Gene Quantification and Expression
Measuring Gene Activity Under a Given Condition
In many research projects, it is necessary to determine the expression level of a specific gene in order to understand its role in an organism or under an experimental condition.
Gene expression corresponds to the production of messenger RNA resulting from DNA transcription.
Analysis of these RNAs allows evaluation of the studied gene's activity and observation of how it evolves according to different biological contexts.
The study of gene expression thus constitutes an essential tool for exploring the molecular mechanisms involved in a biological process, a cellular response, or the effect of a treatment.
Why Quantify Gene Expression?
Gene expression quantification provides answers to numerous scientific questions, particularly to:
- analyze gene regulation under different experimental conditions
- compare gene activity between multiple samples
- identify the impact of an environmental factor or active molecule
- characterize the biological mechanisms involved in a cellular process
- validate the expression of a gene identified during transcriptomic analysis.
These analyses are widely used in molecular biology, microbiology, medical research, and in the field of biotechnology.
How to Measure Gene Expression?
Gene expression is generally studied from the messenger RNA produced during gene transcription. RNAs are first converted into complementary DNA (cDNA), then analyzed to measure their quantity.
RT-qPCR: Precise Quantification of Gene Expression
The most commonly used method for measuring gene expression is real-time quantitative PCR (RT-qPCR). This technique allows amplification of a specific genetic sequence while monitoring the evolution of the reaction throughout the amplification cycles.
It offers several advantages:
- high sensitivity for detecting low quantities of RNA
- precise quantification of gene expression level
- rapid and reproducible analysis
- ability to study multiple genes in a single experiment.
Using this approach, it is possible to compare gene expression levels between different samples or experimental conditions.
Relative or Absolute Quantification
Depending on the study objectives, two main approaches can be used:
Relative Quantification
This method consists of comparing the expression level of a gene between several experimental conditions. Results are generally normalized using reference genes, called housekeeping genes, in order to correct variations between samples.
Absolute Quantification
In certain cases, it is necessary to determine the exact number of copies of an RNA or gene in a sample. This approach provides a precise measurement of the quantity of genetic material present.
Types of Genetic Material Analyzed
Gene expression quantification can be performed from different types of RNA:
- total RNA
- total messenger RNA
- targeted mRNA corresponding to one or more genes of interest.
The choice of analyzed material depends on the type of study and the information sought.
An Approach Tailored to Your Scientific Project
Each gene expression study project has its own specificities: nature of samples, number of genes studied, desired precision, or experimental conditions.
Analysis methods can be adapted to precisely meet the scientific objectives of the project, whether it involves a targeted study of a particular gene or validation of broader transcriptomic analyses.
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