NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/bionet/plants/780

Internet Message Format | 1992-12-22 | 3.2 KB

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From: [e-mail] (Edwin Barkdoll)
Newsgroups: bionet.plants
Subject: Re: Plant communication/sensing references
Message-ID: <[e-mail]>
Date: 22 Dec 92 20:22:26 GMT
References: <[e-mail]> <[e-mail]>
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In article <[e-mail]> [e-mail] (Thomas Bjorkman) writes:
>In article <[e-mail]> Edwin Barkdoll, [e-mail]
>writes:
>>    There is no work on action potentials in plants which
>>approaches the depth of that in animals but there is some evidence
>>that the primary ions are K+ and Cl- not K+ and Na+.  Don't have a
>>reference handy but you might look for a review by Simmons (?) in _The
>>New Phytologist_ I think the year is 1982.  There is probably much
>>more recent work that I know nothing about.


>Considering that the patch clamp (mostly used since 1982) is the tool
>that has yielded most of the information about ion channels, this seems
>an exceptionally dated reference.

    Well, the first paper on patch clamping was in 1976 (5?), and
between that paper and the publication of Sakmann and Neher's _Single
Channel Recording in 1983, there were quite a few papers on the
technique.  Nevertheless single channel recording did not start with
patch clamping rather it was predated by the use of black lipid
membranes which was used to characterize properties of the gramicidin
channel, for example.  The _concept_ of a channel (pore) predates both
of these by about half a century.

    The _New Phytologist_ paper is no doubt dated -- even by
standards of technology available at the time I don't recall that it
was particularly strong.  Nevertheless the discussion had not really
reached the level of "channelology", nor is it necessarily relevant.
So far we had simply discussed what ions are involved -- e.g. Na+ and
K+ vs K+ and Cl- -- this is classic biophysics from the 1950's.  The
use of patch clamping, while it has permmitted amazing things, has not
led to a significant revision of the belief of which ions are involved
in the action potential and _that_ is the issue (or part of the issue)
which started the discussion: in certain plants like mimosa is "signal
an action potential, just like in animal neurons"?  Do you know of any
quantitative papers on the ions underlying the plant action potential?

>  The patch clamp has been used very
>heavily on plants: Hedrich and Neher put it to work on plant cells right
>away.

    Yes, but did they put it to work on plant cells which generate
action potentials as part of their normal behavior?

>So far there are several classes of channels that have been
>characterised.  The main one is the inward rectifying potassium channel.
>If I remeber right, it has a small sodium conductance, but that is
>irrelevant given the very low sodium concentrations.

    The discussion has been about action potentials in plants.
Are these data recorded from AP producing plant membranes?

Edwin Barkdoll
[e-mail]
[e-mail]