Effect of Posttranslational Modifications on the Structure and Activity of FTO Demethylase

The FTO protein is involved in a wide range of physiological processes, including adipogenesis and osteogenesis. This two-domain protein belongs to the AlkB family of 2-oxoglutarate (2-OG)- and Fe(II)-dependent dioxygenases, displaying N⁶-methyladenosine (N⁶-meA) demethylase activity. The aim of the study was to characterize the relationships between the structure and activity of FTO. The effect of cofactors (Fe²⁺/Mn²⁺ and 2-OG), Ca²⁺ that do not bind at the catalytic site, and protein concentration on FTO properties expressed in either E. coli (^ECFTO) or baculovirus (^BESFTO) system were determined using biophysical methods (DSF, MST, SAXS) and biochemical techniques (size-exclusion chromatography, enzymatic assay). We found that ^BESFTO carries three phosphoserines (S184, S256, S260), while there were no such modifications in ^ECFTO. The S256D mutation mimicking the S256 phosphorylation moderately decreased FTO catalytic activity. In the presence of Ca²⁺, a slight stabilization of the FTO structure was observed, accompanied by a decrease in catalytic activity. Size exclusion chromatography and MST data confirmed the ability of FTO from both expression systems to form homodimers. The MST-determined dissociation constant of the FTO homodimer was consistent with their in vivo formation in human cells. Finally, a low-resolution structure of the FTO homodimer was built based on SAXS data.     

Broader Autism Phenotype in Siblings of Children with ASD—A Review

Although less pronounced, social, cognitive, and personality characteristics associated with autism spectrum disorders (ASD) may be present in people who do not meet ASD diagnostic criteria, especially in first-degree relatives of individuals with ASD. Research on these characteristics, referred to as broader autism phenotype (BAP), provides valuable data on potential expressions of autism-specific deficits in the context of family relations. This paper offers a review of research on BAP in siblings of individuals with ASD, focusing on reports regarding social, communication, and cognitive deficits, published from 1993 to 2014. The studies are divided into two groups based on participants’ age: papers on preschool and older siblings of individuals with ASD; and publications on infants at risk for ASD. On the basis of this review, suggestions are offered for further research and its significance for our understanding of the genetic determinants of autism.     

Multifunctional porous membranes with antibacterial properties

Abstract

The paper describes the results of research on obtaining porous membranes produced from polylactide fibers (PLA) by electrospinning, additionally modified with gentamicin antibiotic (GM) at the stage of preparing a spinning solution to provide bactericidal properties. Both solid (1^oPNF) and porous (2^oPNF 3^oPNF) polymer fibers were obtained, and the control of fiber porosity was achieved using various solvent systems: dichloromethane (DCM), dimethylformamide (DMF), chloroform (CHL) and dimethyl sulfoxide (DMSO). Three types of fibers differing in morphology (fiber diameter) and mean pore size were obtained. Physicochemical properties of porous and solid drug-containing fibers were examined, determining their surface free energy (SFE) and wetting angle (CA), and the effectiveness of modification with the drug was confirmed in spectroscopic studies (FTIR-ATR). Antibacterial activity of the prepared drug-modified nonwovens was confirmed by the disk diffusion method against Gram-negative Escherichia coli bacteria strain. The results of tests have shown that depending on the type of solvents used at the electrospinning stage, porous fibers can be obtained from polylactide. The addition of gentamicin affected antibacterial properties, and the pore size determined the rate of drug release monitored by the ion coupled plasma method (ICP).     

α‐Amino acids as initiators of ε‐caprolactone and L,L‐lactide polymerization

Biodegradable polymers/oligomers were successfully synthesized through a ring‐opening polymerization of ε‐caprolactone and L ,L ‐lactide, initiated by L ‐arginine and L ‐citrulline. The α‐amino acid initiators are natural, operationally simple, inexpensive, environmentally friendly and safe for human health. The polymerizations were performed with no solvents and without introducing any metal impurities. The chemical structures of the polymers obtained were elucidated using ¹H NMR, ¹³C NMR and Fourier transform infrared spectroscopies. In addition, incorporation of α‐amino acid molecules into the polymer chain was confirmed using matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry. Due to the significant biological activity of L ‐arginine and L ‐citrulline, these α‐amino acid initiators may open a new route for the synthesis of functional polymers especially for pharmaceutical applications. Copyright © 2011 Society of Chemical Industry     

Synthesis of polylactide/clay composites using structurally different kaolinites and kaolinite nanotubes

Polymer/clay nanocomposites receive much attention due to their interesting mechanical and thermal properties. Currently, the vast majority of plastics are made from petroleum-based synthetic polymers that do not degrade in a natural environment and their disposal poses a serious problem. An environmentally-conscious alternative is to design polymer nanocomposites that are biodegradable.In the present work the synthesis and properties of novel polymer/clay nanocomposites based on biodegradable polymer-polylactide (PLA) were investigated. Kaolinite nanotubes obtained by an intercalation/deintercalation method as well as platey kaolinites of different structural orders were used as fillers. Mechanical properties of composites (tensile strength (S_U) and Young's modulus (E)) were measured. The surface of the formed polymer derivatives was examined by AFM (Atomic Force Microscopy). The structural characterization was carried out using infrared spectroscopy (IR). Composites surface wettability was studied by measuring the water contact angle.The mechanical tests revealed that both S_U and E values increased significantly after addition of the nano-filler in comparison to the pure PLA. Regardless of the filler content the increase of S_U and E values was higher in the case of the nanotubular kaolinite. In particular, a threefold increase of the E value was noticed. For the most homogeneous kaolinite nanotubes/PLA nanocomposite S_U increased from ~ 29 MPa (pure PLA) to ~ 43 MPa, while E increased from ~ 0.7 GPa (pure PLA) to ~ 2.3 GPa. These mechanical parameters were comparable with the ones measured for polypropylene (S_U = 40 MPa; E = 1.5–2.0 GPa) and polystyrene (S_U = 40 MPa; E = 3.0–3.5 GPa). Differential IR spectra of the nanocomposites indicated an interaction of kaolinites inner surface hydroxyls with PLA which was confirmed by an intensity decrease of a band at ~ 3690 cm^? 1. The presence of highly dispersed nanotubular kaolinite particles in the polymer matrix which contributed to the improvement of PLA mechanical properties was observed using AFM. The contact angle measurements showed that the addition of kaolinites led to changes of wettability, yet the synthesized materials still possessed hydrophilic surfaces.     

Determination of the adulteration of butter

The adulteration of butter is a serious problem due to economic advantages taken by replacing expensive milk fat with cheaper oil without informing the customers. The authentication of milk fat methods include analysis of bulk components, especially triacylglycerols, fatty acids, sterols and tocopherols. Fatty acid and sterol composition was analysed by using GC‐MS. TAG and tocopherol profiles were examined by HPLC with diode array (DAD) and fluorescence detectors (FLDs). In addition, identification of selected TAG of butter fat was conducted by LC‐atmospheric pressure chemical ionisation (APCI)/MS technique. The lipid composition of 16 different butters available on Polish market were investigated. The cholesterol content in butter fat ranged from 176.8 to 264.8 mg/100 g of fat and in two samples of milk fat β‐sitosterol was found. The total saturated fatty acid (SFA) content in milk fat was 67.1–73.5%, monounsaturated fatty acid 24.5–30.5% and polyunsaturated fatty acid was 1.2–2.0%. Abnormalities in fatty acid profiles, e.g. high concentration of linoleic fatty acid, were found in two butters. These abnormalities were also determined in TAG profiles. The examination of tocopherols in butter fat confirmed that two products were adulterated by the addition of plant oils because they contained δ‐tocopherol which is typical for plant origin foodstuffs. The methods described are useful for investigating milk fat adulterations, and the most efficient are analysis of sterols and tocopherols composition. Practical applications: The described methods are useful for investigating adulteration of milk fat. Traditional strategies rely on examination of fatty acids methyl esters and TAG; these methods have some disadvantages. Due to the variability of fatty acid composition of milk fat and because TAG analysis is complex and time consuming, FA analysis is not an efficient approach for butter authentication. The most efficient method for butter authentication is qualitative and quantitative analysis of sterols and tocopherols. This analysis will determine if components of plant origin were used for butter production.     

Redox polymer with N,N‐dichlorosulfonamide functional groups as arsenite oxidant in aqueous solutions

A macroporous, styrene‐divinylbenzene polymer with N,N‐dichlorosulfonamide functional groups (? SO₂NCl₂), containing two chlorine atoms with oxidation number +1, have been prepared through the chemical modification of a commercial sulfonic cation exchanger (Amberlyst 15, Rohm and Haas). Obtained product was used as the heterogeneous oxidant of As(III) in aqueous solutions. The polymer's oxidizing capacity, determined as part of the batch studies, amounted to 193.29 mg As(III) g^?1 (pH = 7.7) and 206.03 mg As(III) g^?1 (pH = 2.0). The suitability of the redox polymer for long‐lasting operation in the aqueous environment was confirmed in the column study conducted using a solution with a concentration of 10 mg As(III) dm^?3 at a flow rate of 6 bed volumes (BV) h^?1. The concentration of As(III) in the effluent reached the value of 0.01 mg As(III) dm^?3 only after 8 weeks of continuous operation when 7930 BV of the solution had passed through the bed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41552.     

Involvement of the MetO/Msr System in Two Acer Species That Display Contrasting Characteristics during Germination

The levels of methionine sulfoxide (MetO) and the abundances of methionine sulfoxide reductases (Msrs) were reported as important for the desiccation tolerance of Acer seeds. To determine whether the MetO/Msrs system is related to reactive oxygen species (ROS) and involved in the regulation of germination in orthodox and recalcitrant seeds, Norway maple and sycamore were investigated. Changes in water content, MetO content, the abundance of MsrB1 and MsrB2 in relation to ROS content and the activity of reductases depending on nicotinamide adenine dinucleotides were monitored. Acer seeds differed in germination speed—substantially higher in sycamore—hydration dynamics, levels of hydrogen peroxide, superoxide anion radicals (O₂^•−) and hydroxyl radicals (•OH), which exhibited peaks at different stages of germination. The MetO level dynamically changed, particularly in sycamore embryonic axes, where it was positively correlated with the levels of O₂^•− and the abundance of MsrB1 and negatively with the levels of •OH and the abundance of MsrB2. The MsrB2 abundance increased upon sycamore germination; in contrast, it markedly decreased in Norway maple. We propose that the ROS–MetO–Msr redox system, allowing balanced Met redox homeostasis, participates in the germination process in sycamore, which is characterized by a much higher speed compared to Norway maple.     

The effect of linker of electrodes prepared from sol–gel ionic liquid precursor and carbon nanoparticles on dioxygen electroreduction bioelectrocatalysis

The effect of linker of three-dimensional, hydrophilic-carbon-nanoparticle film-electrodes prepared by layer-by-layer method on redox probe accumulation and bioelectrocatalytic dioxygen reduction was studied and compared for two different electrode scaffolds. The linker in both of these scaffolds was based on the same ionic liquid sol–gel precursor, 1-methyl-3-(3-trimethoxysilylpropyl) imidazolium bis(trifluoromethyl-sulfonyl)imide. The first electrode type was prepared by alternative immersion of tin doped indium oxide substrate in an aqueous suspension of carbon nanoparticles modified with phenyl sulphonic groups and a sol composed of ionic liquid sol–gel precursor and tetramethoxysilane. For the second electrode type sol was replaced by a methanolic suspension of silicate submicroparticles with appended imidazolium functional groups. In both films 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) anions accumulate irreversibly. In the case of the first electrode electrostatic attraction plays the more important role in comparison to the case of the second where stable adsorption of the redox probe takes place. After adsorption of bilirubin oxidase, electrodes obtained from sol and carbon nanoparticles exhibit modest bioelectrocatalytic activity towards dioxygen reduction at pH 4.8, however those obtained from oppositely charged particles are much more efficient. The magnitude of the associated catalytic current in both cases depends on the number of immersion and withdrawal steps. Interestingly, mediatorless catalysis at electrodes obtained from oppositely charged particles is more efficient than mediated catalysis.