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Dr Julia Davies

Head of Group, Radiation Protection Supervisor
Dr Julia Davies

Julia Davies is accepting applications for PhD students.

Department of Plant Sciences
University of Cambridge
Downing Street

Cambridge CB2 3EA
Office Phone: 01223 333900

Biography:

Julia graduated from the University of Wales and then studied for her PhD on ion transport in a marine fungus at the University of Liverpool and the Marine Biological Association in Plymouth. After post-doc contracts at York and McGill, she was awarded a Royal Society University Research Fellowship and the SEB President’s Medal. Julia joined the Department in 1997 and was awarded the University’s Pilkington Prize in 2009.

Research Interests

The Transport Group primarily studies the plasma membrane (PM) calcium channels involved in root signal transduction, nutrition and growth. Following the first characterisation of a PM calcium channel involved in root hair growth (Véry and Davies, 2000), the group has gone on to identify distinct types of calcium-permeable channels in the PM of Arabidopsis root epidermis, including one that could deliver toxic levels of  sodium into roots (Demidchik et al., 2002, 2003. We have also defined salt stress-induced changes in epidermal PM conductance (Shabala et al., 2006). We have shown that root hair and epidermal PM harbours calcium channels that are differentially regulated by voltage, permitting flexibility of calcium uptake (Miedema et al., 2001; Demidchik et al., 2002). The first characterisation of a plant calcium-permeable channel activated by hydroxyl radicals (Demidchik et al., 2003) lead to the discovery that these channels operate downstream of a PM NADPH oxidase (AtRBOHC) in root and root hair growth (Foreman et al., 2003). Since this first demonstration of NADPH oxidase involvement in development, we have shown that AtRBOHC governs hypoosmotic stress response and wall strength (Macpherson et al., 2008) Epidermal cell development changes the sensitivity of calcium channels to hydrogen peroxide and activation is vectorial (Demidchik et al., 2007), revealing the complexity of the relationship between channels and reactive oxygen species (ROS) that is relevant to stress, immunity and growth.

We identified extracellular ATP (eATP) and eADP as novel upstream regulators of plant PM calcium channels and calcium signalling (Demidchik et al., 2003, 2009. Groups worldwide are now investigating the mechanisms, consequences and applications of eATP signalling such as food preservation. We have established that plant annexins form novel calcium-permeable channels in vitro and in vivo (Laohavisit et al., 2009,2010,2011,2012) and are now working on how they operate in stress signalling and development.

The group has benefited from several national and international collaborations. Funding has come principally from the BBSRC, the Leverhulme Trust, the Royal Society, the Newton Trust and the Brooks Fund. We thank everyone who has helped us.

Key Publications

Laohavisit, A., Shang, Z., Rubio, L., Cuin, T.A., Véry, A.-A., Wang, A., Mortimer, J.C., Macpherson, N., Coxon, K.C., Battey, N.H., Brownlee, C., Park, O.M., Sentenac, H.,  Shabala, S., Webb, A.A.R., Davies, J.M. (2012) Arabidopsis annexin 1 mediates the radical-activated plasma membrane Ca2+- and K+-permeable conductance in root cells. Plant Cell 24, 1522-1533.

Laohavisit, A. Davies, J.M. (2011) Annexins. Tansley Review New Phytologist 189, 40-53.

Demidchik, V., Shang, Z., Shin, R., Colaço, R., Laohavisit, A., Shabala, S., Davies, J.M. (2011) Receptor-like activity evoked by extracellular ADP in Arabidopsis root epidermal plasma membrane. Plant Physiology 156, 375-385.

Anderson, A., Bothwell, J.H., Laohavisit, A., Smith, A.G., Davies, J.M. (2011) NOX or not? Evidence for algal NADPH oxidases. Trends in Plant Sciences 16, 579-581.

Gilroy, S., Davies, J. (2011) Plant cell biology-digging deep into cell function. Current Opinion in Plant Biology 14, 629-631.

Bombelli, P., Bradley, R.W., Scott, A.M., Phillips, A.J. McCormick, A.J., Cruz, S.M., Anderson, A., Yunus, K., Bendall, D.S., Cameron, P.J., Davies, J.M., Smith, A.G., Howe, C.J., Fisher, A.C. (2011)  Quantitative analysis of the factors limiting solar power transduction by Synechocystis sp. PCC 6803 in biological photovoltaic devices. Energy and Environmental Sciences 4, 4690-4698.

Laohavisit A, Brown AT, Cicuta P, and Davies, JM. (2010) Annexins: Components of the calcium and reactive oxygen signalling network. Plant Physiology 152, 1824.

Thompson EP, Wilkins C, Demidchik V, Davies JM, and Glover BJ. (2010) An Arabidopsis flavonoid transporter is required for anther dehiscence and pollen development. Journal of Experimental Botany 61 439.

Thompson EP, Daves JM, and Glover BJ. (2010) Identifying the transporters of different flavonoids in plants. Plant Signaling and Bahavior in press.

Laohavisit A, Demidchik V, Mortimer JC, Coxon KM, Stancombe MA, Macpherson N, Brownlee C, Hofmann A, Webb AAR, Miedema H, Battey NH, and Davies JM. (2009) Zea mays annexins modulate cytosolic free Ca2+, form a Ca2+-permeable conductance and have peroxidase activity. Plant Cell 21, 479.

Demidchik V, Shang Z, Shin R, Thompson EP, Rubio L, Laohavisit A, Mortimer JC, Chivasa S, Slabas AR, Glover BJ, Schachtman DP, and Davies JM. (2009) Plant extracellular ATP signalling by plasma membrane NADPH oxidase and Ca2+ channels. Plant Journal 58 903.

Laohavisit A, and Davies JM. (2009) Multifunctional annexins Plant Science 177, 532.

Mortimer JC, Coxon, KM, Laohavisit A and Davies JM Heme-independent soluble and membrane-associated peroxidase activity of a Zea mays annexin preparation Plant Signaling and Behavior 4 428.

Shang Z and Davies JM Extracellular ADP activates an Arabidopsis plasma membrane Ca2+-permeable conductance Plant Signaling and Behavior 4 989.

Miedema H, Demidchik V, Véry A-A, Bothwell JHF, Brownlee C, and Davies JM. (2008) Two voltage-dependent calcium channels co-exist in the apical plasma membrane of Arabidopsis thaliana root hairs. New Phytologist 179, 378.

Macpherson N, Takeda S, Shang ZL, Dark A, Mortimer JC, Brownlee C, Dolan, L, and Davies JM. (2008) NADPH oxidase involvement in cellular integrity. Planta 227, 1415.

Mortimer JC, Laohavisit A, Macpherson N, Webb AAR, Brownlee C, Battey NH, Davies JM (2008) Annexins: Multi-functional components of growth and adaptation. Journal of Experimental Botany 59, 533.

Roy SJ, Gilliham M, Berger B, Essah PA, Cheffings C, Miller AJ, Widdowson L, Davenport RJ, Liu LH, Skynner MJ, Davies JM, Richardson P, Leigh RA, and Tester M. (2008) Investigating glutamate receptor-like gene co-expression in Arabidopsis thaliana. Plant Cell and Environment 31, 861.

Mortimer JC, Laohavisit A, Miedema H, and Davies JM. (2008) Voltage, reactive oxygen species and the influx of calcium. Plant Signaling and Behavior 3, 698.

Laohavisit A, Davies JM (2007) The gas that opens gates: calcium channel activation by ethylene. New Phytologist 174, 470-473.

Demidchik V, Shabala S, Davies JM (2007) Spatial variation in H2O2 response of Arabidopsis thaliana root epidermal Ca2+ flux and plasma membrane Ca2+ channels. The Plant Journal 49, 377-386.

Shabala S, Demidchik V, Shabala L, Cuin TA, Smith SJ, Miller AJ, Davies JM, Newman IA (2006) Extracellular Ca2+ ameliorates NaCl-induced K+ loss from Arabidopsis root and leaf cells by blocking plasma membrane K+-permeable channels. Plant Physiology 141, 1653-1665.

Martin S, Glover BJ, Davies JM (2005) Lipid microdomains - plant membranes get organized. Trends in Plant Sciences 10, 263-265.

Macpherson N, Shabala L, Rooney H, Jarman MG, Davies JM (2005) Plasma membrane H+ and K+ transporters are involved in the weak acid preservative response of disparate food spoilage yeasts. Microbiology SGM 151, 1995-2003.

Demidchik V, Macpherson M, Davies JM (2005) Potassium transport at the plasma membrane of the food spoilage yeast Zygosaccharomyces bailii. Yeast 22, 21-29.

Dolan L, Davies JM (2004) Cell expansion in roots. Current Opinion in Plant Biology 7, 33-39.

Demidchik V, Nichols C, Dark A, Oliynyk M, Glover BJ, Davies JM (2003) Is ATP a signalling agent in plants? Plant Physiology 133, 456-461.

Foreman J, Demidchik V, Bothwell JHF, Mylona P, Miedema H, Torres MA, Linstead P, Costa S, Brownlee C, Jones JDG, Davies JM, Dolan L (2003) Reactive oxygen species produced by NADPH oxidase regulate plant cell growth. Nature 422, 442-446.

Demidchik V, Shabala SN, Coutts KB, Tester MA, Davies JM (2003) Free oxygen radicals regulate plasma membrane Ca2+ and K+-permeable channels in plant root cells. Journal of Cell Science 116, 81-88.

Demidchik V, Bowen HC, Maathuis FJM, Shabala SN, Tester MA, White PJ, Davies JM (2002) Arabidopsis thaliana root non-selective cation channels mediate calcium uptake & are involved in growth. Plant Journal 32, 799-808.

White PJ, Bowen HC, Demidchik V, Nichols C, Davies JM (2002) Genes for calcium-permeable channels in the plasma membrane of plant root cells. Biochimica Biophysica Acta 1564, 299-309.

Baker A, Northrop FD, Miedema H, Devine GR, Davies JM (2002) The non-steroidal anti-inflammatory drug niflumic acid inhibits Candida albicans growth. Mycopathologia 153, 25-28.

Hanke GT, Northrop FD, Devine GR Bothwell JHF, Davies JM (2001) Chloride channel antagonists perturb growth and morphology of Neurospora crassa FEMS Letters 201, 243-247.

Miedema H., Bothwell JHF, Brownlee C, Davies JM (2001) Calcium uptake by plant cells - channels and pumps acting in concert. Trends in Plant Sciences 6, 514-519.

Véry AA, Davies JM (2000) Hyperpolarization-activated calcium channels at the tip of Arabidopsis root hairs. PNAS USA 97, 9801-9806.

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