Problemas divulgativos

Triángulos cevianos, cuasicevianos y residuales

EcoTILLING for the identification of allelic variants of melon eIF4E, a factor that controls virus susceptibility

<p>Abstract</p> <p>Background</p> <p>Translation initiation factors of the 4E and 4G protein families mediate resistance to several RNA plant viruses in the natural diversity of crops. Particularly, a single point mutation in melon eukaryotic translation initiation factor 4E (eIF4E) controls resistance to <it>Melon necrotic spot virus </it>(MNSV) in melon. Identification of allelic variants within natural populations by EcoTILLING has become a rapid genotype discovery method.</p> <p>Results</p> <p>A collection of <it>Cucumis </it>spp. was characterised for susceptibility to MNSV and <it>Cucumber vein yellowing virus </it>(CVYV) and used for the implementation of EcoTILLING to identify new allelic variants of <it>eIF4E</it>. A high conservation of <it>eIF4E </it>exonic regions was found, with six polymorphic sites identified out of EcoTILLING 113 accessions. Sequencing of regions surrounding polymorphisms revealed that all of them corresponded to silent nucleotide changes and just one to a non-silent change correlating with MNSV resistance. Except for the MNSV case, no correlation was found between variation of eIF4E and virus resistance, suggesting the implication of different and/or additional genes in previously identified resistance phenotypes. We have also characterized a new allele of <it>eIF4E </it>from <it>Cucumis zeyheri</it>, a wild relative of melon. Functional analyses suggested that this new <it>eIF4E </it>allele might be responsible for resistance to MNSV.</p> <p>Conclusion</p> <p>This study shows the applicability of EcoTILLING in <it>Cucumis </it>spp., but given the conservation of eIF4E, new candidate genes should probably be considered to identify new sources of resistance to plant viruses. Part of the methodology described here could alternatively be used in TILLING experiments that serve to generate new <it>eIF4E </it>alleles.</p

Height-diameter models for maritime pine in Portugal: a comparison of basic, generalized and mixed-effects models

Tree height is a key variable in forest monitoring studies and for forest management. However, tree height measurement is time consuming, and the recommended procedure is to use estimates from height-diameter models. Here, we compare height-diameter model forms and approaches for predicting tree height (h) as a function of tree diameter at breast height (d) and additional stand level covariates. Four model forms were evaluated: (i) basic models (which only used d as predictor variable); (ii) generalized models (which used d and stand-level predictor variables); (iii) a mixed-effects model based on the best basic model; and (iv) a mixed-effects model based on the best generalized model. Several alternatives aimed at minimizing height measurement effort were tested in terms of accuracy and applicability. From a practical point of view, the selected generalized model is recommended for estimating the height of maritime pine in Portugal. The results also show that a calibrated basic mixed model provides more accurate results than a basic model locally fitted when the number of h-d observations is limited.S

Pepino mosaic virus RNA-Dependent RNA Polymerase POL Domain Is a Hypersensitive Response-Like Elicitor Shared by Necrotic and Mild Isolate

[SPA] El virus del mosaico del pepino dulce (PepMV) es un patógeno emergente que representa una grave amenaza para la producción de tomate. Las enfermedades inducidas por PepMV se manifiestan con una amplia gama de síntomas, incluyendo la necrosis sistémica. Nuestros resultados muestran que la acumulación de PepMV depende tanto del aislado del virus, como de la variedad de tomate o las condiciones ambientales, asociado todo ello al desarrollo de la necrosis. La sustitución de una lisina por un ácido glutámico en la posición 67 del triple bloque de genes (TGB3), previamente descrita como un determinante de la necrosis, parece favorecer una mayor acumulación del virus pero no parece ser el elemento elicitor de la necrosis sistémica. La sobreexpresión tanto de TGB3 como del dominio polimerasa (POL) de la replicasa (RdRp) produjo necrosis, aunque sólo la expresión local de POL desencadenó síntomas caracteristos de HR. En conjunto, nuestros datos sugieren que el dominio RdRp-POL desempeña un papel importante en la inducción de necrosis de PepMV, dependiendo del nivel de acumulación del virus, que puede ser modulado por la naturaleza de TGB3, el genotipo del huesped y las condiciones ambientales. [ENG] Pepino mosaic virus (PepMV) is an emerging pathogen that represents a serious threat to tomato production worldwide. PepMV-induced diseases manifest with a wide range of symptoms, including systemic necrosis. Our results showed that PepMV accumulation depends on the virus isolate, tomato cultivar, and environmental conditions, and associates with the development of necrosis. Substitution of lysine for glutamic acid at position 67 in the triple gene block 3 (TGB3) protein, previously described as a necrosis determinant, led to increased virus accumulation and was necessary but not sufficient to induce systemic necrosis. Overexpression of both TGB3 and the polymerase domain (POL) of the RNA-dependent RNA polymerase (RdRp) resulted in necrosis, although only local expression of POL triggered HR-like symptoms. Altogether, our data suggest that the RdRp-POL domain plays an important role in PepMV necrosis induction, with necrosis development depending on the virus accumulation level, which can be modulated by the nature of TGB3, host genotype and environmental conditions.Agradecer la financiación del Ministerio de Economía y Competitividad (AGL2012-37390 ) y la fundación Séneca por la financiación de la Beca FPI

Diagnóstico sobre las bacterias rizosféricas asociadas al cultivo de caña de azúcar (Saccharum spp.)

Objective: Characterize the presence of rhizobacteria associated with three varieties of sugar cane: 9640 ATMEX, MEX 69-290 and the MEX SFC 9546, cultivated in the area of supplying the Pdte. Benito Juarez sugar mills (PBJ). Desing/methodology/approach: Three sites were selected for sampling by variety where soil samples were collected from 0 to 30 cm depth. For the isolation of the bacteria are followed by the serial dilution technique by viable. Results:The rhizosphere of the variety ATMEX-9640 presented the greatest number of CFU g-1. Ten of the 26 strains demonstrated capabilities of biological nitrogen fixation (BNF) or solubizacion of phosphorus (SP). Eight of them carried FBN already that degrade the malic acid in the NFb. Five are considered within the group of phosphorus solubilizing bacteria (BSP), because they solubilize the calcium phosphate of Pikovskaya medium. Limitations on study/implications: It was not possible to determine the production of AIA in the strains that grew in the Soya Tripticasa Broth medium. Findings/conclusions: The molecular identification revealed that these bacteria belong to the group of plant growth promoting rhizobacteria (PGPR) belonging Microbacterium, Bacillus y Paenibacillus genera present in the soil Cambisol Fluvic Éutric of the PBJ sugar mills.Objetivo: Evaluar la presencia de rizobacterias asociadas a tres cultivares de caña de azúcar: ATMEX 9640, MEX 69-290 y MEX SFC 9546, cultivados en la zona de abastecimiento del Ingenio Pdte. Benito Juárez (IPBJ). Diseño/Metodología/Aproximación: Se seleccionaron tres sitios de muestreo por cultivar donde se colectaron muestras de suelo de 0 a 30 cm de profundidad. Para el aislamiento de las bacterias se siguió la técnica de dilución seriada por cuenta viable. Resultados: La rizósfera del cultivar ATMEX 9640 presento el mayor número de UFC g-1. 10 de las 26 cepas manifestaron capacidades de fijación biológica de nitrógeno (FBN) o solubización de fósforo (SP). Ocho de ellas llevaron a cabo FBN ya que degradan el ácido málico en el medio NFb. Cinco se consideran dentro del grupo de bacterias solubilizadoras de fósforo (BSF), ya que solubiliza el fosfato de calcio del medio Pikovskaya. Limitaciones del estudio/implicaciones: No fue posible determinar la producción del AIA en las cepas que crecieron en el medio Caldo Tripticasa de Soya. Hallazgos/conclusiones: La identificación molecular reveló que estas bacterias corresponden al grupo de rizobacterias promotoras del crecimiento vegetal del genero Microbacterium, Bacillus y Paenibacillus sp presentes en el suelo Cambisol Fluvico Éutrico del IPBJ

Impulsividad y conciencia del problema predicen la adherencia terapéutica y el abandono del tratamiento en el trastorno por juego de azar

Este estudio investiga el valor predictivo de la impulsividad como rasgo (evaluada con la escala de conducta impulsiva UPPS-P) y de covariados relevantes (variables sociodemográficas, severidad del juego de azar, estado de ánimo disfórico, otras conductas adictivas e inteligencia no verbal), con respecto al abandono del tratamiento y los niveles de cumplimiento de las prescripciones terapéuticas en pacientes con trastorno por juego de azar. Sesenta y seis pacientes con este trastorno, participantes del proyecto G-Brain, fueron evaluados inicialmente en impulsividad rasgo y en los covariados mencionados. Dicha evaluación se realizó durante los seis primeros meses desde el inicio de su tratamiento. En el seguimiento realizado a los 6 meses, 24 pacientes habían abandonado (grupo ABD) y 42 continuaban el tratamiento (grupo NABD). Los análisis multivariados con las subescalas de impulsividad mostraron diferencias prospectivas entre ambos grupos. Aparentemente, estas diferencias son atribuibles a las dimensiones afectivas de impulsividad (urgencias positiva y negativa). Entre ambas dimensiones, solo la urgencia positiva fue un predictor independiente de un ligero incremento en la probabilidad de abandono. Dentro del grupo NABD, un mayor grado de adherencia terapéutica vino predicho, de manera independiente, tanto por una baja búsqueda de sensaciones como por una mayor conciencia de los problemas vinculados al juego. Estos resultados sugieren que los rasgos de impulsividad de origen afectivo son predictores de abandono del tratamiento en pacientes con trastorno por juego. La conciencia de problemas asociados al juego de azar y una baja búsqueda de sensaciones predisponen a una mayor adherencia a las prescripciones terapéuticas

Autoregulatory loop of nuclear corepressor 1 expression controls invasion, tumor growth, and metastasis

Nuclear corepressor 1 (NCoR) associates with nuclear receptors and other transcription factors leading to transcriptional repression. We show here that NCoR depletion enhances cancer cell invasion and increases tumor growth and metastatic potential in nude mice. These changes are related to repressed transcription of genes associated with increased metastasis and poor prognosis in patients. Strikingly, transient NCoR silencing leads to heterochromatinization and stable silencing of the NCoR gene, suggesting that NCoR loss can be propagated, contributing to tumor progression even in the absence of NCoR gene mutations. Down-regulation of the thyroid hormone receptor β1 (TRβ) appears to be associated with cancer onset and progression. We found that expression of TRβ increases NCoR levels and that this induction is essential in mediating inhibition of tumor growth and metastasis by this receptor. Moreover, NCoR is down-regulated in human hepatocarcinomas and in the more aggressive breast cancer tumors, and its expression correlates positively with that of TRβ. These data provide a molecular basis for the anticancer actions of this corepressor and identify NCoR as a potential molecular target for development of novel cancer therapiesThis work was supported by Grants BFU2011-28058 and BFU2014-53610-P from Ministerio de Economía y Competitividad; Grant S2011/BMD-2328 from the Comunidad de Madrid; Grant RD12/0036/0030 from the Instituto de Salud Carlos III (to A.A.); Grants PI080971 and RD12 0036/0064 from the Instituto de Salud Carlos III (to J.P.); and Grant PI12/00386 from the Instituto de Salud Carlos III (to I.I.d.C.). O.A.M.-I. is supported by an Asociación Española Contra el Cáncer contrac