Acclimation Response of Green Microalgae Chlorella Sorokiniana to 2,3′,4,4′,6-Pentachlorobiphenyl

The effect of the toxicant 2,3′,4,4′,6-pentachlorobiphenyl (PCB-119) on the growth, chlorophyll content, and PSII activity of C. sorokiniana cells was investigated. A strong negative effect of the toxicant was observed at PCB concentration of 0.05 μg mL⁻¹, when culture growth ceased, chlorophyll strongly bleached, and cell death occurred. The use of original highly sensitive fluorimeter to measure three types of high-resolution chlorophyll fluorescence kinetics allowed us to detect an initial dramatic decrease in the activity of primary photosynthetic reactions, followed by their almost complete recovery at the end of the incubation period when most cells were dead. The study of the distribution of individual cells in culture in terms of F_v/F_m parameter, which reflects the quantum yield of PSII photochemistry, revealed the existence of 2–3% of cells retaining high F_v/F_m (>0.7) in the presence of the toxicant. The treated cultures were able to resume growth after prolonged incubation in fresh medium. The high sensitivity fluorescence methods used made it possible to identify stress-resistant cells which maintain high photosynthetic activity in the presence of lethal doses of toxic substances; these cells provide recovery of the population after stress.     

Acetylation Rather than H50Q Mutation Impacts the Kinetics of Cu(II) Binding to α-Synuclein

The interaction between α-synuclein (αSyn) and Cu²⁺ has been suggested to be closely linked to brain copper homeostasis. Disruption of copper levels could induce misfolding and aggregation of αSyn, and thus contribute to the progression of Parkinson's disease (PD). Understanding the molecular mechanism of αSyn-Cu²⁺ interaction is important and controversies in Cu²⁺ coordination geometry with αSyn still exists. Herein, we find that the pathological H50Q mutation has no impact on the kinetics of Cu²⁺ binding to the high-affinity site of wild type αSyn (WT-αSyn), indicating the non-involvement of His50 in high-affinity Cu²⁺ binding to WT-αSyn. In contrast, the physiological N-terminally acetylated αSyn (NAc-αSyn) displays several orders of magnitude weaker Cu²⁺ binding affinity than WT-αSyn. Cu²⁺ coordination mode to NAc-αSyn has also been proposed based on EPR spectrum. In addition, we find that Cu²⁺ coordinated WT-αSyn is reduction-active in the presence of GSH, but essentially inactive towards ascorbate. Our work provides new insights into αSyn-Cu²⁺ interaction, which may help understand the multifaceted normal functions of αSyn as well as pathological consequences of αSyn aggregation.     

Using nutritional and oxidative stress to increase content of healthbeneficial fatty acids in oleaginous and non-oleaginous yeasts

Yeast responses to stress conditions include an increase in lipid content and concomitant changes in content of saturated and unsaturated fatty acids. Some fatty acids are among the dietetically important fatty acids and new possibilities are sought for their biotechnological production in addition to those already exploited from marine organisms, nuts and other sources. The possibility of the production of palmitoleic and linoleic acids resulting from new approaches to traditional biotechnologically useful yeast species (Kluyveromyces polysporus, Saccharomyces cerevisiae, Torulospora delbrueckii) and species capable of high accumulation of lipids (Rhodotorula glutinis, Trichosporon cutaneum, Candida sp., Yarrowia lipolytica) was explored. The most promising was the combination of two stress factors: limitation of N-sources (C/N mass ratio of 70: 1) and oxidative stress induced by zero- valent iron nanoparticles. These conditions were conducive to the production of palmitoleic acid commonly used in cosmetics and medicine and ω-6-linoleic acid, a precursor of thromboxanes, prostaglandins and leucotrienes. The yield of these two fatty acids in T. cutaneum was more than 500 mg g^?1 (dry mass) and in Candida sp. more than 600 mg g-1 (dry mass).     

Time of acquisition and high spatial resolution mass spectrometry imaging

The field of mass spectrometry imaging (MSI) is constantly evolving to analyze a diverse array of biological systems. A common goal is the need to resolve cellular and subcellular heterogeneity with high spatial resolution. As the field continues to progress towards high spatial resolution, other parameters must be considered when developing a practical method. Here, we discuss the impacts of high spatial resolution on the time of acquisition and the associated implications they have on an MSI analysis (e.g., area of the region of interest). This work presents a brief tutorial serving to evaluate high spatial resolution MSI relative to time of acquisition and data file size.     

Stable Pyrrole-Linked Bioconjugates through Tetrazine-Triggered Azanorbornadiene Fragmentation

An azanorbornadiene bromovinyl sulfone reagent for cysteine-selective bioconjugation has been developed. Subsequent reaction with dipyridyl tetrazine leads to bond cleavage and formation of a pyrrole-linked conjugate. The latter involves ligation of the tetrazine to the azanorbornadiene-tagged protein through inverse electron demand Diels–Alder cycloaddition with subsequent double retro-Diels–Alder reactions to form a stable pyrrole linkage. The sequence of site-selective bioconjugation followed by bioorthogonal bond cleavage was efficiently employed for the labelling of three different proteins. This method benefits from easy preparation of these reagents, selectivity for cysteine, and stability after reaction with a commercial tetrazine, which has potential for the routine preparation of protein conjugates for chemical biology studies.     

Modulation of Uptake and Reactivity of Nitrogen Dioxide in Metal-Organic Framework Materials

We report the modulation of reactivity of nitrogen dioxide (NO₂) in a charged metal–organic framework (MOF) material, MFM-305-CH₃ in which unbound N-centres are methylated and the cationic charge counter-balanced by Cl⁻ ions in the pores. Uptake of NO₂ into MFM-305-CH₃ leads to reaction between NO₂ and Cl⁻ to give nitrosyl chloride (NOCl) and NO₃⁻ anions. A high dynamic uptake of 6.58 mmol g⁻¹ at 298 K is observed for MFM-305-CH₃ as measured using a flow of 500 ppm NO₂ in He. In contrast, the analogous neutral material, MFM-305, shows a much lower uptake of 2.38 mmol g⁻¹. The binding domains and reactivity of adsorbed NO₂ molecules within MFM-305-CH₃ and MFM-305 have been probed using in situ synchrotron X-ray diffraction, inelastic neutron scattering and by electron paramagnetic resonance, high-field solid-state nuclear magnetic resonance and UV/Vis spectroscopies. The design of charged porous sorbents provides a new platform to control the reactivity of corrosive air pollutants.     

Myosin-cross-reactive antigen (MCRA) protein from <Emphasis Type="Italic">Bifidobacterium breve</Emphasis> is a FAD-dependent fatty acid hydratase which has a function in stress protection

Background  

The aim of this study was to determine the catalytic activity and physiological role of myosin-cross-reactive antigen (MCRA) from Bifidobacterium breve NCIMB 702258. MCRA from B. breve NCIMB 702258 was cloned, sequenced and expressed in heterologous hosts (Lactococcus and Corynebacterium) and the recombinant proteins assessed for enzymatic activity against fatty acid substrates.     

Graphane Nanostripes

Graphane, the hydrogenated counterpart of graphene, was shown to exhibit properties such as tunable band gaps through varied degrees of hydrogenation, fluorescence, or ferromagnetism. Graphane nanostripe properties have also been theoretically predicted. Herein, we show that graphane nanostripes can be prepared by opening carbon nanotubes using Birch reduction in liquid ammonia utilizing potassium as a reducing agent and water as a proton donor. The prepared graphane nanostripes exhibit several exceptional properties when coupled with trace metal dopants. The interplay of metallic nanoparticles and defects lead to a spin polarization and induction of ferromagnetic moment, as well as to enhanced electrocatalytic properties in the hydrogen evolution reaction when compared to non‐hydrogenated carbon nanotubes.     

Amino Acid Functionalized Superparamagnetic Nanoparticles Inhibit Lysozyme Amyloid Fibrillization

Nanoparticles have great potential to be used in various biomedical applications, including therapy or diagnosis of amyloid-related diseases. The physical and chemical properties of iron oxide superparamagnetic nanoparticles (MNPs) functionalized with different amino acids (AAs), namely, with lysine (Lys), glycine (Gly), or tryptophan (Trp), have been characterized. The cytotoxicity of nanoparticles and their effect on amyloid fibrillization of lysozymes in vitro was also verified. The AA-MNPs under study are nontoxic to human SHSY5Y neuroblastoma cells. Moreover, the AA-MNPs were able to significantly inhibit lysozyme amyloid fibrillization and destroy amyloid fibrils. Kinetic studies revealed that the presence of AA-MNPs affected lysozyme fibrillization, namely, the lag phase and steady-state phase of the growth curves. The most effective activities were observed for Trp-MNPs, which revealed the importance of aromatic rings in the structure of AAs used as coating agents. The obtained results indicate the possible application of these AA-MNPs in the treatment of amyloid diseases associated with lysozyme or other amyloidogenic proteins.