Experiment
A short term selection breeding strategy was used to confirm previously mapped QTLs (Lrncs1, Lrnx10, Lrnx7, Lrnx8, and Lrnx9) associated with contextual fear conditioned learning behavior. Starting with (C57BL/6J x DBA/2J)F2 progenitors, phenotype-drivenselection was used to generate a high line (where animals display high level of fear induced freezing response) and a low line (where animals display high level of fear induced freezing response) for 3 generations. At each generation, animals were assessed for DBA/2J-derived allele distribution at each of the previously mapped QTLs for confirmation of QTLs. Since parental strain DBA/2J displays decreased fear response compared to parental strain C57BL/6J, low lines should increase in DBA/2J-derived allele distribution at the QTLs in successive generations while high lines should decrease in DBA/2J-derived alleles. Lrnx10 on mouse Chromosome 2 (LOD = 3 at D2Mit52), Lrnx7 on mouse Chromosome 3 (LOD = 4.1 at D3Mit51), and Lrnx9 on mouse Chromosome 16 (LOD =4.5 at D16Mit57) were confirmed using this approach. Lrncs1 on mouse Chromosome 1 and Lrnx8 on mouse Chromosome 10 followed the expected allele distribution patterns at each generation but did not reach statistical significance.
Analysis Tools