Using Affiliation Networks to Study the Determinants of Multilateral Research Cooperation Some empirical evidence from EU Framework Programs in biotechnology

This paper studies multilateral cooperation networks among organizations and work on a two-mode representation to study the decision to participate in a consortium. Our objective is to explain the underlying processes that give rise to multilateral collaboration networks. Particularly, we are interested in how heterogeneity in organizations' attributes plays a part and in the geographical dimension of this formation process. We use the data on project proposals submitted to the 7th Framework Program (FP) in the area of Life sciences, Biotechnology and Biochemistry for Sustainable Non-Food. We employ exponential random graph models (p* models) (Frank and Strauss, 1986 ; Wasserman and Pattison, 1996) with node attributes (Agneessens et al., 2004), and we make use of extensions for affiliation networks (Wang et al., 2009). These models do not only enable handling variability in consortium sizes but also relax the assumption on tie/triad independence. We obtained some preliminary results indicating institutional types as a source of heterogeneity affecting participation decisions. Also, these initial results point out that organizations take their potential partners' participations in other projects into account in giving their decision ; organizations located in the core European countries tend to participate in the same project ; the tendency to preserve the composition of a consortium across projects and the tendency of organizations with the same institutional type to co-participate are not significant

The Sixth Framework Program as an Affiliation Network: Representation and Analysis

In this paper, we compare two different representations of Framework Programs as affiliation network: 'One-mode networks' and 'Two-mode networks'. The aim of this article is to show that the choice of the representation has an impact on the analysis of the networks and on the results of the analysis. In order to support our proposals, we present two forms of representation and different indicators used in the analysis. We study the network of the 6th Framework Program using the two forms of representation. In particular, we show that the identification of the central nodes is sensitive to the chosen representation. Furthermore, the nodes forming the core of the network vary according to the representation. These differences of results are important as they can influence innovation policies

Early Events Induced by the Elicitor Cryptogein in Tobacco Cells: Involvement of a Plasma Membrane NADPH Oxidase and Activation of Glycolysis and the Pentose Phosphate Pathway.

Application of the elicitor cryptogein to tobacco (cv Xanthi) is known to evoke external medium alkalinization, active oxygen species production, and phytoalexin synthesis. These are all dependent on an influx of calcium. We show here that cryptogein also induces calcium-dependent plasma membrane depolarization, chloride efflux, cytoplasm acidification, and NADPH oxidation without changes in NAD+ and ATP levels, indicating that the elicitor-activated redox system, responsible for active oxygen species production, uses NADPH in vivo. NADPH oxidation activates the functioning of the pentose phosphate pathway, leading to a decrease in glucose 6-phosphate and to the accumulation of glyceraldehyde 3-phosphate, 3- and 2-phosphoglyceric acid, and phosphoenolpyruvate. By inhibiting the pentose phosphate pathway, we demonstrate that the activation of the plasma membrane NADPH oxidase is responsible for active oxygen species production, external alkalinization, and acidification of the cytoplasm. A model is proposed for the organization of the cryptogein responses measured to date

Vacuolar membrane localization of the Arabidopsis 'two-pore' K+ channel KCO1

Potassium (K+) channels play multiple roles in higher plants, and have been characterized electrophysiologically in various subcellular membranes. The K+ channel AtKCO1 from Arabidopsis thaliana is the prototype of a new family of plant K+ channels. In a previous study the protein has been functionally characterized after heterologous expression in Baculovirus-infected insect cells. In order to obtain further information. on the physiological function of AtKCO1, the gene expression pattern and subcellular localization of the protein in plants were investigated. The regulatory function of the 5' region of the AtKCO1 gene was examined in transgenic A. thaliana plants carrying beta-glucuronidase (GUS) fusion constructs. Our analysis demonstrates that the AtKCO1 promoter is active in various tissues and cell types, and the highest GUS activity could be detected in mitotically active tissues of the plant. Promoter activity was strongly dependent on the presence of a 5' leader intron, The same overall structure was identified in two genes encoding AtKCO1-like K+ channels from Solanum tuberosum (StKCO1alpha and StKCO1beta). To investigate the subcellular localization of AtKCO1, the channel protein, as well as a fusion protein of AtKCO1 with green fluorescence protein (GFP), were expressed in transgenic tobacco BY2 cells. In sucrose density gradients, both proteins co-fractionate with tonoplast markers (Nt-TIPa, vATPase). In fluorescence images from transgenic AtKCO1-GFP BY2 cells fluorescence was exclusively detected in the tonoplast. Thus AtKCO1 is the first cloned K+ channel demonstrated to be a vacuolar K+ channel

Integrative Mechanobiology of Growth and Architectural Development in Changing Mechanical Environments

Mention d'édition : P. Wotjaszek (ed)Mechanosensitive control of plant growth is a major process shaping how terrestrial plants acclimate to the mechanical challenges set by wind, self-weight, and autostresses. Loads acting on the plant are distributed down to the tissues, following continuum mechanics. Mechanosensing, though, occurs within the cell, building up into integrated signals; yet the reviews on mechanosensing tend to address macroscopic and molecular responses, ignoring the biomechanical aspects of load distribution to tissues and reducing biological signal integration to a "mean plant cell." In this chapter, load distribution and biological signal integration are analyzed directly. The Sum of Strain Sensing model S 3 m is then discussed as a synthesis of the state of the art in quantitative deterministic knowledge and as a template for the development of an integrative and system mechanobiology