Beta-glucan fluorescence?

[Spurmanis, Aleks]

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Hi all,

 

One of our researchers has been attempting to use a GFP-based reporter gene microtitre plate assay to test the efficacy of a variety of bioactive test compounds.  They've had no problem with the assay itself (controls and other compounds provide anticipated readouts).  They did however notice that one of these test compounds, an 80% pure beta-glucan suspension extracted from an undisclosed yeast source, displayed significant concentration-dependent fluorescence that overlapped the emission range of GFP even when measured in the absence of cells.   So far we haven't been able to find any reference in the literature to suggest that fungal beta-glucans typically exhibit significant fluorescence in this range.  On the contrary, beta-glucans more commonly seem to require fluorescent labeling to be seen (e.g., Toyotome et al, Microbial Pathogenesis (2008); 44(2) 141-150).  The closest that I've come to an answer is a reference suggesting that polyphenolics, chitin, or plasmalemma components from the cell walls of mycorrhizal fungi could be a potential source of green/yellow fluorescence (Dreyer et al, mycological  research 110 (2006) 887– 897).  Has anyone run into this situation and/or have any additional references to suggest why this yeast extract could be fluorescing? 

 

Thanks

 

Aleks Spurmanis

Fluorescence Core Facility Manager

National Research Council of Canada

Institute for Nutrisciences and Health

550 University Avenue INH Building

Room 324

Charlottetown PE

C1A 4P3

tel:  (902)- 566-7557

fax: (902) - 367-7539

e-mail:  [hidden email]

 

 

 

[Mayandi Sivaguru]

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Aleks, In my experience, partially pure cell wall extracts might have
inherent autofluorescence from lignins and phenolic substances, you can
try quench this autofluorescence by treating the samples with 0.1%
toluidine blue in PBS.
Shiv

> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> Hi all,
>
> One of our researchers has been attempting to use a GFP-based reporter
> gene microtitre plate assay to test the efficacy of a variety of
> bioactive test compounds.  They've had no problem with the assay itself
> (controls and other compounds provide anticipated readouts).  They did
> however notice that one of these test compounds, an 80% pure beta-glucan
> suspension extracted from an undisclosed yeast source, displayed
> significant concentration-dependent fluorescence that overlapped the
> emission range of GFP even when measured in the absence of cells.   So
> far we haven't been able to find any reference in the literature to
> suggest that fungal beta-glucans typically exhibit significant
> fluorescence in this range.  On the contrary, beta-glucans more commonly
> seem to require fluorescent labeling to be seen (e.g., Toyotome et al,
> Microbial Pathogenesis (2008); 44(2) 141-150).  The closest that I've
> come to an answer is a reference suggesting that polyphenolics, chitin,
> or plasmalemma components from the cell walls of mycorrhizal fungi could
> be a potential source of green/yellow fluorescence (Dreyer et al,
> mycological  research 110 (2006) 887- 897).  Has anyone run into this
> situation and/or have any additional references to suggest why this
> yeast extract could be fluorescing?
>
> Thanks
>
> Aleks Spurmanis
> Fluorescence Core Facility Manager
> National Research Council of Canada
> Institute for Nutrisciences and Health
> 550 University Avenue INH Building
> Room 324
> Charlottetown PE
> C1A 4P3
> tel:  (902)- 566-7557
> fax: (902) - 367-7539
> e-mail:  [hidden email]
>
>
>
>