Supplementary Figure 7: Targeting GCaMP6s and jRGECO1a to dendritic spines with and without transcriptional regulatory system.

a, Image of a neuron expressing GCaMP6s fused to the CH domain of Utrophin (GCaMP6s-Utr) with zinc finger binding sequence. GCaMP6s was stained with anti-GFP antibody. GCaMP6s co-localized with endogenous PSD-95, a marker for dendritic spines. PSD95 puncta not associated with GCaMP6s puncta were due to spines from neighboring neurons not expressing GCaMP6s. Scale bar, 10 μm. b, GCaMP6s-Utr without ZFBS exhibited more diffuse localization compared to regulated GCaMP6s-Utr. c,d, Examples from additional neurons as in a and b, respectively (a–d, n = 5 neurons; representative data are shown). e,f, Example fluorescence line sections transecting two spines and a parent dendrite along the lines shown in a and b, respectively. g, Quantification of ratio of fluorescence in spines to adjacent parent dendrites in cells expressing GCaMP6-Utr with or without the ZFBS (n = 5 neurons of each type, ~200 spines per neuron, **P = 0.027, two-sided t-test). h, Quantification of spine fluorescence as a function of distance from the soma (n = 5 neurons of each type, ~200 spines per neuron). i, Spine-jRGECO1a and cytosolic jRGECO1a expressed in HEK293 cells gave the same fluorescence response to a Ca²⁺ transient induced by 10 μM ionomycin (ΔF/F 1.6 ± 0.1 versus 1.5 ± 0.07, n = 26 cells for spine-jRGECo1a, n = 29 for cytosolic jRGECO1a, P = 0.4, two-sided student’s t-test). All error bars, s.e.m. All statistics are mean ± s.e.m.