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Dementia, Science, and Society 4 Introduction to basic human neuroscience leading to a discussion of brain diseases classified under the rubric Dementia. Lectures, reading, and discussions about the responsible conduct and reporting of research, working with others in science, and social responsibilities; the course is designed as an option for meeting current federal regulations. Students may receive credit only once for BGGN on a given topic. Sakano, K. Plant Microbe Interact.
Early and late events in plant—herbivore interaction Direct intracellular monitoring of calcium fluctuations in vivo has been done by either using fluorescent probes or the Timed hierarchy of consecutive events detectable in plant tissues, bioluminescence-based aequorin technology . When which are initiated by feeding insects Figure I. H2O2 has been already confirmed  Box 2. There clearly is a need for a further characterization of signal- Figure I.
Given that ion fluxes through channels ROS production and short-term effects on Vm directly influence Vm it seems reasonable to assume that The generation of ROS is a common response to pathogen unknown elicitors regulate the activities of various chan- invasion, and they have a dual role: at low concentration nels and, thus, might be considered as important factors they act as second messengers involved in cell signaling inducing electrical signals.
The calcium ion is recognized as a second messenger in Pathogen-induced ROS production, in particular H2O2, numerous plant signaling pathways. In response to herbivores, tained at a level between and nM. This is times H2O2 levels increase as long as the attacks persist. ROS can inter- signal . Calcium signatures is the term used to refer to act with ion channels and modify their activity .
Moreover, the same signal can induce damage . Mechanically damaged Lima bean tissue, or the cell type in a tissue . The proteins fall into two main classes, referred to as sensor long-lasting depolarization of the Vm by H2O2 could be relays and sensor responders, respectively .
Sensor considered a strategy by the insect to silence plant relays such as calmodulin CaM , CaM-related proteins responses  given that the insect actively introduces and calcineurin B-like proteins CBL can function through considerable amounts of H2O2 into the damaged tissue bimolecular interactions . Treatment with a chelator of . NO can function as a www.
Early events in plant—herbivore interactions The primary candidate for intercellular signaling in higher plants is Amplex Red can be used to detect the presence of active the stimulus-induced change in plasma membrane potential Vm. The subcellular localization of Ia. Chloroplasts Figure Id limited to the few cell layers surrounding the area in which the insect stained in green do not show any localization of H2O2.
Figure I. In plant— transduction chains in plant cells and, more specifically, pathogen interactions, jasmonic acid JA treatment whether they represent a component relaying herbivory- results in a strong NO-production, suggesting a self-ampli- mediated changes in ion fluxes to specific transcription fying JA—NO loop . NO is also known to induce the factors suspected to be involved in the activation of accumulation of salicylic acid SA , the crucial mediator for defense-related responses.
Several kinases, CDPKs and the establishment of the systemic resistance response . MAPKs have been described to be activated in both Nicoti- Therefore, the role of NO in responses to biotic stresses ana attenuata and Solanum nigrum after attack by the appears to be fine-tuned by SA, which might inhibit JA solanaceous generalist herbivore Manduca sexta . Ethylene, jasmonates and salicylates: how early do Although the presence and function of NO has not been they respond?
More and detailed by the network of phytohormones. By means of synergistic studies on the integration of NO in the network of signaling and antagonistic interactions cross-talk , which depend on pathways involved in herbivory are necessary. In plants, there is evi- level of abscisic acid and indole acetic acid is often dence for MAPKs playing a role in the signaling of a biotic decreased . The time course for the individual phyto- stresses, pathogens and plant hormones.
The aver- protein kinase MAPK whose transcript began to accumu- age resting level for JA has been found to be 10—40 ng g 1 late in the leaves only minutes after a single mechanical FW; this increases 10—fold within the first 1—2 h after wounding event [43,44]. This protein kinase WIPK was damage in various plants [55—57]. In Lima bean, the first essential for JA formation and JA-induced responses increase of JA was observed as early as 10 min after because silenced plants were unable to produce JA and damage and reached a maximum after 80—90 min.
At methyl-JA after wounding. NtWIF is a transcription factor be established. In the neighboring leaves, only an increase activated upon phosphorylation by wound-induced protein in the level of OPDA, not of JA, was observed. Given kinase WIPK in tobacco plants. Transgenic relevant for induction of a certain subset of defense tobacco plants overexpressing NtWIF exhibited constitutive responses. Other oxylipins that are simultaneously formed accumulation of transcripts for the pathogenesis-related with JA might also play a role in plant defense, but their genes PR-1a and PR-2 and an enhanced level of SA.
The function is, as yet, less clear . Because were more vulnerable to insect attack, demonstrating the calcium-dependent protein kinases CDPKs are regularly importance of this pathway for plant defense against involved in signal transduction of a variety of biotic and insects . Enhanced ethylene pro- . In potato Solanum tuberosum plants, JA has been duction is another early and active response of plants to reported to affect CDPK transcript level , and in tobacco biotic stress.
It will be herbivory [63—65]. Finally, in Arabidopsis, key elements interesting to further address the question as to where the for the integration of the signals resulting from JA and www.
As a pioneering work on plant electrophysiology, this exciting reference compiles new findings from the work of internationally renowned experts in the fields of. Methods in plant electrophysiology following herbivore attack Our model . Plant Electrophysiology – Theory & Methods (ed. by Volkov).
Accumulation of inducible antimicrobial with regard to the molecules that perceive and transmit compounds is often orchestrated through signal-transduc- signals associated with invaders. In plant—pathogen and tion pathways linked to perception of the pathogen by plant—herbivore interactions, early events, such as Vm receptors . Recently, inceptins proteolytic fragments of signaling networks, interconnecting branch pathways that chloroplastic ATP synthase g-subunit have been demon- amplify and specify the physiological response  strated to function as potent indirect signals eliciting Figure 1.
A more complete understanding of trade-offs specific plant responses to insect attack, such as the induc- between resistance to pathogens and herbivores at the tion of volatiles, phenylpropanoids, and protease inhibitor cellular level requires knowledge of the respective signal defenses . JA, SA and ethylene are central players transduction pathways that are activated in response to in mediating responses to pathogens and wounds.
JA insects and microbes . In plant—pathogen interactions, is usually associated with wounding pathways, whereas plant receptor proteins perceive pathogen- or interaction- SA is most often thought to function in pathogen responses derived signals, initializing downstream signaling events. Infection of pepper Capsicum and in plant—herbivore interactions . In both cases, annuum plants by incompatible Xanthomonas strains was Figure 1. Early events in plant—pathogen and plant—herbivore interactions. In plant—pathogen interactions, plant receptor proteins perceive pathogen-derived or interaction- dependent signals, followed by downstream signaling events, including ion fluxes.
Both pathogen and herbivores induce activation of the NADPH oxidase complex that generates the anion superoxide, which is quickly converted by the action of superoxide dismutase to H2O2. H2O can accumulate in the extracellular matrix or enter the cell, where it prompts a concentration-dependent Vm depolarization.
Plant Pathol. FEBS Lett. Membrane potentials, intracellular calcium variations, oral secretions, and regurgitate components. Plant Physiol. Science , — breakthroughs are related to the identification of herbi- 16 Schmelz, E. The challenge for further research in 17 White, P. BBA- this area is to determine their mode of action, whether these Biomembranes , — signals are transduced by receptor-mediated processes or if 18 Lecourieux, D. New Phytol. One approach to Opin. Plant Biol. Plant not responsive to a particular herbivory-related signal.
Phytochemistry 65, — 22 Jonak, C. Such an approach might yield important insight emission of ethylene in neighboring lima bean plants. This type of recording is often called "multi-unit recording", and is often used in conscious animals to record changes in the activity in a discrete brain area during normal activity.
Recordings from one or more such electrodes that are closely spaced can be used to identify the number of cells around it as well as which of the spikes come from which cell. This process is called spike sorting and is suitable in areas where there are identified types of cells with well defined spike characteristics. If the electrode tip is bigger still, in general the activity of individual neurons cannot be distinguished but the electrode will still be able to record a field potential generated by the activity of many cells. Extracellular field potentials are local current sinks or sources that are generated by the collective activity of many cells.
Usually, a field potential is generated by the simultaneous activation of many neurons by synaptic transmission. The diagram to the right shows hippocampal synaptic field potentials. At the right, the lower trace shows a negative wave that corresponds to a current sink caused by positive charges entering cells through postsynaptic glutamate receptors , while the upper trace shows a positive wave that is generated by the current that leaves the cell at the cell body to complete the circuit.
For more information, see local field potential. Amperometry uses a carbon electrode to record changes in the chemical composition of the oxidized components of a biological solution. Oxidation and reduction is accomplished by changing the voltage at the active surface of the recording electrode in a process known as "scanning". Because certain brain chemicals lose or gain electrons at characteristic voltages, individual species can be identified. Amperometry has been used for studying exocytosis in the nervous and endocrine systems.
Many monoamine neurotransmitters ; e. The method can also be used with cells that do not secrete oxidizable neurotransmitters by "loading" them with 5-HT or dopamine. Planar patch clamp is a novel method developed for high throughput electrophysiology. A single cell is then positioned on the hole by suction and a tight connection Gigaseal is formed. The planar geometry offers a variety of advantages compared to the classical experiment:. Schematic drawing of the classical patch clamp configuration.
The patch pipette is moved to the cell using a micromanipulator under optical control. Relative movements between the pipette and the cell have to be avoided in order to keep the cell-pipette connection intact. In planar patch configuration, the cell is positioned by suction. Relative movements between cell and aperture can then be excluded after sealing. An antivibration table is not necessary. Scanning electron microscope image of a planar patch clamp chip. Both the pipette and the chip are made from borosilicate glass. With this electrophysiological approach, proteo liposomes , membrane vesicles , or membrane fragments containing the channel or transporter of interest are adsorbed to a lipid monolayer painted over a functionalized electrode.
This electrode consists of a glass support, a chromium layer, a gold layer, and an octadecyl mercaptane monolayer. Because the painted membrane is supported by the electrode, it is called a solid-supported membrane. It is important to note that mechanical perturbations, which usually destroy a biological lipid membrane, do not influence the life-time of an SSM. The capacitive electrode composed of the SSM and the absorbed vesicles is so mechanically stable that solutions may be rapidly exchanged at its surface. The bioelectric recognition assay BERA is a novel method for determination of various chemical and biological molecules by measuring changes in the membrane potential of cells immobilized in a gel matrix.
Apart from the increased stability of the electrode-cell interface, immobilization preserves the viability and physiological functions of the cells. BERA is used primarily in biosensor applications in order to assay analytes that can interact with the immobilized cells by changing the cell membrane potential. In this way, when a positive sample is added to the sensor, a characteristic, "signature-like" change in electrical potential occurs. The method has also been used for the detection of environmental toxins, such as pesticides    and mycotoxins  in food, and 2,4,6-trichloroanisole in cork and wine,   as well as the determination of very low concentrations of the superoxide anion in clinical samples.
A recent advance is the development of a technique called molecular identification through membrane engineering MIME. This technique allows for building cells with defined specificity for virtually any molecule of interest, by embedding thousands of artificial receptors into the cell membrane. While not strictly constituting an experimental measurement, methods have been developed to examine the conductive properties of proteins and biomembranes in silico. These are mainly molecular dynamics simulations in which a model system like a lipid bilayer is subjected to an externally applied voltage.
Studies using these setups have been able to study dynamical phenomena like electroporation of membranes  and ion translocation by channels. The benefit of such methods is the high level of detail of the active conduction mechanism, given by the inherently high resolution and data density that atomistic simulation affords. There are significant drawbacks, given by the uncertainty of the legitimacy of the model and the computational cost of modeling systems that are large enough and over sufficient timescales to be considered reproducing the macroscopic properties of the systems themselves.
While atomistic simulations may access timescales close to, or into the microsecond domain, this is still several orders of magnitude lower than even the resolution of experimental methods such as patch-clamping. Clinical electrophysiology is the study of how electrophysiological principles and technologies can be applied to human heath. For example, clinical cardiac electrophysiology is the study of the electrical properties which govern heart rhythm and activity. Cardiac electrophysiology can be used to observe and treat disorders such as arrhythmia irregular heartbeat.
For example, a doctor may insert a catheter containing an electrode into the heart to record the heart muscle's electrical activity. Another example of clinical electrophysiology is clinical neurophysiology.
In this medical specialty, doctors measure the electrical properties of the brain , spinal cord , and nerves. Scientists such as Duchenne de Boulogne — and Nathaniel A. Buchwald — are considered to have greatly advanced the field of neurophysiology , enabling its clinical applications. Minimum Information MI standards or reporting guidelines specify the minimum amount of meta data information and data required to meet a specific aim or aims in a clinical study. The "Minimum Information about a Neuroscience investigation" MINI family of reporting guideline documents aims to provide a consistent set of guidelines in order to report an electrophysiology experiment.
In practice a MINI module comprises a checklist of information that should be provided for example about the protocols employed when a data set is described for publication. From Wikipedia, the free encyclopedia. Study of the electrical properties of biological cells and tissues. This section needs expansion.
You can help by adding to it. July Main article: Voltage clamp. Not to be confused with Current clamp in electronics. Main article: Patch clamp. Main article: single-unit recording. Archived from the original on 10 October Retrieved 5 May Hubel; Wiesel, TN 1 January The Journal of Physiology. Archived from the original on 23 December Archived PDF from the original on 31 March Retrieved 17 January Pistola, P.
Bomsel, N. Alexandropoulos, F.
Bem, I. Biselis, R. Sensors 9: — Biosensors Bioelectron. Talanta — Chimica Acta — 90— Yialouris, P. Blouchos, G. Moschopoulou, V. Tsourou, Kintzios, S. BioMed Research International. Article ID Journal of Molecular Recognition — Biophysical Journal.