Study of morphological and phenological diversity in chestnut trees (‘Judia’ variety) as a function of temperature sum

Morphological and histological adaptation of chestnut leaves at the different altitudes and edaphoclimate conditions were shown. The study was carried out on Castanea sativa Mill. var. ‘Judia’. The growth range altitudes of ‘Judia’ were between 709 m a.s.l. and 860 m a.s.l. (above sea level), corresponding to a variation in the sum of temperatures (expressed in degree-day values – °D) of 2751 °D to 2316 °D in 2006 and 2338 °D to 1700 °D in 2007, between May and October. In 2007 the thickest leaves (319.9 μm), the highest stomata density (469.1 stomata mm⁻²), one of the largest leaf areas (69.2 cm²) and the highest fruit size (71.7 fruit kg⁻¹) were observed in Alfândega da Fé (759 m a.s.l., 2186 °D, during the May–October period) whereas in 2006 the highest fruit size (86.8 fruit kg⁻¹) was observed in Valpaços (860 m a.s.l., 2316 °D, during the same period).Additionally, the leaves of the trees grown in this locality (Valpaços) displayed one of the largest areas (57.0 cm²). Overall results suggest that annual climate conditions do significantly influence both fruit and leaf biometric characteristics, and that the range of temperatures from 2100 °D to 2300 °D (between May and October) correspond to the optimal temperature sum, which can be ascribed to different places, depending on the year in question. Concerning the molecular characterisation using nuclear microsatellites, the individuals more distant are those from Macedo de Cavaleiros and Alfândega da Fé (genetic distance = 0.227), while the ecotypes with closer similarities were those collected in Murça and Vinhais (genetic identity = 1.171). The current results suggest that the morphological and phenological differences among ecotypes are not related to the small genetic differences, but are simply phenotypic adaptations to diffent climatic conditions.     

IR and Raman study on the interactions of the 5′-GMP and 5′-CMP phosphate groups with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III)

The chief motive behind this research is the interest provoked by the presence of metal ions as necessary stabilizers of the negative charges of phosphate groups in nucleic acids. The effect that the presence of different metal ions produces on the band principally assigned to the nu(s) PO(3)(2-) mode has been studied using FT-IR and FT-Raman spectroscopy. The results obtained reveal the diagnostic capacity of these techniques in determining the type of metal ion interaction with respect to the mononucleotides that form DNA and RNA, providing a tool for improving the knowledge of the stabilizing or destabilizing effects of these ions on such macromolecules. The metal complexes of the ribonucleotides 5'-CMP and 5'-GMP with Mg(II), Ca(II), Sr(II), Ba(II), Cr(III), Co(II), Cu(II), Zn(II), Cd(II), Al(III) and Ga(III) were obtained in this study. After studying and analyzing the IR and Raman spectra of all these complexes and comparing them with the spectra of the corresponding disodium salts, it was verified that, independently of the type of nucleotide involved, the presence of the metal in the vicinity of the phosphate group produces an alteration in the aforementioned nu(s) PO(3)(2-) band. This effect is related to the type of interaction that the phosphate group has with the metal. Three components are observed: (1) one near 983-975 cm(-1) (detectable in IR and Raman), associated with phosphate groups in an electrostatic type of interaction with the metal ion, separated by two or more water molecules; (2) another near 989-985 cm(-1) (only in IR), associated with phosphate groups in indirect interaction through the water molecules of the coordination sphere of the metal ions; and (3) the IR and Raman bands near 1014-1001 cm(-1), which represent phosphate groups directly bonded to the metal ion. These results are supported by the behavior of 5'-CMP in aqueous solution in the presence of Mg(II) ions.     

Phallus impudicus loaded with γ-Fe2O3 as solid phase bioextractor for the preconcentrations of Zn(II) and Cr(III) from water and food samples

We investigated the application of fungus Phallus impudicus loaded γ-Fe₂O₃ nanoparticles as a biosorbent for magnetic solid phase extractions of trace levels of Zn(II) and Cr(III) ions from natural samples before their measurements by inductively coupled plasma optical emission spectrometry. The characterization of magnetized P. impudicus was performed using the scanning electron microscope, the energy dispersive X-ray and Fourier transform infrared spectroscopy. Important experimental factors were investigated. The experimental results fitted well to the Langmuir adsorption model and pseudo-second order kinetic model. Limit of detections of targeted ions by magnetic solid phase extraction method based on use of P. impudicus were found as 10.5 ngL⁻¹ and 12.6 ngL⁻¹ respectively for Cr(III) and Zn(II). The sorption capacities of the biosorbent were 22.8 mgg⁻¹ for Cr(III) and 25.6 mgg⁻¹ for Zn(II). The preconcentration factors were achieved as 100 for both of ions. RSDs for inter- and intraday precisions were found as lower than 2.0% and 2.1% respectively for both of targeted ions. The accuracy of the recommended process was tested by recovery measurements on the certificated reference materials and successfully applied for quantification recoveries of Cr(III) and Zn(II) ions from water and food samples.     

Synthesis and in vitro and in vivo evaluation of manganese(III) porphyrin–dextran as a novel MRI contrast agent

5-(4-Aminophenyl)-10,15,20-tris(4-sulfonatophenyl) manganese(III) porphyrin conjugated with dextran was synthesized. Its potential of being used as a tumor-targeting magnetic resonance imaging contrast agent was evaluated in vitro and in vivo. The results demonstrated that the compound has a longitudinal relaxivity (R₁) higher than Gd-DTPA, low cytotoxicity and binding specificity to tumor cell membrane.     

Preparation and reactivity of a tetranuclear Fe(II) core in the metallothionein α-domain

Metallothioneins (MTs) are small cysteine-rich proteins which exhibit high affinities for various metal ions and play roles in storage of essential metals and detoxification of toxic metals. Studies on the redox properties of MTs have been quite limited. Recently, we focused on the α-domain of MT (MTα) as a protein matrix and incorporated a tetranuclear metal cluster as a reductant. UV-visible, CD and MS data indicate the formation of the stable tetranuclear metal-cysteine cluster in the MTα matrix with Fe^II₄-MTα and Co^II₄-MTα species existing in water. Furthermore, the Fe^II₄-MTα species was found to promote the reduction of met-myoglobin and azobenzene derivatives under mild conditions. Particularly, the stoichiometric reduction of methyl red with Fe^II₄-MTα (1:1) was found to proceed with a conversion of 98% over a period of 6 h at 25 °C. This indicates that all of the four Fe(II) cores contribute to the reduction. In this paper, we describe the preparation and reactivity of the tetranuclear iron cluster in the protein matrix.     

Binding of α-synuclein with Fe(III) and with Fe(II) and biological implications of the resultant complexes

Parkinson’s disease (PD) is hallmarked by the abnormal intracellular inclusions (Lewy bodies or LBs) in dopaminergic cells. Amyloidogenic protein α-synuclein (α-syn) and iron (including both Fe(III) and Fe(II)) are both found to be present in LBs. The interaction between iron and α-syn might have important biological relevance to PD etiology. Previously, a moderate binding affinity between α-syn and Fe(II) (5.8 × 10³ M⁻¹) has been measured, but studies on the binding between α-syn and Fe(III) have not been reported. In this work, electrospray mass spectrometry (ES-MS), cyclic voltammetry (CV), and fluorescence spectroscopy were used to study the binding between α-syn and Fe(II) and the redox property of the resultant α-syn-Fe(II) complex. The complex is of a 1:1 stoichiometry and can be readily oxidized electrochemically and chemically (by O₂) to the putative α-syn-Fe(III) complex, with H₂O₂ as a co-product. The reduction potential was estimated to be 0.025 V vs. Ag/AgCl, which represents a shift by −0.550 V vs. the standard reduction potential of the free Fe(III)/Fe(II) couple. Such a shift allows a binding constant between α-syn and Fe(III), 1.2 × 10¹³ M⁻¹, to be deduced. Despite the relatively high binding affinity, α-syn-Fe(III) generated from the oxidation of α-syn-Fe(II) still dissociates due to the stronger tendency of Fe(III) to hydrolyze to Fe(OH)₃ and/or ferrihydrite gel. The roles of α-syn and its interaction with Fe(III) and/or Fe(II) are discussed in the context of oxidative stress, metal-catalyzed α-syn aggregation, and iron transfer processes.     

Dinuclear compounds with a μ-cyano ligand. Part XIII. Synthesis,characterization and solid state kinetics of the formation of (μ-cyano)(tricyanometal(II))pentaamminerhodium(III) and iridium(III) (metal(II) = nickel,palladium, platinum). Influence of the PtPt interactions

Six new dinuclear complexes of (μ-cyano)(tricyanometal(II))pentaamminerhodium(III) or iridium(III), metal(II) being nickel, palladium and platinum, have been obtained by solid state reaction of the tetracyanometallate(II) of aquopentaamminerhodium(III) and iridium(III), respectively. All these complexes have been characterized by chemical analysis, electronic and IR spectra and TG measurements. The kinetics of the solid-state deaquation-anation has been studied by thermogravimetric measurements under both nonisothermal and isothermal conditions. The activation energies so obtained are 105.3 and 107.7 kJ/mol for the Ni compounds; 115.0 and 118.1 kJ/mol for the Pd compounds and 90.2 and 92.2 kJ/ mol for the Pt compounds. These low values of activation energy can indicate an S_N1 dissociative mechanism with an activated complex of square- based-pyramidal geometry. The marked difference in the kinetic parameters between the Ni, Pd compounds and Pt compounds may be explained in terms of Pt-Pt association in the crystal lattice, which causes distortion and allows the water molecules to escape easily from the crystal structure. These Pt-Pt interactions are shown in the electronic spectrum by the appearance of a very strong band at about 355 nm in the solid state and at about 330 nm and 300 nm in solution.     

The many faces (and phases) of ceramide and sphingomyelin II – binary mixtures

A rather widespread idea on the functional importance of sphingolipids in cell membranes refers to the occurrence of ordered domains enriched in sphingomyelin and ceramide that are largely assumed to exist irrespective of the type of N-acyl chain in the sphingolipid. Ceramides and sphingomyelins are the simplest kind of two-chained sphingolipids and show a variety of species, depending on the fatty acyl chain length, hydroxylation, and unsaturation. Abundant evidences have shown that variations of the N-acyl chain length in ceramides and sphingomyelins markedly affect their phase state, interfacial elasticity, surface topography, electrostatics, and miscibility, and that even the usually conceived “condensed” sphingolipids and many of their mixtures may exhibit liquid-like expanded states. Their lateral miscibility properties are subtlety regulated by those chemical differences. Even between ceramides with different acyl chain length, their partial miscibility is responsible for a rich two-dimensional structural variety that impacts on the membrane properties at the mesoscale level. In this review, we will discuss the miscibility properties of ceramide, sphingomyelin, and glycosphingolipids that differ in their N-acyl or oligosaccharide chains. This work is a second part that accompanies a previous overview of the properties of membranes formed by pure ceramides or sphingomyelins, which is also included in this Special Issue.     

On the conformational dependence of the proton chemical shifts in nucleosides and nucleotides III. Proton chemical shifts of 5′-nucleotides as a function of different conformational parameters

The variation of the chemical shift of the protons of 5′-UMP and 5′-AMP is calculated as a function of χ_CN, ψ and ? torsion angles. The shift of H8 of 5′-AMP and H6 of 5′-UMP is found to be very sensitive to the value of χ_CN. For the anti conformations the shift of these protons is more sensitive to the value of the rotation about CS′-05′ than about C4′-CS′. For the protons of the ribose the calculations show that for the C2′-endo pucker H3′ and H2′ undergo the largest chemical shift variations when ? and ψ vary. The calculated variations are considered in relation with the role of the conformation of the nucleotides in the chemical shift variation between mono and polynucleotides and between the different helical structures of polynucleotides.     

Application of 2,4,5-tris(2-pyridyl)imidazole as ‘turn-off’ fluorescence sensor for Cu(II) and Hg(II) ions and in vitro cell imaging

The 2,4,5-tris(2-pyridyl)imidazole ( L ) molecule has been evaluated as a probe for dual sensing of Hg²⁺ and Cu²⁺ ions in EtOH/HEPES buffer medium (5 mM, pH = 7.34, 1:1, v/v). Probe L shows a good sensitive and selective turn-off response in the presence of both Hg²⁺ and Cu²⁺ ions, which is comprehensible under long UV light. The probe can detect Cu²⁺ ion in the pH range 3–11 and Hg²⁺ ion in pH 6–8. The limit of detection for Cu²⁺ (0.77 μM) is well under the allowable limit prescribed by the United States Environmental Protection Agency. Two metal (Cu²⁺/Hg²⁺) ions are needed per L for complete fluorescence quenching. The probe shows marked reversibility on treatment with Na₂EDTA, making the protocol more economical for practical purposes. Paper strip coated with the L solution of EtOH can detect the presence of Cu²⁺ and Hg²⁺ ions in the sample using visible quenching of the fluorescence intensity. Density functional theory–time-dependent density functional theory (DFT–TDDFT) calculations support experimental observations, and d-orbitals of Cu²⁺/Hg²⁺ provide a nonradiative decay pathway. Cell imaging study using HDF and MDA-MB-231 cells also supported the viability of L in detecting Cu²⁺ and Hg²⁺ ions in living cells.     

Reactivity of glycoconjugate in membrane system II: Can a neutral glycolipid function as lectin receptor in the presence of gangliosides in plasma membrane?

To examine how surface Potential controls the reactivity of glycoconjugates at cell surface, the interaction of galactose-sPecific lectinse.g. peanut agglutinin,Ricinus cummunis agglutinin with liPosomes bearing asialo GM₁ were studied in the Presence of varying amount of ganglioside mixture, GM_n. The Presence of 5% GM_n causes comPlete slowing down of PreciPitin reaction and thereby make carbohydrate moiety of asialo GM₁ comPletely inaccessiblei.e. ‘cryPtic’. In contrast the Presence of 1–2% GM_n enhances the aPParent rate and amPlitude of the PreciPitin reaction as surface Potential becomes more negative. The relevance of the findings has been discussed in relation to the exPression and involvement of the cell-surface sialic acid residues during develoPment and differentiation.     

Raman Spectroscopy Study of the B-Z Transition in (dG-dC)n · (dG-dC)n and a DNA Restriction Fragment

Abstract

The B to Z conformational transition of (dG-dC)_n·(dG-dC)_n and a 157 bp DNA restriction fragment were followed using Raman spectroscopy. The 157 bp DNA has a 95 bp segment from the E. coli lactose operon sandwiched between 26 and 32 bp of (dC-dG) sequences. Raman spectra of the DNAs were obtained at varying sodium chloride concentrations through the region of the transition. A data analysis procedure was developed to subtract the background curves and quantify Raman vibrational bands. Profiles of relative intensity vs. sodium chloride concentration are shown for bands at 626, 682, 831–833 and 1093 cm^?1. Both (dG-dC)_n·(dG-dC)_n and the 157 bp DNA show changes in the guanine vibration at 682 cm^?1 and backbone band at 831–3 cm^?1 preceeding a highly cooperative change in the 1093 cm^?1 PO 7 vibration. This result indicates that there are at least two conformational steps in the B to Z conformational pathway.

We review the effect of the (dC-dG) portion of the 157 bp DNA on the 95 bp segment. Comparison of Raman spectra of the 157 bp DNA, the 95 bp fragment and (dG-dC)_n·(dG- dC)_n indicate that in 4.5 M NaC/the (dC-dG) segments are in a Z-conformation. Base stacking in the 95 bp portion of the 157 bp DNA appears to maintain a B-type conformation. However, a substantial portion of this region no longer has a B-type backbone vibration.     

Preparation and characterization of oxovanadium(IV), acetatomanganese(III), chloroiron(III), nickel(II), copper(II), zinc(II) and palladium(II) complexes of 3,3′-(1,2-phenylenediimino)diacrolein

The oxovanadium(IV), acetatomanganese(III), chloroiron(III), nickel(II), copper(II), zinc(II) and palladium(II) of 3,3′-(1,2-phenylenediimino)diacrolein were prepared and investigated by means of mass, electronic, vibrational, NMR and ESR spectroscopy as well as magnetic susceptibility measurements. The acetatomanganese(III) and chloroiron(III) complexes were confirmed to be of high spin type. The absorption bands appearing in the energy range greater than 23 000 cm⁻¹ were attributed to π→π^* transitions within a ligand molecule and charge- transfer transitions from metal to ligand. The metal complexes assume the square-planar configuration type since the ligand-field bands were detected in the 12 700–18 500 cm⁻¹ region. Strong bands appearing at 1601 and 1627 cm⁻¹ were assigned to the CC and CO stretching vibrational modes, respectively, and were shifted to lower frequency upon metal-coordination. A VO stretching band was observed at 982 cm⁻¹ for the oxovanadium(IV) complex and a CO stretching band was observed at 1547 cm⁻¹ for the acetatomanganese(III) complex. Upon complex formation the amine proton signal is found to vanish and the aldehydic methine proton signal in the lowest field is shifted upfield for the nickel(II), zinc(II) and palladium(II) complexes. ¹³C NMR spectra support the coordination structure of the complexes which is revealed by ¹H NMR spectra. As judged by the spin Hamiltonian parameters, the oxovanadium(IV) complex is of a square- planar type with an unpaired electron in the d_xy orbital and the copper(II) complex assumes a distorted square-planar coordination due to the presence of five- and six-membered chelate rings with an unpaired electron in the d_x2−y2 orbital.     

The rate of ATP synthesis as a function of ΔpH in normal and dithiothreitol-modified chloroplasts

The rate of ATP synthesis catalyzed by normal and by dithiothreitol-modified ATPases is investigated as a function of ΔpH in spinach chloroplasts at constant pH_out. The transmembrane ΔpH was generated by an acid-base transition and the reaction time was limited to 150 ms by using a rapidly mixing quenched-flow apparatus. The result was that the functional dependence of the rate on ΔpH is shifted to lower ΔpH values and that the shape of this curve is altered after dithiothreitol modification. The maximal rate (400 ATP / CF₁ per s) is the same under both conditions.     

Dufour’s gland possible role in the evolution of sting morphology and function in hover wasps (Hymenoptera Stenogastrinae)

The sting is the most effective defense of social Hymenoptera against vertebrate predators but in the hover wasps (subfamily Stenogastrinae) it is scarcely used. In these wasps a quite enlarged Dufour’s gland and the extensive use of its secretion in the peculiar rearing of the larvae and defense determined important morphological modifications of the sting structure. Connecting anatomical and morphological data with behavioral observations we determined that in these wasps the Dufour’s gland secretion is attached to the egg during oviposition but can be also channeled to the outside via the sting when it is collected by adult females for larval rearing or construction of the nest ant guards. The anatomical modifications of the sting reduced the function of the sting as a defensive weapon in hover wasps.     

CD16 (FcRγIII) as a potential marker of osteoclast precursors in psoriatic arthritis

Introduction  

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis characterized by bone erosion mediated by osteoclasts (OC). Our previous studies showed an elevated frequency of OC precursors (OCP) in PsA patients. Here, we examined if OC arise from CD16-positive monocytes in PsA.     

6,6’-Dihydroxythiobinupharidine as a poison of human type II topoisomerases

A number of natural products with medicinal properties increase DNA cleavage mediated by type II topoisomerases. In an effort to identify additional natural compounds that affect the activity of human type II topoisomerases, a blind screen of a library of 341 Mediterranean plant extracts was conducted. Extracts from Nuphar lutea, the yellow water lily, were identified in this screen. N. lutea has been used in traditional medicine by a variety of indigenous populations. The active compound in N. lutea, 6,6’-dihydroxythiobinupharidine, was found to enhance DNA cleavage mediated by human topoisomerase IIα and IIβ ∼8-fold and ∼3-fold, respectively. Mechanistic studies with topoisomerase IIα indicate that 6,6’-dihydroxythiobinupharidine is a “covalent poison” that acts by adducting the enzyme outside of the DNA cleavage-ligation active site and requires the N-terminal domain of the protein for its activity. Results suggest that some of the medicinal properties of N. lutea may result from the interactions between 6,6’-dihydroxythiobinupharidine and the human type II enzymes.     

Recent advances in structure and function of cytosolic IMP-GMP specific 5′nucleotidase II (cN-II)

Cytosolic 5′ nucleotidase II (cN-II) catalyses both the hydrolysis of a number of nucleoside monophosphates (e.g., IMP + H₂O→ inosine + Pi), and the phosphate transfer from a nucleoside monophosphate donor to the 5′ position of a nucleoside acceptor (e.g., IMP + guanosine → inosine + GMP). The enzyme protein functions through the formation of a covalent phosphoenzyme intermediate, followed by the phosphate transfer either to water (phosphatase activity) or to a nucleoside (phosphotransferase activity). It has been proposed that cN-II regulates the intracellular concentration of IMP and GMP and the production of uric acid. The enzyme might also have a potential therapeutic importance, since it can phosphorylate some anti-tumoral and antiviral nucleoside analogues that are not substrates of known kinases. In this review we summarise our recent studies on the structure, regulation and function of cN-II. Via a site-directed mutagenesis approach, we have identified the amino acids involved in the catalytic mechanism and proposed a structural model of the active site. A series of in vitro studies suggests that cN-II might contribute to the regulation of 5-phosphoribosyl-1-pyrophosphate (PRPP) level, through the so-called oxypurine cycle, and in the production of intracellular adenosine, formed by ATP degradation.     

pH-dependence of the specific binding of Cu(II) and Zn(II) ions to the amyloid-β peptide

Metal ions like Cu(II) and Zn(II) are accumulated in Alzheimer's disease amyloid plaques. The amyloid-β (Aβ) peptide involved in the disease interacts with these metal ions at neutral pH via ligands provided by the N-terminal histidines and the N-terminus. The present study uses high-resolution NMR spectroscopy to monitor the residue-specific interactions of Cu(II) and Zn(II) with (15)N- and (13)C,(15)N-labeled Aβ(1-40) peptides at varying pH levels. At pH 7.4 both ions bind to the specific ligands, competing with one another. At pH 5.5 Cu(II) retains its specific histidine ligands, while Zn(II) seems to lack residue-specific interactions. The low pH mimics acidosis which is linked to inflammatory processes in vivo. The results suggest that the cell toxic effects of redox active Cu(II) binding to Aβ may be reversed by the protective activity of non-redox active Zn(II) binding to the same major binding site under non-acidic conditions. Under acidic conditions, the protective effect of Zn(II) may be decreased or changed, since Zn(II) is less able to compete with Cu(II) for the specific binding site on the Aβ peptide under these conditions.