Detection and analysis of UV-induced mutations in mammalian cell DNA using a lambda phage shuttle vector

Area of Science:

• Molecular Biology
• Genetics
• Mammalian Cell Mutagenesis

Background:

• Mammalian cell mutagenesis studies are crucial for understanding DNA damage and repair.
• A lambda phage vector containing the Escherichia coli supF gene provides a sensitive target for mutagenesis detection.

Purpose of the Study:

• To establish stable mouse L-cell lines for studying mutagenesis.
• To identify the primary mutation sites induced by ultraviolet (UV) light in mammalian cells.

Main Methods:

• Stable mouse L-cell lines containing multiple copies of a lambda phage vector with the supF gene were created.
• Lambda phage was rescued in vitro from high molecular weight mouse cell DNA.
• DNA sequence analysis was performed on rescued mutant phage.

Main Results:

• Efficient rescue of viable phage (5 per microgram of cell DNA) with negligible background mutants was achieved.
• Exposure to 254-nm UV light induced mutations in the supF gene.
• Sequence analysis revealed UV mutagenesis predominantly occurs at pyrimidine-cytosine (Y-C) sequences.

Conclusions:

• The study successfully established a system for mutagenesis studies in mammalian cells.
• UV mutagenesis in mammalian cells primarily targets Y-C sequences.
• The most frequent UV-induced mutation observed was a cytosine to thymine transition.