I'll bet the rhodamine spheres were made of polystyrene, which are 
VERY soluble in xylene. Been there, done that, bought the shirt!
Greg

Date sent:      	Fri, 05 Apr 2002 01:03:59 -0500
From:           	"J. A. Kiernan" 
Subject:        	Re: Cover flourescence ?
To:             	"Dianne Holmes (by way of Histonet)" 
Copies to:      	HistoNet@pathology.swmed.edu

> "Dianne Holmes (by way of Histonet)" wrote:
> > 
> > We are using Rhodamine microspheres to label rat brains.  Got great
> > labelling - - coverslipped with DPX and lost half of the signals!!!
> > HELP!  Is it the xylene?  Any suggestions ...
> 
> Xylene and DPX do not abolish fluorescence of rhodamine-labelled
> proteins, which are denatured (made permanently insoluble) when a
> apecimen passes through a chemically unreactive fixative (alcohol 
> etc). You are probably correct in your assumption that a solvent 
> dissolved the stuff the microspheres were made of. Do you know 
> what it was? If you don't, why did you use it? Even if there is
> trade secrecy about the microspheres, their maker must surely
> issue some information about solvents to avoid.
> -- 
> -------------------------
> John A. Kiernan
> Department of Anatomy and Cell Biology
> The University of Western Ontario
> London,   Canada   N6A 5C1
>    kiernan@uwo.ca
>    http://publish.uwo.ca/~jkiernan/
> 


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Greg Dobbin
Pathology Lab
Atlantic Veterinary College, U.P.E.I.
550 University Ave.
Charlottetown, P.E.I.
Canada,  C1A 4P3
Phone: (902)566-0744
Fax: (902)566-0851