Hi, This is an interesting question. I just interwiewed a colleague, who is a specialist on photobiology. In comparison to UV-irradiation found in nature, the does-rate in a cytometer is of course enormous while the actual dose is minimal due to the short exposure. For comparison: the UV-radiation measured at 3000m a.s.l may be approximately 600 milliWatt/square-meter. While the radiation in a 50micron focus of a 50mW laser is about 25 Megawatt/square-meter. Thus, mathematically, a 500 nanosecond flight through the laser would be equivalent to a 10 second sunbath in the mountains. The DNA doesn't absorb at 350nm, so UV light at this wavelength shouldn't cause direct mutation. On the other hand it can lead to the production of radicals within the cell, which happens within picoseconds. However, to estimate from this basis the actual damage to a cell in the cytometer is just speculation. Unfortunately, I don't know of any investigations done specifically for this situation. Best Regards Stefan ------------------------------------------------- Stefan Andreatta Institute of Zoology and Limnology University of Innsbruck, Austria phone: ++43-512-507-6122; fax (..)-2930 Mark Kukuruga wrote: > > Hi all . . . > Considering the use of DAPI as an exclusion dye, I'm wondering about the effects of > (albeit brief) UV irradiation on the cells that we sort "viably." Should we worry, > or is it negligible? > MAK. > > -- > Mark A. KuKuruga, Managing Director > University of Michigan Flow Core > 7416 CCGC 0946 > (734) 647-3216, fax (734) 936-7376 > kukuru@umich.edu --
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