Establishment of comsomic mice to clarify host susceptibility to caries

Objectives: The authors found inbred mice strains with high and low susceptibilities to dental caries. C57BL/6J (B6) and C3H/HeJ (C3H) strains of mice revealed high and low caries-susceptible, respectively. Quantitative trait locus (QTL) analysis was performed in genomewide scan on F₂ genetic crosses of B6 and C3H mice. The analysis showed two effective values, one significant QTL was found on chromosome2, and one suggestive QTL detected on chromosome17. As a strategy for the elucidation of the causative genes of susceptibility to dental caries, we have constructed the mice which were replaced the chromosome2 derived from B6 with the chromosome2 derived from C3H, termed consomic mice (B6-Chr.2^C3H) .

Methods: For construction of consomic mice, 2^nd generation mice were obtained by mating B6 and F₁ (B6 x C3H). During confirmation of the genomic recombination used microsatellite markers, the recombination mice that showed heterozygous genotype on chromosome2 were crossed to the next generation continuously.

Finally, consomic strain was produced by mating B6 as the host strain and C3H as the donor strain, and carried one copy of chromosome2 derived from C3H and the other chromosomes derived from B6.

Results: Until 13^th generation, the mice were continued to genetically crossed by backcross and checked the genotype of all chromosomes. The selected mice of 13^th generation were checked heterozygous genotype of B6 and C3H on chromosome2 and all homozygous of B6 on all chromosomes except chromosome2. The consomic mice (B6-Chr.2^C3H) were established by intercrossing the selected mice of 13^th generation which were obtained using about 400 mice for the duration of 6 years.

Conclusion: We established consomic mice (B6-Chr.2^C3H) that were able to use as a model animal for investigating the causative genes to the dental caries susceptibility.