Label-free characterization of cancer-activated fibroblasts using infrared spectroscopic imaging 
Sarah Holton
Graduate Student Department of Bioengineering

The Mechanical sensitivity of vesicle dynamics in neurons
Wylie W. Ahmed
Department of Mechanical Science and Engineering

Mechanical tension in neuronal axons is known to exist in vitro, and it has been suggested that tension may play a role in the morphogenesis of the in vivo nervous system.  Recent work has shown that mechanical tension exists in in vivo motor neurons and that it contributes to neurotransmitter clustering at the presynaptic terminal, highlighting the role of tension in neuronal function.  To study the mechanical response of both in vivo and in vitro neurons, we have developed a novel platform for in-situ high-resolution live-imaging of cells and tissues under applied mechanical strain.  Our system allows us to stretch/compress neurons while observing the effect on vesicle dynamics in real-time.  Here we present evidence indicating that vesicle transport is sensitive to mechanical stimulation for both in vivo and in vitro neurons: (1) Mechanical tension induces synaptic vesicle accumulation at the presynaptic terminal of in vivo Drosophila motor neurons and this effect persists after cessation of stretch.  (2) Mechanical compression causes a decrease in range and processivity of vesicle motion which persists for at least 20 minutes after compression is removed.