A modular chemigenetic calcium indicator enables in vivo functional imaging with near-infrared light

Farrants, H.; Shuai, Y.; Lemon, W. C.; Hernandez, C. M.; Yang, S.; Patel, R.; Qiao, G.; Frei, M. S.; Grimm, J. B.; Hanson, T. L.; Tomaska, F.; Turner, G. C.; Stringer, C.; Keller, P. J.; Beyene, A. G.; Chen, Y.; Liang, Y.; Lavis, L. D.; Schreiter, E. R.

doi:10.1101/2023.07.18.549527

bioRxiv · 10.1101/2023.07.18.549527

A modular chemigenetic calcium indicator enables in vivo functional imaging with near-infrared light

Farrants, H.·Shuai, Y.·Lemon, W. C.·Hernandez, C. M.·Yang, S.·Patel, R.·Qiao, G.·Frei, M. S.·Grimm, J. B.·Hanson, T. L.·Tomaska, F.·Turner, G. C.·Stringer, C.·Keller, P. J.·Beyene, A. G.·Chen, Y.·Liang, Y.·Lavis, L. D.·Schreiter, E. R.

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Abstract

Genetically encoded fluorescent calcium indicators have revolutionized neuroscience and other biological fields by allowing cellular-resolution recording of physiology during behavior. However, we currently lack bright, genetically targetable indicators in the near infrared that can be used in animals. Here, we describe WHaloCaMP, a modular chemigenetic calcium indicator built from bright dye-ligands and protein sensor domains that can be genetically targeted to specific cell populations. Fluorescence change in WHaloCaMP results from reversible quenching of the bound dye via a strategically placed tryptophan. WHaloCaMP is compatible with rhodamine dye-ligands that fluoresce from green to near-infrared, including several dye-ligands that efficiently label the central nervous system in animals. When bound to a near-infrared dye-ligand, WHaloCaMP1a is more than twice as bright as jGCaMP8s, and shows a 7x increase in fluorescence intensity and a 2.1 ns increase in fluorescence lifetime upon calcium binding. We use WHaloCaMP1a with near-infrared fluorescence emission to image Ca2+ responses in flies and mice, to perform three-color multiplexed functional imaging of hundreds of neurons and astrocytes in zebrafish larvae, and to quantitate calcium concentration using fluorescence lifetime imaging microscopy (FLIM).

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Farrants, H., Shuai, Y., Lemon, W. C., Hernandez, C. M., Yang, S., Patel, R., Qiao, G., Frei, M. S., Grimm, J. B., Hanson, T. L., Tomaska, F., Turner, G. C., Stringer, C., Keller, P. J., Beyene, A. G., Chen, Y., Liang, Y., Lavis, L. D., Schreiter, E. R.. 2023-07-19. A modular chemigenetic calcium indicator enables in vivo functional imaging with near-infrared light. https://doi.org/10.1101/2023.07.18.549527

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