Jan Keij wrote- >For a tutorial on fluorescent MAb tags, I'm looking for a way to visualize the >colors of the different fluorochromes in a PowerPoint presentation. > >One way would be to overlay the emission spectrum from a fluorimeter with >the a >picture of the visible spectrum (after matching the wavelength scale). I've >hunted the web for a PICT file of the visible spectrum, but have only >found very >small .jpeg files on astronomy pages. Useless. > >Another way would be to display the color of the emission peak wavelength. So >here I looking for a way to match say the RBG settings to the wavelength >of the >color. Is there a color mixing algorithm in fairly generic software that does >this? > >I can't be the first one to think of this... The problem with this is that spectrally distinct colors at the violet and red ends of the spectrum are harder to distinguish visually than spectrally distinct colors near the middle, and, at the red end, the colors get hard to see. A second problem is that the dyes' emission spectra have long tails, so the color you see by eye is not the color of the light that comes through the bandpass filter. So there is no point using a color matching algorithm. You can hold the bandpass filters used up to white light and get a good idea of what colors to use, at least toward the middle of the spectrum. Texas red (610 nm) is an orangey red; phycocyanin (625 nm) is a redder red, but when you get to Cy5 or APC (675 nm), they are darker red, and not easy to distinguish from Cy5.5 or oxazine 750 (695 nm and 730 nm), and Cy7 (above 750 nm) is just plain hard to see. So you probably want to use orange, red, magenta, and brown or something like that. Phycoerythrin is really yellow (the range perceived as yellow is fairly narrow, running from about 565 to 585 nm, whereas everything from about 500 nm to at least 560 nm is green, although many shades are distinguishable in this range). The Windows color set has a distinguishable blue-green, and yellow-green. The argon laser (488 nm) is perceived as cyan, which is also a reasonable color for Hoechst dye or DAPI emission. At the short end, 438 or 441 nm sources are deep blue; 457 nm is not that different. 395-415 nm is purple, and you can use either a deep purple or black for UV. -Howard
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