cell wall question

Elizabeth Harris chlamy at duke.edu
Mon Mar 17 10:20:26 EST 2003

Forwarded from the chlamyteach list - can anyone here answer her question?

To whom that knows well this algae,

I am measuring the adsorption (and internalization)of Cd to the cell
wall of Chlamydomonas in relationship with time, through EDTA-
extraction methods. It is known from literature that EDTA can complex
very quickly (1 min contact time) all metals that are adsorbed on the
algal surface (probably to COO- groups found to the cell wall of
microorganisms). It is known also (from literature) that adsorption
for a certain metal concentration normally is a rapid process (less
than one minute) and constant with time. But for Chlamydomonas I am
measuring an increasing of the Cd adsorption with time, which is very
surprising. And I am analyzing different hypothesis for this
observation such as EDTA-extraction kinetic, EDTA-Cd- complex
diffusion to the cell wall of this alga, and other physicochemical
parameters. Another hypothesis needs the helps of biologists that
know this alga.

Is it possible that this alga produces continuously cell wall
material that remains attached to the existent cell wall? If it is
so, I can explain the increasing of Cd adsorbed to the cell wall even
in the short period of 25 minutes. If not I have really to look for
some chemical kinetic explanations. Cell wall of this alga, from my
experience, is really different from other green algae!!

I am not asking for the production of exudas that are release to the
solution by this alga in case of stress.

Thank you fror your attention


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