Experiment
Genetic mapping of sensory development traits was performed using 7 recombinant inbred (RI) strains derived from C57BL/6By and BALB/cBy. The parental strain C57BL/6By is considered a fast developer compared to parental strain BALB/cBy.
The rooting reponse refers to a behavior apparent at birth where the pup buries its snout underneath the mother's abdomen. This behavior disappears between 6 to 12 days after birth. In the inbred strain C57BL/6By, rooting response begins to disappear at the fifth day afterbirth and is absent by the tenth day. In the inbred strain BALB/cBy, the rooting response begins to disappear at the seventh or eighth day after birth, but persists even after the twelfth day.
The disappearance of rooting response showed significant strain-dependent differences (p<0.001). The strain distribution pattern mapped a single locus named Adre (age at disappearance of rooting response) to mouse Chromosome 4 near H21 (38 cM) and Tyrp1 (38 cM). C57BL/6By-derived alleles at Adre confer faster disappearance of the rooting response with a codominant mode of inheritance.
Several other traits also exhibit significant strain-dependent effects but genetic loci have not yet been mapped. These traits include locomotion, righting response, hind limb placing, crossed extensor response, vibrissa placing, and bar holding.
Analysis Tools