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Evolution and the meaning of metaphase
1Department of Zoology, Duke University, Durham, NC 27706.
Journal of Cell Science
|August 1, 1992
Summary
Chromosome congression to the spindle equator evolved independently multiple times. This likely occurred with the metaphase checkpoint to ensure accurate sperm formation and prevent cell death.
Area of Science:
- Evolutionary Biology
- Cell Biology
- Genetics
Background:
- Chromosome congression to the spindle equator is a key event in cell division.
- Newly formed trivalents (three chromosomes) typically do not congress, instead aligning near a pole.
- The evolutionary significance of congression has been debated.
Purpose of the Study:
- To investigate the evolutionary importance of chromosome congression.
- To determine if congression evolves when initially absent.
- To understand the role of congression in meiosis and cell cycle checkpoints.
Main Methods:
- Studied ancient sex-chromosome trivalents in praying mantids and grasshoppers.
- Examined the behavior of newly formed trivalents and quadrivalents.
- Utilized an evolutionary test to infer the selective pressures on congression.
Main Results:
- Ancient trivalents consistently congress to the spindle equator, some precisely.
- Congression appears to have evolved independently at least twice.
- Newly formed quadrivalents show variable degrees of congression.
Conclusions:
- Chromosome congression is not a mere happenstance but an evolved trait.
- Congression likely co-evolved with the metaphase checkpoint to ensure accurate chromosome segregation.
- This co-evolution prevents the loss of cells that would produce abnormal sperm.