Dr Helen R. Irving
Senior Lecturer
Department of Pharmaceutical Biology & Pharmacology
Victorian College of Pharmacy
Monash University
381 Royal Parade
Parkville VIC 3052
Australia

Personal Website Address:
Email: Helen.Irving@vcp.monash.edu.au

Research Aims

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The Big Question

My research has focused on signal transduction mechanisms in both the plant and animal kingdoms. I am particularly interested in understanding plant signalling networks and how they interconnect and allow plants to rapidly respond to and survive environmental stresses, such as salinity and drought. For plants to survive such stresses, they must respond rapidly and in a co-ordinated fashion to regulate their growth and development. This in turn will affect how they absorb and direct their nutrients. How do plants do it? How do they perceive the signals and then how do the signalling networks work to allow them to respond?

The Short-term goals

1. Our previous research has demonstrated the presence and biological activity of an interesting novel and promising class of small proteins called: P lant N atriuretic P eptides (PNPs). Most importantly, PNPs are an example of a systemic protein hormone that modulates plant water and solute balance and elongation growth. We predict that PNPs play a major role in plant responses to drought and salinity stresses. Our aim is to characterize the function of PNPs at molecular and cellular levels to elucidate their signaling interactions, particularly in response to drought and saline stresses. Hence, we are planning the molecular and cellular characterization of the two Arabidopsis PNPs, AtPNP-A and AtPNP-B. We will examine AtPNP-A and AtPNP-B expression at the cellular and tissue level to determine the effect of environmental stresses using molecular and cell biological techniques. Our preliminary knock-out mutant data suggests that AtPNP-A, at least, is necessary for normal plant growth and development as our plants show a stunted phenotype. We will follow up these experiments to establish the functional role(s) of PNPs.

2. Since it is critical for plants to respond promptly to environmental stresses to survive, plants have developed a complex network of signaling pathways involving signals from “classical” plant hormones that are linked to environmental responses. It is highly probable that PNPs, which are up-regulated by environmental stresses, modulate and interact with these pathways. Of the classical hormones, abscisic acid ( ABA ) is recognized as the “stress” hormone with major roles in regulating plant water status in response to environmental stresses. To investigate their interaction at a molecular level, we will develop a transient expression system in Arabidopsis protoplasts to study the signaling processes activated by PNPs and their interdependence with ABA .

3. Plant growth is often limited by soil nitrogen and this has resulted in the evolution of symbiotic interactions between plants and prokaryotes. Rhizobia are soil bacteria that interact symbiotically with legumes to form nitrogen-fixing nodules in nitrate poor soils. Rhizobia excrete Nod ulation (Nod) factors that initiate nodule formation in the host plant; root hairs are particularly responsive to Nod factors. Critical to optimizing this interaction is understanding the cellular signaling events that occur in this dynamic interaction at both a molecular and biological ( in planta ) level. We developed a collaborative project to investigate the early host responses of legume root hairs to Nod factors. We have identified G-proteins, phospholipase C and phosphatidylinositol 3 phosphate kinases as key components of these responses. We plan to investigate how these signaling components interact with other aspects of the cellular machinery to initiate the host symbiotic responses

We operate an active research laboratory (PC2) with molecular, biochemical and cell biology (including plant growth cabinets) equipment and facilities. Dr Irving is a co-ordinator of the “Centre for Pre-Clinical Drug Candidate Selection” that is funded in the Department of Pharmaceutical Biology & Pharmacology. Thus fluorescent microscopes and imaging software, real-time PCR and POLARstar galaxy plate reader are available for use in these projects.

 

General Research Interests

• Signal transduction mechanisms in plant and animal tissues
• Molecular and functional distribution of receptors
• Novel analogues of animal peptide hormones

Current Research Areas

• Role of natriuretic peptide analogues in plants and their effect on animal tissues
• Signal transduction mechanisms in plant symbiotic interactions
• Distribution and function of 5-HT receptors

Group (lab) Members and areas of research

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Prof Chris Gehring ( University of Western Cape ) and Dr David Cahill ( Deakin University ) are partner investigators in my research on Plant Natriuretic Peptides

Ms Marilyn Kelly – Nod factor signalling

Ms Nav Chetty – 5-HT 3 receptors (animals)

Ms Nathalie Tochon-Danguy – 5-HT 4 receptors (animals)

Research Aims Funding

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Current

Pouton (CI), Coupar (CI), Irving (CI) & Taylor (CI), “Centre for Pre-Clinical Drug Candidate Selection”, New Research Area - Monash Research Fund

Applications submitted or planned

Irving (CI), Cahill (CI) & Gehring (PI), “Plant Protein Signaling Networks”

Coupar (CI), Irving (CI) & Desmond (CI), “Human Receptor Isoforms: Potential for minimizing drug side effects”

Techniques in the Laboratory

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Currently active:

Nested RT-PCR, Real time quantitative PCR, Co-immunoprecipitation, cGMP assays, GTP binding, root hair deformation assays, protein expression, pharmacological binding and cell cultures

In development:

Transient protoplast expression systems

Main areas of expertise

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Top three areas of knowledge

1. Signal transduction mechanisms, particularly in relation to abscisic acid ( ABA ) and plant natriuretic peptides (PNPs)
2. Rhizobia – legume symbiosis, particularly in relation to host responses to Nod factors
3. Plant Natriuretic Peptides – function and sigalling pathways

Top three technical skills

1. Basic biochemical and molecular assays
2. Imaging intracellular signalling responses
3. Real time quantitative PCR

Significant contributions to this research field

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Dr Irving is involved as a team leader in two major research areas, namely: “Novel signal transduction pathways in plants” and “Molecular characterisation of mammalian receptors”. These two areas reflect an established interest in novel signalling pathways that has existed throughout her research career. Moreover, significant contributions have been made in both mammalian and plant signal transduction fields (e.g. Irving and Exton 1987 J Biol Chem 262 : 3440-3; Irving et al. 1992 Proc Natl Acad Sci USA 89 : 1790-4).

Dr Irving's fundamental training is in biochemistry and her experience and contribution to plant physiology and signalling processes, in particular, is both consistent and long-standing (e.g. Irving et al . 1992; Irving et al . 2000). Her work has focussed on understanding the roles of the second messengers Ca 2+ , pH i and cGMP in plant responses and, in particular, drought and salinity stress responses. A major area of study has involved the underlying signalling mechanisms employed by the drought-indicating hormone, abscisic acid ( ABA ). In collaboration with Dr Gehring and Prof Parish at La Trobe University, she showed that the ABA signal was in part mediated by increases in intracellular pH (Gehring, Irving & Parish 1990 Proc Natl Acad Sci USA 87 : 9645-9; Irving et al . 1992). Also her work was among the first to implicate heterotrimeric G-proteins in the ABA signalling pathway (Irving 1998 Aust J Plant Physiol 25 : 539-46). She played a significant role in identifying the plant natriuretic peptide (PNP) gene family (Ludidi et al. 2002 J Mol Evol 54 : 587-94) and prosecuting the studies into signalling networks employed by PNPs (e.g. Pharmawati et al . 1998 Plant Sci 137 : 107-15; 2001 Plant Physiol Biochem 39 :385-94). This work has provided evidence that transient increases in intracellular cGMP mediate, at least part, of PNP signal. Our recent finding that PNPs are up-regulated in response to drought and salinity (Rafudeen et al. 2003 Physiol Planta 119 : 554-62) have led her to examine the interactions between PNPs and ABA signalling networks.

Other evidence of impact and contributions to the field

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Other measures of research success include invitations to undertake external research-related activities where Dr Irving contributes to the broader scientific community in several ways. For example, she is actively involved in reviewing manuscripts for various journals, grant applications and examining theses (Masters and PhD) in her general areas of expertise in Plant Physiology and Biochemistry.

She was an active member of the ComBio2003 Committee where she represented the Australian Society of Plant Scientists (ASPS) co-ordinating the Plant Growth and Development stream and also chaired the Plant Hormones and Signal Transduction symposia. She is an ordinary partner of the Phaseomics Global Initiative ( http://www.phaseolus.net/ ). Currently Dr Irving is co-ordinating editor of Phytogen; the newsletter of ASPS.

Any aspects of career and opportunities for research that are relevant to assessment and have not been detailed elsewhere

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Despite receiving only limited funding for the last few years, significant contributions have been made to understanding signalling pathways in plants During the last 5 years, 22 presentations have been made at national and international conferences and this work is currently published in peer-reviewed journals (11 papers and 2 reviews), submitted (1 paper) and being prepared for publication (a further 5 papers). Of this work, over half has been directly concerned with investigations into plant physiology with an emphasis on novel signalling pathways. The remainder is concerned with her other major research interest, characterisation of vertebrate receptor signalling systems. This is also reflected in her role as a co-ordinator of the Centre for Pre-Clinical Drug Candidate Selection established in 2002 with seed funding from Monash Research Fund. Currently, she is supervising two PhD students and a post-doctoral fellow.

Publications – last 5 Years

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• Rafudeen, S., Gxaba, G., Makgoke, G., Bradley, G., Pironcheva, G., Raitt, L., Irving, H. and Gehring, C.  (2003)  A role for plant natriuretic peptide immuno-analogues in NaCl and drought stress responses. Physiologia Plantarum 119 : 554-562.

• Gehring , C.A. and Irving, H.R .  (2003)  Natriuretic peptides – a class of heterologous molecules in plants. Molecules in focus. International Journal of Biochemistry & Cell Biology 35: 1318–1322.

• Liu, H., Coupar, I.M. and Irving , H.R .  (2003)  Effects of some antidepressant drugs on tryptaminergic response of the rat small intestine. Pharmacology 69 : 88–92.

• Maryani, M.M., Morse, M.V., Bradley, G ., Irving, H.R., Cahill, D.M. and Gehring, C.A .  (2003)  In situ localisation associates biologically active plant natriuretic peptide immuno-analogues with conductive tissue and stomata. Journal of Experimental Botany 54: 1553-1564.

• Kelly, M.N. and Irving , H.R.  (2003)  Nod factors activate both heterotrimeric and monomeric G-proteins in Vigna unguiculata (L.) Walp.  Planta 216 : 674-685.

• Ludidi, N.N., Heazlewood, J.L., Seoighe, C.J, Irving, H.R. and Gehring , C.A . (2002) Expansin-like molecules: Novel functions derived from common domains. Journal of Molecular Evolution 54 : 587-594.

• Liu H., Irving H.R. and Coupar I.M . (2001) Expression patterns of 5-HT 7 receptor isoforms in the rat digestive tract. Life Sciences 69 : 2467-2475.

• Kelly M.N. and Irving H.R . (2001) Nod factors stimulate plasma membrane delimited phospholipase C activity in vitro. Physiologia Plantarum 113 : 461-468.

• Pharmawati M., Maryani M.M., Nikolakopoulos T., Gehring C.A. and Irving H.R . (2001) Cyclic GMP modulates stomatal opening induced by natriuretic peptides and immunoreactive analogues in Vicia faba. Plant Physiology and Biochemistry 39 : 385-394.

• Darroch S.A., Irving H.R. and Mitchelson F.J . (2000) Characterisation of muscarinic receptor subtypes in avian smooth muscle. European Journal of Pharmacology 402 : 161-169.

• Irving H.R., Boukli N.M. , Kelly M.N. and Broughton W.J . (2000) Nod-factors in symbiotic development of root hairs. In " Root Hairs: Cell and Molecular Biology " (editors: R.W. Ridge and A.M. Emons) Berlin Springer-Verlag pp 241-265.

• Suwastika, I.N., Toop, T., Irving, H.R. and Gehring , C.A . (2000) In situ and in vitro binding of natriuretic peptide hormones in Tradescantia multiflora. Plant Biology 2 : 1-3.

• Irving, H.R., Dyson, G., McConchie, R., Parish, R.W., and Gehring , C.A . (1999) Effects of exogenously applied jasmonates on growth and intracellular pH in maize coleoptile segments. Journal of Plant Growth Regulation 18 : 93-100.

Ten career-best publications

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1. Irving , H.R . and Grant, B.R. The effects of pectin and plant root surface carbohydrates on encystment and development of Phytophthora cinnamomi zoospores. Journal of General Microbiology 130 : 1015-1018, 1984.

2. Irving , H.R . and Exton, J.H. Phosphatidylcholine breakdown in rat liver plasma membranes: roles of guanine nucleotides and P 2 -purinergic agonists. Journal of Biological Chemistry 262 : 3440-3443, 1987.

3. Gehring , C.A. , Irving, H.R . and Parish, R.W. Effects of auxin and abscisic acid on cytosolic calcium and pH in plant cells. Proceedings of the National Academy of Science , USA 87 : 9645-9649, 1990.

4. Irving, H.R ., Gehring , C.A. and Parish, R.W. Changes in cytosolic pH and calcium of guard cells precede stomatal movements. Proceedings of the National Academy of Science , USA 89 : 1790-1794, 1992.

5. Gehring , C.A . , Irving, H.R . † , Kabbara, A.A., Parish, R.W., Boukli , N.M. and Broughton, W.J. Rapid, plateau-like increases in intracellular free calcium are associated with Nod-factor--induced root-hair deformation. Molecular Plant-Microbe Interactions 10 : 791-802, 1997. † equal first author

6. Irving , H.R., Boukli , N.M. , Kelly, M.N. and Broughton, W.J. Nod-factors in symbiotic development of root hairs. In “ Root Hairs: Cell and Molecular Biology ” (editors: R.W. Ridge and A.M. Emons) Springer-Verlag Tokyo, pp 241-265, 2000.

7. Pharmawati, M., Maryani, M.M., Nikolakopoulos, T., Gehring , C.A. , and Irving, H.R . Cyclic GMP modulates stomatal opening induced by natriuretic peptides and immunoreactive analogues in Vicia faba . Plant Physiology and Biochemistry 39 : 385-394, 2001.

8. Ludidi, N.N., Heazlewood, J.L., Seoighe, C.J, Irving , H.R . and Gehring , C.A. Expansin-like molecules: Novel functions derived from common domains. Journal of Molecular Evolution 54 : 587-594, 2002.

9. Kelly, M.N. and Irving , H.R . Nod factors activate both heterotrimeric and monomeric G-proteins in Vigna unguiculata ( L.) Walp. Planta 216 : 674-685, 2003 .

10. Maryani, M.M., Morse, M.V., Bradley, G., Irving , H.R ., Cahill, D.M. and Gehring , C.A. In situ localisation associates biologically active plant natriuretic peptide immuno-analogues with conductive tissue and stomata. Journal of Experimental Botany 54: 1553-1564, 2003.