Researchers have many tools at their disposal to measure differential gene expression.1 Certainly microarrays are a viable option,2 but relatively few researchers have access to this big ticket technology. Instead scientists often rely on relatively "low tech" protocols including Northern blotting, RNase protection assays, differential plaque hybridization, subtractive hybridization, differential display, representational difference analysis, serial analysis of gene expression (SAGE), and rapid analysis of gene expression (RAGE).3,4
Many companies now offer one-step RT-PCR kits, in which reverse transcription and amplification occur within the same reaction tube and cycle. Furthermore, scientists can run multiple reactions in the same tube, a process called multiplexed PCR, to control for sample-to-sample variation. This technique involves the use of primers that amplify an internal standard--typically a housekeeping gene--within each experimental reaction. Analogous to the interpretation of Northern blot signals, the quantification of the experimental signal relative to the control reflects expression changes between samples. Alternatively, ...
