Gerhard Nebe-v.Caron Unilever Research, Colworth Lab.
Sharnbrook, Beds. GB-MK44 1LQ Tel.:+44(0)1234 222066
Fax.: 222344 Gerhard.Nebe-von-Caron@unilever.com
______________________________ Reply Separator
_________________________________ Subject: Re: Membrane polarization
Author: t-delohery@ski.mskcc.org at INTERNET Date: 03/05/96 00:30
> We are trying to measure membrane polarization by flow
cytometry >using the probe TMA-DPH. So far we've had no luck. Is
anyone else doing >this? If so, can you tell me which probes you have
found most successful >and the specs on your polarization filters. We
are using a FACS Vantage >and "hand-me-down" polarizers (no specs).
The polarizers we're using are >yellow, and we're wondering if we were
just cutting out most of the >TMA-DPH emitted signal.
Besides your filters you also have to determine the plane of
polarization of your laser at the stream intercept. While the beam is
vertically polarized as it exits the laser, it may be in any direction
after passing through all the prisms on the Vantage. It may not even
be polarized.
Fluorescence polarization measurments depend on "photoselection" -
selectively exciting molecules whose absorption dipole moments are
parallel to plane of polarization of the exciting light, ie, the
laser. Molecular motion during the excited state lifetime determines
the degree of fluorescence polarization. A freely moving fluorochrome
can reorient to all possible planes during the excited state lifetime
and no fluorescence polarization is observed. An immobilized
fluorochrome at low temperature can yield highly polarized
fluorescence.
It's also extremely convenient to be able to change the lasers'
polarization for calibration purposes.
td i've been waiting years to say that.
-- ============================================================================== Thomas Delohery | Internet: t-delohery@ski.mskcc.org Manager, Flow Cytometry Core Facility | Phone: (212) 639-8729 Memorial Sloan-Kettering Cancer Center | Fax: (212) 794-4019 1275 York Ave. Box 98 | New York, NY 10021 | ==============================================================================
CD-ROM Vol 3 was produced by Monica M. Shively and other staff at the
Purdue University Cytometry Laboratories and distributed free of charge
as an educational service to the cytometry community.
If you have any comments please direct them to
Dr. J. Paul Robinson, Professor & Director,
PUCL, Purdue University, West Lafayette, IN 47907.
Phone: (765)-494-0757;
FAX(765) 494-0517;
Web