19 research outputs found

    Vitamina E: ubiqüitat tissular i relació amb els jasmonats, claus de la interacció entre la resposta a l'estrès abiòtic i biòtic en plantes

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    [cat] Tots els organismes fotosintètics són capaços de sintetitzar vitamina E, la qual s’acumula de forma ubiqua en els teixits vegetals, tant en els fotosintètics com en els no fotosintètics. Mentre que la vitamina E és un important antioxidant cloroplàstic que respon als estressos ambientals, els jasmonats, hormones derivades de la peroxidació lipídica en els cloroplasts, són reguladors essencials de la resposta a l’estrès biòtic. La relació entre aquestes dues famílies moleculars juga un paper important en el control de l’estat redox cloroplàstic sota condicions d’estrès, el qual és determinant en la senyalització retrògrada. A més, aquesta relació és de gran rellevància fisiològica donada la implicació de la vitamina E i dels jasmonats en la resposta a l’estrès abiòtic i biòtic, respectivament. En aquest treball s’estudia, per una banda, la presència i funció de la vitamina E en teixits tant fotosintètics com no fotosintètics en Fragaria x ananassa var. Albion sota condicions controlades d’estrès hídric, planta que ens ofereix una singular varietat de teixits no fotosintètics en el fals fruit (receptacle i aquenis), i per altra banda, s’estudia la relació de la vitamina E amb els jasmonats i la seva implicació en la interacció entre la resposta a l’estrès abiòtic i biòtic en un arbust mediterrani (Cistus albidus L.) en condicions naturals on coincideixen diversos estressos abiòtics i biòtics. Els resultats posen en rellevància la universalitat de la vitamina E en teixits fotosintètics i no fotosintètics, tant en plantes d’interès agronòmic com en plantes d’interès ecològic. A més, la relació entre la vitamina E i els jasmonats resulta ser bidireccional, essent compatible l’acumulació d’ambdós però amb algunes limitacions. La possible implicació d’aquesta relació en la interacció entre la resposta a l’estrès abiòtic i biòtic es discuteix en relació a l’estudi de C. albidus sota condicions naturals de convergència d’estressos. A més, es posa de manifest la relació d’aquesta espècie amb l’herbivorisme i el parasitisme causat per Cytinus hypocistis, planta holoparàsita que també acumula vitamina E en els seus teixits no fotosintètics. En conclusió, la vitamina E es troba de forma ubiqua en plantes (tant en les que realitzen fotosíntesi com en plantes holoparàsites), s’acumula tant en teixits fotosintètics com en teixits no fotosintètics, i en conjunt juga un paper fonamental en la resposta de les plantes a l’estrès, tant pel seu paper antioxidant com per la seva relació amb els jasmonats, la qual cosa pot tenir implicacions ecofisiològiques en la interacció entre la resposta a l’estrès abiòtic i biòtic.[eng] All the photosynthetic organisms are capable of synthesising vitamin E, which is accumulated in both photosynthetic and non-photosynthetic tissues. While vitamin E is an important chloroplastic antioxidant that responds to environmental stresses, jasmonates, hormones that derive from lipid peroxidation in chloroplasts, are essential regulators of the response to biotic stress. The relationship between these molecular families plays a key role in the control of the chloroplastic redox state under stress conditions, which is a determinant in retrograde signalling. Furthermore, this relationship is important from a physiological point of view due to the involvement of vitamin E and jasmonates in the abiotic and biotic stress response, respectively. In the present study, the presence and function of vitamin E in both photosynthetic and non-photosynthetic tissues are studied on the one hand in Fragaria x Ananassa var. Albion under controlled conditions of drought stress. This plant offers us a singular variety of non-photosynthetic tissues in the false fruit (flesh and achenes). On the other hand, the relationship between vitamin E and jasmonates and its implication in the interaction between the abiotic and biotic stress responses is studied in a Mediterranean shrub (Cistus albidus L.) under natural conditions where abiotic and biotic stresses converge. Results highlight the universality of vitamin E in photosynthetic and non-photosynthetic tissues, both in plants of agronomical and ecological interest. Furthermore, the relationship between vitamin E and jasmonates is bidirectional so their accumulation is compatible but with some limitations. The possible implication of this relationship in the abiotic and biotic stress response interaction is discussed in relation to the study of C. albidus under natural conditions where stresses converge. In addition, the relationship between this species and herbivory and parasitism caused by Cytinus hypocistis, an holoparasitic plant that also accumulates vitamin E in its non-photosynthetic tissues, is highlighted. It is concluded that vitamin E is accumulated widely in plant tissues, both in photosynthetic and non-photosynthetic plants and tissues, and it plays a key role in plant stress response, because of its antioxidant function but also because of its relationship with jasmonates, which could have ecophysiological implications in the interaction between abiotic and biotic stress response

    Paradoxes of Interactivity

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    Current findings from anthropology, genetics, prehistory, cognitive and neuroscience indicate that human nature is grounded in a co-evolution of tool use, symbolic communication, social interaction and cultural transmission. Digital information technology has recently entered as a new tool in this co-evolution, and will probably have the strongest impact on shaping the human mind in the near future. A common effort from the humanities, the sciences, art and technology is necessary to understand this ongoing co- evolutionary process. Interactivity is a key for understanding the new relationships formed by humans with social robots as well as interactive environments and wearables underlying this process. Of special importance for understanding interactivity are human-computer and human-robot interaction, as well as media theory and New Media Art. »Paradoxes of Interactivity« brings together reflections on »interactivity« from different theoretical perspectives, the interplay of science and art, and recent technological developments for artistic applications, especially in the realm of sound

    Paradoxes of interactivity: perspectives for media theory, human-computer interaction, and artistic investigations

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    Current findings from anthropology, genetics, prehistory, cognitive and neuroscience indicate that human nature is grounded in a co-evolution of tool use, symbolic communication, social interaction and cultural transmission. Digital information technology has recently entered as a new tool in this co-evolution, and will probably have the strongest impact on shaping the human mind in the near future. A common effort from the humanities, the sciences, art and technology is necessary to understand this ongoing co- evolutionary process. Interactivity is a key for understanding the new relationships formed by humans with social robots as well as interactive environments and wearables underlying this process. Of special importance for understanding interactivity are human-computer and human-robot interaction, as well as media theory and New Media Art. "Paradoxes of Interactivity" brings together reflections on "interactivity" from different theoretical perspectives, the interplay of science and art, and recent technological developments for artistic applications, especially in the realm of sound

    A Flat Process Calculus for Nested Membrane Interactions

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    The link-calculus has been recently proposed as a process calculus for representing interactions that are open (i.e., that the number of processes may vary), and multiparty (i.e., that may involve more than two processes). Here, we apply the link-calculus for expressing, possibly hierarchical and non dyadic, biological interactions. In particular, we provide a natural encoding of Cardelli's Brane calculus, a compartment-based calculus, introduced to model the behaviour of nested membranes. Notably, the link-calculus is flat, but we can model membranes just as special processes taking part in the biological reaction. Moreover, we give evidence that the link-calculus allows one to directly model biological phenomena at the more appropriate level of abstraction

    A flat process calculus for nested membrane interactions

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    The link-calculus has been recently proposed as a process calculus for representing interactions that are open (i.e. that the number of processes may vary), and multiparty (i.e. that may involve more than two processes). Here, we apply the link-calculus for expressing, possibly hierarchical and non dyadic, biological interactions. In particular, we provide a natural encoding of Cardelli's Brane calculus, a compartment-based calculus, introduced to model the behaviour of nested membranes. Notably, the link-calculus is at, but we can model membranes just as special processes taking part in the biological reaction. Moreover, we give evidence that the link-calculus allows one to directly model biological phenomena at the more appropriate level of abstraction

    Structured Operational Semantics for Graph Rewriting

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    Process calculi and graph transformation systems provide models of reactive systems with labelled transition semantics (LTS). While the semantics for process calculi is compositional, this is not the case for graph transformation systems, in general. Hence, the goal of this article is to obtain a compositional semantics for graph transformation system in analogy to the structural operational semantics (SOS) for Milner's Calculus of Communicating Systems (CCS). The paper introduces an SOS style axiomatization of the standard labelled transition semantics for graph transformation systems that is based on the idea of minimal reaction contexts as labels, due to Leifer and Milner. In comparison to previous work on inductive definitions of similarly derived LTSs, the main feature of the proposed axiomatization is a composition rule that captures the communication of sub-systems so that it can feature as a counterpart to the communication rule of CCS

    RPO Semantics for Mobile Ambients

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    The paper focuses on the synthesis of labelled transition systems (LTSs) for process calculi, choosing as testbed Mobile Ambients (MAs). The proposal is based on a graphical encoding: a process is mapped into a graph equipped with interfaces, such that the denotation is fully abstract with respect to the standard structural congruence. Graphs with interfaces are amenable to the synthesis mechanism based on borrowed contexts (BCs), an instance of relative pushouts (RPOs). The BC mechanism allows the effective construction of a LTS that has graphs with interfaces as states and labels, and such that the associated bisimilarity is a congruence. Our paper focuses on the analysis of a LTS over processes as graphs with interfaces: we use the LTS on graphs to recover a LTS directly defined over the structure of MAs processes, further defining a set of SOS inference rules capturing the same operational semantics

    Adequacy Issues in Reactive Systems: Barbed Semantics for Mobile Ambients

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    Reactive systems represent a meta-framework aimed at deriving behavioral congruences for those specification formalisms whose operational semantics is provided by rewriting rules. The aim of this thesis is to address one of the main issues of the framework, concerning the adequacy of the standard observational semantics (the IPO and the saturated one) in modelling the concrete semantics of actual formalisms. The problem is that IPO-bisimilarity (obtained considering only minimal labels) is often too discriminating, while the saturated one (via all labels) may be too coarse, and intermediate proposals should then be put forward. We then introduce a more expressive semantics for reactive systems which, thanks to its flexibility, allows for recasting a wide variety of observational, bisimulation-based equivalences. In particular, we propose suitable notions of barbed and weak barbed semantics for reactive systems, and an efficient characterization of them through the IPO-transition systems. We also propose a novel, more general behavioural equivalence: L-bisimilarity, which is able to recast both its IPO and saturated counterparts, as well as the barbed one. The equivalence is parametric with respect to a set L of reactive systems labels, and it is shown that under mild conditions on L it is a congruence. In order to provide a suitable test-bed, we instantiate our proposal over the asynchronous CCS and, most importantly, over the mobile ambients calculus, whose semantics is still in a flux
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