Of note, no other marked phenotypic differences were observed in SFB colonized mice in comparison with mock-colonized controls (Supporting Fig. 9).
In order to explain the marked phenotypic differences between these two alleles, we further compared their gene structures by DNA gel blot analysis.
Our results demonstrate no significant phenotypic differences in DMH and LHA c-fos expression despite marked phenotypic differences in the magnitude of FAA, indicating that differential activation of these regions is not associated with enhanced FAA in KO animals.
However, a role for any of the five loci in maintaining the marked phenotypic differences is discouraged by the complete lack of lineage sorting into the two geographic populations.
Neither hyperosmotic media, nor H2O2, which induces oxidative stress, nor sodium dodecylsulphate, which induces cell-wall damage, led to marked phenotypic differences between wild type and mutant strains (data not shown).
Despite the marked phenotypic differences between these two strains, however, we also found variation in the direction of strain differences among laboratories in some measures, indicating that the same test conducted in different laboratories may lead to fundamentally different conclusions.
