Building a Simple and Versatile Illumination System for Optogenetic Experiments
January 12th, 2021
This protocol describes how to perform optogenetic experiments for controlling gene expression with red and far-red light using PhyB and PIF3. Included are step-by-step instructions for building a simple and flexible illumination system, which enables the control of gene expression or other optogenetics with a computer.
The system allows for researchers to easily construct an inexpensive and versatile illumination system for optogenetic experiments. Advantages of this technique include the ability to program the LED illumination timing with available wavelengths that span the visible near IR spectrum, and that the LEDs can be used in a variety of contexts To build an electrical circuit, clip the printed circuit board onto the helping hands and insert the jumper wires, connecting them to form the A1 and A3 pinholes to the ground, the D2 jumper wire into the D6 pinhole, and the power supply plus number seven jumper wires into the A7 pinhole. Bend the terminals 45 degrees and add flux.
After soldering, trim the backs of the wires. Insert one end of the soldered female wire to wire connector into the A5 hole. Then connect one end of the resistor to the A5 hole.
Connect the other end of the connector to the ground. Then connect the other end of the resistor to the ground and solder the connection. For the Arduino connector, crimp the ends of the wire to wire connectors and push the crimped ends through the rectangular connector.
To set up the LEDs, tin a wire by heating from below while adding solder from the top. Place a generous amount of solder over the large soldering tip and use the tip to heat the LED base at the contact containing flux. After a few seconds, individually drag the solder across each contact and fix the black wire onto the cathode using a hair clip.
Place a generous amount of solder onto the large soldering tip, and press the tip onto the wire until the solder on the LED base melts. Hold down the wire and remove the soldering iron while holding the wire in place. Place a small amount of solder paste onto the pads for the LED connections and use forceps to place the LED over the pads.
Hold the pre-tinned red wire on the anode and use a hair clip to clip the wire. Add solder to the large tip as demonstrated and press the tip onto the connection until the solder on the LED base melts and the solder paste melts and becomes silver. For making the LED wires, place a 4.76 millimeter shrink tube over the wire cut to length and a 3.18 millimeter shrink tube over the wire to wire connector.
Strip and add flux to the wire ends. Use the helping hands to clip the wire to wire connector and twist the connector end with one wire end. Solder the materials together and attach the other wire to the setup in the same manner and solder.
Then clip the LED wires to the helping hands with tape under the LED base. Next, mix epoxy according to the manufacturer's instructions and spread the epoxy over the top of the soldered LED. Using the spade drill bit, drill a 1.5 centimeter hole through the top of the box onto which the LED will be placed and use a high speed rotary tool to make a notch on one side of the hole to make room for the LED wire.
Tape a 25 to 30 millimeter piece of privacy film onto the black box covering the hole that the LED will illuminate through and tape the LED outside of the black box on top of the hole. For a four LED control system, drill four 0.83 centimeter holes 3.81 centimeters apart into the lid of the box and use a high speed rotary tool to cut a 1.19 by 1.90 centimeter rectangular hole into the top left corner. Using a spade drill bit, drill a 1.5 centimeter hole in the back of the box and insert a grommet into the hole.
For the computer controlled LEDs, sandpaper the area where the microcontroller will be glued in the box as well as the bottom side of the microcontroller holder. Snap the microcontroller onto the holder then epoxy the holder and the box together before securing the holder in the black box. Then place double-sided tape on the clip and secure the clip inside the box.
In samples transfected to express phytochrome B but not phycocyanin bilin, leakiness increases as the amount of reporter DNA increases. In addition, when the entire phytochrome B gene switch including the phycocyanin bilin chromofour producing plasmid are illuminated with far red light, luciferase expression also increases with the increasing amounts of reporter construct within the transfection mix. Similarly, when the light sensitive cells are illuminated with red light, luciferase expression also increases with increased reporter amount.
When comparing induction levels of the red light treated cells to the far red light treated cells, a small decrease in the fold activation is found with increasing amounts of reporter. It is essential to carefully follow each step when building the electrical circuit and to double check the pinhole numbers line by line before soldering each component. This protocol can be used for the optical stimulation of many types of samples or optogenetic tools using a variety of wavelengths and allows the programming of illumination schedules.
Overview
This protocol describes the construction of a versatile illumination system for optogenetic experiments, enabling control of gene expression with red and far-red light. Step-by-step instructions are provided for building the system and programming LED illumination.
Key Study Components
Area of Science
- Optogenetics
- Gene expression control
- Illumination systems
Background
- Optogenetics allows precise control of cellular functions using light.
- PhyB and PIF3 are key components in light-responsive gene regulation.
- LEDs can be programmed for various illumination schedules.
- This system is designed to be cost-effective and adaptable for different experimental setups.
Purpose of Study
- To provide a detailed protocol for constructing an optogenetic illumination system.
- To enable researchers to control gene expression using specific wavelengths of light.
- To facilitate the use of optogenetic tools in diverse experimental contexts.
Methods Used
- Construction of an electrical circuit for LED control.
- Programming LED illumination timing and wavelengths.
- Assembly of a microcontroller for automated control.
- Testing the system with various reporter constructs.
Main Results
- Successful construction of a flexible illumination system.
- Increased luciferase expression observed with higher reporter DNA amounts.
- Demonstrated control over gene expression using red and far-red light.
- System allows for optical stimulation across different sample types.
Conclusions
- The protocol provides a reliable method for optogenetic experimentation.
- Researchers can utilize this system for various applications in gene regulation.
- Careful adherence to the protocol ensures successful outcomes.
Frequently Asked Questions
Executive Industry Relevance
Optogenetic control of cellular pathways enables precise mechanistic interrogation in target validation and phenotypic screening. A low-cost, programmable illumination system supports reproducible light delivery for gene expression studies, reducing technical variability in preclinical models. This approach enhances predictive confidence by allowing standardized optical stimulation across diverse experimental contexts.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables hypothesis testing of light-sensitive gene switches to clarify pathway function and target mechanism.
- Operational Value: Provides adjustable LED intensity and timing for controlled perturbation of signaling pathways in cellular assays.
Screening & Assay Development
- Scientific Value: Supports preparation of standardized biological systems for quantifying optogenetic responses across compound or genetic perturbations.
- Operational Value: Facilitates assay standardization through programmable illumination schedules and wavelength selection for reproducible readouts.
Translational & Preclinical Research
- Scientific Value: Demonstrates continuity from discovery through preclinical validation by enabling optical stimulation of disease-relevant systems with tunable light parameters.
- Operational Value: Allows risk-adjusted advancement decisions by quantifying dose-dependent responses to red and far-red light in reporter-based assays.
Pipeline & Workflow Integration
The illumination system integrates into discovery biology workflows by enabling controlled optical perturbation of gene expression, supporting lead identification through quantifiable phenotypic outputs.
- Discovery Biology: Supports mechanistic de-risking by allowing precise temporal and spatial control of optogenetic tools to interrogate target function.
- Screening: Enables quantitative dependent variable measurements such as luciferase expression under defined illumination conditions.
- Analytics: Generates reproducible light-dose response data that inform statistical analysis for target validation and hit confirmation.
- Translational Research: Connects to preclinical continuity by providing a reusable platform for testing optogenetic constructs in disease models.
- Enterprise Reuse: Designed as a scalable, adaptable capability for multiple projects requiring optical control of cellular processes.
Operational & Enterprise Impact
- Scientific Value: Predictive confidence in target validation through reduced mechanistic ambiguity in light-controlled experiments.
- Operational Value: Standardization and scalability of illumination protocols across laboratories and experimental setups.
- Strategic Value: Improved go/no-go decisions via reliable, quantifiable optogenetic readouts that reduce false positives in target validation.
- Portfolio Impact: Enables risk-adjusted prioritization of targets based on reproducible optical stimulation outcomes.
Implementation Considerations
- Basic electronics proficiency for circuit assembly and soldering of LED connections.
- Access to Arduino-compatible microcontrollers and soldering instrumentation for system construction.
- Standardization of illumination protocols across teams to ensure reproducible experimental conditions.
- Adaptation considerations for different optogenetic tools requiring specific wavelengths or intensity ranges.
- Practical limitation: Manual calibration may be required to optimize LED positioning and light penetration for specific sample types.
