Dr Mary Jane Beilby
Senior Lecturer
Group of Plant Membrane Biophysics
School of Physics
The University of New South Wales
SYDNEY 2052
Australia
Personal Website Address: http://www.phys.unsw.edu.au/~mjb/
Email: mjb@newt.phys.unsw.edu.au
The Big Question
I study electrical properties of membranes surrounding living plant cells. Many life processes involve moving ions in and out of the cell. The ionic currents flowing through a multitude of specific transport systems, protein molecules imbedded in the lipid bilayer, show characteristic PD (potential difference) dependencies. Such current-voltage (I/V) curves allow isolation, characterisation and modeling of different transporters. Work has been done on the electrogenic proton pump, unusual K + pump, K + channels, H + /OH - channels, Ca ++ - activated Cl - channels, the action potential, amine uniport, Cl - /2H + symport and mechanosensitive channels. The experiments are performed on giant-celled plants
- characeae (single cylindrical cells up to 1 mm in diameter, several cm long)
- Ventricaria ventricosa (spherical cells up to several cm in diameter)
The size of single cells allows extensive manipulation, such as perfusion of the cell contents with artificial solutions, removal of vacuole or permeabilization of the outer cell membrane. The patch clamp technique is also employed to measure single channel currents in the inner cell membrane, the tonoplast. Despite their size, charophyte cells are excellent models of higher plants, while Ventricaria exhibits unusual survival strategies. I have developed apparatus and refined experimental techniques to work on the large cells. My work has helped to establish the basis of modern plant cell electrophysiology.
The Short-term goals
Since 1995, I have focused the range of topics addressed by my research onto salt-tolerance. The project now has five important interlocking strands:
- ion transporters involved in salt tolerance
- modeling of transporters' electrical characteristics
- characterization of detectors of salt stress, mechano-sensory ion channels
- turgor regulation in an unusual marine organism
- the connections of the mechano-sensory channel proteins to the cell wall
| Group (lab) Members and areas of research
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Mary Beilby , group leader (electrophysiology and modeling)
Virginia Shepherd , Visiting Fellow (electrophysiology, microscopy and imaging)
Alan Walker FAA, Visiting Professor (electrophysiology, ion sensitive electrodes, modeling)
Chris Cherry-Gaedt, Ph. D. Student (ion sensitive electrodes)
Enid Mahomudally , Ph. D. student (co-supervision with UTS: atomic force and electron microscopy)
Past and Current
Year |
Type of grant |
Funding received |
1993 |
ARC Electrophysiology of Plant cells under salinity stress |
16,000 |
1995/97 |
ARC Field effect gating mechanisms in membrane transport proteins: a study of correlation between structure and function (with Coster and Chilcott) |
201,800 |
1995 |
ARC Electrophysiology of Plant cells under salinity stress |
22,000 |
1995 |
Infrastructure NSW (with Coster, Smith) |
9,000 |
1996/98 |
ARC Molecular basis of salt tolerance in alga Lamprothamnium |
151,718 |
1996 |
ARC Patch-clamping the tonoplast membrane of salt-tolerant charopyte Lamprothamnium papulosum |
24,000 |
1997 |
Infrastructure NSW (with Coster, Curmi, Smith and Walker) |
80,000 |
1998 |
ARC : Alternative survival strategy of members of Bryopsidophycae algae |
5,000 |
1999-01 |
ARC: Interaction of extra- and intra-cellular compartments with ion channels involved in turgor regulation in charophyte Lamprothamnium |
102,083 |
1999 |
Infrastructure NSW (with Coster, Smith) |
24,000 |
2000 |
ARC: The electrophysiology and structure of marine alga Ventricaria ventricosa at the time of turgor regulation |
25,000 |
2000 |
Australian Academy of Science Travel grant: Role of mechanosensory ion channels in cell salinity tolerance
(To Dr. Shepherd, Research Associate on Large ARC) |
7,000 |
2000 |
Australian Academy of Sciences Travel Grant to Europe : Turgor regulation in marine alga Ventricaria ventricosa |
6,575 |
2001 |
Small ARC: The mechanism of hypertonic turgor regulation in charophyte Lamprothamnium. ventricosa |
12,465 |
2002 |
VC's strategic development fund Goldstar maintenance award:
Salt stress and tolerance: detectors and effectors
(with Prof. Walker) |
$15,000
+$5,000 from the School |
2003 |
FRG: Role of extracellular matrix and cytoskeleton in plant cell development |
$18,000 |
2003 |
Australian Academy of Science Travel grant: Role of mechanosensory ion channels in cell salinity tolerance
(to Dr. Shepherd) |
$6,000 (6 weeks) |
2004 |
FRG: The role of ion channels, vacuolar compartment and extracellular matrix in plant mechanoperception |
$11,000 |
Applications submitted or planned
ARC Discovery (2005):
- Turgor sensing and transduction
- The virtual charophyte: modeling salt tolerance
| Techniques in the Laboratory
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Currently active
Experimental material: charophytes, Ventricaria or Valonia
- Electrophysiology: computer-controlled voltage clamping, current-voltage (I/V) analysis, impedance measurements (1 - 100 Hz), moving ion sensitive electrodes (TRIFID)
- Compartment manipulation: vacuolar or cytoplasmic perfusion, plasmalemma permeabilization, single membrane constructs, protoplast formation in Ventricaria
- Microscopy: light, fluorescent, confocal, electron and atomic force
- Imaging: film, video, digital techniques
- Modeling: I/V characteristics, time-course analysis
In development
- Moving ion sensitive electrodes (TRIFID)
- Electron and atomic force microscopy
- Pressure probe measurement and pressure clamp
- Collaboration with genetic research
Top three areas of knowledge
- Membrane transport
- Plant electrophysiology
- Electrophysiology of salt tolerance
Top three technical skills
- Voltage-clamping
- Fluorescent microscopy
- Cell compartment manipulation
| Publications - Last 5 Years
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Shepherd VA , Beilby MJ and Bisson MA, 2004, When is a cell not a cell? A theory relating coenocytic structure to the unusual electrophysiology of Ventricaria ventricosa (Valonia ventricosa) Protoplasma, in press
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Bisson MA and Beilby MJ, 2002, Transport systems of Ventricaria ventricosa: Hypotonic and hypertonic turgor regulation. Journal of Membrane Biology 190: 43 -56.
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Shepherd VA , Beilby MJ and Shimmen T (2002), Mechanosensory ion channels in charophyte cells: the response to touch and salinity stress. European Biophysics Journal , 31 : 341 - 355.
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Tyerman SD, Beilby MJ, Whittington J, Juswono U, Newman I and Shabala S ( 2001) Oscillations in proton transport revealed from simultaneous measurements of net current and net proton fluxes from isolated root protoplasts: MIFE meets patch- clamp. Australian Journal of Plant Physiology 28: 591 - 604.
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Shepherd VA , Shimmen T and Beilby MJ (2001) Mechanosensory ion channels in Chara : The influence of cell turgor pressure on touch-activated receptor potentials and action potentials. Australian Journal of Plant Physiology 28: 551 - 566.
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Beilby MJ and Shepherd VA (2001) Modeling the current-voltage characteristics of charophyte membranes: III. K + state of Lamprothamnium . Australian Journal of Plant Physiology 28: 541 - 550.
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Beilby MJ and Shepherd VA , (2001) Modeling the current-voltage of charophyte membranes: II. The Effect of salinity on membranes of Lamprothamnium papulosum. J Membrane Biol., 181: 77 - 89.
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Beilby MJ and Bisson MA, (1999) Transport systems of Ventricaria ventricosa : I/V analysis of both membranes in series as a function of [K + ] o . J Membrane Biol., 171: 63 - 73.
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Shepherd VA and Beilby MJ, (1999) The effect of an extracellular mucilage on the response to osmotic shock in the charophyte alga Lamprothamnium papulosum . J Membrane Biol. 170: 229-242.
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Shepherd, VA, Beilby, MJ and Heslop, D, (1999) Ecophysiology of the hypotonic response in the salt-tolerant charophyte alga Lamprothamnium papulosum . Plant Cell Environ. 22 : 333 - 346.
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Beilby, MJ, Cherry, CA and Shepherd, VA,(1999) Dual turgor regulation response to hypotonic stress in Lamprothamnium papulosum. Plant Cell Environ . 22: 347 - 360
most significant Publications
- Beilby MJ and Coster HGL, 1979, The action potential in Chara corallina: II. Two activation-inactivation transients in voltage clamps of the plasmalemma. Aust. J. Plant Physiol.6: 323-335
- Beilby MJ and Walker NA, 1981, Chloride transport in Chara: I. Kinetics and current-voltage curves for a probable proton symport. J. Exp. Bot.32: 43 - 54
- Beilby MJ and Beilby BN, 1983, Potential dependence of the admittance of Chara plasmalemma. J. Membrane Biol. 74: 229 - 245
- Beilby MJ, 1984, Calcium and plant action potentials. Plant Cell Environ.7: 415-421 (commissioned review)
- Beilby MJ, 1984, Current-voltage characteristics of the proton pump at Chara plasmalemma. I. pH dependence. J. Membrane Biol. 81: 113-125
- Beilby MJ, 1985, Potassium channels at Chara plasmalemma. J. Exp. Bot.36: 228-239
- Beilby MJ and Walker NA, 1996, Modeling the current-voltage characteristics of Chara membranes: I. The Effect of ATP removal and zero turgor. J Membrane Biol.,149: 89-101
- Shepherd VA and Beilby MJ, 1999, The effect of an extracellular mucilage on the response to osmotic shock in the charophyte alga Lamprothamnium papulosum. J Membrane Biol. 170: 229 - 242
- Shepherd VA , Beilby MJ and Shimmen T, 2002, Mechanosensory ion channels in charophyte cells: the response to touch and salinity stress. European Biophysics Journal , 31: 341 – 355
- Shepherd VA , Beilby MJ and Bisson MA, 2004,When is a cell not a cell? A theory relating coenocytic structure to the unusual electrophysiology of Ventricaria ventricosa (Valonia ventricosa) Protoplasma, in print (accepted October 15, 2003)
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