Graduate Student Seminar Scheduled for February 9th

The Spring 2011 Beckman Institute Graduate Student Seminar Series continues on Wednesday, February 9th. The seminar will feature two short talks from students Sarah Holton and Wylie Ahmed. The seminar will be held in Beckman Institute Room 1005 and a pizza lunch will be served to those attending the talks.

Label-free characterization of cancer-activated fibroblasts using infrared spectroscopic imaging 
Sarah Holton

Graduate Student Department of Bioengineering

FibroblastsThe presence of an activated stroma surrounding a primary tumor is characterized by the expression of α-SMA protein by stromal fibroblasts, the cell type that maintains the microenvironment. It is advantageous to study the molecular profile of stromal activation for potential therapeutic targets. We report a direct comparison between α-SMA expression in primary normal human dermal fibroblasts and chemical spectra obtained through Fourier transform- infrared (FT-IR) spectroscopic imaging. Fibroblasts were stimulated using the growth factor TGFβ1 and through co-culture with MCF-7 tumorigenic breast epithelial cells in trans-well co-culture and three-dimensional cell culture. This correlation is also compared with expression of α-SMA and spectra obtained from normal and tumorigenic human breast tissue biopsies.

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

Dynamic neurons

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.