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Hi,

We have been using a prepared diatom slide from Carolina Biological 
as a quick demo for our confocal (Leica SP1).  According to Carolina, 
they stain the mixed diatoms slide "2 different ways and then mix 
them together.  Some of the diatoms are stained with Harris 
hematoxylin and fast green, and others are stained with Harris 
hematoxylin and phloxine. " 

When the sample is illuminated with blue light (488nm), we get very 
little fluorescence.  When the same sample is illuminated with green 
light (543nm), we get very bright fluorescence in the chloroplasts.  
The surprise is that when we illuminate with red light (633nm), we 
get dramatic fluorescence of the cell walls in the far red (about 700 
and beyond). 

Can anyone suggest why we see this long wave fluorescence?

Joel


--
Joel B. Sheffield, Ph.D.
Biology Department, Temple University
1900 North 12th Street
Philadelphia, PA 19122
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(215) 204 8839, fax (215) 204 0486
http://astro.temple.edu/~jbs