Date: Mon, 17 Mar 2003 11:54:30 -0700 (MST)
From: John Kessler <kessler at physics.arizona.edu>
I described this method in
Progress in Phycological Research, vol 4, Round&Chapman eds, Biopress 1986
257-307, see especially pp 286, 287. It's also written up in
Applied Phycology Forum, 1,2 1984
Chlamy swims upward, on average, especially in the dark. If re-mixing
via Rayleigh-Taylor instability and gyrotactic streamers is prevented,
you can easily separate swimming cells from other stuff. Re-mixing can be
prevented by delaying onset of the hydrodynamic instability with a
Put the culture in a conical flask (Erlenmeyer) up to the neck, or
into a straight culture tube, about an inch from the top. Put a
cotton plug (WETTING-type cotton wool) just barely touching, or not
quite touching the meniscus, leaving a space, say 1/2 inch above it.
Then slowly pour fresh clear culture medium, whatever you are using,
e.g. Bold's Basal, on top of the cotton ( which should stay in place,
not slip down... ) until the flask or culture tube is filled ~to the
top. You should now have green fluid below, a cotton plug saturated
with clean media, and a short section of clear media above the cotton.
Depending on the species of Chlamy, most of the swimming cells will
swim into that formerly clear space, making it intensely green. You
can harvest with a pasteur pipette. For many species it works better
and faster if you put the whole shebang, after doing the above, into
a dark place.. e.g. covering it with an old coffee can. You can get
pretty good accumulation within an hour or two, overnight, etc .
It is important not to have the cotton wool too compact, so that the
algal cells have room to swim through.. but not too loose, or it will
not do its job of preventing the gravitational fluid instability.
Don't give up after the first time!
If the cotton wool sticks up above the final liquid level, you will
find an intense accumulation af algae in that region, to which they
will have swum up through the capillary layers of media that surround
the cotton fibres. The non swimmers and other detritus will stay
behind, below the cotton zone, together with a few swimming cells
bent on demonstrating that nothing is perfect.
Good luck, let me know/call me if there are problems. If successful, you
might post it.
Cheers, John K
Prof. John O. Kessler
Physics dept, Bldg 81
University of Arizona
Tucson, AZ 85721, USA
520 621 2797 office
621 4721 fax
On Mon, 17 Mar 2003, Douglas Benjamin Weibel wrote:
> I am trying to find a simple technique for separating large numbers of motile
> Chlamy from non-motile cells. Does anyone have any information on such a
>> Many thanks in advance,