Subject: Mimosa expert

From: [email-masked]
Date: 20 Oct 1995 16:56:14 +0100

It seems indeed that the potassium pumps are involved in the swelling and
shrinking of the motor cells. When I wrote "activating and deactivating" of
the potassium pumps I did not mean turning them on and off but simply increa-
sing and decreasing their activity. A basal pumping of K+ will be always on
since K+/H+ pumping is necessary for plant cell life (as K+/Na+ is necessary
for animal cell life).An increase of K+ concentr.inside the cells (swelling of
the motor cells) can be produced either by increasing active K+ pumping-in or
decreasing K+ release (probably passive) through the channels. I think a pos-
sible mechanism for motor cells could be increase of K+ into the cells through
active pumping during swelling and increase of passive release through channels
during shrinking, but combination of these and reverse processes are quite pos-
sible. In any case what at present is scarcely known in the rapid movement of
leaves ia what happen between the reception of the signal (light, touching,
biological clock) by the cells and the movement of potassium ions, e.g. which
are the elements of the signal transduction chain. But scientists are working
at it and soon we will have a lot of new things to tell to curious people.

A nice weekend to all plant lovers !

Fernando from Rome