Protective effect of bacterial lipopolysaccharides in the grapevine- Agrobacterium vitis interaction

Cell-associated lipopolysaccharides (LPS) were extracted by the phenol-chloroform-petroleum ether extraction method (PCP) from a nopaline strain of Agrobacterium vitis, purified by treatment with DNase/RNase, proteinase K and dialysis, characterized by polyacrylamide gel electrophoresis (SDS-PAGE), and bioassayed on grapevine shoot nodal segments. LPS preparation used for the experiments in planta was a mixture of rough-type LPS, obtained from precipitation with water after PCP-extraction, and some smooth- and rough-type LPS from the remaining phenol phase. Infiltration of an aqueous dispersion of the mixture in concentrations of 25-1000 µ g.ml-1 did not cause grapevine tissue necrosis, and callus formed within one month. When the LPS dispersions were infiltrated in the grapevine nodal segments, 24 h before challenge inoculation with A. vitis (5x102 cells per 5 µ l droplet), they prevented tumorgenesis and tissue necrosis; but, when the pathogen was inoculated at a higher concentration (5x105 cells per 5 CII droplet), these LS applications were active in protecting plant tissue from necrosis and did not prevent tumor induction. The potential role of LPS as candidate molecules in the protection of grapevine from A. vitis infection is discussed

Modification of the Pseudomonas syringae pv. tabaci -tobacco leaf interaction by bacterial oligosaccharides

Cell-associated oligosaccharides were extracted with trichloroacetic acid treatment from Pseudomonas syringae pv. aptata, purified by column chromatography, analysed by GC-MS and fast atom bombardment-mass spectrometry, and bioassayed on tobacco leaves. The material was shown to be a mixture of neutral oligosaccharides, with a mol. wt of 800-1800, degree of polymerization 5-11, and linear glucose and mannose chains. Local infiltrations of the mixture, in concentrations of 1 mg, 100, 10 and 1 μg ml-1, did not cause tobacco tissue necrosis within 1 week. When the mixture was infiltrated in the interveinal leaf panels, in concentrations of 1 μg, 100, 10 and 1 ng ml-1, 48 h before challenge inoculation, it delayed or prevented normosensitive necrosis by P. syringae pv. tabaci but not hypersensitive necrosis by P. syringae pv. aptata. Five days after inoculation with P. syringae pv. tabaci, inhibition of normosensitive necrosis, as compared with the control tissue, was 80·55, 77·21, 56·36 and 45·46 % for the four concentrations. In the bioassay with P. syringae pv. tabaci the efficacy threshold was assessed at approx. 1 ng ml-1. Pre-treatment with oligosaccharides (1 μg ml-1) significantly inhibited the growth of P. syringae pv. tabaci between 3 and 5 days after inoculation and, between day 6 and 8, it delayed the death of bacteria when the tissue was not subject to necrosis. An interval of 6 h was necessary between the infiltration of oligosaccharides (1 μg ml-1) and inoculation of P, syringae pv. tabaci for a clear inhibition of normosensitive necrosis. These oligosaccharides acted as signal molecules by modifying, at nanomolar concentrations, the P. syringae pv. tabaci-tobacco leaf interaction, but they were not elicitors of the hypersensitive reaction. © 1994 Academic Press, Inc

Trajectories and resource management of flying base stations for C-V2X

In a vehicular scenario where the penetration of cars equipped with wireless communication devices is far from 100% and application requirements tend to be challenging for a cellular network not specifically planned for it, the use of unmanned aerial vehicles (UAVs), carrying mobile base stations, becomes an interesting option. In this article, we consider a cellular-vehicle-to-anything (C-V2X) application and we propose the integration of an aerial and a terrestrial component of the network, to fill the potential unavailability of short-range connections among vehicles and address unpredictable traffic distribution in space and time. In particular, we envision a UAV with C-V2X equipment providing service for the extended sensing application, and we propose a UAV trajectory design accounting for the radio resource (RR) assignment. The system is tested considering a realistic scenario by varying the RRs availability and the number of active vehicles. Simulations show the results in terms of gain in throughput and percentage of served users, with respect to the case in which the UAV is not present

Biological control of Agrobacterium vitis using non-tumorigenic agrobacteria

The potential use of non-tumorigenic agrobacteria for the biological control of grapevine crown gall in Italy was investigated. Four Agrobacterium strains belonging to the species radiobacter and vitis were used to protect the susceptible cv. Malvasia Istriana grafted on the rootstock 420 A. Moreover, the effect of each treatment on grapevine vitality and growth was assessed, including the percentage of marketable vines, as determined by industry standards. Treatments with the antagonists clearly reduced tissue colonization by the pathogen, with a drop of more than 100-fold in pathogen populations in the samples collected at the graft point. Another important effect was the reduction of internal necrosis possibly induced by the high concentration of the nopaline strain CG 49 used in the experiments. According to viticultural and commercial parameters, treatments with the antagonists improved the quality of the vines, with fewer discards and a high percentage of marketable material. Therefore, these antagonists can be considered beneficial for grapevine

Hot-water treatment of dormant grape cuttings: Its effects on Agrobacterium tumefaciens and on grafting and growth of vine

Hot-water treatment (50°C for 20-30 min) was carried out to confirm its efficacy in eradicating Agrobacterium tumefaciens biovar 3 (AT3) in symptomless grape cuttings.After the forcing period, analyses of callus from cuttings of grape cvs Albana, Lambrusco Grasparossa, Rulander and Fortana, and from their graft combinations with the rootstocks 420A, 41B, 5BB and 1103P, revealed the low infection level in the grape material used. Dormant scion and rootstock cuttings treated identically in the U.S. gave similar results. Despite this, it was possible to confirm the efficacy of thermotherapy in eradicating the pathogen.An assessment was also made of the effect of treatment on growth parameters of grafted vines in the greenhouse and after 8 months in a field nursery. The effect of hot-water treatment on the vitality and growth of vines varied with the different scion-rootstock combinations. Treatment did not generally have detrimental effects on vitality; there were some negative effects on graft-take. The number and length of canes, as well as the diameter of the trunks, increased in most instances.The treatments and times usually did not affect bud survival and, in most cases, increased the level of callus formation at the base of cuttings.

A New Measurement of Kaonic Hydrogen X rays

The $\bar{K}N$ system at threshold is a sensitive testing ground for low energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we have measured the $K$-series x rays of kaonic hydrogen atoms at the DA$\Phi$NE electron-positron collider of Laboratori Nazionali di Frascati, and have determined the most precise values of the strong-interaction energy-level shift and width of the $1s$ atomic state. As x-ray detectors, we used large-area silicon drift detectors having excellent energy and timing resolution, which were developed especially for the SIDDHARTA experiment. The shift and width were determined to be $\epsilon_{1s} = -283 \pm 36 \pm 6 {(syst)}$ eV and $\Gamma_{1s} = 541 \pm 89 {(stat)} \pm 22 {(syst)}$ eV, respectively. The new values will provide vital constraints on the theoretical description of the low-energy $\bar{K}N$ interaction.Comment: 5 figures, submitted to Physics Letters

Performance Analysis of Sidelink 5G-V2X Mode 2 through an Open-Source Simulator

The Third Generation Partnership Project (3GPP) has recently published a new set of specifications to enable advanced driving applications in fifth generation (5G) vehicle-to-everything (V2X) scenarios, with particular effort dedicated to the sidelink resource allocation in the autonomous mode, named Mode 2. In this paper, we conduct a comprehensive analysis of Mode 2 performance via an open-source system-level simulator, which implements the 5G New Radio (NR) flexible numerology and physical layer aspects together with the newly specified sidelink resource allocation modes for V2X communications and different data traffic patterns. Results collected through extensive simulation campaigns, under a wide variety of vehicle density, data transmission settings and traffic patterns, showcase the effects of the new 5G-V2X features on the sidelink resource allocation performance and provide some insights into possible ways to further improve Mode 2 performance

Future directions in kaonic atom physics

Recent progress and open problems in kaonic atom physics are presented. A connection between phenomenological deep potentials and the underlying $K^-N$ interaction is established as well as the need for a theory for multinucleon absorption of kaons. $K^-$ absorption at rest to specific $\Lambda$ hypernuclei states is briefly discussed.Comment: 6 pages, 3 figures, proceedings of the EXA2011 conference, to appear in Hyperfine Interaction