A sensitive orange fluorescent calcium ion indicator for imaging neural activity
Aggarwal et al. develop OCaMP, an orange fluorescent calcium indicator optimised for imaging neural activity at wavelengths above 1000 nm, enabling improved deep tissue imaging and expanded compatibility with existing se
Genetically encoded calcium indicators (GECIs) are vital tools for fluorescence-based visualization of neuronal activity with high spatial and temporal resolution. However, current highest-performance GECIs are predominantly green or red fluorescent, limiting multiplexing options and efficient excitation with fixed-wavelength femtosecond lasers operating at 1030 nm.
In an effort to overcome these limitations, researchers developed OCaMP, an orange fluorescent GECI engineered from O-GECO1 through targeted substitutions to improve calcium affinity while retaining the favorable photophysical properties of mOrange2. OCaMP exhibits improved two-photon cross-section, responsiveness, photostability, and calcium affinity relative to O-GECO1.
In cultured neurons, zebrafish, and mouse cortex, OCaMP outperforms the red GECIs jRCaMP1a and jRGECO1a in sensitivity, photostability, and signal-to-noise ratio. This orange fluorescent calcium indicator is a robust tool for high-fidelity neural imaging optimized for wavelengths above 1000 nm.
The improved performance of OCaMP makes it a practical option within the spectral gap between existing green and red GECIs, enabling expanded compatibility with existing sensors and improved deep tissue imaging capabilities.
While OCaMP shows promise as a tool for neural imaging, its use should be considered in the context of established protocols and guidelines to ensure optimal results and minimize potential drawbacks.
Further research is needed to fully explore the potential applications and limitations of OCaMP in various neural imaging contexts.