PT  - JOURNAL ARTICLE
AU  - Yong Qian
AU  - Danielle M. Orozco Cosio
AU  - Kiryl D. Piatkevich
AU  - Sarah Aufmkolk
AU  - Wan-Chi Su
AU  - Orhan T. Celiker
AU  - Anne Schohl
AU  - Mitchell H. Murdock
AU  - Abhi Aggarwal
AU  - Yu-Fen Chang
AU  - Paul W. Wiseman
AU  - Edward S. Ruthazer
AU  - Edward S. Boyden
AU  - Robert E. Campbell
TI  - Improved genetically encoded near-infrared fluorescent calcium ion indicators for <em>in vivo</em> imaging
AID  - 10.1101/2020.04.08.032433
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.04.08.032433
4099  - http://biorxiv.org/content/early/2020/04/10/2020.04.08.032433.short
4100  - http://biorxiv.org/content/early/2020/04/10/2020.04.08.032433.full
AB  - Near-infrared (NIR) genetically-encoded calcium ion (Ca2+) indicators (GECIs) can provide advantages over visible wavelength fluorescent GECIs in terms of reduced phototoxicity, minimal spectral cross-talk with visible-light excitable optogenetic tools and fluorescent probes, and decreased scattering and absorption in mammalian tissues. Our previously reported NIR GECI, NIR-GECO1, has these advantages but also has several disadvantages including lower brightness and limited fluorescence response compared to state-of-the-art visible wavelength GECIs, when used for imaging of neuronal activity. Here, we report two improved NIR GECI variants, designated NIR-GECO2 and NIR-GECO2G, derived from NIR-GECO1. We characterized the performance of the new NIR GECIs in cultured cells, acute mouse brain slices, and C. elegans and Xenopus laevis in vivo. Our results demonstrate that NIR-GECO2 and NIR-GECO2G provide substantial improvements over NIR-GECO1 for imaging of neuronal Ca2+ dynamics.Competing Interest StatementThe authors have declared no competing interest.