Separating motile from nonmotile cells (fwd)

Elizabeth Harris chlamy at duke.edu
Mon Mar 17 14:03:39 EST 2003

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
porous medium.

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
>  technique?
>  Many thanks in advance,
>  Doug
>  ---

More information about the Chlamy mailing list

Send comments to us at biosci-help [At] net.bio.net