Limits...
Elasticity and structure of eukaryote chromosomes studied by micromanipulation and micropipette aspiration.

Houchmandzadeh B, Marko JF, Chatenay D, Libchaber A - J. Cell Biol. (1997)

Bottom Line: Larger deformations of 10 to 100 times irreversibly and progressively transform the chromosomes into a "thin filament," parts of which display a helical organization.Chromosomes break for elongations of the order of 100 times, at which time the applied force is around 100 nanonewtons.Knowing the Young modulus allows us to estimate that the force exerted by the spindle on a newt chromosome at anaphase is roughly one nanonewton.

View Article: PubMed Central - PubMed

Affiliation: Centre National de la Recherche Scientifique (CNRS), Laboratoire de Spectrométrie Physique, Saint-Martin-d'Hères, France. bahram@coucou.ujf-grenoble.fr

ABSTRACT
The structure of mitotic chromosomes in cultured newt lung cells was investigated by a quantitative study of their deformability, using micropipettes. Metaphase chromosomes are highly extensible objects that return to their native shape after being stretched up to 10 times their normal length. Larger deformations of 10 to 100 times irreversibly and progressively transform the chromosomes into a "thin filament," parts of which display a helical organization. Chromosomes break for elongations of the order of 100 times, at which time the applied force is around 100 nanonewtons. We have also observed that as mitosis proceeds from nuclear envelope breakdown to metaphase, the native chromosomes progressively become more flexible. (The elastic Young modulus drops from 5,000 +/- 1,000 to 1,000 +/- 200 Pa.) These observations and measurements are in agreement with a helix-hierarchy model of chromosome structure. Knowing the Young modulus allows us to estimate that the force exerted by the spindle on a newt chromosome at anaphase is roughly one nanonewton.

Show MeSH
The tip of a chromosome is grabbed inside  the micropipette, and the  chromosome is suspended  between the ensemble of  other chromosomes and the  pipette (a). The portion between kinetochore and pipette is then progressively  stretched by a factor of 10  (b–d). The micropipette is  then brought back to the  original position (e). No plasticity is observed, and the  chromosome recovers its  original length. The duration  of the deformation–release  cycle was 30 s. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2139812&req=5

Figure 1: The tip of a chromosome is grabbed inside the micropipette, and the chromosome is suspended between the ensemble of other chromosomes and the pipette (a). The portion between kinetochore and pipette is then progressively stretched by a factor of 10 (b–d). The micropipette is then brought back to the original position (e). No plasticity is observed, and the chromosome recovers its original length. The duration of the deformation–release cycle was 30 s. Bar, 10 μm.

Mentions: Large deformations were studied by exploiting the very strong adhesion of the chromosome to the pipette at one end and to the mass of other chromosomes at the other end. The chromosome is suspended between the pipette and the cell, in the culture buffer. The pipette is then moved to deform the chromosome by a given amount and brought back (Fig. 1).


Elasticity and structure of eukaryote chromosomes studied by micromanipulation and micropipette aspiration.

Houchmandzadeh B, Marko JF, Chatenay D, Libchaber A - J. Cell Biol. (1997)

The tip of a chromosome is grabbed inside  the micropipette, and the  chromosome is suspended  between the ensemble of  other chromosomes and the  pipette (a). The portion between kinetochore and pipette is then progressively  stretched by a factor of 10  (b–d). The micropipette is  then brought back to the  original position (e). No plasticity is observed, and the  chromosome recovers its  original length. The duration  of the deformation–release  cycle was 30 s. Bar, 10 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139812&req=5

Figure 1: The tip of a chromosome is grabbed inside the micropipette, and the chromosome is suspended between the ensemble of other chromosomes and the pipette (a). The portion between kinetochore and pipette is then progressively stretched by a factor of 10 (b–d). The micropipette is then brought back to the original position (e). No plasticity is observed, and the chromosome recovers its original length. The duration of the deformation–release cycle was 30 s. Bar, 10 μm.
Mentions: Large deformations were studied by exploiting the very strong adhesion of the chromosome to the pipette at one end and to the mass of other chromosomes at the other end. The chromosome is suspended between the pipette and the cell, in the culture buffer. The pipette is then moved to deform the chromosome by a given amount and brought back (Fig. 1).

Bottom Line: Larger deformations of 10 to 100 times irreversibly and progressively transform the chromosomes into a "thin filament," parts of which display a helical organization.Chromosomes break for elongations of the order of 100 times, at which time the applied force is around 100 nanonewtons.Knowing the Young modulus allows us to estimate that the force exerted by the spindle on a newt chromosome at anaphase is roughly one nanonewton.

View Article: PubMed Central - PubMed

Affiliation: Centre National de la Recherche Scientifique (CNRS), Laboratoire de Spectrométrie Physique, Saint-Martin-d'Hères, France. bahram@coucou.ujf-grenoble.fr

ABSTRACT
The structure of mitotic chromosomes in cultured newt lung cells was investigated by a quantitative study of their deformability, using micropipettes. Metaphase chromosomes are highly extensible objects that return to their native shape after being stretched up to 10 times their normal length. Larger deformations of 10 to 100 times irreversibly and progressively transform the chromosomes into a "thin filament," parts of which display a helical organization. Chromosomes break for elongations of the order of 100 times, at which time the applied force is around 100 nanonewtons. We have also observed that as mitosis proceeds from nuclear envelope breakdown to metaphase, the native chromosomes progressively become more flexible. (The elastic Young modulus drops from 5,000 +/- 1,000 to 1,000 +/- 200 Pa.) These observations and measurements are in agreement with a helix-hierarchy model of chromosome structure. Knowing the Young modulus allows us to estimate that the force exerted by the spindle on a newt chromosome at anaphase is roughly one nanonewton.

Show MeSH