How to detect and how to influence induction of recombination in mice in vivo

The mammalian spot test using the mouse allows one to detect both induced mutations and reciprocal combinations in vivo. Mouse embryos, which are heterozygous for different recessive coat-color genes, are treated in utero between the 9th and 11th days post conception. If this treatment leads to an alteration or loss of a specific wild-type allele in a pigment precursor cell, a spot of altered color may appear in the coat of the adult animal. A recombinational event may also result in a color spot. Gene mutations can be detected as generic alterations at the c locus. It is also possible to detect reciprocal recombinations involving both the p and c loci which are located on the same chromosome, 14 Morgan units apart. Using tumor promoters in combination with a mutagenic carcinogen it is possible to enhance the recombinogenic effects of the carcinogen. On the other hand it is possible to suppress recombination induction by combining cocarcinogens with the mutagenic carcinogen.