B) RNA测序 - Midis

Understanding the Context

What Is RNA Sequencing?

RNA sequencing, commonly abbreviated as RNA-Seq, is a next-generation sequencing (NGS) technology used to analyze RNA in a sample. Unlike traditional methods such as microarrays that measure gene expression using predefined probes, RNA-Seq provides a digital, high-resolution view by directly sequencing RNA molecules. This allows unbiased detection of known and novel transcripts, splice variants, fusion genes, and non-coding RNAs.

RNA-Seq captures the dynamic landscape of gene activity in cells or tissues, helping scientists understand how genes respond to environmental stimuli, disease states, developmental stages, and therapeutic interventions.

Key Insights

How Does RNA Sequencing Work?

The core workflow of RNA-Seq involves several key steps:

1. Sample Preparation
   RNA is extracted from biological samples such as cells, tissues, or biofluids. Depending on the study, researchers may isolate total RNA, poly-A RNA (enriched for coding transcripts), or use methods like ribosomal RNA depletion to focus on messenger RNA (mRNA).

2. Library Construction
   The RNA is converted into complementary DNA (cDNA) via reverse transcription. The cDNA is fragmented, adapters are ligated, and PCR amplification is performed to create a sequencing library enriched with barcodes for multiplexing.

Final Thoughts

3. Sequencing
   The library is sequenced using high-throughput platforms like Illumina, which generate millions of short reads representing the original RNA molecules.

4. Data Analysis
   Raw sequencing data are processed using bioinformatics tools to align reads to a reference genome or transcriptome, quantify expression levels, detect novel transcripts, and identify differential expression between samples.

This multi-stage process ensures accurate, scalable, and comprehensive analysis of the transcriptome.

Key Applications of RNA Sequencing

RNA-Seq has become indispensable across multiple domains of biological research and clinical practice: