The Venus flytrap captures insects with one of the most rapid movements in the plant kingdom. There is a significant difference between properties of electrical signals generated in the Venus flytrap ...described in literature. Amplitudes of action potentials vary from 14 mV to 200 mV with duration of signals from 2 ms to 10 s. Here we present experimental study of potential differences between Ag/AgCl electrodes inserted to the trap, petiole, and into soil or external ECG electrodes attached to surfaces of the Venus flytrap. Diverse types of electrodes with various positions in a plant tissue or in soil show different amplitude and duration of electrical signals because potentials are measured in different electrochemical circuits. Electrical signals in the Venus flytrap were induced by mechanical stimulation of the trigger hairs or by chemical stimulation of a midrib using small drops of H2O2 or HNO3. Here we found that action potentials can propagate with speed up to 10 m/s in the trap of D. muscipula. Results are compared with equivalent electrical circuits.
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•Action potentials in the trap can induce electrotonic potentials in the petiole•Amplitude and duration of signals obtained by extracellular or external electrodes can be different•Arrangement of electrodes inside or outside plants corresponds to different electrical circuits•Action potentials propagate with speed up to 10 m/s in the trap of D. muscipula.•Mechanical or chemical stimuli can generate different electrical signals in the Venus flytrap
Tuberculosis is currently still one of the leading causes of death from a treatable pathogen. The proportion of cases of resistance to common antibiotics is frequently increasing and the development ...of new drugs with new therapeutic targets is becoming necessary. The Mycobacterium tuberculosis phosphoserine phosphatase MtSerB2 is an interesting enzyme to target in drug design because of its ability to allow immune evasion of the bacteria. Research has already been carried out on this protein both from a mechanistic point of view and from the point of view of its inhibition by trisubstituted harmine derivatives. Based on this work, a new approach based on virtual screening is presented in the selection of fragment-sized harmine-derived compounds as well as chelators to target the catalytic magnesium of MtSerB2. The selection of a minimum list of fragments is explained as well as the screening cascade (DSF, Ligand-based NMR, High concentration enzymatic assay) to characterise their affinity for MtSerB2. Crystallogenesis assays have provided structural information on some promising fragments and the development of a pharmacophore model with the structural elements necessary for the development of more complex inhibitors. Ultimately, this work on fragment growth would allow the development of antimycobacterial molecules inhibiting MtSerB2 as well as the growth of the pathogen.
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•A fragment-based drug design approach on MtSerB2 from M.tuberculosis.•In silico fragment screening was utilised to select suitable fragments.•Three orthogonal methods were utilised to assess affinity of those fragments.•Potent fragments were crystallised with a homologue of MtSerB2.•Key features necessary to the inhibition of MtSerB2 were investigated.
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•Plasma induces electrical signals in the bio-tissue with a very high amplitude.•Plasma photography shows a blue aura due to a corona discharge.•Plasma jets generate RONS, UV, and ...high frequency electromagnetic fields.•Plasma can damage bio-tissue it if the plasma treatment is long enough.
Cold atmospheric pressure radio frequency plasma (CAPP) can play an important role in agriculture, medicine, biophysical and bioelectrochemical applications, disinfection and sterilization, synthesis of different compounds, nitrogen fixation, and treatment of surfaces. Here we found that reactive oxygen and nitrogen species, UV–Vis photons, and high-frequency strong electromagnetic fields with an amplitude of a few kV produced by a cold plasma jet can interact with bio-tissue and damage it if the plasma treatment is long enough. The electrophysiological effects of CAPP treatment of bio-tissue and electrical signals transmission were measured in the Venus flytrap. The plasma ball does not produce any visible side effects on the Venus flytrap, but induces electrical signals in bio-tissue with very high amplitude. Plasma (Kirlian) photography shows the existence of a blue aura around the plasma ball due to a corona discharge. Understanding the mechanisms of interactions between CAPP and bio-tissue and preventing side effects can contribute to the application of plasma technology in medicine and agriculture. The use of cold plasma in medicine and agriculture should be monitored for side effects from strong high-frequency electro-magnetic fields, UV photons, and reactive oxygen and nitrogen species to protect against undesirable consequences.
Many biomolecular interactions proceed via lowly populated, transient intermediates. Believed to facilitate formation of a productive complex, these short-lived species are inaccessible to ...conventional biophysical and structural techniques and, until recently, could only be studied by theoretical simulations. Recent development of experimental approaches sensitive to the presence of minor speciesin particular paramagnetic relaxation enhancement (PRE) NMR spectroscopyhas enabled direct visualization and detailed characterization of such lowly populated states. Collectively referred to as an encounter complex, the binding intermediates are particularly important in transient protein interactions, such as those orchestrating signaling cascades or energy-generating electron transfer (ET) chains. Here I discuss encounter complexes of redox proteins mediating biological ET reactions, which are essential for many vital cellular activities including oxidative phosphorylation and photosynthesis. In particular, this Account focuses on the complex of cytochrome c (Cc) and cytochrome c peroxidase (CcP), which is a paradigm of biomolecular ET and an attractive system for studying protein binding and enzymatic catalysis. The Cc-CcP complex formation proceeds via an encounter state, consisting of multiple protein–protein orientations sampled in the search of the dominant, functionally active bound form and exhibiting a broad spatial distribution, in striking agreement with earlier theoretical simulations. At low ionic strength, CcP binds another Cc molecule to form a weak ternary complex, initially inferred from kinetics experiments and postulated to account for the measured ET activity. Despite strenuous efforts, the ternary complex could not be observed directly and remained eagerly sought for the past two decades. Very recently, we have solved its structure in solution and shown that it consists of two binding forms: the dominant, ET-inactive geometry and an ensemble of lowly populated species with short separations between Cc and CcP cofactors, which summarily account for the measured ET rate. Unlike most protein complexes, which require accurate alignment of the binding surfaces in a single, well-defined orientation to carry out their function, redox proteins can form multiple productive complexes. As fast ET will occur any time the redox centers of the binding partners are close enough to ensure efficient electron tunneling across the interface, many protein–protein orientations are expected to be ET active. The present analysis confirms that the low-occupancy states can support the functional ET activity and contribute to the stability of redox protein complexes. As illustrated here, boundaries between the dominant and the encounter forms become blurred for many dynamic ET systems, which are more aptly described by ensembles of functionally and structurally heterogeneous bound forms.
Two decades have passed since the initial proposition that amyloids are not only (toxic) byproducts of an unintended aggregation cascade, but that they can also be produced by an organism to serve a ...defined biological function. That revolutionary idea was borne out of the realization that a large fraction of the extracellular matrix that holds Gram-negative cells into a persistent biofilm is composed of protein fibers (curli; tafi) with cross-β architecture, nucleation-dependent polymerization kinetics and classic amyloid tinctorial properties. The list of proteins shown to form so-called functional amyloid fibers in vivo has greatly expanded over the years, but detailed structural insights have not followed at a similar pace in part due to the associated experimental barriers. Here we combine extensive AlphaFold2 modelling and cryo-electron transmission microscopy to propose an atomic model of curli protofibrils, and their higher modes of organization. We uncover an unexpected structural diversity of curli building blocks and fibril architectures. Our results allow for a rationalization of the extreme physico-chemical robustness of curli, as well as earlier observations of inter-species curli promiscuity, and should facilitate further engineering efforts to expand the repertoire of curli-based functional materials.
Thermodynamics of liquid water in terms of a non-standard approach-the ion-molecular model-is considered. Water is represented as a dense gas of neutral H
O molecules and single charged H
O
and OH
...ions. The molecules and ions perform thermal collisional motion and interconvert due to ion exchange. The energy-rich process-vibrations of an ion in a hydration shell of molecular dipoles-well known to spectroscopists with its dielectric response at 180 cm
(5 THz), is suggested to be key for water dynamics. Taking into account this ion-molecular oscillator, we compose an equation of state of liquid water to obtain analytical expressions for the isochores and heat capacity.
Plants can communicate with other plants using wireless pathways in the plant-wide web. Some examples of these communication pathways are: (1) volatile organic compounds' emission and sensing; (2) ...mycorrhizal networks in the soil; (3) the plants' rhizosphere; (4) naturally grafting of roots of the same species; (5) electrostatic or electromagnetic interactions; and (6) acoustic communication. There is an additional pathway for electrical signal transmission between plants - electrical signal transmission between roots through the soil. To avoid the possibility of communication between plants using mechanisms (1)-(6), soils in pots with plants were connected by Ag/AgCl or platinum wires. Electrostimulation of Aloe vera, tomato, or cabbage plants induces electrotonic potentials transmission in the electro-stimulated plants as well as the plants located in different pots regardless if plants are the same or different types. The amplitude and sign of electrotonic potentials in electrostimulated and neighboring plants depend on the amplitude, rise, and fall of the applied voltage. Experimental results displayed cell-to-cell electrical coupling and the existence of electrical differentiators in plants. Electrostimulation by a sinusoidal wave induces an electrical response with a phase shift. Electrostimulation serves as an important tool for the evaluation of mechanisms of communication in the plant-wide web.
As a pioneering work on plant electrophysiology, this exciting reference compiles new findings from the work of internationally renowned experts in the fields of electrophysiology, ...bio-electrochemistry, biophysics, signal transduction, phloem transport, tropisms, ion channels, plant electrochemistry, and membrane transport. The book starts with a historical introduction to plant electrophysiology, followed by two distinct parts. The first one deals with methods in plant electrophysiology, including, amongst others, measuring membrane potentials and ion fluxes, path-clamp technique, and electrochemical sensors. The second part covers experimental results and their theoretical interpretation.
•Cold plasma can oxidize N2 to HNO3 at the plasma-air/water interface.•Acidification of water correlates with an increase in HNOx concentration in the aqueous phase.•The mechanisms of the interfacial ...multielectron reactions are evaluated.•Plasma-activated water can be used for disinfection, sterilization, and decontamination.•Plasma-induced N2 fixation can be used for production of nitrogen compounds.
There are three major multi-electron reactions in nature: nitrogen fixation by bacteria, water oxidation in photosynthesis, and oxygen reduction during respiration. Here we found that a cold atmospheric pressure He-plasma jet (CAPPJ) can oxidize N2 to HNO3 and HNO2 at low temperature and atmospheric pressure at the plasma-air/water interface. Redox reactions induced by cold plasma occur not only at the plasma/air and plasma/water interfaces, but also in the volume of the aqueous phase. Analysis of the images which displayed the presence of pH indicators in the aqueous phase showed that redox reactions and acid formation occur at the plasma-air/water interface and the products of electrochemical reactions slowly diffuse into the bulk of the aqueous solution. Acidification of an aqueous solution during the CAPPJ treatment correlates with an increase in HNOx concentration in the aqueous phase. HNO2 is unstable and can be oxidized to HNO3 by plasma-generated H2O2 or ozone. The mechanisms of the interfacial multielectron reactions at the plasma-air/water interface are discussed and evaluated. Plasma-activated water can be used in medicine, food industry, and agriculture for disinfection, sterilization, and decontamination. Plasma-induced production of HNOx at the plasma/water interface at room temperature and atmospheric pressure can be used in the industry for nitrogen fixation and production of nitrogen compounds, replacing the expensive old technology processes.
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