopic ◽  
Photosynthetic Membranes ◽  
Blue Green Algae ◽  
Cell Biol ◽  
Cellular Components

Electron microscopic observations of freeze-fracture replicas of Anabaena cells obtained by the procedures described by Bullivant and Ames (J. Cell Biol., 1966) indicate that the frozen cells are fractured in many different planes. This fracturing or cleaving along various planes allows one to gain a three dimensional relation of the cellular components as a result of such a manipulation. When replicas that are obtained by the freeze-fracture method are observed in the electron microscope, cross fractures of the cell wall and membranes that comprise the photosynthetic lamellae are apparent as demonstrated in Figures 1 & 2.A large portion of the Anabaena cell is composed of undulating layers of cytoplasm that are bounded by unit membranes that comprise the photosynthetic membranes. The adjoining layers of cytoplasm are closely apposed to each other to form the photosynthetic lamellae. Occassionally the adjacent layers of cytoplasm are separated by an interspace that may vary in widths of up to several 100 mu to form intralamellar vesicles.

Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim
Keyword(s):  
Chromosome Segregation ◽  
New Technologies ◽  
Early Prophase ◽  
Unique Role ◽  
Kinetochore Assembly ◽  
M Phase ◽  
In Vivo Analysis ◽  
Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

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