Image of Green Fluorescently Labeled Bitter Taste Receptor Cells
in a Mouse Tongue
Video of mouse gustatory ganglion neurons responding to tastants applied to the tongue. GCaMP fluorescence increases in intensity as calcium flows into the neurons, serving as a proxy measure of neural activity.
Our lab is interested in investigating the sense of taste and the molecules, cells, and circuits involved in chemosensation from the tongue and gut to the brain. Taste receptor cells on the tongue are specialized to be activated by one of the five taste qualities, and signal that information to discrete populations of neurons in the gustatory ganglia through "labeled lines." This hard-wired, labeled line connectivity pattern is essential for our ability to correctly detect and discriminate tastes. The lab is interested in understanding how this gustatory circuit is organized at the cellular and molecular level.
Less well understood are chemosensory cells in the gut – which have many parallels to taste receptor cells – and may signal the presence of nutrients, toxins, and microbial metabolites to peripheral sensory neurons in the vagal ganglia. We aim to identify the cells and signaling mechanisms necessary for this gut-brain communication.
The Macpherson Lab combines the power of mouse genetics with in vivo functional imaging of gustatory and vagal ganglia neurons. We use molecular cloning and BAC recombineering to engineer transgenic mouse lines for Cre-dependent expression of imaging and optogenetic toolkit genes (like GFP, GCaMP, and Channel Rhodopsin) within specific populations of cells. The lab also use CRISPR gene targeting to create knockout mouse models faster and easier than traditional methods. In addition to using circuit mapping techniques such as GFP Reconstitution Across Synaptic Partners (GRASP), the lab can manipulate these circuits with optogenetics, and assay the effect of their manipulation with behavioral assays.