Related Experiment Videos
Induction of premature mitosis in S-blocked onion cells
1Centre of Advanced Study in Botany, University of Calcutta, Calcutta-700 019, India.
Abstract:
Onion root-tip cells were blocked at S-phase by treating them with 5-aminouracil (5AU). These cells were then further treated with caffeine/2-aminopurine (Caf/2AP) or a combination of both in the presence of 5AU. These tyrosine kinase inhibitors were able to induce premature mitosis in the S-blocked cells as evident from the breaks and gaps in the metaphase chromosomes and the presence of laggards and fragments in anaphase. Immunofluorescence showed normal spindle formation in these cells. Immunoblotting of cyclin B revealed that the level of cyclin B was slightly higher in the recovered and treated samples than the S-blocked one. The level of p(34)was found to be almost equal in all three samples as expected. We failed to observe any significant difference in the level of p(34)containing phosphorylated tyrosine. Such premature induction of mitosis by the purine derivatives has also been reported in BHK cells. However, those cells failed to progress through mitosis. A comparative analysis indicates that the plant cells and the animal cells, perhaps, follow identical pathway for the initiation of mitosis. The possible causes for differential behaviour in mitotic progression in these cells have been discussed.
Insights
Tyrosine kinase inhibitors like caffeine/2-aminopurine (Caf/2AP) induced premature mitosis in S-phase blocked onion root cells, causing chromosomal abnormalities. Plant and animal cells may share similar pathways for initiating mitosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cell cycle progression is tightly regulated by various molecular checkpoints.
- Tyrosine kinase inhibitors are known to affect cell division.
- Understanding mitosis initiation in plant cells can reveal conserved biological pathways.
Purpose of the Study:
- To investigate the effect of tyrosine kinase inhibitors (caffeine/2-aminopurine) on S-phase blocked onion root-tip cells.
- To compare the response of plant cells to purine derivatives with that of animal cells.
- To elucidate the role of specific proteins in premature mitosis induction.
Main Methods:
- Onion root-tip cells were synchronized and blocked at S-phase using 5-aminouracil (5AU).
- Cells were treated with caffeine/2-aminopurine (Caf/2AP) or a combination.
- Immunofluorescence microscopy and immunoblotting were used to analyze spindle formation, cyclin B, and p34 levels.
Main Results:
- Caffeine/2-aminopurine (Caf/2AP) induced premature mitosis in S-blocked onion cells, evidenced by chromosomal aberrations (breaks, gaps, laggards, fragments).
- Spindle formation remained normal, and cyclin B levels were slightly elevated in treated cells.
- No significant difference in p34 or its phosphorylated tyrosine levels was observed across samples.
Conclusions:
- Purine derivatives can trigger premature mitosis in plant cells, similar to observations in animal cells (BHK cells).
- Plant and animal cells likely share conserved pathways for mitosis initiation.
- Differential mitotic progression between plant and animal cells warrants further investigation.