Mise en évidence de molécules effectrices, les flavonoïdes, impliquées dans la régulation croisée des symbioses mycorhizienne arbusculaire et rhizobienne chez Medicago sativa

Deux symbioses végétales partagent la même niche écologique, leur hôte, une légumineuse. Ces deux associations mutualistes sont la mycorhize arbusculaire (MA) et la symbiose Rhizobium/légumineuse. Chacune de ces relations symbiotiques, prise individuellement, peuvent contrôler leur propre colonisation par des mécanismes d'autorégulation. Ce contrôle exclusif s'effectue par rétroaction systémique et parviendrait à limiter le coût en carbone pour l'hôte. En vue d'étudier la restriction exercée par une plante hôte sur le degré de colonisation mycorhizienne et rhizobienne, la légumineuse Medicago sativa a été cultivée en chambre bicompartimentée (Split-Roots). Ce dispositif expérimental a permis de séparer en deux parties distinctes le système racinaire de M. sativa. Le but recherché par ces expérimentations était de vérifier à distance l'autorégulation au sein d'une symbiose sur la seconde partie du système racinaire et de mettre en évidence une régulation négative croisée entre deux symbioses différentes. En effet pour la première fois, il est démontré que l'autorégulation systémique n'est pas l'action d'une seule symbiose sur elle-même, mais que par des signaux communs entre les deux symbioses, il existe une régulation négative croisée entre elles. Cette approche permet d'examiner, sous un nouvel angle, la régulation de l'établissement d'une symbiose par une autre symbiose. Dans ces conditions, nos résultats montrent l'existence d'un lien évident de signalisation entre les deux symbioses végétales. Dans le cas précis d'une pré-colonisation de M. sativa par Sinorhizobium meliloti, les facteurs Nod se sont révélés impliqués au niveau de l'autorégulation. Dans cet exemple, les flavonoïdes exsudés par M. sativa sont non seulement reconnus par les Rhizobia mais aussi par le Glomus mosseae. Ces résultats représentent un acquis important pour l'interprétation de la signalisation au niveau de l'autorégulation des deux symbioses à l'étude. Par ailleurs, l'analyse des exsudats racinaires de M. sativa par chromatigraphie liquide à haute performance (HPLC) montre une modification significative du patron des isoflavonoïdes lorsque cette plante est soumise à différents contrôles dérivant d'autorégulations et de régulations négatives croisées. De plus il est loisible d'observer une variation similaire de patrons de flavonoïdes suite à l'application de facteurs Nod. En soi, d'une façon plus exacte, tous ces traitements provoquent une réduction marquée de la formononétine et de l'ononine. Ces deux isoflavonoïdes semblent être d'excellents candidats comme molécules ± signal ¿ dans la régulation à distance pour les deux symbioses végétales. De plus, l'application externe de ces deux isoflavonoïdes peut normalement restaurer la nodulation et la mycorhization. Les flavonoïdes jouent un rôle clef dans la formation de la symbiose MA chez M. sativa. Lors d'expériences avec diverses souches de G. mosseae nous avons cherché à montrer qu'il y avait bien une régularité et une constance dans le patron de flavonoïdes considérés comme molécule signal et cela peu importe les besoins métaboliques divergents associés à ces souches de G. mosseae. Selon cette prémisse nous concluons que leur production n'est pas subordonnée aux besoins métaboliques des souches fongiques. La constance de l'augmentation ou la réduction du patron de ces flavonoïdes pourraient bien être le résultat du rôle de flanovoïdes impliqués pour des mécanismes de signalisations qui accompagnent nécessairement l'établissement de la symbiose MA

On Transmitting Expressiveness in Belarusian-English Poetic Translation

The present article deals with various lexical, grammatical, stylistic problems encountered by translators while transmitting aspects of expressiveness of the original text (on the example of Belarusian-English poetic translation). The focus of attention is on basic transformation types, which are illustrated by the original and colourful examples. The author of the article considers not only purely linguistic aspects of translation, but also relevant pragmatic adaptation

Neutron Transfer Studied with a Radioactive beam of 24Ne, using TIARA at SPIRAL

A general experimental technique for high resolution studies of nucleon transfer reactions using radioactive beams is briefly described, together with the first new physics results that have been obtained with the new TIARA array. These first results from TIARA are for the reaction 24Ne(d,p)25Ne, studied in inverse kinematics with a pure radioactive beam of 100,000 pps from the SPIRAL facility at GANIL. The reaction probes the energies of neutron orbitals relevant to very neutron rich nuclei in this mass region and the results highlight the emergence of the N=16 magic number for neutrons and the associated disappearance of the N=20 neutron magic number for the very neutron rich neon isotopes.Comment: Proceedings of the Carpathian Summer School of Physics, Mamaia-Constanta, Romania, 13-24 June 200

Remembering Jim Mather

No abstrac

Putting the community in the centre : towards effective village-based planning and development in Vietnam

In addition to successful economic reforms, the Socialist Republic of Vietnam (SRV) is also in the process of implementing reforms in the areas of civil society, decentralisation and grassroots democracy, within what is generally considered a strong state environment. Relevant research argues that uninhibited democracy, decentralisation and civil society are important elements in achieving what has been popularly termed community 'participation' by development practitioners. This process was particularly assisted by the release of the grassroots democracy decree of 1998 and its subsequent update in 2003 that set out the details of what Vietnam required from the village and commune levels as part of the reform process. Interestingly, it is also these two levels that form the dividing line between government and community in Vietnam. Although there have been several studies investigating the strengths and weaknesses of the implementation of the grassroots democracy decree and other related policies, village-based planning and development programs, which are a development approach piloted by several non-government organisations (NGOs) and donors to address these issues, have not been comprehensively evaluated. These programs, which are generally long-term, area-based, holistic and integrated, have frequently been observed to deliver many of the relevant elements within the larger notions of democracy, decentralisation, civil society and participation. The research explores the effectiveness of village-based planning and development approaches within the Vietnamese context using both quality and quantity criteria to assess elements of program effectiveness, focussing primarily on community level perspectives. Four projects of a selected international non-government organisation (INGO), were used as a detailed case study utilising a combination of qualitative focus groups and interviews, complimented by two quantitative household interviews. These community opinions were triangulated against the opinion of other key stakeholders including government, bilateral and multilateral aid donors, as well as Vietnamese and International NGOs involved in such approaches. The research highlights that with careful attention, village-based planning and development approaches do have the ability to more effectively allow the community to be put back into the 'centre of development' in Vietnam, rather than being passive recipients or marginalised by the development process. A set of seven key elements that contribute to more effective village-based planning and development approaches in Vietnam has been outlined in this thesis. It is hoped that these key elements might be further utilised by donor, NGO and government agencies to support the appropriate replication and up-scaling of the approaches to enable development needs and poverty to be more effectively reduced in Vietnam However, the approaches are not without their challenges, in particular in terms of achieving integrated planning from village to national level, being flexible enough for the variety of ethnic minority and geographical areas, effectively involving a broad and appropriate range of individuals and organised civil society groups and, perhaps most importantly, taking the approaches beyond the current few pilot programs to a national scale that forms a more integral part of the government's overall poverty reduction strategy

A conceptual map of invasion biology: Integrating hypotheses into a consensus network

Background and aims Since its emergence in the mid‐20th century, invasion biology has matured into a productive research field addressing questions of fundamental and applied importance. Not only has the number of empirical studies increased through time, but also has the number of competing, overlapping and, in some cases, contradictory hypotheses about biological invasions. To make these contradictions and redundancies explicit, and to gain insight into the field’s current theoretical structure, we developed and applied a Delphi approach to create a consensus network of 39 existing invasion hypotheses. Results The resulting network was analysed with a link‐clustering algorithm that revealed five concept clusters (resource availability, biotic interaction, propagule, trait and Darwin’s clusters) representing complementary areas in the theory of invasion biology. The network also displays hypotheses that link two or more clusters, called connecting hypotheses, which are important in determining network structure. The network indicates hypotheses that are logically linked either positively (77 connections of support) or negatively (that is, they contradict each other; 6 connections). Significance The network visually synthesizes how invasion biology’s predominant hypotheses are conceptually related to each other, and thus, reveals an emergent structure – a conceptual map – that can serve as a navigation tool for scholars, practitioners and students, both inside and outside of the field of invasion biology, and guide the development of a more coherent foundation of theory. Additionally, the outlined approach can be more widely applied to create a conceptual map for the larger fields of ecology and biogeography

Suppression of arbuscular mycorrhizal colonization and nodulation in split‐root systems of alfalfa after pre‐inoculation and treatment with Nod factors

Roots of legumes establish symbiosis with arbuscular mycorrhizal fungi (AMF) and nodule‐inducing rhizobia. The existing nodules systemically suppress subsequent nodule formation in other parts of the root, a phenomenon termed autoregulation. Similarly, mycorrhizal roots reduce further AMF colonization on other parts of the root system. In this work, split‐ root systems of alfalfa (Medicago sativa) were used to study the autoregulation of symbiosis with Sinorhizobium meliloti and the mycorrhizal fungus Glomus mosseae. It is shown that nodulation systemically influences AMF root colonization and vice versa. Nodules on one half of the split‐root system suppressed subsequent AMF colonization on the other half. Conversely, root systems pre‐colonized on one side by AMF exhibited reduced nodule formation on the other side. An inhibition effect was also observed with Nod factors (lipo‐chito‐oligosaccharides). NodSm‐IV(C16:2, S) purified from S. meliloti systemically suppressed both nodule formation and AMF colonization. The application of Nod factors, however, did not influence the allocation of 14C within the split‐root system, excluding competition for carbohydrates as the regulatory mechanism. These results indicate a systemic regulatory mechanism in the rhizobial and the arbuscular mycorrhizal association, which is similar in both symbiose

Kalbos (ne)atitikimai vertime: Roaldo Dahlio The Big Fat Giant ir jo albaniškasis vertimas

[full article, abstract in English; abstract in Lithuanian] The aim of this article is to observe how semantic peculiarities travel across languages and cultures. The original book, The Big Fat Giant, by Roald Dahl lends itself perfectly to such a comparative study due to its linguistic and semantic features that need to be explored in order to understand how they were brought to the Albanian language and culture. Classifications of several levels at which mismatches occur are mentioned, such as mismatches at the level of syntax, semantics and phonetics. Examples are given to illustrate each level. The discussion is enriched with observations and examples from the intertextual level. The paper concludes with findings which refer to this tale in particular and recommendations for further research.[straipsnis ir santrauka anglų kalba, santrauka lietuvių kalba] Vertimo procese kalbų ir kultūrų skirtumai išryškėja įvairiuose lygmenyse: sintaksės, semantikos, fonetikos ir pan. Šiame straipsnyje siekiama palyginti garsaus anglų rašytojo Roaldo Dahlio knygos The BFG (liet. DGM – vertė D. Žalytė) originalo tekstą su jo vertimu į albanų kalbą. Šis palyginimas atskleidė gana daug įvairių neatitikimų visuose kalbos lygmenyse, ypač verti dėmesio semantikos pokyčiai vertime. Pateikti pavyzdžiai skirti ne tik parodyti faktiškai užfiksuotus skirtumus, vertėjui kėlusius daugiausia problemų, bet ir atkreipti dėmesį į veiksnius, kurie daro poveikį pačiam vertimo procesui