RNAi Feeding in Liquid Culture: A High-Throughput Method to Knockdown Gene Expression in C. elegans
JoVE Encyclopedia of Experiments
Biología
0 vistas • 3:15 min • April 30th, 2023
- To begin, add carbenicillin and one millimolar IPTG to control and test culture flasks containing S basal media. Spin a tube containing larvae at growth stage one, also called L1 larvae, for a few minutes. Now remove the supernatant and place two microliters of L1s on an agar plate. Place the plate under a dissecting microscope and count the number of larvae.
Add RNAi bacteria carrying a non-specific RNAi plasmid to the control flask and bacteria with gene- targeting RNAi to the test flask. The amount of bacteria added should be proportional to the number of worms.
Let the larvae grow with continuous shaking to ensure proper oxygenation. The larvae feed on the bacteria. Inside the larva, the small interfering RNA binds to the complementary mRNA produced by the targeted gene and inhibits protein expression. Finally, examine the worms for your phenotype of interest.
In the example protocol, we will treat L1 larvae with RNAi targeting the daf-2 gene, in liquid culture.
- To begin treatment, add 207.45 milliliters of S basal media with additional reagents as described in the accompanying text protocol to a 2,800 milliliter Fernbach culture flask. Add a final concentration of 50 micrograms per milliliter of carbenicillin and 1 millimolar of IPTG, and close the flask with a membrane screw cap.
Take the L1s out of the 25 degree Celsius incubator and transfer them to 15 milliliter tubes. Centrifuge the L1s at 1,900 times g for three minutes. After spinning, remove the supernatant. Under a microscope, count the L1s per two microliters, and average the numbers obtained from at least nine drops.
Next, add 50,000 worms for the young worm collection and 100,000 worms for the aged worm collection into four Fernbach culture flasks prepared in the previous step. Then add control RNAi bacteria and RNAi bacteria for the gene of interest proportionally to the number of worms.
After adding bacteria, complete worm culture with S basal to bring the total volume to 300 milliliters. Incubate the worm culture at 25 degrees Celsius in a shaking incubator with 150 RPM until collection.
Overview
This article describes a protocol for using RNA interference (RNAi) to study gene function in L1 larvae. The focus is on targeting the daf-2 gene to observe its effects on phenotype.
Key Study Components
Area of Science
- Neuroscience
- Genetics
- Developmental Biology
Background
- RNA interference is a powerful tool for gene silencing.
- The daf-2 gene is known to play a role in development and aging.
- L1 larvae are a model organism for studying genetic functions.
- This protocol allows for controlled experimentation with RNAi.
Purpose of Study
- To investigate the effects of gene silencing on L1 larvae.
- To understand the role of the daf-2 gene in development.
- To provide a detailed methodology for researchers.
Methods Used
- Preparation of S basal media with carbenicillin and IPTG.
- Centrifugation of L1 larvae to isolate them for experimentation.
- Counting larvae under a microscope for accurate dosing.
- Inoculating cultures with RNAi bacteria targeting specific genes.
Main Results
- Successful growth of L1 larvae in controlled conditions.
- Effective gene silencing observed with RNAi treatment.
- Phenotypic changes noted in treated larvae.
- Protocol validated for future studies on gene function.
Conclusions
- RNAi is an effective method for studying gene function in L1 larvae.
- The daf-2 gene significantly impacts larval development.
- This protocol can be adapted for other genes of interest.
Frequently Asked Questions
Executive Industry Relevance
This high-throughput RNAi feeding method in liquid culture enables scalable gene knockdown in C. elegans, supporting target validation and phenotypic screening in early discovery. By increasing worm throughput beyond plate-based limitations, the approach enhances assay reproducibility and predictive confidence for mechanistic de-risking of therapeutic targets. It positions RNAi as a scalable tool for lead identification pipelines in neurodegeneration and aging research.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of gene function via daf-2 knockdown to assess impact on larval development and aging-related phenotypes.
- Operational Value: Supports high-throughput screening by treating larger worm populations in liquid culture compared to traditional plate feeding.
Screening & Assay Development
- Scientific Value: Generates quantitative phenotypic readouts through worm counting and growth monitoring under controlled liquid conditions.
- Operational Value: Standardizes worm dosing and bacterial RNAi delivery using volumetric protocols proportional to worm count.
Translational & Preclinical Research
- Scientific Value: Provides a disease-relevant system for studying insulin/IGF-1 signaling pathways linked to longevity and metabolic disorders.
- Operational Value: Enables continuity from target hit validation to mechanistic follow-up using scalable worm cultures.
Pipeline & Workflow Integration
The method fits within early discovery workflows, supporting target validation through RNAi-mediated gene silencing and enabling progression to lead identification via phenotypic assessment in C. elegans.
- Discovery Biology: Facilitates hypothesis testing by knocking down daf-2 to observe effects on development and protein aggregation phenotypes.
- Screening: Delivers reproducible, quantitative outputs through standardized worm culture and RNAi bacteria inoculation.
- Analytics: Enables measurement of phenotypic changes via larval counting and growth tracking under defined culture conditions.
- Translational Research: Connects daf-2 modulation to aging pathways, supporting biomarker alignment in longevity-focused discovery.
- Enterprise Reuse: Establishes a reusable liquid-culture RNAi platform applicable across multiple gene targets and screening campaigns.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence in target validation by enabling consistent, scalable gene knockdown in a genetically tractable model.
- Operational Value: Enhances reproducibility through standardized media preparation, worm counting, and proportional RNAi bacteria dosing.
- Strategic Value: Improves go/no-go decisions by reducing false negatives in target screening via higher worm throughput and uniform exposure.
- Portfolio Impact: Supports risk-adjusted prioritization of targets by generating reliable phenotypic data from large-scale liquid culture assays.
Implementation Considerations
- Requires expertise in C. elegans handling, RNAi techniques, and liquid culture maintenance.
- Depends on shaking incubators, Fernbach flasks, and microscopy for larval counting and phenotypic assessment.
- Necessitates cross-team standardization of worm counting protocols and RNAi bacteria preparation for reproducibility.
- Involves adaptation considerations when extending beyond daf-2 to other genes of interest in different genetic backgrounds.
- Includes practical limitations such as potential bacterial overgrowth and oxygen transfer constraints in high-density liquid cultures.
Biopharma FAQs
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Última actualización: 29 agosto 2026