NEWS FROM
PHYSIOLOGIA PLANTARUM
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Published monthly on behalf of SPPS by Wiley-Blackwell.
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Arabidopsis get excited
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Action potentials, i.e. rapid and transient changes of the membrane potential that travel over long distances, are not unique to animals. Several plants exploit them for various purposes: capturing insects in the carnivorous Venus flytrap, rapid movement of leaves in Mimosa and triggering of a systemic response following injure in tomato. However, action potentials in plants have not been thoroughly studied due to the lack of a suitable and reproducible model system. Now Swiss scientists propose Arabidopsis thaliana as such a model. Excitation by electrodes in the distal part of the leaf caused reproducible action potentials that travelled down through the petiole at a speed of 1.2 mm/s.
Read full article free: Favre & Agosti (October 2007) Physiologia Plantarum 131: 263-272
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NEWS IN BRIEF
FROM OTHER JOURNALS
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Potatoes highlight the plant-fungi relationship
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Little is known about the evolutionary origin of mycorrhiza, the symbiotic relationship between plant and fungus. Arbuscular mychorriza (AM) helps 80% of all vascular plants in extracting phosphate and other nutrients from the soil and is believed to have been critical for land plant development. Now a team of mainly Swiss scientists have discovered that lyso-phosphatidylcholine act as a molecular signal that turn on mycorrhiza-specific genes in potato. The lysolipid also induced other mycorrhiza-specific genes in tomato and caused extracellular alkalinization, which is known to lead to alterations in gene expression.
Source: Drissner et al (12 October 2007) Science 318: 265-268
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Recipe for better and sustainable rice
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Rice is one of the world's most important food crops, but despite the fact that yield has more than doubled in the last few decades, the cultivars need improvement in order to remain sustainable and nourishing. Pesticides and fertilizers are currently overused to secure the harvest, and problems with pests, diseases, drought and marginal land use are becoming increasingly more severe. Qifa Zhang from Huazhong Agricultural University in Wuhan, China has outlined a strategy for developing new 'green super rice'. The genes for most of the desired traits are known and have been isolated, and they can eventually be combined in a single cultivar using marker-assisted breeding, transformation and hybrid production.
Source: Zhang (1 October 2007) PNAS doi:10.1073/pnas.0708013104
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More speakers announced for the SPPS PhD conference
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Transgenic Arabidopsis that turn red in the presence of explosives will be presented at the SPPS PhD conference. Photo by Henrik Freek.
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A couple more speakers have been announced for the 5th biannual SPPS PhD conference that will take place January 24-27 2008 at Haslev Højskole 60 km south of Copenhagen. It is Professor Heribert Hirt from University of Vienna, Austria, who will deliver the keynote presentation on the topic Abiotic and Biotic Stress. Heribert Hirt makes extensive use of Arabidopsis mutants to investigate perception and transduction of stress signalling as well as programmed cell death and other stress related responses.
The other new speaker is Dr. Edgar Peiter from University of York, UK. He recently published a Nature paper on the role of Ca2+-activated ion channels in germination and stomatal movement, and at the conference the will deliver the keynote speech on the topic Transport and Signalling.
Also new to the programme is a speech under the Applied Methods section about Landmine reporter system in plants. It will be delivered by Agnieszka Janina Zygadlo, Denmark, who is working for the start-up biotech company Aresa that have developed the proprietary RedDetect plants for landmine detection.
You can register and read more about the conference on its official homepage.
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Bioimaging - a coloured revolution
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Above: The fluorescent probe (black sphere) absorb a photon (blue) and moves to an exited state. When it returns to the stable ground state a photon (green) is released. In some cases, two low-energy photons (red) can excite a probe which subsequently emits a single high-energy photon (green). Below: Typical excitation and emission spectra for a fluorescent probe. From Vonesh et al (May 2006) IEEE Sig Proc Mag
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Biologists have come to depend more and more on bioimaging as a tool to identify and locate specific proteins and molecules in their natural environment. With the recent development of probes and microscopes, biological processes can be monitored in real time in two or three dimensions. And observations can even be made non-invasively so a cellular process can be followed over an extended period of time.
Bioimaging relies on probes that are attached to proteins or other molecules of interest. These probes are fluorescent and as such emit light of a specific wavelength when they are excited by light of another - usually shorter - wavelength. Cells and their components are mainly transparent and the myriad of molecules within them are indistinguishable from each other in a normal microscope. But if the protein of interest lights up in bright green, it is easy to detect and distinguish from all other molecules in the cell.
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Scandinavian research institute:
CARB - Centre for Carbohydrate Recognition and Signalling, Aarhus, Denmark
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Carbohydrate signalling in e.g. symbiosis is studied by CARB. From www.carb.dk
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Less than a year ago, CARB was announced as a new Centre of Excellence by the Danish National Research Foundation. CARB (Centre for Carbohydrate Recognition and Signalling) is headed by Professor Jens Stougaard at University of Aarhus, and most researchers from the new centre come from his group at the Department of Molecular Biology. However, Professor Knud Jørgen Jensen from University of Copenhagen (Denmark), Professor Herman Spaink from University of Leiden (The Netherlands) and Professor Clive Ronson from University of Otago (New Zealand) do also participate.
CARB seeks to elucidate the involvement of carbohydrates in interactions between cells and organisms, which frequently occur as part of pathogenesis, symbiosis and development. The approach taken is multidisciplinary and exploits state-of-the-art technologies like bioinformatics, genomics, proteomics, structural biology and nanobioscience to mention just a few. The model organisms of choice are zebrafish and the legume Lotus japonicus, which exhibit complex interactions with pathogenic and symbiotic microorganisms, respectively.
Such interactions are often controlled by polysaccharides and glycans attached to or secreted from the microbial cell wall, which are then recognized by receptors on the eukaryotic cell surface. By experimental manipulation of both the ligand and the receptor, CARB will attempt to characterize and compare carbohydrate signalling in the two model systems and to investigate how the signals are recognized and turned into a cellular response.
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