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'Signalling' between chromosomes in crane-fly spermatocytes studied using ultraviolet microbeam irradiation
1Biology Department, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J IP3.
Summary
Ultraviolet microbeam irradiation of kinetochores in crane-fly spermatocytes halts chromosome movement during anaphase. This suggests signals from damaged kinetochores temporarily inhibit chromosome segregation via an interzonal pathway.
Area of Science:
- Cell Biology
- Cytogenetics
- Molecular Biology
Background:
- Kinetochores are crucial for chromosome segregation during cell division.
- The mechanisms by which kinetochores regulate chromosome movement are not fully understood.
Purpose of the Study:
- To investigate the role of kinetochore-generated signals in regulating chromosome movement during anaphase.
- To determine the transmission pathway of these signals within the cell.
Main Methods:
- Crane-fly spermatocytes were subjected to targeted ultraviolet microbeam irradiation of kinetochores and the interzone during anaphase.
- Chromosome movement was monitored following single and double irradiation events.
Main Results:
- Irradiation of a kinetochore caused a temporary cessation of movement in all half-bivalents.
- Subsequent irradiation of the interzone partially blocked signal transmission, affecting chromosome movement to only one pole in 20% of cells.
- In 30% of cells, interzone irradiation after kinetochore irradiation led to immediate resumption of movement, indicating signal interruption.
Conclusions:
- Kinetochores emit signals that transiently inhibit chromosome movement during anaphase.
- These signals appear to be transmitted through the interzone, influencing the movement of non-irradiated chromosomes.