Meeting Abstract

8.6  Jan. 4  Zig-zag locomotion alters shape of the murine limb bone diaphysis CARLSON, KJ*; JUDEX, S; Universitaet Zuerich; Stony Brook University carlson@aim.unizh.ch

Many terrestrial animals incorporate rapid turns as a part of predator avoidance behavior, while arboreal animals encounter irregularly spaced substrates necessitating frequent turns during daily travel. Yet consequences of turning behavior on long bone morphology are not resolved. We investigated this relationship in 30 growing BALB/cByJ female mice randomly asssigned to one of three behavioral groups (n = 10). Mice were single-housed for eight weeks in custom-designed cages from day 30 post birth. Enclosures accentuated zig-zag or linear locomotion in the two experimental groups, while a control group lived in standard laboratory mouse conditions. Locomotor behavior was recorded using an instantaneous focal sampling strategy approximately twice per day for the duration of the experiment. Bones were harvested for microCT scanning at day 87 post birth. Femoral cross-sectional properties at midshaft were evaluated relative to body weight and compared. Groups do not differ significantly in mean cortical area, mean body weight, or activity level. Zig-zag mice have significantly more elliptical diaphyses than controls (p = 0.025), and also more elliptical diaphyses than linear mice, though the latter difference is not significant (p = 0.083). Linear and control mice do not differ (p = 0.725). Shape differences at the femoral midshaft primarily reflect reduced anteroposterior rigidity in the zig-zag group relative to the other groups, though none of these differences are significant. Given a virtual absence of genetic variability and equivalent bone mass and activity levels, femoral shape differences reflect a behavioral difference that can be attributed to turning locomotor behavior. Funded by NASA and NSF.