identification of different strains in large cultures

Thu Jan 18 16:38:02 EST 1996

here in the lab of Solange Brault (UMass/Boston) we are looking at the
differential effects of various harvesting pressures on populations of
different strains of C. elegans.  We can then hopefully develop population
model which can be used to prevent overharvesting of, say, certain fish
populations.  To this end, I am posting a few questions.  A response to any
or all of these would be very helpful; this lab is just starting out, and we
need to determine what sort of supplies are most important.

1.  Is there a way to determine population size of large cultures without
having to count thousands of worms by eye?  It might be easy enough to do 
this when the culture consists of only one strain, but in the future we are
likely going need a way of determining relative numbers of two or more strains
within the same culture (competition experiments).  My notion is this:  to find
genetic markers specific to various strains, extract the DNA from an entire
culture, and screen for relative amounts of each marker.  Since we just
got a new phosphoimager here at UMass, it would be nice use it.  Does this
seem plausible?  Are there enough known strain-specific markers or mutations
to be able to do this kind of thing?  I can think of a few problems with
this idea, but I think they should be able to be ironed out.

2.  Along the same lines:  is it possible to screen for different strains
by somehow simply labelling the exterior cuticle?  Better yet, can this be 
done without killing that animals?  Seems unlikely, but thought I'd ask.

3.  Any other idea on how to determine relative numbers of different strains
in the same culture?

4.  It's possible that we may someday need to do parasity-host or predator-prey
types of experiments.  What are some of the worms' natural enemies, and does
anyone have any on hand?  I imagine it's the type of thing most people don't
want hanging aroung in their labs...

5.  What are some other foods the worms eat (different bacterial strains,
etc.), and what other substrates do they like to live on?  

I'll have more questions, I'm sure.  The first one above is the most important.

Evan Mulligan    			phone: (617) 287-6585
Biology Dept., UMass/Boston             email: mulligan at
100 Morrissey Blvd.
Boston, MA  02125

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