Interphase (interphase) is divided into three phases: Pre DNA synthesis (G1 phase), DNA synthesis (S phase), and post DNA synthesis (G2 phase)
The M phase (mitosis), the cell division phase, is divided into: prophase, metaphase, anaphase, and telophase.
Principle of cell cycle detection by PI staining and flow cytometry:
B,C. Xie, Kewei et al. “Yes-associated protein regulates podocyte cell cycle re-entry and dedifferentiation in adriamycin-induced nephropathy.” Cell death & disease vol. 10,12 915. 4 Dec. 2019, doi:10.1038/s41419-019-2139-3
|BrdU assay||After BrdU (5-bromodeoxyuridine) is added to the culture medium, it can be used as the raw material of cell DNA replication, replacing thymidine to integrate into newly synthesized DNA of cells that enter the S phase (DNA synthesis phase). The antibody used to detect BrdU only recognizes the BrdU which is integrated into the single strand of DNA, and PI staining can be used for undenatured double-stranded DNA. Sustained BrdU integration can be used to determine and analyze cells that are in an active state of DNA synthesis, distinguished from those that are in arrest, and thereby used to analysis of the proportion of cells that proliferate; On the other hand, the addition of BrdU at different time points allows the analysis of cell cycle kinetics.||BrdU can integrate into the DNA of S-phase cells and stably exist in daughter cells through DNA replication; BrdU causes irreversible damage to the organism and please be cautious while using.|
|7-AAD assay||7-AAD（7-amino-actinomycin D) is a nucleic acid dye that is unable to pass through the normal plasma membrane. Along with cell apoptosis and cell death, the permeability of the plasma membrane to 7-AAD increases, and 7-AAD can emit a bright red fluorescence upon excitation with an appropriate wavelength of excitation light. Cells could be classified into three populations by the strength of 7-AAD labeling of DNA: 7-AAD-strong as dead cells, 7-AAD-weak as apoptotic cells, and 7-AAD-moderate as normal viable cells. The DNA content in G0 / G1, S, and G2 / M phases can be detected by flow cytometry.||7-AAD has similar fluorescence characteristics as PI, but its emission spectrum is narrower than that of PI and less interference with other detection channels, making it an ideal alternative to PI in multiplex fluorescence staining. And 7-AAD can be used in combination with several 488 nm exciting fluorescent dyes, such as FITC (fluorescein isothiocyanate), PE (Phycoerythrin), APC (Allophycocyanin), etc.|