Description: | Live cell studies of cellular DNA content and cell cycle distribution are useful to detect variations of growth patterns due to a variety of physical, chemical, or biological means, to monitor apoptosis, and to study tumor behavior and suppressor gene mechanisms. In a given population, cells are distributed among three major phases of cell cycle: G0/G1 phase (one st of paired chromosomes per cell), S phase (DNA synthesis with variable amount of DNA), and G2/M phase (two sets of paired chromosomes per cell, prior to cell division). DNA content can be measured using fluorescent, DNA-selective stains that exhibit emission signals proportional to DNA mass. Flow cytometric analysis of these stained populations is then used to produce a frequency histogram that reveals the various cell cycle phases. This analysis is typically performed on permeabilized or fixed cells using a cell-impermeant nucleic acid stain, but is also possible using live cells and a cell-permeant nucleic acid stain. The CellCycle™ Ruby stain is DNA-selective, cell membrane-permeant, and nonfluorescent stain for DNA content analysis in living cells. The CellCycle™ Ruby stain is fluorescent upon binding to double-stranded DNA. CellCycle™ Ruby stain is excited using both 488 nm and 633 nm laser with emission ~685 nm. The staining protocol is simple and includes incubating suspended cells in the presence of CellCycle™ stain and directly measuring the fluorescence without the need for any additional treatment or centrifugation steps. This live cell stain allows the simultaneous co-staining of the cell population for other parameters, and allows for the possibility of cell sorting based on DNA content. |