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Cd/H abstract...some comments

Tue Feb 23 22:50:20 EST 1993

I received these comments from Thomas Bjorkman which I responded to. I
though I would post them to the group as well just to keep things going.
Sorry for the repetition Thomas.

======================================================================== 48

Date:         Tue, 23 Feb 93 22:12:02 EST
From:         david salt <BOTSALT at VM.UoGuelph.CA>
Subject:      Re: Cd/H antiport
To:           Thomas Bjorkman <Thomas_Bjorkman at cornell.edu>
In-Reply-To:  Your message of 23 Feb 93 17:21:55 GMT

Thanks for the reply, I am glad you like the idea of posting my abstract,
why not have a mini electronic meeting as well as the real thing.

>In article <9302190517.AA21702 at net.bio.net> david salt,
>So you are offering your abstract for folks on the net to have a swing at
>it.  Interesting idea.
>1. Is this antiport specifically a cadmium transporter or is it a general
>heavy-metal transporter that drives Cd accumulation among others.

A very good question. The short answer is I don't know YET. At the moment
I am looking at copper transport and people in Wagners lab are looking at
nickle transport but the question of specificity is still wide open. Simple
competition experiments will not tell you much as results are complicated
by competition for the same DpH. A close look at the kinetics of transport
in the presence of other metal ions may reveal something, though this await
me having some time. Cd may well be being transport by the same porter that
transports Ca at this membrane...the km's are about the same but Ca has a
Vmax about double that of Cd.

>2. I understand why one would study transport proteins in oats--the
>techniques are worked out well.  How effective are oats as heavy metal
>accumulators?  And if you want to stretch it further,  amy comments on
>this research in relation to bioremediation?

Oats accumulate Cd in their roots like most grasses (exact figures are in the
lab......will post tomorrow). Most plants accumulate metals to some extent.
Exclusion as a mechanism of metal resistance is not significant. Bioremediation
.......and interesting question. If the gene for this Cd/H antiporter could
be isolated then it might be possible to create a transgentic which
over expresses the protein. It would be important to target the protein into
the tonoplast of leaf cells if the metal is to be removed from the soil by
harvesting the leaves. Another possibility may be to use the porter to
perhaps load the xylem with Cd there by increase foliar accumulation.
Nothing is really know about the way metals are moved in plants so there
is a long way to go yet.

David Salt

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