Which of the following is a common example of solid support hybridization?

• A. Southern blot
• B. Chemiluminescence
• C. Hybridization protection assay
• D. In situ hybridization

Answer: (A)

Solid support hybridization means fixing nucleic acids to a solid surface and probing them with a labeled complementary sequence so the binding can be detected after washing away non-specific interactions. The classic example is Southern blotting, where genomic DNA is first cut with restriction enzymes, separated by size on a gel, and then transferred to a membrane (nitrocellulose or nylon). The DNA on the membrane is immobilized, and a labeled probe that matches the sequence of interest is hybridized to the membrane. After washing, the bound probe is detected, revealing which fragments contain the target sequence and, often, their sizes. This approach exemplifies solid-phase hybridization because the critical steps—binding and detection—occur on the solid support, enabling precise localization and visualization of specific DNA fragments.

Other options describe different aspects or variants: chemiluminescence is a detection signal used after hybridization rather than the hybridization step itself; in situ hybridization also uses a slide as a solid support but aims to localize nucleic acids within cells or tissue rather than identify fragment sizes; the hybridization protection assay is a separate format used for measuring hybridization reactions, not the standard solid-support blot approach.