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Repair capacity of fertilized mouse eggs for X-ray damage induced in sperm and mature oocytes
1Division of Genetics, National Institute of Radiological Sciences, Chiba, Japan.
Abstract:
To study the repair capacity of fertilized mouse eggs for X-ray damage induced in sperm and mature oocytes, the potentiating effects of 3 well-known repair inhibitors, arabinofuranosyl cytosine (ara-C), 3-aminobenzamide (3AB) and caffeine, on the frequency of induced chromosome aberrations were examined in eggs fertilized with X-irradiated sperm or in eggs irradiated with X-rays at the mature oocyte stage immediately before fertilization. Gametic treatment, fertilization and embryo culture were carried out in vitro. Ara-C treatment was done only in the pre-DNA replication period, while treatment with 3AB and caffeine was continuous from fertilization to the first-cleavage metaphase. The induction of chromosome aberrations by exposing sperm or oocytes to X-rays was remarkably potentiated by post-treatment incubation in the presence of each of the 3 inhibitors. This result indicates the possibility that X-ray damage induced in sperm or oocytes is reparable in the fertilized eggs and that various types of repair processes are involved.
Insights
Fertilized mouse eggs can repair X-ray damage in sperm and oocytes. Three inhibitors (arabinofuranosyl cytosine, 3-aminobenzamide, caffeine) enhanced chromosome aberrations, indicating repair mechanisms are active.
Area of Science:
- Reproductive biology
- Radiation biology
- Genetics
Background:
- X-ray irradiation can induce DNA damage in gametes (sperm and oocytes).
- Fertilized eggs possess mechanisms to repair such damage.
- Understanding these repair capacities is crucial for assessing reproductive risks and developing protective strategies.
Purpose of the Study:
- To investigate the repair capacity of fertilized mouse eggs for X-ray induced damage in sperm and oocytes.
- To examine the potentiating effects of known repair inhibitors on chromosome aberrations.
Main Methods:
- Fertilized mouse eggs were exposed to X-rays at the sperm or mature oocyte stage.
- In vitro fertilization and embryo culture were performed.
- Eggs were treated with repair inhibitors: arabinofuranosyl cytosine (ara-C), 3-aminobenzamide (3AB), and caffeine.
Main Results:
- X-ray exposure of sperm or oocytes led to induced chromosome aberrations.
- Post-treatment incubation with ara-C, 3AB, or caffeine significantly potentiated the frequency of these aberrations.
- This potentiation suggests that the damage induced in gametes is subject to repair within the fertilized egg.
Conclusions:
- Fertilized mouse eggs exhibit repair capacity for X-ray damage incurred by sperm and oocytes.
- The repair processes involved are diverse and can be modulated by specific inhibitors.
- These findings highlight the importance of post-fertilization repair in mitigating radiation-induced genetic damage.