PMA is a high affinity photoreactive DNA binding dye developed by Biotium for viability PCR. PMAxx™ is Biotium's new and improved viability PCR dye. The dyes are weakly fluorescent by themselves but become highly fluorescent upon binding to nucleic acids. Upon photolysis, the dye forms a stable covalent bond with the DNA, thus resulting in permanent DNA modification. The dye is cell membrane-impermeable and thus can be used to selectively modify DNA from dead cells with compromised membrane integrity, while leaving DNA from viable cells intact. PMA and PMAxx™ inhibit PCR amplification of modified DNA templates. Consequently the dye is useful in the selective detection of viable pathogenic cells by quantitative real-time PCR.    PMA Enhancer for Gram Negative Bacteria was designed to improve PMA- and PMAxx™ -mediated discrimination between live and dead gram-negative bacteria. PMA Enhancer is provided as a 5X solution, and is added to a sample before the addition of dye. When a sequence from a gram-negative bacteria is amplified by PCR, samples pre-treated with Enhancer show a decrease in the signal from dead cells, with no change in the signal from live cells. Thus, PMA or PMAxx™ plus Enhancer is the optimal way to perform viability PCR on gram-negative bacteria. Note: PMA Enhancer is not intended for use when gram-positive bacteria are to be detected. PMA Enhancer may adversely affect the amplification of live cell DNA from gram-positive bacteria.    For photoactivation of PMA, PMAxx™ or EMA dye, we recommend the use of Biotium's PMA-Lite™ LED Photolysis Device for tubes, or Glo-Plate™ Blue LED Illuminator for plates, which are designed to conduct photolysis under controlled conditions.    Materials from Biotium are sold for research use only.