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RecA-like strand-transfer activity at the meiotic prophase in Bombyx mori
1Department of Physiology, Carlsberg Laboratory, Copenhagen, Denmark.
Abstract:
An ATP-independent strand-transfer activity has been identified in nuclear extracts prepared from Drosophila tissue culture cells and isolated nuclei from Bombyx testes. Extraction of the activity from testes at larval stages where the majority of the cells were in meiotic prophase was only possible when the chromosome scaffold/synaptonemal complex was dissolved by addition of high concentrations of DTT (80 mM). No cross reaction was detected when partly purified extracts were assayed with antibodies against E. coli RecA protein.
Insights
A novel ATP-independent strand-transfer activity was found in Drosophila and Bombyx cells. This DNA repair activity requires dissolving the synaptonemal complex for extraction from meiotic cells.
Area of Science:
- Molecular biology
- Genetics
- Biochemistry
Background:
- DNA repair mechanisms are crucial for maintaining genomic integrity.
- Strand transfer is a key step in homologous recombination and DNA repair.
- Identifying novel enzymes involved in these processes is essential for understanding cellular responses to DNA damage.
Purpose of the Study:
- To identify and characterize an ATP-independent strand-transfer activity in eukaryotic cells.
- To investigate the conditions required for extracting this activity from meiotic cells.
Main Methods:
- Preparation of nuclear extracts from Drosophila tissue culture cells and Bombyx testes.
- Assay of strand-transfer activity in the presence and absence of ATP.
- Extraction optimization using dithiothreitol (DTT) to dissolve the synaptonemal complex.
- Immunological assays using antibodies against E. coli RecA protein.
Main Results:
- An ATP-independent strand-transfer activity was detected in both Drosophila and Bombyx nuclear extracts.
- Efficient extraction from Bombyx testes during meiotic prophase required high concentrations of DTT (80 mM) to disrupt the chromosome scaffold/synaptonemal complex.
- No cross-reactivity was observed with antibodies against E. coli RecA, suggesting a distinct protein.
Conclusions:
- A novel, ATP-independent DNA strand-transfer activity exists in eukaryotes.
- This activity is associated with the chromosome scaffold/synaptonemal complex during meiosis.
- The enzyme responsible is distinct from E. coli RecA.