Direct Visualization of Microtubule Flux during Metaphase and Anaphase in Crane-Fly Spermatocytes

LaFountain, James R.; Cohan, Christopher S.; Siegel, Alan J.; LaFountain, Douglas J.

doi:10.1091/mbc.e04-08-0750

Cited by 58 publications

(80 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8) has provided important insights into the dynamic organization of meiotic spindle microtubules. It has been shown that both kMTs and non-kMTs flux poleward, but at different rates (9)(10)(11)(12). More recently, it has been shown that microtubule flux rate changes across the length of metaphase meiotic spindle (13).…”

mentioning

confidence: 99%

Op18 reveals the contribution of nonkinetochore microtubules to the dynamic organization of the vertebrate meiotic spindle

Houghtaling

Yang

Matov

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Accuracy in chromosome segregation depends on the assembly of a bipolar spindle. Unlike mitotic spindles, which have roughly equal amounts of kinetochore microtubules (kMTs) and nonkinetochore microtubules (non-kMTs), vertebrate meiotic spindles are predominantly comprised of non-kMTs, a large subset of which forms an antiparallel ''barrel'' array at the spindle equator. Though kMTs are needed to drive chromosome segregation, the contributions of nonkMTs are more mysterious. Here, we show that increasing the concentration of Op18/stathmin, a component of the chromosomemediated microtubule formation pathway that directly controls microtubule dynamics, can be used to deplete non-kMTs in the vertebrate meiotic spindle assembled in Xenopus egg extracts. Under these conditions, kMTs and the spindle pole-associated non-kMT arrays persist in smaller spindles. In excess Op18, distances between sister kinetochores, an indicator of tension across centromeres, remain unchanged, even though kMTs flux poleward with a Ϸ30% slower velocity, and chromosomes oscillate more than in control metaphase spindles. Remarkably, kinesin-5, a conserved motor protein that can push microtubules apart and is required for the assembly and maintenance of bipolar meiotic spindles, is not needed to maintain spindle bipolarity in the presence of excess Op18. Our data suggest that non-kMTs in meiotic spindles contribute to normal kMT dynamics, stable chromosome positioning, and the establishment of proper spindle size. We propose that without non-kMTs, metaphase meiotic spindles are similar to mammalian mitotic spindles, which balance forces to maintain metaphase spindle organization in the absence of extensive antiparallel microtubule overlap at the spindle equator or a key mitotic kinesin.stathmin ͉ bipolarity ͉ flux ͉ kinesin-5

show abstract

mentioning

confidence: 99%

Op18 reveals the contribution of nonkinetochore microtubules to the dynamic organization of the vertebrate meiotic spindle

Houghtaling

Yang

Matov

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…This poleward microtubule 'flux' is coupled to minus end disassembly at or near the poles [23,[26][27][28][29][30][31][32]. Anaphase A in these cells is therefore a superposition of a kinetochore's pac-man movement relative to the microtubules and the microtubules' flux relative to the poles.…”

Section: Kinetochore-attached Microtubules Can 'Flux' Continuously Tomentioning

confidence: 99%

Anaphase A: Melting Microtubules Move Chromosomes toward Spindle Poles

Cl¹

2017

Preprint

View full text Add to dashboard Cite

Abstract: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, or 'melting' of the kinetochore-attached microtubule fibers that link chromosomes to poles. Microtubule-marking techniques established that kinetochore-fiber disassembly often occurs through a 'pac-man' mechanism, where tubulin subunits are lost from kinetochore-attached plus ends and the kinetochore appears to consume its microtubule track as it moves poleward. 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 pac-man and flux-based movements, are discussed.

show abstract

“…For example, in crane fly spermatocytes, Flux occurs at nearly twice the rate of anaphase A, since the plus-ends of kinetochore microtubules continue to polymerize even as the kinetochore is pulled poleward (LaFountain et al 2004). Similarly in Xenopus egg extract spindles, the rates of Flux and anaphase A are almost identical (Desai et al 1998).…”

Section: Mechanism Of Flux I: Depolymerization Of Spindle Pole-focusementioning

confidence: 99%

The molecular basis of anaphase A in animal cells

Rath

Sharp

2011

Chromosome Res

View full text Add to dashboard Cite

The mechanisms that move chromatids poleward during anaphase A have fascinated researchers for decades. There is now growing evidence that this movement is tightly linked to the active depolymerization of both ends of kinetochoreassociated microtubules, a mechanism we refer to as "Pacman-Flux." Contemporary data suggest that this is catalyzed by the integration of multiple enzymatic activities including (1) microtubule-end depolymerases housed at the pole or kinetochore, (2) microtubule-severing enzymes used to uncap the ends of kinetochore-associated microtubules, and (3) molecular motors which drive tubulins towards the pole or into kinetochores.

show abstract

Direct Visualization of Microtubule Flux during Metaphase and Anaphase in Crane-Fly Spermatocytes

Cited by 58 publications

References 42 publications

Op18 reveals the contribution of nonkinetochore microtubules to the dynamic organization of the vertebrate meiotic spindle

Op18 reveals the contribution of nonkinetochore microtubules to the dynamic organization of the vertebrate meiotic spindle

Anaphase A: Melting Microtubules Move Chromosomes toward Spindle Poles

The molecular basis of anaphase A in animal cells

Contact Info

Product

Resources

About