It is always advisable to match the sheath and sample as closely as possible to minimize any differences in refractive index. Otherwise, scatter information may suffer significantly, depending on the differences in refractive indices. Sorting fresh water protozoans in a saline sheath will result in a near sheath salinity after deflection (and mixing of sample and sheath). Probably not a good idea... No point in arguing about diffusion during the transition through the laser beam(s) if there is mixing immediately afterwards. Joe Andrew Beernink <ABeernink@novasite.com> on 12/20/2001 02:49:45 PM To: cyto-inbox cc: Subject: RE: [GFP Retention] If the flow is laminar, and we assume that diffusion of salts from sheath to cell suspension medium (water) is negligible (bad assumption?), the sort decision is made while the protozoan is still in fresh water, so it shouldn't change our ability to sort, only to reanalyze our sorted sample, assuming our (bad?) assumption about diffusion is correct. Ideas? Feedback? (please, no gunfire!) Andrew Andrew Beernink Research Scientist - Flow Cytometry Novasite Pharmaceuticals, Inc. 11095 Flintkote San Diego, CA 92121 (858) 638-8584 (858) 597-4943 fax -----Original Message----- From: James Marvin [mailto:jmarvin@flowcity.bsd.uchicago.edu] Sent: Wednesday, December 19, 2001 12:17 PM To: cyto-inbox Subject: [GFP Retention] Hello, We have a client who is trying to sort a fresh water protozoan that expresses GFP. They are very worried about stressing the cells. They have found that stressing these cells causes them to release their GFP and thus show up negative. I was wondering if anybody has determined the minimum concentration of salt that can be used in the sheath fluid that will still hold a charge. Presently we use a 1X PBS solution consisting of NaCl, KCl, Na2HPO4 7H2O, and KH2PO4 Thanx in advance, Marv
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