Discriminating between viable and membrane-damaged cells of the plant pathogen Xylella fastidiosa.

Xylella fastidiosa is a plant pathogenic bacterium with devastating consequences to several crops of economic importance across the world. While this pathogen has been studied for over a century in the United States, several aspects of its biology remain to be investigated. Determining the physiological state of bacteria is essential to understand the effects of its interactions with different biotic and abiotic factors on cell viability. Although X. fastidiosa is culturable, its slow growing nature makes this technique cumbersome to assess the physiological state of cells present in a given environment. PMA-qPCR, i.e. the use of quantitative PCR combined with the pre-treatment of cells with the dye propidium monoazide, has been successfully used in a number of studies on human pathogens to calculate the proportion of viable cells, but has less frequently been tested on plant pathogens. We found that the use of a version of PMA, PMAxx, facilitated distinguishing between viable and non-viable cells based on cell membrane integrity in vitro and in planta. Additional experiments comparing the number of culturable, viable, and total cells in planta would help further confirm our initial results. Enhancers, intended to improve the efficacy of PMAxx, were not effective and appeared to be slightly toxic to X. fastidiosa

New remains of Prochelidella in the Anacleto Formation (Campanian levels) of Neuquén basin, Patagonia, Argentina

The new turtle remains presented here were recovered from the Anacleto Formation (Campanian) exposed in the Aguada Grande site. This area is located 10 km south of Rincón de Los Sauces city, inthe north of the province of Neuquén, Patagonia, Argentina. The specimen (MAU-Pv-AG-452)consists of a partially preserved skull, carapace remains, an almost complete plastron, and a leftilium. The new specimen is assigned to Pleurodira because its ilium is sutured to the carapace. Both Parietals, the posterior part of frontals and post orbitals, the dorsal region of the supraoccipital, both pterygoids, the basisphenoid, and part of the prootics are recognized in the skull. The carapace remains are represented by a left first costal bone in articulation with a peripheral bone, a left paired costal bone, and another fragmented coastal. The plastron is represented by both epiplastra, theen plastron, left hyoplastron, both hypoplastra, and the left xiphiplastron. The skull shows somecharacters that allow its referral to Prochelidella spp. (e.g., a developed retropterygoid foramen, and a big muscle attachment area over the basisphenoid). The visceral view of the first costal bone exhibitslong auxiliary buttresses that extend 2/3 of the costal width. This condition is also observed in the costal bone of Prochelidella buitreraensis from the Candeleros Formation (Cenomanian). The scutepattern observed in the anterior lobe of the plastron shows a large gular that extends along theentoplastral length and small extragulars over the epiplastra. In contrast, on the scheme observed inProchelidella cerrobarcinae and Prochelidella portezuelae, the gular does not extend beyond the first third of the entoplastron. The material recovered from the Anacleto Formation represents the most complete specimen outside the Prochelidella peak of diversity range (Albian Cenomanian) and the second skull recognized in this genusFil: Maniel, Ignacio Jorge. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; ArgentinaFil: de la Fuente, Marcelo Saul. Universidad Tecnologica Nacional. Facultad Reg.san Rafael. Instituto de Evolucion, Ecologia Historica y Ambiente. - Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mendoza. Instituto de Evolucion, Ecologia Historica y Ambiente.; ArgentinaFil: Filippi, Leonardo Sebastián. No especifíca;Simposio de Evolución de TortugasTrelewArgentinaMuseo Paleontológico Egidio FeruglioAsociación Paleontológica Argentin

Grapevine xylem sap enhances biofilm development by Xylella fastidiosa

Xylella fastidiosa is able to form biofilms within xylem vessels of many economically important crops. Vessel blockage is believed to be a major contributor to disease development caused by this bacterium. This report shows that Vitis riparia xylem sap increases growth rate and induces a characteristic biofilm architecture as compared with biofilms formed in PD2 and PW media. In addition, stable cultures could be maintained, frozen and reestablished in xylem sap. These findings are important as xylem sap provides a natural medium that facilitates the identification of virulence determinants of Pierce's diseas

Analysis of active islanding detection methods for grid-connected microinverters for renewable energy processing

[EN] This paper presents the analysis and comparison of the main active techniques for islanding detection used in grid-connected microinverters for power processing of renewable energy sources. These techniques can be classified into two classes: techniques introducing positive feedback in the control of the inverter and techniques based on harmonics injection. Accurate PSIMTM simulations have been carried out in order to perform a comparative analysis of the techniques under study and to establish their advantages and disadvantages according to IEEE standards.This work was supported by the Spanish Ministry of Science and Innovation under Grant ENE2009-13998-C02-02.Trujillo Rodríguez, CL.; Velasco De La Fuente, D.; Figueres Amorós, E.; Garcerá, G. (2010). Analysis of active islanding detection methods for grid-connected microinverters for renewable energy processing. Applied Energy. 87(11):3591-3605. https://doi.org/10.1016/j.apenergy.2010.05.014S35913605871

Primeiro relato de Dactylonectria novozelandica causando necrose de raiz e coroa em morangos no Uruguay

Since 2015, a high mortality rate of strawberry plants has been observed in the north of Uruguay related to crown and root diseases caused by a pathogens complex. In 2016, associated with the death of plants, Cylindrocarpon spp. was isolated with a frequency of 42.4 %, ranking third, preceded by Neopestalotiopsis sp. and Fusarium spp. Aiming to increase the knowledge of the pathogens that integrate the complex, three isolates of Cylindrocarpon spp. were characterized by molecular, morphological and pathogenicity analyses in strawberry plants. Dactylonectria novozelandica was identified as causal agent of crown and root necrosis of strawberry in Salto, Uruguay.Desde 2015, se observó una alta mortandad de plantas de frutilla en el norte de Uruguay relacionada con enfermedades de corona y raíz causadas por un complejo de patógenos. En 2016, asociado con la muerte de plantas, Cylindrocarpon spp. se aisló con una frecuencia de 42,4 %, ocupando el tercer lugar, precedido por Neopestalotiopsis sp. y Fusarium spp. Con el objetivo de incrementar el conocimiento de los patógenos que integran el complejo, se caracterizaron tres aislados de Cylindrocarpon spp. mediante análisis moleculares, morfológicos y de patogenicidad en plantas de frutilla. Se identificó Dactylonectria novozelandica como agente causal de necrosis de corona y raíz de frutilla en Salto, Uruguay.A partir do ano 2015 um número significativo de mortes se observou em plantas de morango no norte do Uruguai devido a doenças da coroa e raiz causadas por um complexo de patógenos. Associado à morte, Cylindrocarpon spp foi isolado com uma frequência de 42,4% no 2016, ocupando o terceiro lugar de incidência depois de Neopestalotiopsis sp. e Fusarium spp. O objetivo do trabalho foi caracterizar três isolados de Cylindrocarpon spp por meio de análises moleculares, morfológicas e patogênicas em morangueiro. Dactylonectria novozelandica causou necorsis de cora e raiz em uma plantas de morango em Salto, Uruguai

An active Anti-islanding method based on phase-PLL perturbation

This paper presents a new active anti-islanding detection method for distributed power generation systems. This method is based on introducing a disturbance at the inverter output and observing the behavior of the voltage at the point of common coupling (PCC), which depends on the impedance connected to the PCC in an islanding situation. The islanding detection is based on the Goertzel algorithm.Velasco De La Fuente, D.; Trujillo Rodríguez, CL.; Garcerá Sanfeliú, G.; Figueres Amorós, E. (2011). An active Anti-islanding method based on phase-PLL perturbation. IEEE Transactions on Power Electronics. 26(4):1056-1066. doi:10.2089643S1056106626

Twitching motility and biofilm formation are associated with tonB1 in Xylella fastidiosa

A mutation in the Xylella fastidiosa tonB1 gene resulted in loss of twitching motility and in significantly less biofilm formation as compared with a wild type. The altered motility and biofilm phenotypes were restored by complementation with a functional copy of the gene. The mutation affected virulence as measured by Pierce's disease symptoms on grapevines. The role of TonB1 in twitching and biofilm formation appears to be independent of the characteristic iron-uptake function of this protein. This is the first report demonstrating a functional role for a tonB homolog in X. fastidios

Photovoltaic Power System With Battery Backup With Grid-Connection and Islanded Operation Capabilities

This paper presents the analysis, design, and experimentation results of a photovoltaic energy management system with battery backup. The proposed system is capable of both grid-connected and islanded operations. The main advantage of the proposed system is that, in grid-connected mode, the inverter works as a current source in phase with the grid voltage, injecting power to the grid and controlling the dc-link voltage. The dc/dc converter manages the battery charge. In islanded mode, the inverter control is reconfigured to work as a voltage source using droop schemes. The dc/dc converter controls the dc-link voltage to enable the maximum power point tracking reference to be followed. An operation protocol is proposed to ensure the quality of the energy supply and minimize energy loss. A battery bank is connected to the dc link as energy storage for islanded operation mode. The aim of this paper is to show that the proposed system performs correctly, without dangerous transients for the inverter or the loads. Simulation and experimental results on a 3-kW prototype show the feasibility of the proposed control strategy.This work was supported by the Spanish Ministry of Science and Innovation under Grant ENE2009-13998-C02-02. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.Velasco De La Fuente, D.; Trujillo Rodríguez, CL.; Garcerá, G.; Figueres Amorós, E.; Ortega González, R. (2013). Photovoltaic Power System With Battery Backup With Grid-Connection and Islanded Operation Capabilities. IEEE Transactions on Industrial Electronics. 60(4):1571-1581. https://doi.org/10.1109/TIE.2012.2196011S1571158160

Modeling and control of a push-pull converter for photovoltaic microinverters operating in island mode

[EN] This paper presents the modeling and control of a push-pull converter integrated into a two-stage photovoltaic microinverter operating in island mode without backup energy storage components (batteries). A push-pull small signal model is presented, from which they are derived all transfer functions needed to implement the controllers that regulate the output current, input voltage and output voltage interacting with the MPPT algorithm. A significant contribution of the paper is the proposal of an innovative control structure that simultaneously regulates in island mode both the ac voltage and the dc voltage of the panels, in order to place it in the best operation point. Such operation point is calculated by a specific control loop that interacts with the MPPT algorithm. To validate the proposed concept, simulations in PSIM (TM) were carried out. (C) 2011 Elsevier Ltd. All rights reserved.This work was supported by the Spanish Ministry of Science and Innovation under Grant ENE2009-13998-C02-02.Trujillo Rodríguez, CL.; Velasco De La Fuente, D.; Figueres Amorós, E.; Garcerá Sanfeliú, G.; Ortega, R. (2011). Modeling and control of a push-pull converter for photovoltaic microinverters operating in island mode. Applied Energy. 88(8):2824-2834. https://doi.org/10.1016/j.apenergy.2011.01.053S2824283488

Efecte dels colorants addicionats a pinsos per a animals de companyia sobre el desenvolupament de soques fúngiques

L'addició de colorants en els aliments és una de les pràctiques més habituals en la tecnologia alimentària, no només en l'àmbit de l'alimentació humana, sinó també de l'animal. El present estudi posa de manifest l'efecte de determinats colorants que s'afegeixen al pinso per a animals de companyia sobre el desenvolupament de diferents soques fúngiques, que habitualment poden créixer sobre aquest tipus de substrats. Els resultats indiquen que els colorants modifiquen el patró d'esporulació dels fongs miceliats i que no afecten el desenvolupament dels llevats.The addition of colourings on food is a very common practice in food technology, both for food and feed. This study shows the effect of certain colourings commonly added to pet food, on the growth of different fungal strains that usually grow on this kind of substrate. The results show that colourings can modify the normal pattern of sporulation in moulds and they exert no effect on yeast growth