Pharmacological analysis of transmission activation of two aphid-vectored plant viruses, turnip mosaic virus and cauliflower mosaic virus

Turnip mosaic virus (TuMV, family Potyviridae) and cauliflower mosaic virus (CaMV, family Caulimoviridae) are transmitted by aphid vectors. They are the only viruses shown so far to undergo transmission activation (TA) immediately preceding plant-to-plant propagation. TA is a recently described phenomenon where viruses respond to the presence of vectors on the host by rapidly and transiently forming transmissible complexes that are efficiently acquired and transmitted. Very little is known about the mechanisms of TA and on whether such mechanisms are alike or distinct in different viral species. We use here a pharmacological approach to initiate the comparison of TA of TuMV and CaMV. Our results show that both viruses rely on calcium signaling and reactive oxygen species (ROS) for TA. However, whereas application of the thiol-reactive compound N-ethylmaleimide (NEM) inhibited, as previously shown, TuMV transmission it did not alter CaMV transmission. On the other hand, sodium azide, which boosts CaMV transmission, strongly inhibited TuMV transmission. Finally, wounding stress inhibited CaMV transmission and increased TuMV transmission. Taken together, the results suggest that transmission activation of TuMV and CaMV depends on initial calcium and ROS signaling that are generated during the plant's immediate responses to aphid manifestation. Interestingly, downstream events in TA of each virus appear to diverge, as shown by the differential effects of NEM, azide and wounding on TuMV and CaMV transmission, suggesting that these two viruses have evolved analogous TA mechanisms

The inside-out planetary nebula around a born-again star

Planetary nebulae are ionized clouds of gas formed by the hydrogen-rich envelopes of low- and intermediate-mass stars ejected at late evolutionary stages. The strong UV flux from their central stars causes a highly stratified ionization structure, with species of higher ionization potential closer to the star. Here, we report on the exceptional case of HuBi 1, a double-shell planetary nebula whose inner shell presents emission from low-ionization species close to the star and emission from high-ionization species farther away. Spectral analysis demonstrates that the inner shell of HuBi 1 is excited by shocks, whereas its outer shell is recombining. The anomalous excitation of these shells can be traced to its low-temperature [WC10] central star whose optical brightness has declined continuously by 10 magnitudes in a period of 46 years. Evolutionary models reveal that this star is the descendant of a low-mass star (≃1.1 M) that has experienced a ‘born-again’ event whose ejecta shock-excite the inner shell. HuBi 1 represents the missing link in the formation of metal-rich central stars of planetary nebulae from low-mass progenitors, offering unique insight regarding the future evolution of the born-again Sakurai’s object. Coming from a solar-mass progenitor, HuBi 1 represents a potential end-state for our Sun.Some of the data presented in this article were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. The Nordic Optical telescope (NOT) is installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in the island of La Palma (Spain). This article is also based on observations carried out at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN SPM), Baja California, Mexico. We thank the daytime and night support staff at the OAN SPM for facilitating and helping obtain our observations. A.A. and C.M. acknowledge support through the CONACyT project CONACyT-CB2015-254132. G.R.-L. acknowledges support from Universidad de Guadalajara, Fundacion Marcos Moshinsky, ProMoFID2018 and CONACyT (grant A1-S-12258). L.S. acknowledges support from PAPIIT grant IA-101316 (Mexico). L.F.M. is supported by Ministerio de Economia, Industria y Competitividad (Spain) grants AYA2014-57369-C3-3 and AYA2017-84390-C2-1-R (cofunded by FEDER funds). M.A.G. acknowledges support of the grant AYA 2014-57280-P, cofunded with FEDER funds. M.M.M.B. is partially supported through ANPCyT grant PICT-2016-0053 and MinCyT-DAAD bilateral cooperation program through grant DA/16/07. S.A.Z. was supported by the ITE-UNAM agreement 1500-479-3-V-04

Discovery of a New Classical Nova Shell Around a Nova-like Cataclysmic Variable

The morphology and optical spectrum of IPHASX J210204.7+471015, a nebula classified as a possible planetary nebula are, however, strikingly similar to those of AT Cnc, a classical nova shell around a dwarf nova. To investigate its true nature, we have obtained high-resolution narrowband [O iii] and [N ii] images and deep optical spectra. The nebula shows an arc of [N ii]-bright knots notably enriched in nitrogen, while an [O iii]-bright bow shock is progressing throughout the ISM. Diagnostic line ratios indicate that shocks are associated with the arc and bow shock. The central star of this nebula has been identified by its photometric variability. Time-resolved photometric and spectroscopic data of this source reveal a period of 4.26 hr, which is attributed to a binary system. The optical spectrum is notably similar to that of RW Sex, a cataclysmic variable star (CV) of the UX UMa nova-like (NL) type. Based on these results, we propose that IPHASX J210204.7 + 471015 is a classical nova shell observed around a CV-NL system in quiescence.© 2018. The American Astronomical Society. All rights reserved.M.A.G. acknowledges support of the grant AYA 2014-57280-P, cofunded with FEDER funds. L.S. acknowledges support from PAPIIT grant IA-101316 (Mexico). G.T. has been supported by grants PAPIIT IN108316 and CONACyT 166376. G. R.-L. acknowledges support from Universidad de Guadalajara, CONACyT, PRODEP, and SEP (Mexico). AA postdoctoral grant and some computational resources are from CONACyT 2015-CB/254132 and UNAM-DGAPA-PAPIIT-107215 projects. N.J.W. acknowledges an STFC Ernest Rutherford Fellowship. This article is partially based upon observations carried out at the Observatorio Astronomico Nacional on the Sierra San Pedro Martir (OAN SPM), Baja California, Mexico. We thank the daytime and night support staff at the OAN SPM for facilitating and helping obtain our observations. Some of the data presented here were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. This article is based in part on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in the island of La Palma. This paper also makes use of data obtained as part of the INT Photometric Ha Survey of the Northern Galactic Plane (IPHAS: http://www.iphas.org) carried out at the Isaac Newton Telescope (INT). The INT is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. All IPHAS data are processed by the Cambridge Astronomical Survey Unit at the Institute of Astronomy in Cambridge. The band-merged DR2 catalog was assembled at the Centre for Astrophysics Research, University of Hertfordshire, supported by STFC grant ST/J001333/1

The inside-out planetary nebula around a born-again star

Planetary nebulae are ionized clouds of gas formed by the hydrogen-rich envelopes of low- and intermediate-mass stars ejected at late evolutionary stages. The strong UV flux from their central stars causes a highly stratified ionization structure, with species of higher ionization potential closer to the star. Here, we report on the exceptional case of HuBi 1, a double-shell planetary nebula whose inner shell presents emission from low-ionization species close to the star and emission from high-ionization species farther away. Spectral analysis demonstrates that the inner shell of HuBi 1 is excited by shocks, whereas its outer shell is recombining. The anomalous excitation of these shells can be traced to its low-temperature [WC10] central star whose optical brightness has declined continuously by 10 magnitudes in a period of 46 years. Evolutionary models reveal that this star is the descendant of a low-mass star (≃1.1 M⊙) that has experienced a ‘born-again’ event1 whose ejecta shock-excite the inner shell. HuBi 1 represents the missing link in the formation of metal-rich central stars of planetary nebulae from low-mass progenitors, offering unique insight regarding the future evolution of the born-again Sakurai’s object2. Coming from a solar-mass progenitor, HuBi 1 represents a potential end-state for our Sun.Fil: Guerrero, Martín A.. Instituto de Astrofísica de Andalucía; EspañaFil: Fang, Xuan. Unversity of Hong Kong; ChinaFil: Miller Bertolami, Marcelo Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Ramos Larios, Gerardo. Instituto de Astronomía y Meteorologia de la Universidad de Guadalajara; MéxicoFil: Todt, Helge. Universitat Potsdam; AlemaniaFil: Alarie, Alexandre. Universidad Nacional Autónoma de México; MéxicoFil: Sabin, Laurence. Universidad Nacional Autónoma de México; MéxicoFil: Miranda, Luis F.. Instituto de Astrofísica de Andalucía; EspañaFil: Morisset, Christophe. Universidad Nacional Autónoma de México; MéxicoFil: Kehrig, Carolina. Instituto de Astrofísica de Andalucía; EspañaFil: Zavala, Saúl A.. Departamento de Ciencias Básicas; Méxic

The inside-out planetary nebula around a born-again star

Planetary nebulae are ionized clouds of gas formed by the hydrogen-rich envelopes of low- and intermediate-mass stars ejected at late evolutionary stages. The strong UV flux from their central stars causes a highly stratified ionization structure, with species of higher ionization potential closer to the star. Here we report on the exceptional case of HuBi 1, a double-shell planetary nebula whose inner shell presents emission from low-ionization species close to the star and emission from high-ionization species farther away. Spectral analysis demonstrates that the inner shell of HuBi 1 is excited by shocks, whereas its outer shell is recombining. The anomalous excitation of these shells can be traced to its low-temperature [WC10] central star whose optical brightness has declined continuously by 10 magnitudes in a period of 46 years. Evolutionary models reveal that this star is the descendent of a low-mass star (≃1.1 M⊙) that has experienced a born-again event whose ejecta shock-excite the inner shell. HuBi 1 represents the missing link in the formation of metal-rich central stars of planetary nebulae from low-mass progenitors, offering unique insight regarding the future evolution of the born-again Sakurai's object. Coming from a solar-mass progenitor, HuBi 1 represents a potential end-state for our Sun.Instituto de Astrofísica de La Plat

Essential Features of an Interstitial Lung Disease Multidisciplinary Meeting An International Delphi Survey

Rationale: The interstitial lung disease (ILD) multidisciplinary meetings (MDM), composed of pulmonologists, radiologists, and pathologists, is integral to the rendering of an accurate ILD diagnosis. However, there is significant heterogeneity in the conduct of ILD MDMs, and questions regarding their best practices remain unanswered. Objectives: To achieve consensus among ILD experts on essential components of an ILD MDM. Methods: Using a Delphi methodology, semi-structured interviews with ILD experts were used to identify key themes and features of ILD MDMs. These items informed two subsequent rounds of online questionnaires that were used to achieve consensus among a broader, international panel of ILD experts. Experts were asked to rate their level of agreement on a five-point Likert scale. An a priori threshold for consensus was set at a median score 4 or 5 with an interquartile range of 0. Results: We interviewed 15 ILD experts, and 102 ILD experts participated in the online questionnaires. Five items and two exploratory statements achieved consensus on being essential for an ILD MDM following two questionnaire rounds. There was consensus that the presence of at least one radiologist, a quiet setting with a visual projection system, a high-quality chest high-resolution computed tomography, and a standardized template summarizing collated patient data are essential components of an ILD MDM. Experts also agreed that it would be useful for ILD MDMs to undergo an annual benchmarking process and a validation process by fulfilling a minimum number of cases annually. Twenty-seven additional features were considered to be either highly desirable or desirable features based on the degree of consensus. Although our findings on desirable features are similar to the current literature, several of these remain controversial and warrant further research. The study also showed an agreement among participants on several future concepts to improve the ILD MDM, such as performing regular self-assessments and conducting research into shared practices to develop an international expert guideline statement on ILD MDMs. Conclusions: This Delphi study showed consensus among international ILD experts on essential and desirable features of an ILD MDM. Our data represent an important step toward potential collaborative research into future standardization of ILD MDMs