Reactive oxygen species mediate growth and death in submerged plants

Aquatic and semi-aquatic plants are well adapted to survive partial or complete submergence which is commonly accompanied by oxygen deprivation. The gaseous hormone ethylene controls a number of adaptive responses to submergence including adventitious root growth and aerenchyma formation. Reactive oxygen species (ROS) act as signaling intermediates in ethylene-controlled submergence adaptation and possibly also independent of ethylene. ROS levels are controlled by synthesis, enzymatic metabolism, and non-enzymatic scavenging. While the actors are by and large known, we still have to learn about altered ROS at the subcellular level and how they are brought about, and the signaling cascades that trigger a specific response. This review briefly summarizes our knowledge on the contribution of ROS to submergence adaptation and describes spectrophotometrical, histochemical, and live cell imaging detection methods that have been used to study changes in ROS abundance. Electron paramagnetic resonance (EPR) spectroscopy is introduced as a method that allows identification and quantification of specific ROS in cell compartments. The use of advanced technologies such as EPR spectroscopy will be necessary to untangle the intricate and partially interwoven signaling networks of ethylene and ROS

Interlaboratory study on lipid oxidation during accelerated storage trials with rapeseed and sunflower oil analyzed by conjugated dienes as primary oxidation products

11 Páginas.-- 5 Figuras.-- 2 Tablas.-- Material suplementarioAccelerated storage tests are frequently used to assess the oxidative stability of foods and related systems due to its reproducibility. Various methods and experimental conditions are used to measure lipid oxidation. Differences between laboratories make it necessary to determine the repeatability and reproducibility of oxidation tests performed under the same conditions. The objective of the present interlaboratory study was to evaluate the outcome of a storage test for two different bulk oils, sunflower oil (SFO) and rapeseed oil (RSO), during a period of 9 weeks at 20°C, 30°C, 40°C, and 60°C. Sixteen laboratories were provided with bottled oils and conducted the storage tests according to a detailed protocol. Lipid oxidation was monitored by the formation of conjugated dienes (CD) and the activation energy (Ea) was determined for comparative purposes and statistically evaluated. An increase in CD formation was observed for both oils when the storage temperature was increased in all laboratories. The Ea,1 ranged from 47.9 to 73.3 kJ mol−1 in RSO and from 27.8 to 62.6 kJ mol−1 in SFO, with average values of 58.2 and 46.8 kJ mol−1, respectively. The reproducibility coefficients were 10.9% and 18.2% for RSO and SFO, respectively. Practical applications: In order to compare results on oxidative stability of foods derived from different studies, the reproducibility of storage tests and methods employed to evaluate the oxidation level should be considered. This study provides fundamental data on the reproducibility of lipid oxidation under accelerated storage conditions and defines important parameters to be considered for the conduction of experiments.Open access funding enabled and organized by Projekt DEAL. We thank Brökelmann + Co – Oelmühle GmbH + Co for the donation of the vegetable oils. The authors gratefully acknowledge Lina Stuthmann from the Food Technology Division, Kiel University and Inge Holmberg from the National Food Institute, Technical University of Denmark for their skillful help.Peer reviewe

Ružička days : International conference 16th Ružička Days “Today Science – Tomorrow Industry” : Proceedings

Proceedings contains articles presented at Conference divided into sections: open lecture (1), chemical analysis and synthesis (3), chemical and biochemical engineering (8), food technology and biotechnology (8), medical chemistry and pharmacy (3), environmental protection (11) and meeting of young chemists (2)

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

EPR spectroscopy and its use in planta - a promising technique to disentangle the origin of specific ROS

While it is widely accepted that reactive oxygen species (ROS) are common players in developmental processes and a large number of adaptations to abiotic and biotic stresses in plants, we still do not know a lot about ROS level control at cellular or organelle level. One major problem that makes ROS hard to quantify and even to identify is their short lifetime. A promising technique that helps to understand ROS level control in planta is the electron paramagnetic resonance (EPR) spectroscopy. Application of the spin trapping method and the spin probe technique by this advanced method enables the quantification and identification of specific ROS in different plant tissues, cells or organelles or under different conditions. This mini review summarizes the knowledge using EPR spectroscopy as a method for ROS detection in plants under different stress conditions or during development. This technique allows disentangling the origin of specific ROS and transient alteration in ROS levels that occur by changes in ROS production and scavenging

Analysis of Natural and Engineered Amyloid Aggregates by Spectroscopic and Scattering Techniques

The increasing knowledge about natural functional fibrils has triggered the interest in synthetic or engineered fibrils. Naturally occurring amyloid fibrils (functional and pathogenic) have been analyzed for many years at different structural levels. Engineered fibrils are structurally similar to natural fibrils and the main sub-structural feature of amyloids is characterized by cross-beta structure stabilizing the fibril formation. However, a number of peculiarities exist comparing natural and engineered fibrils that may affect their analysis, especially in spectroscopic and scattering methods. For this reason, several methods that are commonly used for natural fibril analysis are presented and particularities for their application in the characterization of engineered fibrils are described. In addition, the understanding about structure–function relation of fibrils studied in the different research areas may mutually improve when using the same analytical approaches for natural and engineered fibril

Functional ethanol-induced fibrils: Influence of solvents and temperature on amyloid-like aggregation of beta-lactoglobulin

Solvent-induced fibrillar aggregates of beta-lactoglobulin occur only in a certain balance between hydrophobic forces and electrostatic interactions. We hypothesize, that different hydrophobic solvent molecules as well as rising temperatures influence this equilibrium and thus the optimum to produce amyloid aggregates. Dimethyl sulfoxide (DMSO), methanol and ethanol all resulted in polydisperse solutions with worm-like and spherical-aggregates, albeit to different degrees: the volume fraction required for aggregation was DMSO (50%) > methanol (40%) > ethanol (30%) which does not reflect their hydrophobicity. Further solvent addition decreased the fibrillar aggregation again. Increasing the temperature by 10–20 K decreased the solvent concentration needed to induce amyloid-like aggregates. A targeted production of solvent-based amyloid-like aggregates is therefore not only dependent on the hydrophobicity of the solvents, but also on their direct interaction with the protein (denaturation).</p

Functionality of whey proteins covalently modified by allyl isothiocyanate. Part 2 : Influence of the protein modification on the surface activity in an O/W system

Allyl isothiocyanate (AITC) is a small electrophilic molecule which can be found in cabbage after degradation of glucosinolates. The covalent attachment of AITC to whey protein isolate (WPI) was previously reported to increase their hydrophobicity and structural flexibility at acidic pH values. It is thus hypothesized, that the o/w interface adsorption behaviour and interfacial structure will be altered. To further understand the effect of the AITC-modification on the emulsifying capacity, adsorption kinetic and interfacial properties of unmodified and modified WPI were investigated at the o/w interface. The WPI-modification resulted in a significantly increased surface adsorption kinetic and a lower equilibrium interfacial tension at acidic pH values. The ratio of α-lactalbumin (ALA) and β-lactoglobulin (BLG) at the oil droplet surface differed between unmodified and modified WPI (modBLG > ALA+modALA). Several layers of loosely attached proteins were evident on the oil droplet surface in all modified WPI emulsions. The hyperfine coupling (aN) of the EPR spin probe TB residing at the oil droplet surface reflected an increased hydrophobicity of the modified proteins. A lower order parameter (S) in the lipid phase of the modified WPI emulsions gave evidence of an altered alignment of the modified proteins at the interface, probably sticking into the oil phase. In conclusion, the present results indicate that the increased flexibility and hydrophobicity of the modified whey proteins, especially of modified BLG, surpass the surface activity of unmodified ALA in acidic pH values

Identification of an optimized ratio of amyloid and non-amyloid fractions in engineered fibril solutions from whey protein isolate for improved foaming

Engineered fibril solutions from whey protein beta-lactoglobulin are known for their excellent foaming capacity. These amyloid aggregates solutions (AAS) usually contain a polydisperse mixture of different protein structures. An optimized ratio of amyloid (AF, fibrils) and non-amyloid fractions (n-AF) in AAS may improve foaming, particularly by interactions at the air-water interface. Foamability, surface activity, and monolayer phase behavior at the air-water interface of isolated AF and n-AF as well as AAS with different AF/n-AF-ratios were investigated using drop tensiometry, Langmuir trough and foam analysis. N-AF exhibited faster migration, twice as fast adsorption and thus faster spreading at the air-water interface than the fibrils (AF). N-AF required less energy to assemble in a liquid-expanded phase in a monolayer, i.e., they were more compressible in the monolayer than AF. This resulted in rapid stabilization of lamellae in foam. High surface hydrophobicity of AF results in faster adsorption and formation of capillary forces between adsorbed fibrils, improving the attraction for additional fibrils. Orientation of semi-flexible and larger fibrils in AF consumes high energy. In combination with n-AF, the energy needed for orientation and assembly of fibrils is equivalent, however, the yield of AF in AAS was only 20 %, indicating the interplay of amyloid and non-amyloid proteins at the air-water interface. N-AF can be incorporated into a fibrillar film, which increase the network's density and stiffness and the interfacial film stability. Consequently, in AAS fibrils and non-amyloid material acted synergistically at the air-water interface, whereby only small amounts of amyloid aggregates are required to stabilize foams