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Aggregation in Chlamy liquid cultures

Fri Mar 26 11:13:23 EST 1999

Dear netters,

a couple of weeks ago, I asked what was known about the determinism of the
aggregative behaviour that is observed in some Chlamydomonas strains and has
(often negative) practical implications. I think this question might of
interest to the community so I post back a summary of the various responses
I received. Nevertheless, it appears that the problem is still open...

"The most common origin of aggregates is failure for the cells to hatch out
of the mother cell wall after division.  This is pretty common, and is
usually strain-dependent although there are other possible causes. It is
often seen in auxotrophic or acetate-requiring mutants of C.  reinhardtii,
as well as in the mt+ strain of C. smithii (CC-1373 and its equivalents).
Paralyzed, bald, and short-flagellar mutants also often show the same

Different culture conditions can determine how soon after mitosis the
original cell wall breaks down. If it takes a long time, you can get 2, 4,
8, or 16 daughter cells still enclosed in the original mother-cell wall. For
strains with a high susceptibility to this, there does not seem to be a
standard satisfactory cure in terms of modification of culture conditions,
although adding some autolysin to the medium might take care of it... Does
anyone else have any suggestions?

Another kind of aggregation results from slightly sticky flagella. There is
a gene called agg-1 that seems to influence this behavior."

Thanks to all contributors,
Laurent Cournac
Laboratoire d'Ecophysiologie de la Photosynthèse
DEVM, Bat. 161
CEA, Centre de Cadarache
13108 Saint Paul Lez Durance Cedex
Tel : (33) 4 42 25 43 66
Fax : (33) 4 42 25 62 65
Email : laurent.cournac at cea.fr <mailto:laurent.cournac at cea.fr>

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