Tissue invasion and alteration in eggplant infected with Verticillium dahliae: A light and transmission electron microscopy study

Light and transmission electron microscopy observations of Verticillium-inoculated eggplants are reported. Results of tests for cellulose and chitin are also presented. Opaque, vessel wall lining matter (VWLM) generally occurred, connected to elements identified as fungal cells, and extending into vessel secondary walls and across pits. VWLM was also confluent with similar matter extensively pervading middle lamellae and causing their alterations. The thickest VWLM was stratified as alternating opaque and more lucent bands, with the opaque ones being similar to the first layer deposited. Many loops were included in or bulged from the VWLM layers. Lace-like structures also occurred in vessel lumina as apparent distensions of the basic, first opaque layer of this VWLM. Large amounts of similar opaque matter occurred in the periphery of paratracheal cells with altered content. This matter contained filamentous-like structures and frequently opaque particles reminiscent of ribosomes. The pitted areas were much altered as an internal shred-like network, unlabelled for cellulose, covered by an outer opaque and compact cellulose-labelled layer, itself overlaid by an unlabelled VWLM. Release of labelled material from these altered areas only occurred at locations of VWLM ruptures. Detachment and alterations of the adjacent vessel wall secondary thickenings were noticeable and accounted for the presence of lucent cellulose-labelled matter in vessel lumina.Un objectif de cette étude a été de caractériser, dans des plants inoculés, les composantes exogènes aux éléments de vaisseaux, dont les enduits sur la paroi vasculaire, et leurs liens avec des altérations cellulaires et la présence de matière opaque dans les lamelles mitoyennes et le périplasme de cellules paratrachéales. Des tests pour localiser certains composés pariétaux ont été utilisés. Les enduits étaient formés de diverses couches, dont une première, mince et opaque et d’aspect membranaire, et d’autres plus épaisses et translucides alternant avec des couches opaques. Plusieurs gonflements circulaires se trouvaient dans ou à la marge de ces strates (VWLM). D’autres réseaux sinueux, apparemment issus de l’espacement des bandes formant la première couche de l’enduit, se trouvaient dans les vaisseaux. La matière périplasmique contenait des structures filamenteuses et de nombreuses particules opaques d’allure ribosomique. La partie interne des champs de ponctuations montrait des bandes opaques éparses, non marquées pour la cellulose, recouverte d’une couche plus compacte, marquée pour ce substrat. Les résidus altérés n’étaient libérés dans les vaisseaux qu’en cas de rupture du VWLM montrant l’absence de marquage pour ces deux substrats. Les épaississements secondaires des parois vasculaires étaient souvent altérés ou détachés de leur base, expliquant la présence de matière translucide marquée pour la cellulose dans les vaisseaux

Paper Session I-C - Seeds II: More Tomatoes from Space

NASA Life Sciences Outreach, in collaboration with several other organizations, is getting ready to release space exposed seeds to teachers and students. This project, called Space Exposed Experiment Developed for Students II (SEEDS II) was designed to provide teachers and students with seeds and information so that they can conduct biological research relating to the effects of the space and undersea environments

Social learning against data falsification in sensor networks

Sensor networks generate large amounts of geographically-distributed data. The conventional approach to exploit this data is to first gather it in a special node that then performs processing and inference. However, what happens if this node is destroyed, or even worst, if it is hijacked? To explore this problem, in this work we consider a smart attacker who can take control of critical nodes within the network and use them to inject false information. In order to face this critical security thread, we propose a novel scheme that enables data aggregation and decision-making over networks based on social learning, where the sensor nodes act resembling how agents make decisions in social networks. Our results suggest that social learning enables high network resilience, even when a significant portion of the nodes have been compromised by the attacker

Topological and subsystem codes on low-degree graphs with flag qubits

In this work we introduce two code families, which we call the heavy hexagon code and heavy square code. Both code families are implemented by assigning physical data and ancilla qubits to both vertices and edges of low degree graphs. Such a layout is particularly suitable for superconducting qubit architectures to minimize frequency collisions and crosstalk. In some cases, frequency collisions can be reduced by several orders of magnitude. The heavy hexagon code is a hybrid surface/Bacon-Shor code mapped onto a (heavy) hexagonal lattice whereas the heavy square code is the surface code mapped onto a (heavy) square lattice. In both cases, the lattice includes all the ancilla qubits required for fault-tolerant error-correction. Naively, the limited qubit connectivity might be thought to limit the error-correcting capability of the code to less than its full distance. Therefore, essential to our construction is the use of flag qubits. We modify minimum weight perfect matching decoding to efficiently and scalably incorporate information from measurements of the flag qubits and correct up to the full code distance while respecting the limited connectivity. Simulations show that high threshold values for both codes can be obtained using our decoding protocol. Further, our decoding scheme can be adapted to other topological code families.Comment: 20 pages, 21 figures, Comments welcome! V2 conforms to journal specification

Ultraestructura de la red alveolar y su relación con el recubrimiento de las paredes vasculares en olmos infectados con Ophiostoma novo-ulmi y en otras plantas infectadas con enfermedades similares de marchitamiento

In elms infected with Dutch elm disease, alveolar networks, demarcated by filamentous-like bands and confluent with similar matter (the coating) accumulating on vessel walls, occurred regularly in vessel elements. Similar material lined vessel walls in inoculated, sterilized, thin elm wood sections fixed by high pressure freezing. The coating was observed to connect with fungal cells and occasionally contained small opaque particles, the size of ribosomes, membranous and vesicular structures, and, following incubation of wood chips taken from diseased samples incubated on an agar medium, it still displayed similar matter. Coating and alveolar bands increased in thickness by confluence of other bands or membranous structures. Similar matter and structures also occurred in other plants affected by similar fungal wilt diseases. In all systems, the compact coating did not label for chitin, cellulose and pectin. In staghorn sumac, the probe for DNA attached to the coating. Altogether, in the light of these data, it appears that the coating and alveolar networks are not inert components, a fact which indicates their primordial probable pathogen origin. It is proposed that these elements might be important not only in the initial infection stages but also in older or recurrent infections at a time when host resistance mechanisms are ineffective.En olmos afectados por la grafiosis, la red alveolar, demarcada por bandas filamentosas, y confluente con acumulaciones de la misma sustancia (cubrición) presentes en las paredes de los vasos, aparece regularmente en los elementos conductores. Sustancias similares tapizan las paredes de los vasos en secciones de madera delgada de olmo inoculada y esterilizada, y posteriormente criofijadas a altas presiones. Se observó que la cubrición se conecta con las células del micelio y que ocasionalmente contenía pequeñas partículas opacas del tamaño de los ribosomas, estructuras membranosas y vesiculares, así como que, tras la incubación de astillas leñosas cogidas de muestras enfermas incubadas en agar, aún se presentaba una sustancia similar. La cubrición y las bandas alveolares aumentaron su espesor en la confluencia con otras bandas o estructuras membranosas. Estructuras y sustancias similares aparecieron también en otras plantas afectadas por enfermedades similares originadas por hongos que producen marchitamiento. En todos los sistemas, la cubrición compacta no pudo ser marcada como quitina, celulosa ni pectina. En zumaque (Rhus typhina), la sonda de ADN se pegó a la cubrición. En resumen, a la vista de estos datos, parece ser que la cubrición y la red alveolar no están formados por componentes inertes, un hecho que indica su probable origen patogénico. Se sugiere que esos elementos podrían ser importantes no sólo en las fases iniciales de la infección, sino también, en infecciones más desarrolladas o recurrentes, en el momento en que los mecanismos de resistencia del hospedante no son efectivos

CrO2: a self-doped double exchange ferromagnet

Band structure calculations of CrO2 carried out in the LSDA+U approach reveal a clear picture of the physics behind the metallic ferromagnetic properties. Arguments are presented that the metallic ferromagnetic oxide CrO2 belongs to a class of materials in which magnetic ordering exists due to double exchange (in this respect CrO2 turns out to be similar to the CMR manganates). It is concluded that CrO2 has small or even negative charge transfer gap which can result in self-doping. Certain experiments to check the proposed picture are suggested.Comment: 4 pages, 4 Figure