Measuring surface potential changes on leaves.

We provide here a detailed protocol for studying the changes in electrical surface potential of leaves. This method has been developed over the years by plant physiologists and is currently used in different variants in many laboratories. The protocol records surface potential changes to measure long-distance electrical signals induced by diverse stimuli such as leaf wounding or current injection. This technique can be used to determine signaling speeds, to measure the connectivity between different plant organs and-by exploiting mutant plants-to identify transporters and ion channels involved in electrical signaling. The approach can be combined with the analysis of mRNA expression and of metabolite concentrations to correlate electrical signaling to specific physiological events. We describe how to use this protocol on Arabidopsis, looking at the effects of leaf wounding; however, it is broadly applicable to other plants and can be used to study other aspects of plant physiology. After wound infliction, surface potential recording takes ∼20 min per plant

Multilayered Organization of Jasmonate Signalling in the Regulation of Root Growth.

Physical damage can strongly affect plant growth, reducing the biomass of developing organs situated at a distance from wounds. These effects, previously studied in leaves, require the activation of jasmonate (JA) signalling. Using a novel assay involving repetitive cotyledon wounding in Arabidopsis seedlings, we uncovered a function of JA in suppressing cell division and elongation in roots. Regulatory JA signalling components were then manipulated to delineate their relative impacts on root growth. The new transcription factor mutant myc2-322B was isolated. In vitro transcription assays and whole-plant approaches revealed that myc2-322B is a dosage-dependent gain-of-function mutant that can amplify JA growth responses. Moreover, myc2-322B displayed extreme hypersensitivity to JA that totally suppressed root elongation. The mutation weakly reduced root growth in undamaged plants but, when the upstream negative regulator NINJA was genetically removed, myc2-322B powerfully repressed root growth through its effects on cell division and cell elongation. Furthermore, in a JA-deficient mutant background, ninja1 myc2-322B still repressed root elongation, indicating that it is possible to generate JA-responses in the absence of JA. We show that NINJA forms a broadly expressed regulatory layer that is required to inhibit JA signalling in the apex of roots grown under basal conditions. By contrast, MYC2, MYC3 and MYC4 displayed cell layer-specific localisations and MYC3 and MYC4 were expressed in mutually exclusive regions. In nature, growing roots are likely subjected to constant mechanical stress during soil penetration that could lead to JA production and subsequent detrimental effects on growth. Our data reveal how distinct negative regulatory layers, including both NINJA-dependent and -independent mechanisms, restrain JA responses to allow normal root growth. Mechanistic insights from this work underline the importance of mapping JA signalling components to specific cell types in order to understand and potentially engineer the growth reduction that follows physical damage

Identification of cell populations necessary for leaf-to-leaf electrical signaling in a wounded plant.

The identity of the cell files necessary for the leaf-to-leaf transmission of wound signals plants has been debated for decades. In <i>Arabidopsis</i> , wounding initiates the glutamate receptor-like (GLR)-dependent propagation of membrane depolarizations that lead to defense gene activation. Using a vein extraction procedure we found pools of GLR-fusion proteins in endomembranes in phloem sieve elements and/or in xylem contact cells. Strikingly, only double mutants that eliminated GLRs from both of these spatially separated cell types strongly attenuated leaf-to-leaf electrical signaling. <i>glr3.3</i> mutants were also compromised in their defense against herbivores. Since wounding is known to cause increases in cytosolic calcium, we monitored electrical signals and Ca <sup>2+</sup> transients simultaneously. This revealed that wound-induced membrane depolarizations in the wild-type preceded cytosolic Ca <sup>2+</sup> maxima. The axial and radial distributions of calcium fluxes were differentially affected in each <i>glr</i> mutant. Resolving a debate over which cell types are necessary for electrical signaling between leaves, we show that phloem sieve elements and xylem contact cells function together in this process

The Influence of Dormitory Architecture On Resident Behavior

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66943/2/10.1177_001391657300500402.pd

The energy spectrum of cosmic rays beyond the turn-down around 10^17 eV as measured with the surface detector of the Pierre Auger Observatory

We present a measurement of the cosmic-ray spectrum above 100 PeV using the part of the surface detector of the Pierre Auger Observatory that has a spacing of 750 m. An inflection of the spectrum is observed, confirming the presence of the so-called second-knee feature. The spectrum is then combined with that of the 1500 m array to produce a single measurement of the flux, linking this spectral feature with the three additional breaks at the highest energies. The combined spectrum, with an energy scale set calorimetrically via fluorescence telescopes and using a single detector type, results in the most statistically and systematically precise measurement of spectral breaks yet obtained. These measurements are critical for furthering our understanding of the highest energy cosmic rays

The jasmonate biochemical pathway.

Plants possess an interrelated and interacting family of potent fatty acid-derived regulators--the jasmonates. These compounds, which play roles in both defense and development, are derived from tri-unsaturated fatty acids [alpha-linolenic acid (18:3) or 7Z,10Z,13Z-hexadecatrienoic acid (16:3)]. The lipoxygenase-catalyzed addition of molecular oxygen to alpha-linolenic acid initiates jasmonate synthesis by providing a 13-hydroperoxide substrate for the formation of an unstable allene oxide that is then subject to enzyme-guided cyclization to produce 12-oxo-phytodienoic acid (OPDA). OPDA, a key regulatory lipid in the plant immune system, has several fates, including esterification into plastid lipids or transformation into the 12-carbon co-regulator jasmonic acid (JA). JA, the best-characterized member of the family, regulates both male and female fertility (depending on the plant species), and is an important mediator of defense gene expresssion. JA is itself a substrate for further diverse modifications. Genetic dissection of the pathway is revealing how the different jasmonates modulate different physiological processes. Each new family member that is discovered provides another key to understanding the fine control of gene expression in immune responses, in the initiation and maintenance of long-distance signal transfer in response to wounding, and in the regulation of fertility, among other processes. The Jasmonate Biochemical Pathway provides an overview of the growing jasmonate family, and new members will be included in future versions of the Connections Map. Science Viewpoint R. Liechti, E. E. Farmer, The jasmonate pathway. Science 296, 1649-1650 (2002). [Abstract] [Full Text]]]> Acetic Acids/chemistry; Acetic Acids/metabolism; Arabidopsis/chemistry; Arabidopsis/physiology; Cyclopentanes/chemistry; Cyclopentanes/metabolism; Oxylipins; Signal Transduction/physiology eng oai:serval.unil.ch:BIB_DACE01A4147F 2022-02-19T02:31:57Z <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_DACE01A4147F Dix-huit nouveaux genres d'ammonites du Spathien (Trias inférieur) de l'Ouest américain (Idaho, Nevada, Utah et Californie) : Note préliminaire info:doi:10.5169/seals-281710 info:eu-repo/semantics/altIdentifier/doi/10.5169/seals-281710 Guex, J. Hungerbuehler, A. Jenks, J. Taylor, D.G. Bucher, H. info:eu-repo/semantics/article article 2005 Bulletin de la Société Vaudoise des Sciences Naturelles, vol. 89, pp. 113-143 urn:issn:0037-9603 fre oai:serval.unil.ch:BIB_DACE83004331 2022-02-19T02:31:57Z openaire documents urnserval <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_DACE83004331 Visualizing Futures of Networks in Digital Humanities Research Kaufman, Micki LeBlanc, Zoe Lincoln, Matthew Rochat, Yannick Weingart, Scott B. info:eu-repo/semantics/conferenceObject inproceedings 2017 Digital Humanities Conference 2017, Montréal, Canada, August 8-11, 2017 eng https://serval.unil.ch/resource/serval:BIB_DACE83004331.P001/REF.pdf http://nbn-resolving.org/urn/resolver.pl?urn=urn:nbn:ch:serval-BIB_DACE830043315 info:eu-repo/semantics/altIdentifier/urn/urn:nbn:ch:serval-BIB_DACE830043315 info:eu-repo/semantics/submittedVersion info:eu-repo/semantics/openAccess Copying allowed only for non-profit organizations https://serval.unil.ch/disclaimer application/pdf oai:serval.unil.ch:BIB_DACEB4A886F8 2022-02-19T02:31:57Z <oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd"> https://serval.unil.ch/notice/serval:BIB_DACEB4A886F8 Differential changes in synaptic proteins in the Alzheimer frontal cortex with marked increase in PSD-95 postsynaptic protein info:eu-repo/semantics/altIdentifier/pmid/18780974 Leuba, G. Savioz, A. Vernay, A. Carnal, B. Kraftsik, R. Tardif, E. Riederer, I. Riederer, B. M. info:eu-repo/semantics/article article 2008 Journal of Alzheimer's Disease, vol. 15, no. 1, pp. 139-151 info:eu-repo/semantics/altIdentifier/pissn/1387-2877 <![CDATA[We investigated how synaptic plasticity is related to the neurodegeneration process in the human dorsolateral prefrontal cortex. Pre- and postsynaptic proteins of Brodmann's area 9 from patients with Alzheimer's disease (AD) and age-matched controls were quantified by immunohistochemical methods and Western blots. The main finding was a significant increase in the expression of postsynaptic density protein PSD-95 in AD brains, revealed on both sections and immunoblots, while the expression of spinophilin, associated to spines, remained quantitatively unchanged despite qualitative changes with age and disease. Presynaptic protein alpha-synuclein indicated an increased immunohistochemical level, while synaptophysin remained unchanged. MAP2, a somatodendritic microtubule protein, as well as AD markers such as amyloid-beta protein and phosphorylated protein tau showed an increased expression on immunosections in AD. Altogether these changes suggest neuritic and synaptic reorganization in the process of AD. In particular, the significant increase in PSD-95 expression suggests a change in NMDA receptors trafficking and may represent a novel marker of functional significance for the disease

Jasmonates: what ALLENE OXIDE SYNTHASE does for plants.

Most of the great diversity of oxylipins in plants is produced by a group of specialized cytochrome P450 enzymes, among which is ALLENE OXIDE SYNTHASE (AOS). Many AOSs generate precursors of the defense hormone jasmonate. As a consequence, aos mutants fail to defend themselves against herbivores and do not display restriction of vegetative growth when wounded. These links between growth and defense that are controlled by AOS-derived oxylipins are ancient. Here, we focus on oxylipin-regulated coordination of growth/defense, how this optimizes defense, and how a plant's need for light can override jasmonate activity. AOS-derived oxylipins are candidate regulators throughout land plant evolution