Meeting Abstract

S10-7   13:30 - 14:00  Birds, biomechanics and botox; Lessons about levels of analyses in studies of plasticity across ontogeny Cox, SM*; Salzano, MQ; Katugam, K; Piazza, SJ; Rubenson, J; Duke University; University of Massachusetts, Amherst; The Pennsylvania State University; The Pennsylvania State University; The Pennsylvania State University smc69@duke.edu http://www.zannecox.com/

In a complex integrated biomechanical system, at what level of organization do changes in functional demand during ontogeny alter the adult? Here we study plasticity during ontogeny across several integrative levels (behavior, performance and morphology) to evaluate how an organism plastically responds to local muscle disuse during maturation. To induce disuse, we injected two ankle extensors (lateral and medial gastrocnemius) of guinea fowl (Numida Meleagris, n=8) with a paralytic (Onabotulinum toxin A; BTX-A) repeatedly at six-week intervals from 7 weeks old to skeletal maturity and compared to controls (n=8) receiving saline injections. During growth we monitored behavioral changes (time spent sitting, standing, walking and sprinting). At maturation, we measured behavior (likelihood to jump), form (the gastrocnemius elastic system’s morphology and energy storage capacity) and function (jump performance and energetics). We found no differences in behavior nor in jump performance at adulthood. Yet, BTX-A birds were, surprisingly, more energy efficient during running than controls and both the BTX-A muscles and their antagonists hypertrophied. These results contradict findings of the influence of BTX-A in mature animals. Combined, these results suggest that the influence of local disuse on growing organism might be drastically different than during adulthood and that growing animals might be remarkably resilient to altered local stimuli.