A Brief History of Research on Mitotic Mechanisms

McIntosh, J. Richard; Hays, Thomas S.

doi:10.3390/biology5040055

Cited by 33 publications

(28 citation statements)

References 182 publications

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“…Remarkably, this gel-state still persists when chromosomes are actively moved to form the metaphase plate. In light of our new experiments, assumptions implicit to models of chromosome centering by polar winds or chromosome pushing forces should be reconsidered [38][39][40] . Our experiments clearly show that in C. elegans embryos, forces exerted by the spindle do not primarily serve to compensate drag forces of chromosomes congressing in a viscous medium.…”

Section: Discussionmentioning

confidence: 99%

Active gelation breaks time-reversal-symmetry of mitotic chromosome mechanics

Mittasch

Fritsch

Nestler

et al. 2018

Preprint

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In cell division, mitosis is the phase in which duplicated sets of chromosomes are mechanically aligned to form the metaphase plate before being segregated in two daughter cells.Irreversibility is a hallmark of this process, despite the fundamental laws of Newtonian mechanics being time symmetric.Here we show experimentally that mitotic chromosomes receive the arrow of time by timereversal-symmetry breaking of the underlying mechanics in prometaphase. By optically inducing hydrodynamic flows within prophase nuclei, we find that duplicated chromatid pairs initially form a fluid suspension in the nucleoplasm: although showing little motion on their own, condensed chromosomes are free to move through the nucleus in a time-reversible manner. Actively probing chromosome mobility further in time, we find that this viscous suspension of chromatin transitions into a gel after nuclear breakdown. This gel state, in which chromosomes cannot be moved by flows, persists even when chromosomes start moving to form the metaphase plate. Complemented by minimal reconstitution experiments, our active intra-nuclear micro-rheology reveals time-reversal-symmetry breaking of chromosome mechanics to be caused by the transition from a purely fluid suspension into an active gel. Graphical abstract:One sentence summary: Flows induced in living cell nuclei reveal the rheological changes that bring chromosomes under mechanical control during mitosis. Main text:

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Section: Discussionmentioning

confidence: 99%

Active gelation breaks time-reversal-symmetry of mitotic chromosome mechanics

Mittasch

Fritsch

Nestler

et al. 2018

Preprint

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show abstract

“…Condensed mitotic chromosomes are visible by brightfield microscopy, particularly when phase or differential interference contrast is used. Thus, as summarized in Chapter 1 of this volume [5], they have been observed for over a century. In certain cell types, the mitotic chromosomes are relatively long and their primary constrictions—their centromeres—are also discernable.…”

Section: Centromeres and Kinetochores Usually Lead Anaphase Movemementioning

confidence: 99%

“…Several distinct categories of microtubule filaments exist, with well-defined polarities (as discussed thoroughly in Chapter 1 of this volume [5]). The most important for anaphase A are the kinetochore-attached microtubules, which have one end, their fast-growing ‘plus’ end, located at a kinetochore, while their ‘minus’ ends project poleward.…”

Section: Poleward Chromosome Movement Is Coupled To Shortening Of mentioning

confidence: 99%

Anaphase A: Disassembling Microtubules Move Chromosomes toward Spindle Poles

Asbury

2017

Biology

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The separation of sister chromatids during anaphase is the culmination of mitosis and one of the most strikingly beautiful examples of cellular movement. It consists of two distinct processes: Anaphase A, the movement of chromosomes toward spindle poles via shortening of the connecting fibers, and anaphase B, separation of the two poles from one another via spindle elongation. I focus here on anaphase A chromosome-to-pole movement. The chapter begins by summarizing classical observations of chromosome movements, which support the current understanding of anaphase mechanisms. Live cell fluorescence microscopy studies showed that poleward chromosome movement is associated with disassembly of the kinetochore-attached microtubule fibers that link chromosomes to poles. Microtubule-marking techniques established that kinetochore-fiber disassembly often occurs through loss of tubulin subunits from the kinetochore-attached plus ends. In addition, kinetochore-fiber disassembly in many cells occurs partly through ‘flux’, where the microtubules flow continuously toward the poles and tubulin subunits are lost from minus ends. Molecular mechanistic models for how load-bearing attachments are maintained to disassembling microtubule ends, and how the forces are generated to drive these disassembly-coupled movements, are discussed.

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“…This note is a short account an open-access book chapter that charts stages in the growth of our understanding of mitotic mechanism, beginning with the discovery of the process and running up to about 1990 [1]. Most of the other chapters of the book [2] provide a thorough review of progress in more recent years.…”

mentioning

confidence: 99%

“…In short, the initial chapter [1] and this book as a whole [2] provide the interested reader with access to progress in understanding this ageold problem in cell biology. The combination of the results themselves and the ways in which technology has partnered with exploration science to achieve these advances makes useful and interesting reading.…”

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confidence: 99%

Commentary on “Research on Mitotic Mechanisms”

McIntosh¹

2017

Adv Tech Biol Med

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Mitosis is the cellular process in which the already duplicated chromosomes are segregated into two identical in preparation for successful cell division. The discovery of mitosis in the late 19th century was made possible by the significant improvements in light microscopes achieved over many preceding decades. Since then, both the descriptions of mitotic phenomena and our understanding of the molecular mechanisms that underlie them has been facilitated at every step by technological advances. The following is a brief account of an open-access chapter that describes many of these advances, recently published as the first part of a ten-chapter book on mitotic mechanism. This open-access, on-line book provides reviews of each of the principal components and events of mitosis, such as kinetochores (the chromosomal specializations that attach each of the sister chromatids to spindle fibers), spindle formation, chromosome congression to the metaphase plate, the checkpoints that assesses quality in spindle formation, the two segments of anaphase chromosome segregation, and the consequences of mitotic errors. Anyone interested in the mechanisms that underly complex cellular processes should find these accounts both interesting and useful.

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A Brief History of Research on Mitotic Mechanisms

Cited by 33 publications

References 182 publications

Active gelation breaks time-reversal-symmetry of mitotic chromosome mechanics

Active gelation breaks time-reversal-symmetry of mitotic chromosome mechanics

Anaphase A: Disassembling Microtubules Move Chromosomes toward Spindle Poles

Commentary on “Research on Mitotic Mechanisms”

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