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The moss calyptra: A maternal structure influencing offspring development

BRYOLOGIST 2019年第3期122卷 471-491页

作者： Budke, Jessica M. Univ Tennessee Dept Ecol & Evolutionary Biol Knoxville TN 37996 USA

The calyptra is a small, maternal gametophyte structure that covers the apex of the offspring sporophyte and is critical for the transition from seta formation to capsule differentiation in many moss taxa. It has been hypothesized to function by (1) providing a mechanical constraint that coordinates the development of the presumptive capsule, (2) secreting hormones that influence sporangium differentiation, (3) physically protecting the undifferentiated capsule region, (4) preventing water loss from the sporophyte apex, and/or (5) lowering the rate of sporophyte transpiration. This review explores the experiments that have tested these hypotheses and the evidence that has been found to support or refute them from scientific literature dating back to the late 1700's. Across mosses, calyptrae come in a wide array of shapes and sizes, which may correlate with aspects of morphology, habitat, and function. The overarching objective of this paper is to renew discussion about and research into this small, but important moss organ.

关键词： Anatomy dehiscence development gametophyte mosses morphology sporophyte structure-function relationships maternal effects reproductive biology

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Quercetin and catechin assuage redox imbalance and neurochemical dysfunction in rotenone-induced neurotoxicity: A comparative in vivo experiment supported by in silico study

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Phytomedicine Plus 2021年第4期1卷 100077-100077页

作者： Solomon Josiah, Sunday Umar, Haruna Isiyaku Saliu, Ibrahim Olabayode Akinmoladun, Afolabi Clement Department of Biochemistry School of Sciences The Federal University of Technology P.M.B. 704 Akure 340001 Nigeria

Background: Quercetin and catechin are structurally-related compounds that are capable of preventing or attenuating oxidative damage and mitochondrial dysfunction. Rotenone is a naturally occurring compound that has been used to model neurotoxicity characterized by Parkinson disease-like symptoms. Purpose: This study investigated the comparative property of quercetin and catechin, to ameliorate oxidative damage and neurochemical dysfunction in hippocampal and cortical regions of brain of rats intoxicated with rotenone in vivo, supported by in silico study. Method: Male Wistar rats were subcutaneously administered rotenone for 10 days followed by post-treatment with catechin or quercetin (5, 10 and 20 mg/kg) for 3 days. Markers of oxidative stress and neurochemical dysfunction were biochemically estimated in the hippocampus and cortex of the brain of rats while in silico study was carried out to evaluate the molecular interaction of some neurochemical enzymes with the compounds. Result: Quercetin and catechin ameliorated the reduction in complex 1 and Na⁺K⁺ATPase activities while attenuating the elevated lactate dehydrogenase activity in the brain of rotenone-intoxicated rats. Disturbances in acetylcholine, dopamine and glutamate metabolism as well as the evoked oxidative stress in rotenone-intoxicated rats were mitigated by quercetin and catechin. The in silico study revealed the key molecular interaction between the flavonoids and targeted enzymes (tyrosine hydroxylase, monoamine oxidase, glutamine synthetase and Na⁺K⁺ATPase) to be by hydrogen bond and hydrophobic interaction. Conclusion: Catechin and quercetin significantly assuaged cortical and hippocampal redox stress and attenuated neurochemical dysfunction caused by rotenone toxicity. Furthermore, this study highlighted that the neuroprotective potentials of the flavonoids is a function of their structural patterns, and quercetin elicited superior activity over catec

关键词： Catechin In silico Neurotoxicity Quercetin Rotenone structure-function relationships

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Hydrogen evolution reaction on copper: Promoting water dissociation by tuning the surface oxophilicity

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ELECTROCHEMISTRY COMMUNICATIONS 2019年 100卷 30-33页

作者： Bergamo Dias Martins, Pedro Farinazzo Lopes, Pietro Papa Ticianelli, Edson A. Stamenkovic, Vojislav R. Markovic, Nenad M. Strmcnik, Dusan Argonne Natl Lab Mat Sci Div 9700 S Cass Ave Lemont IL 60439 USA Univ Sao Paulo Inst Quim Sao Carlos 400 Ave Trabalhador Saoo Carlense BR-13560970 Sao Carlos SP Brazil

In order to probe the hydroxyl (OHad) adsorption energy as one of the possible descriptors for hydrogen evolution reaction (HER) in alkaline media, we performed studies on polycrystalline copper (Cu(Poly)), a well-known poor catalyst for HER. By employing three different preparation methods for Cu(Poly), we were able to establish links between surface oxidation extent, oxophilicity, hydrophilicity and their catalytic activity for the HER. Ultimately, we propose that the formation of Cu(I)-OHad---OH2 activated complex is essential for lowering the energy barrier for water dissociation, which leads to higher activity for the HER in alkaline media.

关键词： Hydrogen evolution reaction Electrocatalysis Surface science Copper structure-function relationships

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Active Site-Induced Evolutionary Constraints Follow Fold Polarity Principles in Soluble Globular Enzymes

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MOLECULAR BIOLOGY AND EVOLUTION 2019年第8期36卷 1728-1733页

作者： Mayorov, Alexander Dal Peraro, Matteo Abriata, Luciano A. Univ Cambridge Dept Chem Cambridge England Ecole Polytech Fed Lausanne Lab Biomol Modeling Lausanne Switzerland Swiss Inst Bioinformat Lausanne Switzerland Ecole Polytech Fed Lausanne Prot Prod & Struct Core Facil Lausanne Switzerland

A recent analysis of evolutionary rates in >500 globular soluble enzymes revealed pervasive conservation gradients toward catalytic residues. By looking at amino acid preference profiles rather than evolutionary rates in the same data set, we quantified the effects of active sites on site-specific constraints for physicochemical traits. We found that conservation gradients respond to constraints for polarity, hydrophobicity, flexibility, rigidity and structure in ways consistent with fold polarity principles;while sites far from active sites seem to experience no physicochemical constraint, rather being highly variable and favoring amino acids of low metabolic cost. Globally, our results highlight that amino acid variation contains finer information about protein structure than usually regarded in evolutionary models, and that this information is retrievable automatically with simple fits. We propose that analyses of the kind presented here incorporated into models of protein evolution should allow for better description of the physical chemistry that underlies molecular evolution.

关键词： protein evolution fold polarity structure-constrained evolution structure-function relationships protein biophysics structural biology

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Correlative Analysis of Specific Compatibilization in Composites by Coupling in situ X-Ray Scattering and Mechanical Tensile Testing

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FRONTIERS IN MATERIALS 2020年 6卷

作者： Seidt, Britta Samsoninkova, Valeria Hansske, Felix Gjardy, Andre Fratzl, Peter Boerner, Hans G. Wagermaier, Wolfgang Max Planck Inst Colloids & Interfaces Dept Biomat Potsdam Germany Humboldt Univ Sch Analyt Sci Adlershof Berlin Germany Humboldt Univ Dept Chem Lab Organ Synth Funct Syst Berlin Germany

In this study, a bio-inspired hybrid material is investigated by in situ X-ray scattering experiments in combination with mechanical tensile testing. The material is composed of nanometer-sized spherical magnesium fluoride particles which are linked via material-specific peptide poly(ethylene glycol)-PEG conjugates to a semi-crystalline poly(ethylene oxide) PEO matrix. Mechanically relevant changes in crystal size and orientation in the PEO matrix are followed by wide angle X-ray scattering during the application of tensile stress. The amorphous phase of PEO is stabilized by the surface-engineered MgF2 nanoparticles, leading to increased Young's modulus and tensile strength. Furthermore, small angle X-ray scattering experiments allowed the identification of a layer on the MgF2 particle surfaces, which increases in thickness with the conjugate amount and leads to suppression of the agglomeration of MgF2 nanoparticles. In conclusion, the use of selected peptide-PEG conjugates tailored to link MgF2 particles to a PEO matrix successfully mimics the biological principle of interface polymers and suggests new directions for material fabrication for bio-applications.

关键词： wide and small angle X-ray scattering peptide-polymer conjugate structure-function relationships interface stabilization functional material

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Expression and purification of recombinant extracellular sulfatase HSulf-2 allows deciphering of enzyme sub-domain coordinated role for the binding and 6-O-desulfation of heparan sulfate

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CELLULAR AND MOLECULAR LIFE SCIENCES 2019年第9期76卷 1807-1819页

作者： Seffouh, Amal El Masri, Rana Makshakova, Olga Gout, Evelyne Hassoun, Zahra el Oula Andrieu, Jean-pierre Lortat-Jacob, Hugues Vives, Romain R. Univ Grenoble Alpes CNRS CEA IBS F-38000 Grenoble France RAS FRC Kazan Sci Ctr Kazan Inst Biochem & Biophys Kazan Russia IBS 71 Ave Martyrs CS 10090 F-38044 Grenoble 9 France

Through their ability to edit 6-O-sulfation pattern of iHeparan sulfate (HS) polysaccharides, Sulf extracellular endosulfatases have emerged as critical regulators of many biological processes, including tumor progression. However, study of Sulfs remains extremely intricate and progress in characterizing their functional and structural features has been hampered by limited access to recombinant enzyme. In this study, we unlock this critical bottleneck, by reporting an efficient expression and purification system of recombinant HSulf-2 in mammalian HEK293 cells. This novel source of enzyme enabled us to investigate the way the enzyme domain organization dictates its functional properties. By generating mutants, we confirmed previous studies that HSulf-2 catalytic (CAT) domain was sufficient to elicit arylsulfatase activity and that its hydrophilic (HD) domain was necessary for the enzyme 6-O-endosulfatase activity. However, we demonstrated for the first time that high-affinity binding of HS substrates occurred through the coordinated action of both domains, and we identified and characterized 2 novel HS binding sites within the CAT domain. Altogether, our findings contribute to better understand the molecular mechanism governing HSulf-2 substrate recognition and processing. Furthermore, access to purified recombinant protein opens new perspectives for the resolution of HSulf structure and molecular features, as well as for the development of Sulf-specific inhibitors.

关键词： Glycosaminoglycan structure-function relationships Extracellular matrix Glycocalyx Heparin

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Glycoform-resolved FcγRIIIa affinity chromatography-mass spectrometry

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MABS 2019年第7期11卷 1191-1196页

作者： Lippold, Steffen Nicolardi, Simone Dominguez-Vega, Elena Heidenreich, Anna-Katharina Vidarsson, Gestur Reusch, Dietmar Haberger, Markus Wuhrer, Manfred Falck, David Leiden Univ Med Ctr Ctr Prote & Metabol Leiden Netherlands Roche Diagnost GmbH Pharma Tech Dev Penzberg Penzberg Germany Univ Amsterdam Dept Expt Immunohematol Sanquin Res & Landsteiner Lab Amsterdam UMC Amsterdam Netherlands

Determination of the impact of individual antibody glycoforms on Fc gamma RIIIa affinity, and consequently antibody-dependent cell-mediated cytotoxicity (ADCC) previously required high purity glycoengineering. We hyphenated Fc gamma RIIIa affinity chromatography to mass spectrometry, which allowed direct affinity comparison of glycoforms of intact monoclonal antibodies. The approach enabled reproduction and refinement of known glycosylation effects, and insights on afucosylation pairing as well as on low-abundant, unstudied glycoforms. Our method greatly improves the understanding of individual glycoform structure-function relationships. Thus, it is highly relevant for assessing Fc-glycosylation critical quality attributes related to ADCC.

关键词： Monoclonal antibody (mAb) Fc gamma RIIIa affinity chromatography IgG Fc glycosylation immunoglobulin glycans mass spectrometry FT-ICR-MS structure-function relationships

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A novel crosslinking protocol stabilizes amyloid β oligomers capable of inducing Alzheimer's-associated pathologies

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JOURNAL OF NEUROCHEMISTRY 2019年第6期148卷 822-836页

作者： Cline, Erika N. Das, Arighno Bicca, Maira Assuncao Mohammad, Saad N. Schachner, Luis F. Kamel, Josette M. DiNunno, Nadia Weng, Anthea Paschall, Jacob D. Lo Bu, Riana Khan, Faraz M. Rollins, Madeline G. Ives, Ashley N. Shekhawat, Gajendra Nunes-Tavares, Nilson de Mello, Fernando G. Compton, Philip D. Kelleher, Neil L. Klein, William L. Northwestern Univ Dept Neurobiol Evanston IL 60208 USA Northwestern Univ Dept Chem & Biol Engn Evanston IL USA Northwestern Univ Dept Chem Evanston IL USA Northwestern Univ Dept Mol Biosci Evanston IL USA Northwestern Univ Prote Ctr Excellence Evanston IL USA Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA Univ Fed Rio de Janeiro Inst Biofis Carlo Chagas Filho Rio De Janeiro Brazil

Amyloid beta oligomers (A beta Os) accumulate early in Alzheimer's disease (AD) and experimentally cause memory dysfunction and the major pathologies associated with AD, for example, tau abnormalities, synapse loss, oxidative damage, and cognitive dysfunction. In order to develop the most effective A beta O-targeting diagnostics and therapeutics, the A beta O structures contributing to AD-associated toxicity must be elucidated. Here, we investigate the structural properties and pathogenic relevance of A beta Os stabilized by the bifunctional crosslinker 1,5-difluoro-2,4-dinitrobenzene (DFDNB). We find that DFDNB stabilizes synthetic A beta in a soluble oligomeric conformation. With DFDNB, solutions of A beta that would otherwise convert to large aggregates instead yield solutions of stable A beta Os, predominantly in the 50-300 kDa range, that are maintained for at least 12 days at 37 degrees C. structures were determined by biochemical and native top-down mass spectrometry analyses. Assayed in neuronal cultures and i.c.v.-injected mice, the DFDNB-stabilized A beta Os were found to induce tau hyperphosphorylation, inhibit choline acetyltransferase, and provoke neuroinflammation. Most interestingly, DFDNB crosslinking was found to stabilize an A beta O conformation particularly potent in inducing memory dysfunction in mice. Taken together, these data support the utility of DFDNB crosslinking as a tool for stabilizing pathogenic A beta Os in structure-function studies.

关键词： Alzheimer's disease amyloid beta oligomers crosslinking DFDNB structure-function relationships

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Waxes derived from self-metathesis modified plant oil blends - A case for exploiting oligomerization to mitigate low molecular mass and unsaturation

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INDUSTRIAL CROPS AND PRODUCTS 2020年 143卷 111936-000页

作者： Mohanan, Athira Bouzidi, Laziz Narine, Suresh S. Trent Univ Dept Phys & Astron Trent Ctr Biomat Res 1600 West Bank Dr Peterborough ON K9J 0G2 Canada Trent Univ Dept Chem Trent Ctr Biomat Res 1600 West Bank Dr Peterborough ON K9J 0G2 Canada

The self-metathesis of vegetable oil blends was explored as a means for making functional and environmentally adapted waxes. Several mixtures of soybean oil (SBO) and palm oil (PO), the most readily available triacylglycerol (TAG) oils, were investigated as model unsaturated/saturated systems to determine the advantages and limits of using such blends. The objective was to control the balance between unsaturation which tend to keep the material fluid at low temperature and saturation coupled with the self-metathesis induced oligomerization which promote crystallization and gelling for optimal wax applications. Five compositions of SBO and PO were metathesized and characterized for thermal transition behavior, solid fat content, microstructure, viscosity and hardness;parameters relevant to the functionality of waxes. The characteristic physical properties versus concentration presented peak-shaped curves with maxima at 15 %w/w SBO. This trend is explained by the modification to the molecular ensemble introduced by the self-metathesis, depleting the low melting species (liquid fraction) and enriching the high temperature melting species (solid fraction). The induced oligomerization combined with the pre-existing saturation which promote solidification are demonstrated to counterbalance the fluidization effect of unsaturation to a tipping point after which the unsaturation is overwhelming. The study shows that although limited in extent, appropriate blending can be an economical and effective tool to shift the crystallization toward room temperature of otherwise liquid TAG derivatives and improve their wax properties.

关键词： Self-metathesis Vegetable oils Oligomer Lipid-based waxes structure-function relationships

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relationships between Leaf Anatomy and Physiological functioning of Southern US Oak Species Differing in Flood Tolerance

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FORESTS 2020年第1期11卷 73页

作者： Renninger, Heidi Durbin, Tyler Gentry, Austin Kassahun, Zeima Mississippi State Univ Dept Forestry Mississippi State MS 39762 USA

Research Highlights: Bottomland oaks receive less attention than upland species, however their adaptations to flooding and summer water stress will extend our understanding of the oak genus and links between physiology and leaf anatomy. Background and objectives: Determining links between leaf anatomy and physiology can aid in parameterizing dynamic global vegetation models for oak systems, therefore we sought to (1) compare leaf anatomic, nutrient, and physiological parameters for bottomland oaks differing in flood tolerance, (2) determine correlations across parameters and determine which anatomic and nutrient parameters best predict photosynthetic capacity metrics, and (3) compare these data with reported literature values for oaks across the globe. Materials and Methods: We measured CO2 response curves (A/C-i) on leaves from Nuttall, Shumard, swamp chestnut, water and white oak seedlings planted in the Southeastern United States (US) and estimated stomatal size and density, epidermal cell size, vein density, leaf mass per area (LMA) and nitrogen (N) concentrations. Principal component analysis among these leaf anatomic and nutrient parameters was used to determine the best predictors of photosynthetic parameters including Rubisco-limited carboxylation rate (V-C(max)) and electron transport limited carboxylation rate (J(max)). Results: We found that although physiological parameters were similar, flood-tolerant oaks had lower leaf N concentrations and larger, more infrequent stomata than less flood-tolerant species. Leaf epidermal properties were correlated with N concentrations and a principal component capturing this correlation as well as principal components correlated with mesophyll conductance and leaf carbon concentrations were found to best explain variation in V-Cmax and J(max). These Southeastern US oaks exhibited similar leaf physiological parameters and LMA as oaks reported in the literature but differed in leaf epidermal and stomatal properties as we

关键词： A/C-i curves Quercus photosynthetic capacity principal component analysis structure-function relationships water use efficiency

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