BrdU incorporation assays measure what?

• A. DNA synthesis during replication.
• B. RNA transcription measurement.
• C. Protein synthesis measurement.
• D. Chromatin accessibility assessment.

Answer: (A)

BrdU incorporation assays measure DNA synthesis during replication. BrdU is a thymidine analog that gets incorporated into newly synthesized DNA in place of thymidine, specifically during the S phase when the genome is being copied. After labeling, anti-BrdU antibodies detect the incorporated BrdU, allowing you to quantify cells that are actively replicating their DNA or the extent of DNA synthesis. This reflects DNA replication activity, not RNA transcription or protein synthesis, and it doesn’t directly assess chromatin accessibility. Detection is typically done by immunostaining or flow cytometry, often after mild DNA denaturation to expose BrdU for antibody binding.