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Budding yeast chromosome structure and dynamics during mitosis.

Pearson CG, Maddox PS, Salmon ED, Bloom K - J. Cell Biol. (2001)

Bottom Line: Centromeres are in a metaphase-like conformation, whereas chromosome arms are neither aligned nor separated before anaphase.The stretched chromatin was observed to segregate to the spindle pole bodies at rates greater than centromere to pole movement, indicative of rapid elastic recoil between the chromosome arm and the centromere.These results indicate that the elastic properties of DNA play an as of yet undiscovered role in the poleward movement of chromosome arms.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. cgpearso@email.unc.edu

ABSTRACT
Using green fluorescent protein probes and rapid acquisition of high-resolution fluorescence images, sister centromeres in budding yeast are found to be separated and oscillate between spindle poles before anaphase B spindle elongation. The rates of movement during these oscillations are similar to those of microtubule plus end dynamics. The degree of preanaphase separation varies widely, with infrequent centromere reassociations observed before anaphase. Centromeres are in a metaphase-like conformation, whereas chromosome arms are neither aligned nor separated before anaphase. Upon spindle elongation, centromere to pole movement (anaphase A) was synchronous for all centromeres and occurred coincident with or immediately after spindle pole separation (anaphase B). Chromatin proximal to the centromere is stretched poleward before and during anaphase onset. The stretched chromatin was observed to segregate to the spindle pole bodies at rates greater than centromere to pole movement, indicative of rapid elastic recoil between the chromosome arm and the centromere. These results indicate that the elastic properties of DNA play an as of yet undiscovered role in the poleward movement of chromosome arms.

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Centromere proximal (∼1.1 kb) marker movement to the spindle pole body during anaphase A. Graphical plot of a single representative early anaphase onset (15 observed) using Nuf2–GFP to mark the spindle pole bodies and the ∼1.1-kb CEN11 chromosome marker. Centromere movement to the spindle pole body (anaphase A) began at or shortly after the onset of anaphase B spindle pole body separation. (A) Plot of anaphase onset. (B) Plot showing the separation of spindle pole bodies (▪) and CEN spots (▴) and the distance between the spindle pole body and the CEN proximal spot (•). The onset of anaphase A was defined by the decrease in the distance between the spindle pole body and the ∼1.1-kb spots, indicating that chromosomes were moving toward the spindle pole bodies. (C) Plot of each individual CEN proximal spot to spindle pole bodies with linear regression lines representing the general rate of anaphase A movement to the spindle pole body. The average slope was 0.33 ± 0.16 μm/min (Table ).
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Figure 5: Centromere proximal (∼1.1 kb) marker movement to the spindle pole body during anaphase A. Graphical plot of a single representative early anaphase onset (15 observed) using Nuf2–GFP to mark the spindle pole bodies and the ∼1.1-kb CEN11 chromosome marker. Centromere movement to the spindle pole body (anaphase A) began at or shortly after the onset of anaphase B spindle pole body separation. (A) Plot of anaphase onset. (B) Plot showing the separation of spindle pole bodies (▪) and CEN spots (▴) and the distance between the spindle pole body and the CEN proximal spot (•). The onset of anaphase A was defined by the decrease in the distance between the spindle pole body and the ∼1.1-kb spots, indicating that chromosomes were moving toward the spindle pole bodies. (C) Plot of each individual CEN proximal spot to spindle pole bodies with linear regression lines representing the general rate of anaphase A movement to the spindle pole body. The average slope was 0.33 ± 0.16 μm/min (Table ).

Mentions: The ∼1.1-kb CEN11 lacO marker was integrated into strains containing spindle pole bodies marked with Nuf2–GFP or Spc72–GFP. Z-series time-lapses were acquired at 15–45 s. We observed the ∼1.1-kb CEN11 proximal spots to move toward the GFP-marked spindle pole bodies coincident with or within 3 min after anaphase onset, as defined by the start of anaphase B spindle elongation (Fig. 4A and Fig. B and Fig. 5). Fig. 5 B (arrow) shows the separation of the spindle pole bodies to begin at the 0.0-min time point. Movement of the CEN proximal spots toward the spindle pole body ensues at 1.0 min (Fig. 5 B, arrow). This delay results in a transient increase in the distance between the centromere proximal spot and its spindle pole body. The centromere proximal spot began anaphase A chromosome movement toward the spindle pole body at an average spindle length of 2.87 ± 0.51 μm (Table IV; n = 15). Regression lines were drawn through each plot of centromere proximal chromosome spot movement to the spindle pole body (Fig. 5 C). The average rate observed was 0.33 ± 0.16 μm/min (Fig. 5 C; Table IV; n = 23). The average distance moved was 0.98 ± 0.28 μm (Table III; n = 23).


Budding yeast chromosome structure and dynamics during mitosis.

Pearson CG, Maddox PS, Salmon ED, Bloom K - J. Cell Biol. (2001)

Centromere proximal (∼1.1 kb) marker movement to the spindle pole body during anaphase A. Graphical plot of a single representative early anaphase onset (15 observed) using Nuf2–GFP to mark the spindle pole bodies and the ∼1.1-kb CEN11 chromosome marker. Centromere movement to the spindle pole body (anaphase A) began at or shortly after the onset of anaphase B spindle pole body separation. (A) Plot of anaphase onset. (B) Plot showing the separation of spindle pole bodies (▪) and CEN spots (▴) and the distance between the spindle pole body and the CEN proximal spot (•). The onset of anaphase A was defined by the decrease in the distance between the spindle pole body and the ∼1.1-kb spots, indicating that chromosomes were moving toward the spindle pole bodies. (C) Plot of each individual CEN proximal spot to spindle pole bodies with linear regression lines representing the general rate of anaphase A movement to the spindle pole body. The average slope was 0.33 ± 0.16 μm/min (Table ).
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Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199205&req=5

Figure 5: Centromere proximal (∼1.1 kb) marker movement to the spindle pole body during anaphase A. Graphical plot of a single representative early anaphase onset (15 observed) using Nuf2–GFP to mark the spindle pole bodies and the ∼1.1-kb CEN11 chromosome marker. Centromere movement to the spindle pole body (anaphase A) began at or shortly after the onset of anaphase B spindle pole body separation. (A) Plot of anaphase onset. (B) Plot showing the separation of spindle pole bodies (▪) and CEN spots (▴) and the distance between the spindle pole body and the CEN proximal spot (•). The onset of anaphase A was defined by the decrease in the distance between the spindle pole body and the ∼1.1-kb spots, indicating that chromosomes were moving toward the spindle pole bodies. (C) Plot of each individual CEN proximal spot to spindle pole bodies with linear regression lines representing the general rate of anaphase A movement to the spindle pole body. The average slope was 0.33 ± 0.16 μm/min (Table ).
Mentions: The ∼1.1-kb CEN11 lacO marker was integrated into strains containing spindle pole bodies marked with Nuf2–GFP or Spc72–GFP. Z-series time-lapses were acquired at 15–45 s. We observed the ∼1.1-kb CEN11 proximal spots to move toward the GFP-marked spindle pole bodies coincident with or within 3 min after anaphase onset, as defined by the start of anaphase B spindle elongation (Fig. 4A and Fig. B and Fig. 5). Fig. 5 B (arrow) shows the separation of the spindle pole bodies to begin at the 0.0-min time point. Movement of the CEN proximal spots toward the spindle pole body ensues at 1.0 min (Fig. 5 B, arrow). This delay results in a transient increase in the distance between the centromere proximal spot and its spindle pole body. The centromere proximal spot began anaphase A chromosome movement toward the spindle pole body at an average spindle length of 2.87 ± 0.51 μm (Table IV; n = 15). Regression lines were drawn through each plot of centromere proximal chromosome spot movement to the spindle pole body (Fig. 5 C). The average rate observed was 0.33 ± 0.16 μm/min (Fig. 5 C; Table IV; n = 23). The average distance moved was 0.98 ± 0.28 μm (Table III; n = 23).

Bottom Line: Centromeres are in a metaphase-like conformation, whereas chromosome arms are neither aligned nor separated before anaphase.The stretched chromatin was observed to segregate to the spindle pole bodies at rates greater than centromere to pole movement, indicative of rapid elastic recoil between the chromosome arm and the centromere.These results indicate that the elastic properties of DNA play an as of yet undiscovered role in the poleward movement of chromosome arms.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA. cgpearso@email.unc.edu

ABSTRACT
Using green fluorescent protein probes and rapid acquisition of high-resolution fluorescence images, sister centromeres in budding yeast are found to be separated and oscillate between spindle poles before anaphase B spindle elongation. The rates of movement during these oscillations are similar to those of microtubule plus end dynamics. The degree of preanaphase separation varies widely, with infrequent centromere reassociations observed before anaphase. Centromeres are in a metaphase-like conformation, whereas chromosome arms are neither aligned nor separated before anaphase. Upon spindle elongation, centromere to pole movement (anaphase A) was synchronous for all centromeres and occurred coincident with or immediately after spindle pole separation (anaphase B). Chromatin proximal to the centromere is stretched poleward before and during anaphase onset. The stretched chromatin was observed to segregate to the spindle pole bodies at rates greater than centromere to pole movement, indicative of rapid elastic recoil between the chromosome arm and the centromere. These results indicate that the elastic properties of DNA play an as of yet undiscovered role in the poleward movement of chromosome arms.

Show MeSH
Related in: MedlinePlus