Experiment
A large set of ethological measures of anxiety-related behaviors were analyzed to explore the relationship between the behavioral phenotype and genotype of anxiety. Phenotypic and genotypic data from a total of 1636 mice from two intercosses of (H1 x L1)F2 and (H2 x L2) F2 DeFries strains decribed in a separate paper (J:70479) were obtained.
Five behavorial tests were conducted in the open field arena, the elevated plus maze, the square maze, the light dark box and the mirror chamber. The test results from the two crosses were highly consistent and to maximize power and mapping resoultion the data was combined from both crosses in the current companion study. Likely QTL positions were determined using MAPMAKER-QTL and QTL-CARTOGRAPHER.
The results of this study mapped 3 major QTL influencing anxiety-related behaviors on Chromosomes 1, 4 an 15. Other anxiety-related behavioral QTLs with multiple effects mapped to Chromosomes 7, 12, 14, 18 and X.
Axtrb5, anxiety-related behavior 5 mapped to Chromosome X.
The combined LOD scores from both crosses, for each significant test measurement contributing to Axtrb5 follow:
anxiety-related behavior 5, open field, total activity, LOD=5.3;
anxiety-related behavior 5, elevated plus maze, open arm activity, LOD=4.1;
anxiety-related behavior 5, elevated plus maze, open arm time, LOD=5.3;
anxiety-related behavior 5, square maze, closed arm activity, LOD=3.5;
anxiety-related behavior 5, square maze, open arms activity, LOD= 5.4
anxiety-related behavior 5, light dark box, dark box activity, LOD=3.7.
At each locus the direction of effect of the allele was examined from the less active strains, L1 and L2. All traits measured at Axtrb5 were decreased by the influence of the L1 or L2 allele with the exception of anxiety-related behavior 5, elevated plus maze, open arm activity which was increased by the low allele [Table 2].
Table 3 gives the mapping results for loci influencing defecation in each test apparatus. Differentiation of defecation scores by components of the test apparatus were not possible. However results were consistent for each apparatus.
The following QTL influencing defecation in the test apparatus were mapped to Chromosome X, LOD scores from combined cross data:
Axtofd13, anxiety-open field defecation 13, open field day 1, mapped to 50 cM, LOD=5.36.
Axtofd14, anxiety-open field defecation 14, open field day 2, mapped to 0.0 cM, LOD=3.47.
Axtpmd3, anxiety-plus maze, defecation 3, mapped to 50 cM, LOD=8.92.
Axtldbd3, anxiety-light dark box defecation 3, day 1, mapped to 0.0 cM, LOD=3.72
Axtldbd4, anxiety-light dark box defecation 4, day 3, mapped to 0.0 cM, LOD=4.05
Axtmcd1, anxiety- mirror chamber defecation 1, mapped to 50 cM, LOD=5.64.
All Chr X defecation QTL were influenced by the L1 or L2 allele which decreased defecation.