Which technique can quantify mRNA abundance with high sensitivity?

• A. Northern blot
• B. RNA-Seq
• C. Microarray
• D. RT-qPCR

Answer: (D)

Measuring mRNA abundance with high sensitivity relies on a method that can detect very small amounts and quantify across a wide range. RT-qPCR achieves this by converting RNA to cDNA and then amplifying the target cDNA in real time, with fluorescence signaling how much product accumulates after each cycle. Because PCR amplification is exponential, even trace amounts of starting mRNA produce a detectable signal, giving a low detection limit and a broad dynamic range. This makes RT-qPCR especially reliable for precise quantification of gene expression and for validating results or measuring low-abundance transcripts.

Other techniques have limitations in sensitivity or quantification accuracy. Northern blot requires more RNA and is less sensitive and more labor-intensive. RNA-Seq provides broad, genome-wide information but isn’t always the most sensitive or cost-effective option for targeted, single-gene quantification. Microarrays have a narrower dynamic range and can suffer from cross-hybridization, making them less ideal for accurate quantification of low-abundance targets.