[Histonet] dapi and GFP problem problem

Caroline Bass cbass <@t> bidmc.harvard.edu
Wed Jun 7 13:28:16 CDT 2006

If you mount the unfixed cells do you have any special  
considerations?  In other words do you have to view them right away,  
will the slide last, etc?



On Jun 7, 2006, at 11:53 AM, Gayle Callis wrote:

> You are probably experiencing autofluorescence induced the aldehyde  
> fixation.  You can try Molecular Probes Image - IT image enhancer  
> that is supposed to get rid of the autofluorescence.
> It is important to note that Prolong Gold antifade is supposed to  
> sit overnight and not sealed with fingernail polish, by curing  
> overnight, this mounting media, the refractive index gradually  
> increses as it cures.   This may be why the control appeared black  
> just after you mounted the coverslip.
> You can tell the CLSM to get rid of the autofluorescence too, some  
> might consider this cheating, but it can be done.   What may be  
> better is to NOT fix the cells, and view them with CLSM - GFP is  
> designed for use with living cells and you may find the GFP is even  
> brighter.  The Clontech manual called Living Colours tells you a  
> great deal about handling cells, etc with GFP.  That manual can be  
> accessed online in pdf form.
> Unfixed cells can also be mounted with Prolong Gold antifade w/  
> DAPI - we do this with unfixed frozen sections to avoid all  
> fixation or you can add a DAPI solution to the unfixed cells, and  
> view them without coverslipping or coverslipping with PBS.
>    At 11:13 PM 6/6/2006, you wrote:
>> Hey,
>> I have a GFP labeled g-protein coupled receptor that I am expressing
>> in HEK 293 cells.  I cultured the cells on collagen coated glass
>> chamber slides, fixed the cells with 4% PFA, and then coverslipped
>> with Prolong Gold antifade containing dapi.  Before I coverslipped I
>> checked the slide on a standard fluorescent microscope to make sure
>> everything was expressing correctly.  My transduced cells had a nice
>> signal and my control was black.  The day after coverslipping my
>> control cells showed a noticeable green signal, not quite a bright as
>> the GFP cells, but it is apparent.  I took confocal pics and there
>> was clearly some green in my control cells.
>> Does anyone have a suggestions?  I figure one of two things
>> happened.  Either some cells slid around when I pressed down on the
>> coverslip or maybe I am getting some sort of bleedthrough.  I am not
>> very good with the confocal yet, so I don't know if I did something
>> wrong here.  Does anyone have a good protocol for growing 293 cells
>> on glass slides?  I have heard there of some super adherent clones of
>> 293 that I would like to try, although I haven't found a source for
>> them.
>> Any and all suggestions would be appreciated.
>> Thanks,
>> Caroline
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> Gayle Callis
> Research Histopathology Supervisor
> Veterinary Molecular Biology
> Montana State University - Bozeman
> PO Box 173610
> Bozeman MT 59717-3610
> 406 994-6367
> 406 994-4303 (FAX)

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