Counting cells in the field?

Honorio Americo Campos hcampos at SHADDAM.USB.VE
Thu Sep 15 13:22:23 EST 1994


> 
> Hi there,
> 
> I'm the midst of conducting a taxonomic survey of the lithic algae of the 
> Niagara Escarpment with the Cliff Ecology Research Group here at Guelph and 
> would like some advice on something that may just be impossible.
> The taxonomy aspect of the project is going well, so we're beginning to 
> plan biomass and physiology experiments for next year (or two).  We were 
> wondering if anybody out there knows of an accurate or reasonably reliable 
> way to measure the comparative abundance of the components of a 
> micro-community (i.e. 40% Pseudopleurococcus sp., 30% Nostoc muscorum, 
> 10% Gloeocapsa alpina, etc.).  
> These numbers may come in handy when we start measuring photosynthesis, 
> etc.  You can't just count them under the microscope, can you?  This 
> seems a fairly goofy way to do it, but it's what we seem to be stuck with.  
> Any ideas are much appreciated.  
> 
> Thanks in advance.
> 
> John Gerrath,
> Research Technician,
> University of Guelph.
> jagerrat at uoguelph.ca
> 
> 
As goofy as it might seems, I wonder if 
there is something else you can do, that is 
an interesting question... 
Having only available a direct microscope
counting method available, your problem seems
to be mainly an statistical one, that is, how
you sample in the  field, how many samples you have,
how many replicates per sample... a lot of
counting, I am afraid.  I am curious, in that
kind of environment you have little diversity?
Because if you have a lot of different bugs around
your task is real hard to acomplish.

If you have the probes, there is a methodology
developed by people at the U. of Tennessee for 
in situ detection of bacteria, one hybridizes
the DNA probe (which has a fluorescent dye attached)
and then developes it.  I guess (I guess) this method
is or can be made quantitative.
If there are specific antibodies for the different
bugs, something can be done, too.
And there is quantitative PCR, which many people claim
is not so quantitative...

But, as usual with these bugs, one does not count
with the luxuries E. coli people enjoy...
(one does not get spoiled, tough...) 

Please, let me know if you find a better way!!!

Miguel




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