INSTABILITY OF THE D4MIT12 MICROSATELLITE MARKER IN C57BL 6J X BALB/CJF(1) HYBRID MICE IS INDEPENDENT OF THE TUMOR PHENOTYPE/

We examined the stability of different types of DNA microsatellite mar kers in gamma-radiation-induced thymic lymphomas as well as normal, no ntumorous tissues of F-1 hybrid mice derived from the parental strains C57BL/6J, RF/J, and BALB/cJ. Surprisingly, the D4Mit12 microsatellite showed genomic instability in a significant fraction of DNAs of the ( C57BL/6J x BALB/cJ) F-1 hybrids with independence of the tumor phenoty pe. This instability was not found in the reciprocal F-1 DNAs, in DNAs of the parental strains, or in DNAs of (C57BL/6J x RF/J) F-1 hybrid m ice. These results suggest that the instability of the D4Mit12 microsa tellite is dependent on its repeat length, the genetic background of F -1 hybrids, and the maternal origin of the C57BL/6J allele.