The Hydrophilic Loop of Arabidopsis PIN1 Auxin Efflux Carrier Harbors Hallmarks of an Intrinsically Disordered Protein

Much of plant development depends on cell-to-cell redistribution of the plant hormone auxin, which is facilitated by the plasma membrane (PM) localized PIN FORMED (PIN) proteins. Auxin export activity, developmental roles, subcellular trafficking, and polarity of PINs have been well studied, but their structure remains elusive besides a rough outline that they contain two groups of 5 alpha-helices connected by a large hydrophilic loop (HL). Here, we focus on the PIN1 HL as we could produce it in sufficient quantities for biochemical investigations to provide insights into its secondary structure. Circular dichroism (CD) studies revealed its nature as an intrinsically disordered protein (IDP), manifested by the increase of structure content upon thermal melting. Consistent with IDPs serving as interaction platforms, PIN1 loops homodimerize. PIN1 HL cytoplasmic overexpression in Arabidopsis disrupts early endocytic trafficking of PIN1 and PIN2 and causes defects in the cotyledon vasculature formation. In summary, we demonstrate that PIN1 HL has an intrinsically disordered nature, which must be considered to gain further structural insights. Some secondary structures may form transiently during pairing with known and yet-to-be-discovered interactors.     

Synthesis and Cell Growth Inhibitory Activity of Six Non-glycosaminoglycan-Type Heparin-Analogue Trisaccharides

The design and synthesis of heparin mimetics with high anticancer activity but no anticoagulant activity is an important task in medicinal chemistry. Herein, we present the efficient synthesis of five Glc-GlcA-Glc-sequenced and one Glc-IdoA-Glc-sequenced non-glycosaminoglycan, heparin-related trisaccharides with various sulfation/sulfonylation and methylation patterns. The cell growth inhibitory effects of the compounds were tested against four cancerous human cell lines and two non-cancerous cell lines. Two d -glucuronate-containing tetra-O-sulfated, partially methylated trisaccharides displayed remarkable and selective inhibitory effects on the growth of ovary carcinoma (A2780) and melanoma (WM35) cells. Methyl substituents on the glucuronide unit proved to be detrimental, whereas acetyl substituents were beneficial to the cytostatic activity of the sulfated derivatives.     

Electrosynthesis of a manganese(iii) aminopolycarboxylate complex in alkaline media

Mn(iii)CyDTA [(trans-cyclohexane-1,2-diamine-N,N,N,N-tetraacetato) manganate(iii)] was generated electrochemically from Mn(ii)CyDTA (6–54 mm) in 0.1 m NaHCO₃ at pH 9.0 and 10.5, respectively, 25 °C, for two CyDTA/Mn molar ratios (1/1 and 2/1). A divided batch electrochemical reactor was employed with anode current densities from 2.6 to 102 A m^–2. Separate cyclic voltammetry experiments of Mn(iii)CyDTA in alkaline media showed a prepeak behaviour, indicating the adsorption of Mn(ii) species. The visible anodic deposit, formed during the electrosynthesis of Mn(iii)CyDTA at pH 10.5 and 1/1 CyDTA/Mn molar ratio on stainless steel and PbO₂/Pb, reduces the current efficiency for Mn(iii). For a Mn(ii) concentration of 18 mm and at 13 A m^–2, the graphite and platinized titanium anodes gave a current efficiency for Mn(iii) of 78% and 66%, respectively, without a visible deposit. A 2/1 CyDTA/Mn molar ratio, avoided a visible anodic deposit formation, but gave lower current efficiencies for Mn(iii) than in the case of a 1/1 ligand to metal ratio. The electrosynthesis of Mn(iii)CyDTA is recommended for routine preparation of the complex and is also suitable for in situ electrochemically mediated oxidations in alkaline media (up to pH 11).     

Functional properties of protein preparations from amaranth seeds in model system

The gross chemical composition and functional properties (solubility, emulsifying and foaming properties) of different amaranth protein preparations were studied in model systems and were compared to those of casein and soy protein isolates. Preparations of alkaline-soluble total protein, albumin, globulin, and glutelin-like alkaline-soluble residual protein were produced from two different types of defatted amaranth meals by extraction and fractionation. Although similarity can be shown between protein patterns of legumes (including soy) and amaranth, the emulsifying and foaming properties of amaranth protein preparations are relatively poor in comparison to the reference proteins, except foaming properties of albumin preparations. Nevertheless, taking in mind that these properties depend on interactions with other food components and textural requirements of individual food products, the amaranth protein preparations may be treated as potential protein sources and food ingredients.     

Primary structure of water buffalo alpha-lactalbumin variants A and B

A novel electrophoretic alpha-lactalbumin (alpha-la) variant was detected in the Italian water buffalo breed. The isoelectric point of the variant, labelled A, was lower than the most frequent variant B. It presented an allelic frequency of 0.5% compared with the 97.1% of the BB allele. From Liquid Chromatography-Electrospray Ionization/Mass spectrometry, the molecular mass of the two alpha-la A and B variants were measured as 14,235.1+/-0.8 and 14,236.1+/-0.9 Da, respectively. The two proteins were sequenced and differentiated from one another by a single amino acid substitution, Asn45(B)-->Asp45(A). As this amino acid substitution altered the N-glycosylation sequence consensus Asn45-X-Ser46 it may be deduced that the protein glycosylation level of the alpha-la A would decrease.     

Early and late effects of absorbable poly(vinyl alcohol) hernia mesh to tissue reconstruction

Hernia is a defect of the abdominal wall. Treatment is principally surgical mesh implantation. Non‐degradable surgical meshes produce numerous complications and side‐effects such as inflammatory response, mesh migration and chronic pain. In contrast, the biodegradable, poly (vinyl alcohol) (PVA) based polymers have excellent chemical, mechanical and biological properties and after their degradation no chronic pain can be expected. The toxicology of PVA solution and fibers was investigated with Human dermal fibroblast‐ Adult cell line. Implantation tests were observed on long‐term contact (rat) and large animal (swine) models. To measure the adhesion formation, Diamond and Vandendael score were used. Macroscopical and histological responses were graded from the samples. In vitro examination showed that PVA solution and fibers are biocompatible for the cells. According to the implantation tests, all samples were integrated into the surrounding tissue, and there was no foreign body reaction. The average number of adhesions was found on the non‐absorbable suture line. The biocompatibility of the PVA nanofiber mesh was demonstrated. It has a non‐adhesive, non‐toxic and good quality structure which has the potential to be an alternative solution for the part of the hernia mesh.     

Insights into the Electrochemical Behavior of Manganese Oxides as Catalysts for the Oxygen Reduction and Evolution Reactions: Monometallic Core-Shell Mn/Mn3O4

Overcoming the sluggish electrode kinetics of both oxygen reduction and evolution reactions (ORR/OER) with non-precious metal electrocatalysts will accelerate the development of rechargeable metal-air batteries and regenerative fuel cells. The authors investigated the electrochemical behavior and ORR/OER catalytic activity of core-porous shell Mn/Mn₃O₄ nanoparticles in comparison with other manganese dioxides (β- and γ-MnO₂), and benchmarked against Pt/C and Pt/C-IrO₂. Under reversible operation in O₂-saturated 5 M KOH at 22 °C, the early stage activity of core-shell Mn/Mn₃O₄ shows two times higher ORR and OER current density compared to the other MnO₂ structures at 0.32 and 1.62 V versus RHE, respectively. It is revealed that Mn(III) oxidation to Mn(IV) is the primary cause of Mn/Mn₃O₄ activity loss during ORR/OER potential cycling. To address it, an electrochemical activation method using Co(II) is proposed. By incorporating Co(II) into MnO_x, new active sites are introduced and the content of Mn(II) is increased, which can stabilize the Mn(III) sites through comproportionation with Mn(IV). The Co-incorporated Mn/Mn₃O₄ has superior activity and durability. Furthermore, it also surpassed the activity of Pt/C-IrO₂ with similar durability. This study demonstrates that cost-effective ORR/OER catalysis is possible.     

Ozonolysis of α-PINENE, β-PINENE,d- and l-Turpentine Oil Studied by Chirooptical Methods; Some Implications on the Atmospheric Chemistry of Biogenic Volatile Organic Compounds

The main constituents of biogenic volatile organic compounds (BVOC) released in the atmosphere from vegetation are terpenes. The most common terpenes are α-pinene and β-pinene. These molecules react with ozone, forming oxidized derivatives which have low vapor pressure and which nucleate into secondary organic aerosol (SOA). Such aerosol-forming reactions have been simulated in the gas phase on laboratory scale with the visualization of the formation of SOA. Electronic absorption spectroscopy shows that the UV peak of pinenes at 205 nm is shifted to 225 nm during and after ozonolysis and is accompanied by a series of spectral features in the near infrared region (between 850 nm and 1100 nm). Optical rotatory dispersion (ORD) spectra were recorded on pure β(+)pinene and β(?)pinene. After ozonolysis β-pinene enantiomers are converted into nopinone enantiomers. The ORD spectra of both (?)nopinone and (+)nopinone respectively were recorded. The former showed a peak at 453 nm, an inflection point at 430 nm and a trough at 405 nm. The ORD spectrum of (?)-nopinone appears completely symmetrical to that of (+)nopinone. Thus, ORD spectroscopy can distinguish between BVOC and oxidized BVOC quite easily at least in the case of β-pinene. The ORD spectra of α-pinene enantiomers are different from those of β-pinene enantiomers and although the ORD spectra of ozonized α-pinene are not easily distinguishable from those of the primary compounds, they are completely different from those of ozonized β-pinene enantiomers. A reasonable natural model of BVOC is offered by l- and d-turpentine oil whose composition reflects that of the BVOC from conifer forests. The ORD spectra of ozonized l- and d-turpentine has permitted to distinguish between the levorotatory and dextrorotatory oxidation products and showing the ketone peak at about 367–380 nm, thus permitting in a real model to distinguish between primary BVOC (turpentine) and oxidized BVOC (or SOA) corresponding to ozonized turpentine. It has been proposed that ORD spectra in the gas phase could be used to detect chiral BVOC and oxidized chiral BVOC.     

Alterations in ACE and ACE2 Activities and Cardiomyocyte Signaling Underlie Improved Myocardial Function in a Rat Model of Repeated Remote Ischemic Conditioning

Post-ischemic left ventricular (LV) remodeling and its hypothetical prevention by repeated remote ischemic conditioning (rRIC) in male Sprague–Dawley rats were studied. Myocardial infarction (MI) was evoked by permanent ligation of the left anterior descending coronary artery (LAD), and myocardial characteristics were tested in the infarcted anterior and non-infarcted inferior LV regions four and/or six weeks later. rRIC was induced by three cycles of five-minute-long unilateral hind limb ischemia and five minutes of reperfusion on a daily basis for a period of two weeks starting four weeks after LAD occlusion. Sham operated animals served as controls. Echocardiographic examinations and invasive hemodynamic measurements revealed distinct changes in LV systolic function between four and six weeks after MI induction in the absence of rRIC (i.e., LV ejection fraction (LVEF) decreased from 52.8 ± 2.1% to 50 ± 1.6%, mean ± SEM, p < 0.05) and in the presence of rRIC (i.e., LVEF increased from 48.2 ± 4.8% to 55.2 ± 4.1%, p < 0.05). Angiotensin-converting enzyme (ACE) activity was about five times higher in the anterior LV wall at six weeks than that in sham animals. Angiotensin-converting enzyme 2 (ACE2) activity roughly doubled in post-ischemic LVs. These increases in ACE and ACE2 activities were effectively mitigated by rRIC. Ca²⁺-sensitivities of force production (pCa₅₀) of LV permeabilized cardiomyocytes were increased at six weeks after MI induction together with hypophosphorylation of 1) cardiac troponin I (cTnI) in both LV regions, and 2) cardiac myosin-binding protein C (cMyBP-C) in the anterior wall. rRIC normalized pCa₅₀, cTnI and cMyBP-C phosphorylations. Taken together, post-ischemic LV remodeling involves region-specific alterations in ACE and ACE2 activities together with changes in cardiomyocyte myofilament protein phosphorylation and function. rRIC has the potential to prevent these alterations and to improve LV performance following MI.