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Studies on chemically induced dominant lethality. III. Cytogenetic analyses of TEM-effects on maturing dictyate mouse
Abstract:
A comparative cytogenetic study was done on metaphase-I oocytes and first cleavage mitoses following treatment of young mature female mice with triethylenemelamine (TEM). The ova were collected at intervals ranging from 12 h to 10.5 days after single intraperitoneal injection of TEM. Very few structural aberrations were seen in the metaphase-I cells after TEM treatment. There was, however, a very clear effect on the female genome when first cleavage mitoses were analyzed. The aberrations seen were principally chromatid deletions and interchanges, and their frequency varied with dose and the time between treatment and mating.
Insights
Triethylenemelamine (TEM) exposure caused minimal chromosomal damage in mouse oocytes. However, TEM significantly impacted the female genome, leading to chromatid deletions and interchanges in early embryonic development.
Area of Science:
- Cytogenetics
- Developmental Biology
- Toxicology
Background:
- Triethylenemelamine (TEM) is a known alkylating agent.
- Oocyte quality is crucial for successful reproduction and embryonic development.
- Assessing genotoxicity in female germ cells is vital for reproductive health.
Purpose of the Study:
- To investigate the cytogenetic effects of triethylenemelamine (TEM) on mouse oocytes.
- To compare chromosomal aberrations in metaphase-I oocytes and first cleavage mitoses after TEM exposure.
- To determine the dose- and time-dependent genotoxic effects of TEM on the female genome.
Main Methods:
- Female mice were injected intraperitoneally with TEM.
- Oocytes were collected at various intervals post-injection (12 h to 10.5 days).
- Comparative cytogenetic analysis of metaphase-I oocytes and first cleavage mitoses was performed.
Main Results:
- TEM treatment resulted in very few structural aberrations in metaphase-I oocytes.
- Significant chromosomal aberrations, including chromatid deletions and interchanges, were observed in first cleavage mitoses.
- The frequency of these aberrations was dependent on both TEM dose and the time interval between treatment and mating.
Conclusions:
- TEM exhibits a delayed genotoxic effect on the female genome, primarily affecting early embryonic stages rather than mature oocytes.
- First cleavage mitoses are a sensitive indicator for assessing TEM-induced genomic instability.
- These findings highlight the potential reproductive risks associated with TEM exposure.