Fig. 4

Testing the functionality of recombinant GEPII 1.0 in vivo. a Schemes showing the area of interest (musculus cremaster, arrow, upper panel) and the mouse prepared for imaging using the 2-photon imaging device (lower panel). b Representative in vivo FRET ratio signals of GEPII 1.0 loaded into the cremaster tissue of a living mouse. Signals were imaged using a 2-photon fluorescence imaging system at different z-positions. As indicated 10 mM KCl was applied to the tissue during intravital microscopy and subsequently washed out using a perfusion system. c Representative images showing the FRET signal (yellow, left images), mseCFP signal (blue, middle images) and FRET ratio signal (pseudocolored, right images) of GEPII 1.0 loaded into the musculus cremaster prior to (upper images) and upon the addition of 10 mM KCl (lower images) as indicated in b. White scale bar in the lower right image represents 100 µm