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. 2021 Apr 15;8(2):ENEURO.0110-21.2021. doi: 10.1523/ENEURO.0110-21.2021

Figure 1.

Figure 1.

Characterization of iGluSnFRs as reporters of glutamatergic signaling onto MT cells. A, Expression of SF-iGluSnFR in MT cells of the OB. Image shows confocal stack with expression in MT cells after injection of AAV2.1.hSynap.Flex.SF-iGluSnFR.A184V in the OB of a Tbet-Cre mouse. White arrows indicate a tufted cell with expression in the soma and primary dendrite extending to the glomerular layer (GL). MCL, mitral cell layer. B, Top left, Mean fluorescence image taken in vivo, showing iGluSnFR expression in glomeruli after injection of AAV2.1.hSynap.Flex.SF-iGluSnFR into the OB a Pcdh21-Cre mouse. Top right, ΔF image showing responses to ethyl butyrate (mean of eight presentations, 2-Hz inhalation). Bottom, Traces showing odorant-evoked iGluSnFR signal in three glomeruli, with dashed region expanded at right. Note distinct temporal responses across successive inhalations for each glomerulus. C, Examples of SF-iGluSnFR.A184S responses imaged at high zoom from different glomeruli. Images show mean F (left) and ΔF response maps (right) to ethyl butyrate, showing localization of iGluSnFR signal to the glomerular neuropil (glom.), with a lack of signal on primary dendrites (pr. dend.) or MT cell somata (somas). D, Traces showing responses to ethyl butyrate taken from the glomerular neuropil, primary dendrite, and MT somata (locations indicated in D), indicating negligible signal on the apical dendrite or somata. E, SF-iGluSnFR.A184S expression imaged in vivo from Tbet-positive MT cell lateral dendrites in the superficial external plexiform layer (EPL). F, Top: Odorant-evoked response maps imaged from the field of view in (a), showing responses to two odorants, 2-hexanone and ethyl butyrate. Bottom: Traces showing stronger excitatory and weak suppressive SF-iGluSnFR signals on different dendrites, evoked by each odorant.