Response Mechanism of Polymeric Liquid Junction-Free Reference Electrodes Based on Organic Electrolytes.

To achieve a transition from conventional liquid-junction reference electrodes (LJF REs) to their all-solid-state alternatives, organic electrolytes are often introduced into the polymeric electrode membranes. In this article, we implement a theoretical approach to the explanation and quantification of the boundary potential stabilization phenomenon for the electrodes modified with organic electrolytes (QB). For the first time, stabilization of the phase boundary potential due to the partition of lipophilic ions of the QB electrolyte between the polymeric and aqueous phases is numerically simulated to predict the LJF electrodes behavior.

Affinity-based alleviation of dissolved organic matter (DOM) on tetracycline toxicity to photosynthesis of green algae Chlorella vulgaris: roles of hydrophilic and hydrophobic DOM.

The environmental fate and toxic effects of antibiotics such as tetracycline (TC) could be influenced by the ubiquitous dissolved organic matter (DOM). However, DOM from different origins has different hydrophilic and hydrophobic properties. It is still unknown the effects of hydrophilic and hydrophobic DOM on the toxic effect of TC.

Time Is a Critical Factor When Evaluating Oligonucleotide Therapeutics in hERG Assays.

In accord with International Conference on Harmonization S7B guidelines, an human ether-a-go-go-related gene (hERG) assay is one component of an integrated risk assessment for delayed ventricular repolarization. Function of hERG could be affected by direct (acute) mechanisms, or by indirect (chronic) mechanisms. Some approved oligonucleotide therapeutics had submitted hERG data to regulatory agents, which were all collected with the same protocol used for small-molecule testing (incubation time <20 min; acute), however, oligonucleotides have unique mechanisms and time courses of action (indirect).

2-Hydroxychalcone as a Novel Natural Photosynthesis Inhibitor against Bloom-Forming Cyanobacteria.

The control of harmful cyanobacterial blooms has been becoming a global challenge. The development of eco-friendly algicides with strong specificity is urgently needed. The photosynthetic apparatus is a promising target site for algicides to minimize the possible harmful effects on animals and humans.

Regulation of light energy conversion between linear and cyclic electron flow within photosystem II controlled by the plastoquinone/quinol redox poise.

Ultrapurified Photosystem II complexes crystalize as uniform microcrystals (PSIIX) of unprecedented homogeneity that allow observation of details previously unachievable, including the longest sustained oscillations of flash-induced O yield over > 200 flashes and a novel period-4.7 water oxidation cycle. We provide new evidence for a molecular-based mechanism for PSII-cyclic electron flow that accounts for switching from linear to cyclic electron flow within PSII as the downstream PQ/PQH pool reduces in response to metabolic needs and environmental input.

Functional Water Networks in Fully Hydrated Photosystem II.

Water channels and networks within photosystem II (PSII) of oxygenic photosynthesis are critical for enzyme structure and function. They control substrate delivery to the oxygen-evolving center and mediate proton transfer at both the oxidative and reductive endpoints. Current views on PSII hydration are derived from protein crystallography, but structural information may be compromised by sample dehydration and technical limitations.

Insights into melatonin-induced photosynthetic electron transport under low-temperature stress in cucumber.

In this study, the differences in chlorophyll fluorescence transient (OJIP) and modulated 820 nm reflection (MR) of cucumber leaves were probed to demonstrate an insight into the precise influence of melatonin (MT) on cucumber photosystems under low temperature stress. We pre-treated cucumber seedlings with different levels of MT (0, 25, 50, 100, 200, and 400 μmol · L) before imposing low temperature stress (10 °C/6 °C). The results indicated that moderate concentrations of MT had a positive effect on the growth of low temperature-stressed cucumber seedlings.

Electron Transfer Route between Quinones in Type-II Reaction Centers.

In photosynthetic reaction centers from purple bacteria (PbRCs) and photosystem II (PSII), the photoinduced charge separation is terminated by an electron transfer between the primary (Q) and secondary (Q) quinones. Here, we investigate the electron transfer route, calculating the superexchange coupling () for electron transfer from Q to Q in the protein environment. is significantly larger in PbRC than in PSII.

Crystal structures of photosystem II from a cyanobacterium expressing psbA in comparison to psbA reveal differences in the D1 subunit.

Three psbA genes (psbA, psbA, and psbA) encoding the D1 subunit of photosystem II (PSII) are present in the thermophilic cyanobacterium Thermosynechococcus elongatus and are expressed differently in response to changes in the growth environment. To clarify the functional differences of the D1 protein expressed from these psbA genes, PSII dimers from two strains, each expressing only one psbA gene (psbA or psbA), were crystallized, and we analyzed their structures at resolutions comparable to previously studied PsbA1-PSII. Our results showed that the hydrogen bond between pheophytin/D1 (Pheo) and D1-130 became stronger in PsbA2- and PsbA3-PSII due to change of Gln to Glu, which partially explains the increase in the redox potential of Pheo observed in PsbA3.

The effect of adulteration with a bitter tastant, denatonium benzoate, on the reinforcing value of sucrose.

According to the Multiplicative Hyperbolic Model of reinforcer value (MHM), the value of a reinforcer is an increasing hyperbolic function of its size (q). A recent experiment examined the effect of adulterating a sucrose solution with citric acid on the value of a sucrose reinforcer. In contrast to expectations derived from MHM, the effect of citric acid was consistent with the summation of positive (sucrose) and negative (citric acid) values.

Tools for analyzing protonation states and for tracing proton transfer pathways with examples from the Rb. sphaeroides photosynthetic reaction centers.

Protons participate in many reactions. In proteins, protons need paths to move in and out of buried active sites. The vectorial movement of protons coupled to electron transfer reactions establishes the transmembrane electrochemical gradient used for many reactions, including ATP synthesis.

Effect of Mycotoxin Cytochalasin A on Photosystem II in .

Biological herbicides have received much attention due to their abundant resources, low development cost, unique targets and environmental friendliness. This study reveals some interesting effects of mycotoxin cytochalasin A (CA) on photosystem II (PSII). Our results suggested that CA causes leaf lesions on due to its multiple effects on PSII.

Iron Deficiency Promotes the Lack of Photosynthetic Cytochrome and Affects the Binding of the Luminal Extrinsic Subunits to Photosystem II in the Diatom .

In the diatom , iron limitation promotes a decrease in the content of photosystem II, as determined by measurements of oxygen-evolving activity, thermoluminescence, chlorophyll fluorescence analyses and protein quantification methods. Thermoluminescence experiments also indicate that iron limitation induces subtle changes in the energetics of the recombination reaction between reduced Q and the S/S states of the water-splitting machinery. However, electron transfer from Q to Q, involving non-heme iron, seems not to be significantly inhibited.

An insight into algicidal characteristics of Bacillus altitudinis G3 from dysfunctional photosystem and overproduction of reactive oxygen species.

Cyanobacterial blooms negatively affect aquatic ecosystems and human health. Algicidal bacteria can efficiently kill bloom-causing cyanobacteria. Bacillus altitudinis G3 isolated from Dianchi Lake shows high algicidal activity against Microcystis aeruginosa.

Singlet oxygen production by photosystem II is caused by misses of the oxygen evolving complex.

Singlet oxygen ( O ) is a harmful species that functions also as a signaling molecule. In chloroplasts, O is produced via charge recombination reactions in photosystem II, but which recombination pathway(s) produce triplet Chl and O remains open. Furthermore, the role of O in photoinhibition is not clear.

Proton-mediated photoprotection mechanism in photosystem II.

Photo-induced charge separation, which is terminated by electron transfer from the primary quinone Q to the secondary quinone Q, provides the driving force for O evolution in photosystem II (PSII). However, the backward charge recombination using the same electron-transfer pathway leads to the triplet chlorophyll formation, generating harmful singlet-oxygen species. Here, we investigated the molecular mechanism of proton-mediated Q stabilization.

Results of the North American Complex Abdominal Aortic Debranching (NACAAD) Registry.

Background: Hybrid debranching repair of pararenal and thoracoabdominal aortic aneurysms was initially designed as a better alternative to standard open repair, addressing the limitations of endovascular repair involving the visceral aorta. We reviewed the collective outcomes of hybrid debranching repairs using extra-anatomic, open surgical debranching of the renal-mesenteric arteries, followed by endovascular aortic stenting.

Methods: Data from patients who underwent hybrid repair in 14 North American institutions during 10 years were retrospectively reviewed.

Intrinsic Adrenal TWIK-Related Acid-Sensitive TASK Channel Dysfunction Produces Spontaneous Calcium Oscillations Sufficient to Drive AngII (Angiotensin II)-Unresponsive Hyperaldosteronism.

Background: Ion channel mutations in calcium regulating genes strongly associate with AngII (angiotensin II)-independent aldosterone production. Here, we used an established mouse model of in vivo aldosterone autonomy, -driven deletion of TWIK-related acid-sensitive potassium channels (TASK-1 and TASK-3, termed zona glomerulosa [zG]-TASK-loss-of-function), and selective pharmacological TASK channel inhibition to determine whether channel dysfunction in native, electrically excitable zG cell rosette-assemblies: (1) produces spontaneous calcium oscillatory activity and (2) is sufficient to drive substantial aldosterone autonomy.

Methods: We imaged calcium activity in adrenal slices expressing a zG-specific calcium reporter (GCaMP3), an in vitro experimental approach that preserves the native rosette assembly and removes potentially confounding extra-adrenal contributions.

Macromolecular conformational changes in photosystem II: interaction between structure and function.

Conformational changes play an important role in the functioning of proteins and their complexes. This is also true for the pigment-protein super-complex of photosystem II (PSII). The data testify about the pH-induced macromolecular conformational changes in the water-oxidizing complex (WOC) on the donor side of PSII, the interaction between the spatial structure of WOC proteins and the distribution of cytochrome 559 redox-forms, and the electron transfer efficiency between Q and Q on the acceptor side of PSII.

Distribution characteristics of ABO blood groups in China.

ABO blood groups distribution shows obvious geographical differences globally, but the reliability of the Blood data for assessing relationships between population groups is limited. This is mostly due to the lack of availability and interchange of this important data. We collected data of 23 million ABO blood group population from 34 provincial-level administrative regions in China.

Prying into the green black-box.

Life-long efforts of the Tartu photosynthesis research group have been summarized. The measurements were facilitated by self-designed instruments, distinct in multifunctionality and fastresponse time. The black-box type kinetical analysis on intact leaves has revealed several physiologically significant features of leaf photosynthesis.

Growth, ROS accumulation site, and photosynthesis inhibition mechanism of Chlorella vulgaris by triclosan.

Although the addition of triclosan (TCS) in consumer products has been strictly restricted, its continuous applications in hospitals and other medical facilities and its numerous residues still pose a potential risk to aquatic organisms and aquatic ecosystems. In this study, we investigated the growth, biochemical alterations, and physiological responses of Chlorella vulgaris exposed to different concentrations of TCS. The potential toxicity mechanisms associated with excessive production of reactive oxygen species (ROS) and disruption of photosynthetic system II (PSII) were also analyzed.

Structure-based ligand design and discovery of novel tenuazonic acid derivatives with high herbicidal activity.

Introduction: Computer-aided design has become an important tool to develop novel pesticides based on natural lead compounds. Tenuazonic acid (TeA), a typical representative of the natural tetramic acid family, was patented as a potential bioherbicide. However, its herbicidal efficacy is still not up to the ideal standard of commercial products.

Coffee Leaf Tea from El Salvador: On-Site Production Considering Influences of Processing on Chemical Composition.

The production of coffee leaf tea () in El Salvador and the influences of processing steps on non-volatile compounds and volatile aroma-active compounds were investigated. The tea was produced according to the process steps of conventional tea () with the available possibilities on the farm. Influencing factors were the leaf type (old, young, yellow, shoots), processing (blending, cutting, rolling, freezing, steaming), drying (sun drying, oven drying, roasting) and fermentation (wild, yeast, ).