The spin-orbit interaction couples the electrons' motion to their spin. As a result, a charge current running through a material with strong spin-orbit coupling generates a transverse spin current ...(spin Hall effect, SHE) and vice versa (inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as charge-to-spin interconversion mechanisms offers a variety of novel spintronic functionalities and devices, some of which do not require any ferromagnetic material. However, the interconversion efficiency of SHE and ISHE (spin Hall angle) is a bulk property that rarely exceeds ten percent, and does not take advantage of interfacial and low-dimensional effects otherwise ubiquitous in spintronic hetero- and mesostructures. Here, we make use of an interface-driven spin-orbit coupling mechanism-the Rashba effect-in the oxide two-dimensional electron system (2DES) LaAlO
/SrTiO
to achieve spin-to-charge conversion with unprecedented efficiency. Through spin pumping, we inject a spin current from a NiFe film into the oxide 2DES and detect the resulting charge current, which can be strongly modulated by a gate voltage. We discuss the amplitude of the effect and its gate dependence on the basis of the electronic structure of the 2DES and highlight the importance of a long scattering time to achieve efficient spin-to-charge interconversion.
A rust fungus attack was observed on Tree Spurge (Euphorbia dendroides) in two regions of southern Italy. Uredinia and telia of a Melampsora species were detected on the leaves, bracts of the cyathia ...and capsules of E. dendroides. On the basis of the morphological characteristics and rDNA ITS sequences of the above mentioned structures, the fungus was identified as M. gelmii. This report suggests that M. gelmii seems to be a specific taxon in the M. euphorbiae complex and to be more widespread than previously detected in Italy. Further investigations within the M. euphorbiae complex would be desirable in order to elucidate the identity of M. gelmii as a peculiar form of a still poorly explored species.
The radical S-adenosyl-L-methionine tryptophan lyase NosL converts L-tryptophan into 3-methylindolic acid, which is a precursor in the synthesis of the thiopeptide antibiotic nosiheptide. Using ...electron paramagnetic resonance spectroscopy and multiple L-tryptophan isotopologues, we trapped and characterized radical intermediates that indicate a carboxyl fragment migration mechanism for NosL. This is in contrast to a proposed fragmentation-recombination mechanism that implied Cα–Cβ bond cleavage of L-tryptophan. Although NosL resembles related tyrosine lyases, subtle substrate motions in its active site are responsible for a fine-tuned radical chemistry, which selects the Cα–C bond for disruption. This mechanism highlights evolutionary adaptation to structural constraints in proteins as a route to alternative enzyme function.
For aromatic organic radicals, pulsed electron-electron double resonance (PELDOR) experiments at high magnetic fields provide information not only about the distance between the paramagnetic species ...but also about their relative orientation. However, the three-dimensional biradical structure is encoded in a complex pattern of orientation-selected PELDOR traces and the execution of the experiment is generally aggravated by constraints posed by the available hardware and the intrinsically low modulation depth observed. We present a 94 GHz PELDOR experiment performed with a commercial spectrometer and probe heads that permit separation of pump and detection frequencies up to 150 MHz. The setup is employed to examine the orientation selections on a general case of rigid biradicals with non-collinear
g
axes. The interacting radicals, a tyrosyl radical (Y
122
·) located in the β2 subunit and an 3-aminotyrosyl radical (NH
2
Y
731
·) located in the α2 subunit, are generated by
Escherichia coli
ribonucleotide reductase with a 3-aminotyrosine (NH
2
Y) site specifically incorporated into α2 in the presence of cytidine 5′-diphosphate and adenosine 5′-triphosphate. The experimental designs as well as some characteristic features of the observed modulation pattern are discussed.
Germination tests were carried out on seeds from three Italian populations of Abies alba. Seed germinability was up to 38%. HgCl
2
, NaClO and plant preservative mixture were used as seed-sterilising ...agents. Despite chemical treatments, Papulaspora rubida and Chaetomium globosum were isolated. The possible role of these fungi in the physiology of silver fir seed germination process was discussed.
Summary
Attempts to design species‐specific PCR primers from six European Armillaria species in the ribosomal RNA genes are reported. Primers were developed on the basis of the nucleotide sequence ...variability of the internal transcribed spacers (ITS) and the intergenic spacer (IGS1) of the ribosomal DNA. Four sets of primers gave specific PCR products for Armillaria tabescens, Armillaria mellea and Armillaria ostoyae. However, due to the high sequence similarities between Armillaria borealis and Armillaria ostoyae and between Armillaria cepistipes and Armillaria gallica no species specific amplification was obtained for these taxa.
Résumé
Des essais ont été réalisés pour obtenir des amorces PCR spécifiques de 6 espèces européennes d’Armillaria dans les gènes de l'ARNr. Les amorces ont été développées sur la base de la variabilité de séquence nucléotidique dans les ITS et IGS (IGS1) de l'ADN ribosomal. Quatre couples d'amorces ont permis d'obtenir des produits PCR spécifiques pour A. tabescens, A. mellea et A. ostoyae. Cependant, compte tenu des très fortes similarités de séquence entre A. borealis et A. ostoyae, et entre A. cepistipes et A. gallica, il n'a pas été obtenu d'amplification spécifique pour ces taxons.
Zusammenfassung
Es wird über Versuche berichtet, artspezifische Primer für sechs europäische Armillariaarten in der Region der ribosomalen RNA‐Gene zu entwickeln. Als Grundlage dafür diente die Variabilität der Nukleotidsequenzen der ITS‐ und der IGS 1‐Region der ribosomalen DNA. Vier Primerpaare ergaben spezifische PCR‐Produkte für A. tabescens, A. mellea und A. ostoyae. Dagegen wurden aufgrund der grossen Ähnlichkeit der Sequenzen von A. borealis und A. ostoyae sowie von A. cepistipes und A. gallica für diese Taxa keine artspezifischen Amplifikationsprodukte erhalten.
Abstract
A new approach is described for the insertion of nitroxide spin-labels at specific positions within DNA oligomers. The latter bioconjugaison strategy is based on a click chemistry ...1,3-dipolar cycloaddition between a spin-labeling reagent, namely the 4-azido-TEMPO, and alkyne modified uridine-containing oligonucleotides. This highly efficient labeling method was applied for site-specific incorporation of two TEMPO units within a set of double-stranded DNA constructs. Then the determination of the inter-nitroxide distances was achived by using a four-pulses DEER technique that successfully validates the new site-directed spin labeling strategy.
Cyclic or acyclic: Not only modified cyclodextrins but also modified linear dextrins like the silylated (R)and acetylated (R1) maltoheptaose derivatives 1 are suitable selectors for separating ...racemic N‐trifluoroacetyl‐O‐alkyl esters of α‐amino acids by gas chromatography. In the example shown, racemic N‐trifluoroacetylserine O‐ethyl ester is resolved.
Outbreaks of Armillaria root rot in conifer plantations and declining oak stands are frequently due to the spread of the fungus in the soil over long periods. This paper examines the occurrence and ...distribution of Armillaria genets in a declining mixed oak stand of Southern Italy. Samples of rhizomorphs, mycelial mats and fruit bodies of Armillaria were collected from the soil, stumps and living and dead trees. A total of 111 Armillaria isolates were collected, all belonging to the species A. gallica. They were grouped in 28 genets by somatic incompatibility. The largest genet covered an area of about 2.6 ha, with a linear extent of 300 m. On the basis of an estimated 0.5 m annual growth in the soil, its age was assumed to be about 3 centuries. The results confirm the ability of A. gallica to remain alive and stable in a large area over a long time
Gli attacchi di marciume radicale da Armillaria in piantagioni di conifere e in querceti soggetti a deperimento sono dovuti frequentemente alla diffusione del fungo nel terreno nel corso di lunghi periodi. Questo contributo esamina la presenza e distribuzione di cloni di Armillaria in un querceto misto soggetto a deperimento dell'Italia Meridionale. Campioni di rizomorfe, feltri di micelio e corpi fruttiferi di Armillaria sono stati prelevati dal terreno, da ceppi e da alberi vivi e morti. E' stato raccolto un totale di 111 isolati di Armillaria, tutti appartenenti alla specie A. gallica. Essi sono stati raggruppati in 28 cloni in base all'incompatibilita' somatica. Il clone piu' ampio copriva un'area di 2,6 ha, con un'estensione lineare di 300 m. Sulla base di una crescita annuale stimata di 0,5 m nel terreno, si presume che la sua eta' sia di circa 3 secoli. I risultati confermano la capacita' di A. gallica di rimanere viva e stabile in una vasta area per un lungo periodo di tempo
In Southern Italy, Heterobasidion abietinum Niemelae et Korhonen (Hab) is a widespread necrothophic fungus in natural and artificial stands of silver-fir (Abies alba Mill.) where it can cause root ...and butt rot in single or in groups of trees. Inoculation were carried out with 18 H. abietinum isolates collected from stumps and seedlings of nine different silver fir woods from Apulia, Calabria, Campania and Basilicata (Southern Italy). Three-year-old seedlings (obtained from seeds collected in a silver-fir stand in the Pollino mountains) were inoculated at the collar with a block of silver fir wood colonized by each Hab strain. The block was attached to the bark after or without wounding the seedling. Four-month-old silver fir seedlings obtained from seeds collected in Serra San Bruno (Vibo Valentia province), "Pollino" and Laurenzana (Potenza province) forests were inoculated by dipping roots and stem into a mycelial and conidial suspension. Seedlings were maintained in test tubes with a Murashige and Skoog basal salt mixture solution. Differences among strains were recorded as symptoms on leaves and woody tissues following fungal invasion and decay. Hab strains from Serra San Bruno induced a mild infection of root tissues and did not cause rot on a number of seedlings. A white decay was generally observed five months after inoculation.
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