Cell cycle stage

One of the first applications developed for flow cytometry was cell cycle analysis.2 There are numerous intercalating fluorescent DNA and RNA staining reagents that can be used to determine the amount of DNA in cells, an indicator of cell cycle stage and progression, as demonstrated in Figure 7.3. Nucleic acid dyes may be selective for DNA... 

In a cell cycle assay, the percentage of cells in each cell cycle stage is the most crucial measurement. Cells can be classified into Glor G2 phase by their DNA content, the M phase (mitotic or interphase) by the phospho-histone H3 mitotic marker, and the S phase by a pulsed label with dU to detect DNA synthesis. Each cell has four intensity parameters and has to be classified into the Gl, G2, S, or M phase based on these parameters. Because we are potentially dealing with billions of cells, cell cycle classification must be automated. 

This definition includes transient chromatin modifications, which are associated with DNA repair or cell-cycle stages, and stable chromatin modifications that are maintained across multiple cell generations. 

Figure 9. Dose response curve for CPD specific fluorescence against the UV-B dose in Cyclotella sp. cells, measured with flow cytometry. Filled circles G1 cells, open circles G2 cells. Error bars, standard deviations of the mean for G1 and G2 cells (at least 4000 cells analysed per condition/cell cycle stage). [Redrawn form Buma et al. 10.]...

PROTOCOL 1 ASSAY FOR CELL-CYCLE STAGE SPECIFIC APOPTOSIS... 

Reid, S., Cross, R., and Snow, E. C. (1996) Combined Hoechst 33342 and merocyanine 540 staining to examine murine B cell cycle stage, viability and apoptosis. J. Immunol. Methods 192(1-2), 43-54. 

Most cyclins are the target of ubiquitin-mediated proteolysis, and this degradation is a major mechanism for reducing cyclin concentrations at distinct cell cycle stages. 

Apoptosis mediated by p75 requires specific conditions, with regard to cell type, cell cycle stage, developmental stage, injury or stress. This could be due to time in culture, metabolic impairment, hypoxia, or other types of stress signals, such as nerve injury or trauma (Gu et al., 1999). Sensitive cells may be highly susceptible to injury and inflammation and may become more reactive to released growth factors and cytokines by upregulating receptor expression at the site of injury. 

Cells in colony at various cell-cycle stages... 

The main feature of normal animal cell is its compartmentalization [7]. The DNA of the animal cell is restricted to the nucleus at all cell cycle stages except during metaphase when no nucleus exists. The synthesis of RNA occurs in the nucleus and most of it remains there, but messenger RNA and transfer RNA migrate to the cytoplasm. Ribosomal RNA is synthesized in the nucleolus the two ribosomal subunits are partly assembled in the nucleolus and nucleus then migrate to the cytoplasm. All protein synthesis proceed in the cytoplasm. The mitochondria, which is located only in the cytoplasm, contains DNA-s, RNA- and protein-synthesizing systems of their own [7]. 

Fig. 1. Influence of SAB on the distribution of BrdUrd-substituted cells over the cell cycle stages...

Collas, P., Balise, J. J., and Robl, J. M. (1992) Influence of cell cycle stage of the donor nucleus on development of nuclear transplant rabbit embryos. Biol. Reprod. 46, 492-500. 

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