Agriculture Reference
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Fig. 25.8. Pattern of AK isozymes after chromatography on DEAE-cellulose. Growing condi-
tions as in Fig. 25.7, however, with 0.3 M glucose application. There is a dramatic increase of
AK I abundance in mitochondria as compared with that in untreated plants (c.f. vegetative
pattern, control, Fig. 25.6). The abundance of AK IV in the nucleus increased over the
detection limit (Wagner et al. 1983)
The electrodes essentially cover, i.e. surround, the stem axis or the peti-
oles of leaves completely. This geometry of contact between surface elec-
trodes and the plant tissue assures, in contrast to intracellular penetrating
electrodes, that the potential changes to be recorded are not due to single
cells but that they represent the electrochemical activity of the whole area of
contact of the electrode with the plant tissue in question. For this reason the
potentials recorded with surface electrodes are named “surface sum poten-
tial”or“surfacepotential”.Toreducetheresistancebetweentheplantand
the electrode surface, the contact surfaces between electrode and plant can
be covered with a thin contact gel like one used in medicine, e.g. for record-
ing electroencephalograms. The analysis or evaluation of the recorded
changes in membrane potential are performed on the basis of the frequency,
the temporal distribution and/or the direction of propagation of action po-
tentials. In long-term experiments, using bipolar surface electrodes specific
changes in the direction of propagation of action potentials in response to
different flower-inducing and non-flower-inducing photoperiods could be
observed. The recordings have shown that the propagation of action poten-
tials along the stem axis of the model plants under investigation, C . rubrum
 
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