ISSN:
1615-6102
Keywords:
Mitosis
;
Microtubules
;
Kinetochore
;
Metaphase
;
Anaphase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Treatment of metaphase PtK1 cells with 0.2 M to 0.5 M sucrose and anaphase cells with 0.5 M sucrose has previously been shown to stop chromosome motion probably due to a significant alteration in the functional attachment of kinetochore microtubules (kMTs) with the kinetochore lamina. The work presented here examines the effects of 0.15 M to 0.25 M sucrose on PtK1 metaphase and anaphase cells with a focus on the ultrastructural changes in the kinetochore and rates of chromosome motion. Metaphase PtK1 cells treated with 0.15 M and 0.20 M sucrose from 5 to 15 min showed spindle elongation with sister chromatids remaining at the metaphase plate; these cells failed to enter anaphase. Ultrastructural analysis revealed MTs did not insert directly into the kinetochore lamina but rather associated tangentially with an amorphous material proximal to the kinetochore region much like that described previously with higher concentrations of osmotica. Treatment of metaphase cells with 0.25 M sucrose arrested the cell in metaphase and ultrastructural analysis revealed novel osmiophilic spherical structures approximately 0.50 μm in diameter located proximal to kinetochores. MTs appeared to stop just short of. or associate laterally with, these spherical structures. Anaphase PtK1 cells treated with 0.15 M and 0.20 M sucrose showed reduced rates of chromosome segregation during 5 min treatments, suggesting they retained functional kinetochore/kMT interactions. However, treatment of anaphase cells with 0.25 M sucrose blocked anaphase A chromosome motion and produced electron dense spherical structures approximately 0.50 μm in diameter, identical to those observed in similarly treated metaphase cells. Removal of 0.25 M sucrose in treated anaphase cells resulted in normal chromosome segregation within 1 min. Cells released from sucrose treatment showed the absence of spherical structures and reformation of normal kinetochore/MT interactions which was temporally correlated with the resumption of chromosome motion.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01379040
