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Dose-response relationship for X-ray induced dominant lethal mutations detected in mouse embryos in vitro
Abstract:
X-Irradiated male mice sired offspring that expressed dominant lethal mutations during development in vitro. These mutations were expressed as arrest of the embryo either before or after blastocyst formation and were induced in germ cells irradiated as spermatids. When the dose-response data for the induced dominant lethal mutation rate were fit to a linear-quadratic model for dose-response curves, they were found to be compatible with mutation induction by both one-track and two-track processes, and the calculated interaction distance agreed well with those values found for radiation-induced translocations in Vicia faba and mouse spermatogonia. This correlation suggests that dominant lethal mutations in embryos and translocations in germ cells both result from similar radiation-induced chromosome damage.
Insights
X-irradiation of male mice induces dominant lethal mutations in offspring, affecting embryonic development. These mutations, linked to radiation-induced chromosome damage, suggest similar mechanisms underlie both lethal mutations and translocations.
Area of Science:
- Radiation Biology
- Developmental Biology
- Genetics
Background:
- X-irradiation is known to induce genetic damage in germ cells.
- Dominant lethal mutations can arise from unrepaired DNA damage in sperm.
- Embryonic development is sensitive to genetic defects.
Purpose of the Study:
- To investigate the induction of dominant lethal mutations in mouse offspring following paternal X-irradiation.
- To characterize the dose-response relationship for these mutations.
- To explore the underlying mechanisms of radiation-induced germ cell mutations.
Main Methods:
- Male mice were exposed to varying doses of X-irradiation.
- Irradiated males sired offspring, and embryonic development was assessed in vitro.
- Dose-response data were analyzed using a linear-quadratic model.
- Mutation induction mechanisms (one-track and two-track) were evaluated.
- Interaction distances were compared to radiation-induced translocations.
Main Results:
- X-irradiation of male mice induced dominant lethal mutations in their offspring.
- Mutations manifested as embryonic arrest before or after blastocyst formation.
- The mutation rate was induced in germ cells irradiated as spermatids.
- Dose-response data fit a linear-quadratic model, indicating both one-track and two-track mutation processes.
- Calculated interaction distances correlated with those for radiation-induced translocations.
Conclusions:
- Dominant lethal mutations in embryos and translocations in germ cells likely stem from similar radiation-induced chromosome damage.
- The findings support a mechanistic link between paternal germ cell radiation exposure and subsequent embryonic developmental defects.