Source 1review2019Frontiers in Physiology
Toolkit/genetically encoded sensors
genetically encoded sensors
Taxonomy: Technique Branch / Method. Workflows sit above the mechanism and technique branches rather than replacing them.
Summary
Optical readouts of specific cellular events, including ion transients, voltage changes or activity in biochemical signaling cascades, using small detecting molecules or genetically encoded sensors now offer powerful opportunities for all-optical control and monitoring of cellular activity.
Usefulness & Problems
Why this is useful
Genetically encoded sensors provide optical readouts of voltage, ion transients, or biochemical signaling during cardiac optogenetic experiments.; optical readout of ion transients; optical readout of voltage changes; optical readout of biochemical signaling activity; all-optical control and monitoring
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Genetically encoded sensors provide optical readouts of voltage, ion transients, or biochemical signaling during cardiac optogenetic experiments.
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optical readout of ion transients
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optical readout of voltage changes
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optical readout of biochemical signaling activity
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all-optical control and monitoring
Problem solved
They enable all-optical monitoring so that stimulation and readout can both be performed optically.; enables optical monitoring of cellular events during optogenetic experiments
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They enable all-optical monitoring so that stimulation and readout can both be performed optically.
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enables optical monitoring of cellular events during optogenetic experiments
Problem links
enables optical monitoring of cellular events during optogenetic experiments
LiteratureThey enable all-optical monitoring so that stimulation and readout can both be performed optically.
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They enable all-optical monitoring so that stimulation and readout can both be performed optically.
Published Workflows
Objective: Implement cardiac optogenetic experiments by selecting an appropriate opsin class, establishing expression in the target cardiac system, delivering light effectively, and measuring physiological or optical responses.
Why it works: The review links tool performance first to opsin biophysical properties, then to successful expression in the cardiac target, then to practical light delivery, and finally to physiological or optical readout. This ordering reflects that optical control requires both a suitable actuator and a feasible delivery-and-measurement setup.
light-gated transmembrane ion movementdepolarizationhyperpolarizationG-protein coupled intracellular signaling modulationopsin selectionviral transductionspark-cell couplingtransgenic expressionin vivo adenoviral deliverylaser illuminationLED illuminationelectrophysiological readoutoptical readout
Stages
- 1.Select optogenetic actuator class and spectral properties(library_design)
The abstract explicitly states that opsin biophysical properties determine whether stimulation or silencing will be reliable and precise, and that spectral shifts can improve penetration and combinatorial use.
Selection: Choose among depolarizing, hyperpolarizing, GPCR-signaling, and spectrally shifted optogenetic tools based on biophysical properties needed for reliable and precise stimulation or silencing.
- 2.Establish expression in the cardiac target(library_build)
The review states that expression of the chosen optogenetic tool is required before optical control can be attempted in cardiac cells or whole systems.
Selection: Introduce opsin-encoding genes by viral transduction or use spark-cell coupling at single-cell level; at system level use transgenic mice or in vivo adenoviral injection.
- 3.Deliver light to the preparation(functional_characterization)
Even with a suitable opsin and expression strategy, optical control depends on practical light delivery to the cardiac tissue.
Selection: Use laser or LED illumination with widespread or multipoint delivery appropriate to the preparation.
- 4.Measure physiological or optical responses(confirmatory_validation)
The abstract presents these readouts as the means to confirm and monitor the effects of cardiac optogenetic stimulation.
Selection: Assess responses using patch clamp, multi-unit microarray recordings, Langendorff heart electrical recordings, or optical reporters including small detecting molecules and genetically encoded sensors.
Taxonomy & Function
Primary hierarchy
Technique Branch
Method: A concrete measurement method used to characterize an engineered system.
Mechanisms
fluorescent optical reporting of cellular state changesgenetically encoded sensing of ion transients, membrane voltage, and biochemical signaling activityTechniques
Functional AssayTarget processes
signalingInput: Light
Implementation Constraints
cofactor dependency: cofactor requirement unknownencoding mode: genetically encodedimplementation constraint: context specific validationimplementation constraint: spectral hardware requirementoperating role: sensor
They require optical detection instrumentation and compatibility with the stimulation setup.; requires compatible optical readout instrumentation
specific sensor classes and compatibility constraints are not detailed in the abstract
Validation
Cell-freeBacteriaMammalianMouseHumanTherapeuticIndep. Replication
Supporting Sources
Ranked Claims
Spectrally shifted opsin variants can support enhanced tissue penetration, combinatorial stimulation of different cell subpopulations, and all-optical read-in and read-out studies.
In cardiac physiology, optogenetics has mainly used optically controlled depolarizing ion channels to control heart rate and for optogenetic defibrillation.
Cardiac optogenetic stimulation can be read out using patch clamp, multi-unit microarray recordings, Langendorff heart electrical recordings, and optical reporters including small detecting molecules or genetically encoded sensors.
Optogenetic techniques use genetically expressed light-gated microbial channels or pumps to modulate cellular excitability with millisecond precision.
ChR2-expressing cardiomyocytes show normal baseline and active excitable membrane and Ca2+ signaling properties and are sensitive even to approximately 1 ms light pulses.
light pulse sensitivity 1 ms
Expression of the chosen optogenetic tool in cardiac cells requires gene introduction by viral transduction or coupling via spark cells at the single-cell level, and transgenic expression or in vivo adenoviral delivery at system level.
Light delivery by laser or LED is relatively straightforward in vitro but is challenged in cardiac tissue by motion and light scattering.
Biophysical properties of microbial opsins determine their ability to evoke reliable and precise stimulation or silencing of electrophysiological activity.
Approval Evidence
1 source1 linked approval claimfirst-pass slug genetically-encoded-sensors
Optical readouts of specific cellular events, including ion transients, voltage changes or activity in biochemical signaling cascades, using small detecting molecules or genetically encoded sensors now offer powerful opportunities for all-optical control and monitoring of cellular activity.
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assay summarysupports
Cardiac optogenetic stimulation can be read out using patch clamp, multi-unit microarray recordings, Langendorff heart electrical recordings, and optical reporters including small detecting molecules or genetically encoded sensors.
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Comparisons
Source-stated alternatives
The abstract pairs them with small detecting molecules as another optical readout option.
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The abstract pairs them with small detecting molecules as another optical readout option.
Source-backed strengths
supports all-optical control and monitoring of cellular activity
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supports all-optical control and monitoring of cellular activity
Compared with small detecting molecules
The abstract pairs them with small detecting molecules as another optical readout option.
Shared frame: source-stated alternative in extracted literature
Strengths here: supports all-optical control and monitoring of cellular activity.
Relative tradeoffs: specific sensor classes and compatibility constraints are not detailed in the abstract.
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The abstract pairs them with small detecting molecules as another optical readout option.
Ranked Citations
- 1.