An improved genetically encoded red fluorescent Ca2+ indicator for detecting optically evoked action potentials

Masamichi Ohkura, Takuya Sasaki, Chiaki Kobayashi, Yuji Ikegaya, Junichi Nakai

Research output: Contribution to journalArticlepeer-review

91 Citations (Scopus)

Abstract

Genetically encoded Ca2+ indicators (GECIs) are powerful tools to image activities of defined cell populations. Here, we developed an improved red fluorescent GECI, termed R-CaMP1.07, by mutagenizing R-GECO1. In HeLa cell assays, R-CaMP1.07 exhibited a 1.5-2-fold greater fluorescence response compared to R-GECO1. In hippocampal pyramidal neurons, R-CaMP1.07 detected Ca2+ transients triggered by single action potentials (APs) with a probability of 95% and a signal-to-noise ratio &7 at a frame rate of 50 Hz. The amplitudes of Ca2+ transients linearly correlated with the number of APs. The expression of R-CaMP1.07 did not significantly alter the electrophysiological properties or synaptic activity patterns. The co-expression of R-CaMP1.07 and channelrhodpsin-2 (ChR2), a photosensitive cation channel, in pyramidal neurons demonstrated that R-CaMP1.07 was applicable for the monitoring of Ca2+ transients in response to optically evoked APs, because the excitation light for R-CaMP1.07 hardly activated ChR2. These technical advancements provide a novel strategy for monitoring and manipulating neuronal activity with single cell resolution.

Original languageEnglish
Article numbere39933
JournalPloS one
Volume7
Issue number7
DOIs
Publication statusPublished - 2012 Jul 10

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

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