Presenter(s): Nelly Nouboussi—Biology
Faculty Mentor(s): Matt Smear, Amanda Welch
Session 3: The Substance of Us
The olfactory system is the least studied sense although it is very important for our existence . Our lab has examined the behavioral structure of olfactory navigation . Our next goal is to compare sampling movements directly against sensory input in order to establish a correlation between neural activity and behavior . The first step in this goal, which is the topic of my thesis, is to successfully express fluorescence indicators in the olfactory bulb and to detect this expression using our imaging apparatus . We are focusing specifically in the glomeruli, which contains the neurons responsible for converting odor information into action potentials . To achieve the expression of our fluorescence sensor GCaMP, we either injected a virus encoding the fluorescence protein into mice brains or engineered mice to encode the sensor gene in their genome . We worked with three mice strains:
B6 mice which can express GCaMP anywhere, Tbet-Cre mice which can express the virus only in the mitral layer and Tbet-Cre-Ai148D mice which contain the GCaMP gene in their genome . Histology revealed that we successfully expressed GCaMP in B6 mice, but we could only observe background fluorescence in Tbet-Cre and Tbet-Cre-Ai148D mice . This could result from the frying of the bulb due to continuous expression of the protein or the degradation of the virus . Despite the difficulty of the surgeries, we could visualize activity in the glomeruli of live mice with the two-photon microscope, although our success rate remains low . We are continuously adjusting our protocol to improve our techniques, so we can move on to the next stage of our project .