Meeting Abstract

P1.79  Saturday, Jan. 4 15:30  Development and implementation of a nano-Newton ergometer for examining fight or flight modulation of power output in D. melanogaster SCIBELLI, A.E.*; MULCAHY, S.L.; KRANS, J.L.; Western New England University scibelli.a@gmail.com

The biogenic amines octopamine and tyramine are an established model for investigating fight or flight physiology amongst arthropods (Roeder, 2005). The augmentation of force by octopamine in the small longitudinal muscle fibers of D. melanogaster larvae was recently demonstrated (Ormerod et al., 2013). The action of tyramine, although statistically attenuating contractile forces at high dose, was much smaller than octopamine’s contribution. Here we set out to examine the physiological relevance of modulation by these two biogenic amines via oscillation of muscle length comparable to that observed during larval locomotion. We describe the change in work loops achieved during amine modulation. A custom, highly sensitive ergometer and force transducer were created specifically for this project and their development is also considered. We report here the profound action of these amines upon potential contractile power using two main experimental manipulations: (a) amine dose / concentration, (b) stimulus frequency. Based upon Nishikawa’s recent hypothesis of the “winding filament theory”, we believe that higher rates of stimulation or the presence of octopamine will increase the winding of the titin-like, giant sarcomere associated proteins (Nishikawa et al., 2012)(gSAPs). We have engaged this characterization of wildtype tissue in order to compare it to tissue with knocked down titin / gSAP expression (via novel mutations of the D. melanogaster genome).