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Cytokinesis in cells undergoing mitosis without genome replication.
1Department of Biological Sciences, Mississippi State University, Mississippi State, MS 39762, USA. daw1@ra.msstate.edu
Cell Biology International
|April 25, 2000
Summary
Chinese hamster ovary cells can enter mitosis without DNA replication, forming spindles but lacking anaphase B. This study reveals that intact chromosomes aren't essential for cell division, but kinetochores may play a role.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cell cycle progression is tightly regulated, with DNA replication preceding mitosis.
- Disruptions in cell cycle control can lead to abnormal mitotic events.
Purpose of the Study:
- To investigate the consequences of inducing mitosis without prior DNA replication in Chinese hamster ovary (CHO) cells.
- To determine the roles of chromosomes and kinetochores in cell division and cytokinesis.
Main Methods:
- Treatment of CHO cells with hydroxyurea and caffeine to block DNA replication and entry into mitosis.
- Microscopic analysis of spindle formation, kinetochore behavior, and cytokinesis.
Main Results:
- Cells entered mitosis without replicating DNA, assembling functional spindles that failed to elongate during anaphase B.
- Chromatin detached from unreplicated kinetochores, which fragmented but still formed microtubule attachments and migrated to the metaphase plate.
- Kinetochore fragments partitioned on schedule, and typical midbodies and cleavage furrows formed, resulting in equal-sized daughter cells.
Conclusions:
- Intact chromosomes are not required for accurate cleavage furrow placement.
- Kinetochores may be essential for proper cleavage furrow positioning.
- Cleavage furrow placement is independent of anaphase spindle elongation.