GEVIBench › All sensors › QuasAr6a
QuasAr6a
Archon1 variant evolved through video-based pooled screening with improved SNR.
- Category: Opsin GEVI
- Published: 2023-01-09 — Nature Methods 2023
- Derived from: Archon1
- Response polarity: positive-going (fluorescence increases on depolarization)
- Spectrum: excitation peak 590 nm, emission peak 715 nm (QuasAr6a)
- Plasmid: Addgene #178822
- Tags: Archaerhodopsin, Far-red
Headline values (as shown in the GEVIBench table)
| Metric | Value | Definition |
|---|---|---|
| Brightness (B/B_EGFP) | 0.0066× EGFP | Molecular brightness relative to EGFP (extinction coefficient × quantum yield, or a measured ratio). Sensors not measured against EGFP directly are placed through a chain of pairwise brightness comparisons, combined by geometric mean. |
| Kinetics τ_on / τ_off (ms) | 2.3 / 1.6 ms | Activation / decay time constants in ms (amplitude-weighted mean τ for multi-exponential fits). The value shown averages the measurements made at physiological temperature (≥33 °C); if there are none, it is the measurement closest to 33 °C. |
| ΔF/F per 100 mV | +73% | Steady-state fluorescence change for a 100 mV depolarization step (−70 → +30 mV); the sign gives the polarity. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting. |
| ΔF/F per mV | 0.7% (estimated from the F–V curve) | Subthreshold sensitivity: fluorescence change per mV near rest (−90 to −50 mV). Where no value is reported directly, it is estimated from the F–V curve. |
| ΔF/F per AP | 23% | Fluorescence change per single action potential in neurons. The table shows the first listed measurement; the median across measurements (one-photon preferred) is used for sorting. |
| AP width (FWHM, ms) | 2.4 ms | Full width at half maximum of the optical spike waveform. |
| Photostability t75% @ 100 mW/mm² | 5.2 h | Time for fluorescence to fall to 75% of its initial value under one-photon illumination, linearly dose-scaled to 100 mW/mm² (t50% is used where the 75% crossing falls inside a fast initial transient). Two-photon curves are not dose-scaled and are excluded. |
| Papers using it (N_used) | 5 | Number of published research papers, tracked by GEVIBench, that used the sensor for an experiment (a popularity / track-record measure). |
Measurements and sources
Kinetics
- τ_on 2.3 ms, τ_off 1.6 ms at 30°C — Tian 2023, Ext. Fig. 4e
ΔF/F per 100 mV
- +73%, 1P — Tian 2023, Ext. Fig. 4c
ΔF/F per action potential
- 23%, 1P — Tian 2023, Fig. 3i
AP width (FWHM)
- 2.4 ms at 1000 Hz sampling, Mouse, visual cortex layer 1 NDNF interneurons, in vivo, 1P, 37°C — Tian 2023, Fig. 4d
Brightness comparisons
- 1.7× the brightness of Archon1 — Tian 2023, Ext. Fig. 4b
Photobleaching
- t75% = 445 s at 4200 mW/mm², 1P — Tian 2023, Ext. Fig. 4f
Fluorescence–voltage (F–V) curve
ΔF/F (%) at each membrane potential, normalized to 0 at −70 mV: -70 mV: 0%; -60 mV: 7%; -50 mV: 15%; -40 mV: 22%; -30 mV: 29%; -20 mV: 37%; -10 mV: 44%; 0 mV: 51%; 10 mV: 58%; 20 mV: 66%; 30 mV: 73% — Tian 2023, Ext. Fig. 4c
Research papers using QuasAr6a (5)
- Video-based pooled screening yields improved far-red genetically encoded voltage indicators — Tian H, Davis HC, Wong-Campos JD, Park P, Fan LZ, Gmeiner B, Begum S, Werley CA, Borja GB, Upadhyay H, Shah H, Jacques J, Qi Y, Parot V, Deisseroth K, Cohen AE, Nature Methods 2023 (HEK293T cells, in vitro; Cultured rat hippocampal neurons, in vitro; Mouse cortex NDNF interneurons, in vivo; Mouse hippocampus PV interneurons, in vivo)
- Dendritic branch structure compartmentalizes voltage-dependent calcium influx in cortical layer 2/3 pyramidal cells — Landau AT, Park P, Wong-Campos JD, Tian H, Cohen AE, Sabatini BL, eLife 2022 (Mouse, cortical layer 2/3 pyramidal cells, acute brain slices)
- Diminishing neuronal acidification by channelrhodopsins with low proton conduction — Hayward RF, Brooks FP 3rd, Yang S, Gao S, Cohen AE, eLife 2023 (Rat, cultured hippocampal neurons, in vitro; HEK293T cells, in vitro)
- Retrograde endocannabinoid signaling at inhibitory synapses in vivo — Dudok B, Fan LZ, Farrell JS, Malhotra S, Homidan J, Kim DK, Wenardy C, Ramakrishnan C, Li Y, Deisseroth K, Soltesz I, Science 2024 (Mouse, hippocampus CA1, in vivo)
- Plasmonic Enhancement of Fluorescence and Protein Dynamics in Living Mammalian Cells — Locarno M, Dong Q, Post M, Meng X, Glessi C, Hettema NM, Brandsma N, Blokhuizen S, Castaneda Garcia A, Ganapathy S, Schmidt T, van Roemburg L, Xu B, Cho CT, Laan L, Chien M, Brinks D, Advanced Materials 2026 (HEK293T cells, in vitro)
Data and citation
- llms.txt — summary for language models
- llms-full.txt — every sensor in full (Markdown)
- gevis.json — all values and measurements with sources (JSON)
- gevis.csv — one row per sensor (CSV)
Cite GEVIBench as: Adam E. Cohen and Daozheng Gong (2026). Voltage imaging: A practical guide. Neuron. https://doi.org/10.1016/j.neuron.2026.08.002
Generated from the GEVIBench database on 2026-10-12.