The protein-mapping-method employed to test for chemically induced point mutations in mice

Area of Science:

• Toxicology
• Genetics
• Developmental Biology

Background:

• A prior test system for detecting chemically induced germ cell mutations in mice was proposed.
• The mutagenic effects of methylnitrosourea (MNU) were investigated using this system.

Purpose of the Study:

• To evaluate the efficacy of MNU as a mutagen in the mouse germ cell test system.
• To assess the sensitivity of the protein-mapping method for detecting induced point mutations.

Main Methods:

• Male BALB/c mice were treated with varying doses of MNU (40-150 mg/kg) over 4-14 days.
• Spermatogonia were exposed to MNU, with treatments timed for mature sperm at mating.
• Liver proteins from F1-foetuses were analyzed using isoelectric focusing and electrophoresis (protein-mapping).

Main Results:

• No protein variations were observed in 312 control foetuses.
• Two individuals with variant proteins were identified among 72 offspring from male parents exposed to high MNU doses.
• These variants suggest point mutations induced in spermatogonia.

Conclusions:

• Methylnitrosourea (MNU) can induce point mutations in mouse germ cells under the tested conditions.
• The employed mutagenicity test system shows promise as a sensitive method for detecting induced genetic changes.