I am interested in the structure and function of plasmodesmata,
the channels responsible for intercellular transport of ions, metabolites,
signals and viruses in plants. Despite their fundamental importance
in plant development physiology and health, little is known of the
details of the mode of transport through these channels and the
mechanisms used to regulate their permeablity. In order to identify
the macromolecular architecture of plasmodesmata we are using both
direct isolation of plasmodesmatal proteins and immuno-gold cytochemistry
with antibodies to known proteins. The details of their structure
are being probed using high resolution scanning electron microscopy
and freeze-substitution. The function of plasmodesmata is monitored
using either electrophysiological techniques or microinjection of
fluorescently labelled dyes.
The shape of plant cells and tissues is orchestrated by the precise
alignment of inelastic cellulose microfibrils in the cell wall,
which is in turn oriented by the microtubules in the cortex of plant
cells. However, it is not known what controls the orientation of
these cortical microtubules. We are attempting to answer this question,
in particular assessing a possible role for electrical and mechanical
fields.
Plants generate steady electrical fields around themselves which
can be measured with a vibrating probe. We are assessing the hypothesis
that these fields play a central role in the development and maintenance
of polarity and co-ordination in growth of plant tissues by studying
the effects of small applied electric fields on the orientation
of cell expansion and polar auxin transport.
Studying the electric field induced re-orientations of cortical
microtubules have led us to be interested in the detailed mechanism
of this reorientation. We have been studying the details of microtubule
dynamics in living plant cells following microinjection of fluorescently
labelled tubulin. We are also attempting to identify the component
which perceives the electric field and transduces the orienting
signal to the microtubules.
My laboratory is well equipped with a Zeiss confocal scanning laser
microscope, microinjection apparatus and electrophysiological set-ups.
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