Question

How can the fluorescence intensity be measured?

Answer 1

Measurement for fluorescence intensity:

1. A large population of cells is treated with a fluorescent DNA dye and then injected into an instrument known as a flow cytometer, which can rapidly measure the fluorescence intensity, and thus the DNA content of each cell within the population.
2. Cells which are present in the S phase can also be specifically labelled by treatment with bromodeoxyuridine (BrdU), an analogue of the nucleotide thymidine.
3. DNA that is included in this nucleotide during the S phase can be detected with fluorescent antibodies against BrdU.
4. We also see that a microscope or flow cytometer can reveal the fraction of cells that are actively synthesizing DNA during the treatment period.