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Chemical and radiation induced late dominant lethal effects in mice
Abstract:
Although theoretically expected, experimental data to date have not shown dominant lethal expression to occur throughout the developmental period. Specifically, late post-implantation effects have not been demonstrated. We routinely use an experimental technique in which parental females mated to mutagenically treated males are allowed to give birth and wean their litter, and their uterine horns are then inspected for uterine scars indicative of live and dead embryos. In a number of experiments in which males were mutagenically treated with either chemicals or X-irradiation, a discrepancy was observed between the number of live embryos as determined by the scar technique and the number of live observed at birth, suggesting the possibility of embryonic losses at a late stage in development. Initial analyses showed that mutagenic treatment increased the percentage of these late losses. These differences were statistically significant in 2 of 3 analyses. Factors affecting statistical significance and an understanding of dominant lethal mutations are discussed.
Insights
Mutagenic treatments in male mice can cause late-stage embryonic losses, a phenomenon not previously well-demonstrated. This study provides evidence for dominant lethal mutations impacting later development.
Area of Science:
- Developmental Biology
- Toxicology
- Genetics
Background:
- Dominant lethal mutations are theoretically expected to cause embryonic death.
- Previous experimental data have not conclusively shown dominant lethal expression throughout the entire developmental period, particularly late post-implantation effects.
Purpose of the Study:
- To investigate the occurrence of late post-implantation embryonic losses in mice exposed to mutagenic agents.
- To determine if mutagenic treatments increase the incidence of these late-stage embryonic losses.
Main Methods:
- Utilized a standard experimental technique involving mating mutagenically treated male mice with females.
- Assessed embryonic viability by inspecting uterine scars for evidence of live and dead embryos post-weaning.
- Compared the number of live embryos indicated by uterine scars with the number of live offspring observed at birth.
Main Results:
- A discrepancy was observed between uterine scar counts and live births, suggesting late-stage embryonic losses.
- Mutagenic treatment of male mice (chemicals or X-irradiation) significantly increased the percentage of these late losses in 2 out of 3 analyses.
- The findings indicate that dominant lethal mutations can indeed cause embryonic death at a late developmental stage.
Conclusions:
- Experimental evidence supports the occurrence of dominant lethal mutations causing late post-implantation embryonic losses.
- The study highlights the importance of considering late developmental stages when assessing mutagenic effects.
- Further investigation into factors influencing statistical significance and the mechanisms of dominant lethal mutations is warranted.