Microspore embryogenesis in barley: anther pre-treatment stimulates plant defence gene expression

Microspore embryogenesis (ME) is a process in which the gametophytic pollen programme of the microspore is reorientated towards a new embryo sporophytic programme. This process requires a stress treatment, usually performed in the anther or isolated microspores for several days. Despite the universal use of stress to induce ME, very few studies have addressed the physiological processes that occur in the anther during this step. To further understand the processes triggered by stress treatment, we followed the response of anthers by measuring the expression of stress-related genes in two barley (Hordeum vulgare L.) cultivars differing in their ME response. Genes encoding enzymes involved in oxidative stress (glutathione-S-transferase, GST; oxalate oxidase, OxO), in the synthesis of jasmonic acid (13-lipoxygenase, Lox; allene oxide cyclase, AOC; allene oxide synthase, AOS) and in the phenylpropanoid pathway (phenylalanine ammonia lyase, PAL), as well as those encoding PR proteins (Barwin, chitinase 2b, Chit 2b; glucanase, Gluc; basic pathogenesis-related protein 1, PR1; pathogenesis-related protein 10, PR10) were up-regulated in whole anthers upon stress treatment, indicating that anther perceives stress and reacts by triggering general plant defence mechanisms. In particular, both OxO and Chit 2b genes are good markers of anther reactivity owing to their high level of induction during the stress treatment. The effect of copper sulphate appeared to limit the expression of defence-related genes, which may be correlated with its positive effect on the yield of microspor

Effet des taches foliaires causées par le Phaeosphaeria nodorum inoculé à différents stades de développement sur le rendement du blé de printemps

Des études en serre ont été réalisées pour évaluer l'effet du Phaeosphaeria nodorum sur le rendement du blé de printemps (Triticum aestivum, cv. Laval 19). Les plants de blé étaient inoculés aux stades gonflement épiaison, pleine floraison et grain laiteux. L'essai a été réalisé au cours de l'hiver 1993 et répété au cours de l'hiver 1994. L'inoculation du champignon pathogène P. nodorum entraîne généralement une augmentation significative de la surface foliaire infectée et une réduction du rendement comparativement aux témoins non inoculés. La surface foliaire infectée mesurée uniquement sur la feuille étendard est similaire à celle mesurée sur la plante entière. Le stade phénologique a un effet significatif sur toutes les variables observées: surface foliaire infectée, poids des tiges et des feuilles, poids des épis, poids des grains, poids des biomasses végétative et totale et indice de récolte. L'inoculation du pathogène au stade grain laiteux, le plus tardif de l'étude, semble avoir provoqué moins d'effets négatifs sur le rendement du blé comparativement aux trois autres stades étudiés. Selon les résultats de cette étude et les observations réalisées au Québec au cours des 15 dernières années, il est peu probable que les taches foliaires causées par le P. nodorum provoquent des baisses appréciables de rendement du blé de printemps au Québec.Greenhouse studies were carried out to evaluate the effects of foliar leaf spots caused by P. nodorum on spring wheat (Triticum aestivum, cv. Laval 19) yield. Wheat plants were inoculated at booting, heading, flowering and milking growth stages. Experiments were first performed in winter 1993 and repeated in winter 1994. Inoculation of P. nodorum usually resulted in an increase of leaf spots and a decrease of yield compared to uninoculated plants. Foliar flag leaves spots were similar to total plant foliar leaf spots. All variables were significantly affected by inoculation stages : infected foliar area, biomass of straw and leaves, biomass of spikes, biomass of grains, vegetative biomass and harvest index. Inoculation at milking growth stage seemed to resul in the least negative impacts on yield compared to all other stages. From the results of this study and observations performed in Quebec during the 15 past years, leaf spots caused by P. nodorum should not resul in important spring wheat yield losses in Quebec

Horizontal evaluation: Stimulating social learning among peers

Horizontal evaluation is a flexible evaluation method that combines self-assessment and external review by peers. We have developed and applied this method for use within an Andean regional network that develops new methodologies for research and development (R&D). The involvement of peers neutralizes the lopsided power relations that prevail in traditional external evaluations, creating a more favourable atmosphere for learning and improvement. The central element of a horizontal evaluation is a workshop that brings together a group of ‘local participants’ who are developing a new R&D methodology and a group of ‘visitors’ or ‘peers’ who are also interested in the methodology. The workshop combines presentations about the methodology with field visits, small group work and plenary discussions. It elicits and compares the perceptions of the two groups concerning the strengths and weaknesses of the methodology; it provides practical suggestions for improvement, which may often be put to use immediately; it promotes social learning among the different groups involved; and it stimulates further experimentation with and development of the methodology in other settings

A Sip of Cool Water: Pregnancy Accommodation After the ADA Amendments Act

When April Roller began making repeated trips to the restroom because of morning sickness and pregnancy-related dizziness, her supervisor told her that her employer did not pay [her] to pee. Rather than accommodating her need for more frequent restroom visits, the supervisor offered to buy her a larger wastebasket so that she could take care of vomiting without having to visit the bathroom or leave her seat. Similarly, a sales associate was denied permission to carry a water bottle, which she needed for her pregnancy-related urinary tract and bladder infections. A cashier was denied permission to use a stool, which she needed because her doctor had forbidden her to stand for more than six hours at a time because of pregnancy-related circulation problems. A nursing home activity director was denied accommodation when her doctor imposed lifting restrictions to prevent miscarriage, despite the fact that lifting was a minor part of her job with which her co-workers were willing to help. All four women eventually lost their jobs

A Sip of Cool Water: Pregnancy Accommodation After the ADA Amendments Act

When April Roller began making repeated trips to the restroom because of morning sickness and pregnancy-related dizziness, her supervisor told her that her employer did not pay [her] to pee. Rather than accommodating her need for more frequent restroom visits, the supervisor offered to buy her a larger wastebasket so that she could take care of vomiting without having to visit the bathroom or leave her seat. Similarly, a sales associate was denied permission to carry a water bottle, which she needed for her pregnancy-related urinary tract and bladder infections. A cashier was denied permission to use a stool, which she needed because her doctor had forbidden her to stand for more than six hours at a time because of pregnancy-related circulation problems. A nursing home activity director was denied accommodation when her doctor imposed lifting restrictions to prevent miscarriage, despite the fact that lifting was a minor part of her job with which her co-workers were willing to help. All four women eventually lost their jobs

Innovación agrícola pro-pobre para la seguridad y soberanía alimentaria en la región andina: el caso IssAndes en Ecuador.

El proyecto "Innovación para la seguridad y la soberanía alimentaria en la región andina"- IssAndes, se inició en marzo del 2011 y culminó en marzo del 2015. El proyecto fue ejecutado en Bolivia, Ecuador, Perú y Colombia, con socios de agricultura, salud y educación en cada país. Fue coordinado por el Centro Internacional de la Papa (CIP) y financiado por la Unión Europea a través del Fondo Internacional de Desarrollo Agrícola (FIDA). El objetivo de IssAndes fue fortalecer la innovación para la seguridad alimentaria a diferentes niveles territoriales (local, nacional y regional) en la región andina, en respuesta a las necesidades de los grupos rurales vulnerables y así contribuir a la reducción de la desnutrición de niño/as menores de tres años mediante mejoras en la alimentación y nutrición de las familias. En el Ecuador, el proyecto se implementó en las provincias de Chimborazo, Tungurahua y Cotopaxi, en un total de 10 cantones y 17 parroquias, llegando a 44 comunidades con 1135 familias vinculadas al rubro papa. El proyecto tuvo un total de siete socios a nivel nacional (Instituto Nacional Autónomo de Investigaciones Agropecuarias - INIAP, Escuela Superior Politécnica de Chimborazo - ESPOCH, Visión Mundial, Estrategia Acción Nutrición - EAN, Oficina para Estudios del Agro - OfiAgro, Centro Latinoamericano para el Desarrollo Rural-RIMISP y la Fundación Minga para la Acción Rural y la Cooperación - MARCO) y dos socios a nivel regional (CIP y el Instituto de Investigación Nutricional - IIN). IssAndes estructuró sus acciones de investigación y desarrollo en cuatro componentes: i) Contribución de la papa a la nutrición y salud; ii) Mejoras en los sistemas de producción basados en papa; iii) Educación nutricional para el cambio de comportamiento; e iv) Incidencia pública y política

Interaction between C/EBPβ and Tax down-regulates human T-cell leukemia virus type I transcription

AbstractThe human T-cell leukemia virus type I (HTLV-I) Tax protein trans-activates viral transcription through three imperfect tandem repeats of a 21-bp sequence called Tax-responsive element (TxRE). Tax regulates transcription via direct interaction with some members of the activating transcription factor/CRE-binding protein (ATF/CREB) family including CREM, CREB, and CREB-2. By interacting with their ZIP domain, Tax stimulates the binding of these cellular factors to the CRE-like sequence present in the TxREs. Recent observations have shown that CCAAT/enhancer binding protein β (C/EBPβ) forms stable complexes on the CRE site in the presence of CREB-2. Given that C/EBPβ has also been found to interact with Tax, we analyzed the effects of C/EBPβ on viral Tax-dependent transcription. We show here that C/EBPβ represses viral transcription and that Tax is no more able to form a stable complex with CREB-2 on the TxRE site in the presence of C/EBPβ. We also analyzed the physical interactions between Tax and C/EBPβ and found that the central region of C/EBPβ, excluding its ZIP domain, is required for direct interaction with Tax. It is the first time that Tax is described to interact with a basic leucine-zipper (bZIP) factor without recognizing its ZIP domain. Although unexpected, this result explains why C/EBPβ would be unable to form a stable complex with Tax on the TxRE site and could then down-regulate viral transcription. Lastly, we found that C/EBPβ was able to inhibit Tax expression in vivo from an infectious HTLV-I molecular clone. In conclusion, we propose that during cell activation events, which stimulate the Tax synthesis, C/EBPβ may down-regulate the level of HTLV-I expression to escape the cytotoxic-T-lymphocyte response

Conductivity in organic semiconductors hybridized with the vacuum field

Organic semiconductors have generated considerable interest for their potential for creating inexpensive and flexible devices easily processed on a large scale [1-11]. However technological applications are currently limited by the low mobility of the charge carriers associated with the disorder in these materials [5-8]. Much effort over the past decades has therefore been focused on optimizing the organisation of the material or the devices to improve carrier mobility. Here we take a radically different path to solving this problem, namely by injecting carriers into states that are hybridized to the vacuum electromagnetic field. These are coherent states that can extend over as many as 10^5 molecules and should thereby favour conductivity in such materials. To test this idea, organic semiconductors were strongly coupled to the vacuum electromagnetic field on plasmonic structures to form polaritonic states with large Rabi splittings ca. 0.7 eV. Conductivity experiments show that indeed the current does increase by an order of magnitude at resonance in the coupled state, reflecting mostly a change in field-effect mobility as revealed when the structure is gated in a transistor configuration. A theoretical quantum model is presented that confirms the delocalization of the wave-functions of the hybridized states and the consequences on the conductivity. While this is a proof-of-principle study, in practice conductivity mediated by light-matter hybridized states is easy to implement and we therefore expect that it will be used to improve organic devices. More broadly our findings illustrate the potential of engineering the vacuum electromagnetic environment to modify and to improve properties of materials.Comment: 16 pages, 13 figure

Radiative properties of desert aerosols by optical ground-based measurements at solar wavelengths

Les caractéristiques radiatives des poussières atmosphériques ont été mesurées d'avril à mai 1986 à la station de Mbour (16,9°W; 14,3°N) située à 80 km au sud de Dakar (Sénégal). Couplée avec des mesures satellitaires cette étude présente les premières conclusions des observatoires au sol pendant 15 journées consécutives. L'épaisseur optique varie fortement d'un évènement à l'autre (0,4-2 dans la bande spectrale de 450 mm). Les propriétés radiatives des aérosols sont en accord avec les modèles proposés notamment par SHETTLE's (1984) sur l'impact des brumes sèches sur le bilan énergétique de la planète (Résumé d'auteur