La sénescence constitue la dernière étape du cycle de vie de certains organes des plantes. Elle permet leur dégradation tout en réallouant les constituants des tissus sénescents vers d’autres organes. Dans le contexte de la nodulation symbiotique fixatrice d’azote entre certaines plantes légumineuses et des bactéries rhizobia, un processus de sénescence a été décrit. Cependant, les connaissances sur les mécanismes de régulation de la sénescence des nodosités symbiotiques sont limitées. Au sein du laboratoire, le facteur de transcription MtNAC969 a été identifié comme un régulateur de la sénescence des nodosités. L'objectif de cette thèse est d'identifier et de caractériser de nouveaux régulateurs de la sénescence de l'organe symbiotique. Nous avons développé : (i) une approche visant à identifier des facteurs de transcription corégulés avec MtNAC969 ou avec une cystéine protéase MtCP6 utilisée comme marqueur de la sénescence des nodosités ; et (ii), une approche avec "à priori" se focalisant sur la fonction des différentes voies de signalisation des cytokinines. Cette thèse a permis d'identifier deux facteurs de transcription, MtbHLH107 et MtNAC009 et de décrypter le rôle des cytokinines dans la sénescence des nodosités. Cette thèse a permis d'identifier d'une part, deux nouveaux gènes potentiellement régulateurs de la sénescence nodositaire, MtbHLH107 et MtNAC009; et d’autre partde décrypter le rôle des cytokinines dans la sénescence de cet organe symbiotique. / Senescence is the last step of plant organ lifespan and allows their degradation in order to remobilize components from senescent tissues toward others organs. In the nitrogen fixing symbiosis nodulation occurring between legume plants and rhizobia bacteria, a senescence process has been described. However, limited knowledge about regulatory systems controlling senescence in the symbiotic nodule is available. In the laboratory, the MtNAC969 transcription factor was identified as a regulator of nodule senescence. The aim of this PhD project is to identify and characterize new regulatory factors involved in nodule senescence. We developed two independent approaches : (i) the identification of genes coregulated with MtNAC969 or a cystein protease MtCP6 used as nodule senescence marker ; and (ii), targeted approach focused on the role of cytokinin signaling pathways in nodule senescence. This project allowed us to identify two regulator transcription factors, MtbHLH107 and MtNAC009 ; and to decipher the cytokinin role in the senescence of the symbiotic organ. This PhD thesis allowed us to identify two new potential regulators of nodule senescence, MtbHLH107 and MtNAC009; and to decipher the role of cytokinins in the senescence of this symbiotic organ.

La majorité des Légumineuses sont capables d’établir une symbiose avec des bactéries du sol nommées Rhizobia. Lors de cette interaction symbiotique, un nouvel organe est formé, la nodosité. Dans cet organe, les bactéries fixent l’azote atmosphérique au profit de la plante hôte. Pendant la symbiose Rhizobia-Légumineuse, deux grands changements transcriptômiques ont été observés par différentes technologies, comme le RNASeq (Maunoury et al., 2010) ou les expériences de microarrays (Benedito et al., 2008). Ces grands changements interviennent aux différentes étapes de développements des nodosités et sont médiés par différents régulateurs de l’expression génique comme certains FTs clés et des petits ARN. Ces petits ARN régulateurs sont produits après le clivage de précurseurs de long ARN double brin ou d’ARN en épingle à cheveux par des enzymes particulières de la famille des ribonucléases de type III (RNase III), nommées DICER-LIKE (DCL). De plus, des gènes codant des RNases III additionnelles sont présents dans le génome de plantes et leurs rôles restent encore à être déterminés.Dans cette étude, nous avons caractérisés la famille des RNases III chez Medicago truncatula mais aussi chez d’autres espèces de légumineuse. Nous avons également recherchés l’implication de MtRTL1b, une RNase III, lors du développement des nodosités.Cette RNase III est un orthologue spécifique des nodosités d’AtRTL1, un répresseur de silencing chez Arabidopsis thaliana. Tout d'abord, nous avons montré que l’expression de ce gène est activée juste avant la différenciation et est principalement restreinte à l’interzone, là où les bactéroïdes deviennent totalement différenciés dans les cellules hôtes, et dans la zone de fixation de la nodosité. La répression de l’expression de MtRTL1b, par ARN interférence dans des racines transgéniques, affecte le développement de la nodosité, la fixation de l’azote et la viabilité des bactéroïdes. Un phénotype opposé est observé lorsque MtRTL1b est exprimé de façon ectopique dans la racine. Les analyses des données de séquençage nous ont permis de mettre en évidence que le RNAi conduit à la sous-expression de 1038 gènes, incluant plus de 109 gènes codant des NCRs qui sont des peptides intervenant dans le développement des bactéroïdes et/ou pour leur viabilité dans les nodosités indéterminées. De plus,des gènes impliqués dans les voies métaboliques et la régulation de l’état d'oxydo-réduction mais aussi dans le processus symbiotique, comme la leghémoglobine, sont également sous-exprimés. Des données de séquençage de petits ARN et d’ARN double brins sont en cours d’analyse afin de caractériser les changements dans les populations de petit ARN et identifier les substrats ARN double brin de cette RNase III lors du développement des nodosités. / Almost all Legumes are able to establish symbiosis with soil bacteria called Rhizobia. During this interaction, a new organ is formed, the nodule. In this organ, bacteria fix the atmospheric nitrogen for the host plant. During Rhizobia-Legumes symbiosis twotranscriptomic changes were observed by different technologies like RNAseq (Maunoury et al., 2010) or microarrays experiment (Benedito et al., 2008). These dramatic changes occur at the different steps of nodule development and are mediated by various gene expression regulators including several keys transcription factors and small RNAs. These small regulatory RNAs are produced after cleavage of long double-stranded or hairpin RNA precursors by particular enzymes of the ribonuclease III (RNase III) family, called DICERLIKEproteins (DCL). However, additional RNase III encoding genes are present in plant genomes, whose roles remain to be fully determined.In this work, we characterized the RNAse III family in the model M. truncatula, as well as other legumes species. We also investigated the involvement in nodule development of MtRTL1b, one RNAse III, a nodule-specific orthologue of AtRTL1, a putative silencing repressor in Arabidopsis thaliana. First, we showed that the expression of this gene is activated just before differentiation and is mainly restricted in the interzone, where bacteroid become fully differentiated into the host cells and in the nitrogen fixation zone of the nodule. Repression of MtRTL1b expression, by RNA interference in transgenic roots, affected nodule development, nitrogen fixation and bacteroid viability while an opposite phenotype was observed in roots with ectopic expression of this gene. Then, RNASeq analyses showed that the RNAileads to the down-regulation of 1038 genes, including more than 109 NCRs, encoding peptides involved in bacteroid development and/or viability in indeterminate nodules. Moreover, genes involved in metabolic pathways and redox regulations as well as other genes involved in symbiosis, like leghemoglobins, are also down-regulated. RNAseq of small RNAs and double strand RNAs are under analysis to characterize changes in sRNA populations and identify dsRNA substrates of this RNAse III during nodule development.

En esta investigación se aborda el desarrollo bibliográfico discursivo “Administración: practica y disciplina del saber”, un tema importante para entender y profundizar los conocimientos sobre este campo. En primer lugar, esta investigación busca explicar de manera detallada los principios y orígenes de la teoría y práctica de la administración, para la recolección de información y aclaración de paradigmas entre uno y otro. Se hará énfasis en el significado real de la administración y su epistemología, donde se detallan los orígenes filosóficos, su objeto y naturaleza. Luego, se expone las posturas de diversos autores sobre la administración práctica y la disciplina del saber y la simbiosis entre estas. Por último, la investigación presenta un análisis sobre las mallas curriculares de la carrera de Administración de Empresas de las diferentes universidades de Lima, desde el punto de vista práctico y teórico. / This research addresses the discursive bibliographic development "Administration: practice and discipline of knowledge", an important topic to understand and deepen knowledge in this field. First, this research seeks to explain in detail the principles and origins of the theory and practice of administration, for the collection of information and clarification of paradigms between one and the other. Emphasis will be placed on the real meaning of administration and its epistemology, where the philosophical origins, its object and nature are detailed. Then, the positions of different authors on the practical administration and discipline of knowledge and the symbiosis between them are presented. Finally, the research presents an analysis of the curricula of the business administration career of the different universities of Lima, from the practical and theoretical point of view. / Trabajo de Suficiencia Profesional

Aim: The aim of this thesis is to describe possible steps of how circular partnerships can be formed, and how they can connect the different steps of a material loop, such as design and recycling. The focus of the empirical study within this thesis is the reconnection of recycling, design and production within the household goods industry. By this we will answer the following research question:“What are the rationales and circumstances needed for separate organizations to develop a sustainability-oriented innovative partnership in the context of the Circular Economy?” The Case: This research project is based on a case study of a collaboration between Stena Recycling AB, a Swedish recycling company, and Electrolux AB, a global appliances producer. Together those two companies formed a pilot project, called the “Infinity Project”, whose goal is to produce a vacuum cleaner which is made out of 100% post-consumer recycled materials, and is 100% recyclable. Methodology: The researchers participated in the meetings of the Infinity Project, and interviewed the people who were involved in the beginning of the collaboration. The research is done in an abductive process, as literature was analyzed that explained the findings made in our observations. From the theory and our findings we created a model, which helps explain the what, why, and how of Stena Recycling AB and Electrolux AB reconnecting recycling with design and production processes. Key findings: Through industrial symbiotic lenses and a corporate social innovation mindset the two companies recognized the enormous amount of waste as a problem of linear business models. With a mindset driven by corporate social innovation, they saw the potential of a collaboration in order to achieve a shared competitive advantage. By selecting each other as a partner for this circular economic collaboration, they identified how they could combine their respective knowledge and resources to reach their mutual goals. Through a long term strategic approach with a clear and shared vision, clear targets from the directing management, and a team with complementary skills, many program synergies have been realized, with potentially outsized successes for each organization. This setting also created an environment of trust and a common identity within the project, which was fundamental to create social innovation and to find successful ways to reconnect recycling with design and production. Additionally, the existence of the project within each organization seemed to function as a talent magnet, attracting like-minded sustainability-motivated talent who would best perform towards the goals of the project.

Numerous attempts have been made to create or facilitate Industrial Symbiosis networks and self-organized networks have been uncovered. Existing networks have been studied to identify its success or failure and its context. This thesis tries to suggest and assess an adapted approach to establish successful industrial symbiosis, with a case study on the northern Stockholm region. An extensive literature review, meetings with experts and stakeholder interaction by questionnaires, interviews and a workshop were used. Potential obstructions were identified, possibilities of self-organizations and planning explored and solutions suggested. Combined with the feedback from 25 questionnaires and a workshop with local stakeholders an approach to establishing industrial symbiosis in northern Stockholm was suggested and assessed. A neutral coordinator or waste companies were concluded to have a good chance of establishing an industrial symbiosis network in the region. Using existing networks, creating awareness and providing knowledge and examples are important factors for establishing an industrial symbiosis network.

No description available.

Arbuscular mycorrhizal (AM) fungi are key soil symbiotic microorganisms, intensively studied for their roles in improving plant fitness and their ubiquity in terrestrial ecosystems. Research on AM fungi is difficult because their obligate biotrophic nature makes it impossible to culture them in the absence of a host. Over the last three decades, Ri T-DNA transformed roots have been the gold standard to study AM fungi under in vitro conditions. However, only two host plant species (Daucus carota and Cichorium intybus) have been routinely used to in vitro propagate less than 5% of the known AM fungal species. There is much evidence that host identity can significantly affect AM symbioses, therefore, we investigated any potential host-specific effects of two novel Ri T-DNA transformed root species, Medicago truncatula and Nicotiana benthamiana, by associating them with seven AM fungal species selected based on their contrasting behaviors when grown with Ri T-DNA transformed D. carota roots. To evaluate the performance of new Ri T-DNA transformed roots to host and propagate AM fungal species, a factorial set-up was used to generate nine unique pairs of hosts (M. truncatula, N. benthamiana, D. carota) and AM fungi (Rhizophagus irregularis, R. clarus, Glomus sp.). Using statistical modeling, all pairs of hosts and AM fungi were compared by their symbiosis development (SD) and sporulation patterns in the hyphal compartments (HCs) of two-compartment Petri dishes. Our results show that 1) most of the variation between host and AM fungus pairs relating to SD or HC sporulation was explained by an interaction between host and AM fungal identity, i.e., host identity alone was not sufficient to explain AM fungal behaviour, 2) AM symbioses involving different combinations of symbiont identities trigger heterogenous fungal behaviours. This work provides a robust framework to develop and evaluate new Ri T-DNA roots for the in vitro propagation of AM fungi, an important asset for germplasm collections and biodiversity preservation.

The partnerships, or symbioses, between diatom hosts and cyanobacteria are widespread in the tropical and subtropical oceans. Many populate low nutrient waters where the heterocystous cyanobacteria fix N2 and provide reduced nitrogen (N) to the host. These types of symbioses are believed to be important in the global ocean biogeochemical cycle of N and carbon (C). The cyanobacteria morphology, cellular locations differ as well as genome size and content. The genome size and content are related to the cellular location: internal symbionts have smaller more eroded genomes, while external symbionts have larger genomes more similar to free-living cyanobacteria. Based on previously identified characteristics the aim of this report is to classify taxonomically, unidentified environmental metagenomic assembled genomes (MAGs) to the heterocystous symbionts of diatoms: Richelia and Calothrix. A select number of targeted gene sequences will be compared. MAGs and four draft genomes of Richelia and Calothrix were collected from public repositories (GTDB, NCBI and Tara project) and an initial comparison of GC-content and genome size was made. Based on this comparison, seven of the MAGs were determined as similar as the draft genomes of the known symbionts. After, a heatmap was created based on 27 targeted genes, some of which are highly conserved, to further characterize the phylogeny of the MAGs (Appendix 2). Results from the GC-content and genome size graph and the heatmap indicated similar trends which could connect one of the MAGs being most similar to the RintRC01 draft genome whereas the other five MAGs resembled the RintHH01 draft genome. Based on these results, conclusions can be drawn that the unknown MAGs are likely derived from symbionts of diatoms and could also possess similar characteristics, such as their cellular location, function and role in the N and C cycles.

In the world of architecture a field of tension exist between permanence and temporality. The aim of this study was to explore the possibilities residing within this duality. During the urban investigation conducted in the Pretoria CBD, scars of vacant space were found that exposed the possibility of temporarily utilizing these empty spaces. In general vacant spaces tend to become unsafe, degraded and illegally occupied. If these vacant spaces could be temporarily reused it would benefit the owners, users and community at large. The binding workshop of The Government Printing Works on Vermeulen Street just west of Church Square is in the process of being relocated and no planned future use is evident. The investigation proposes that the workshop be adapted to accommodate a temporary performance space. Through the process of matching a vacant permanent space with a temporary program their interdependence became evident resulting in an approach towards a mutuality beneficial symbiosis between the temporary and the permanent. The permanent host will benefit the temporary guest by providing shelter, safety and physical support. The temporary guest will benefit the permanent host by giving it life, activity and the opportunity to contribute to its local context. The temporary program will preserve the existing host and protect it from deterioration. Production design as an inherently, temporary form of space creation was selected as the medium for this investigation. Performance space positions architecture within the realm of temporary experience and lasting memory. Circles in a Forest are the inspiration behind the design of the temporary performance space. This novel by author Dalene Matthee speaks of a segment in the history of South Africa, but also tells a universal story; that serves as a warning against the exploitation of people and natural resources. The design focused on creating layers of permanence and temporality dependant on each other. As these layers are peeled away the space can be reinterpreted and adapted for other performances and programmes. / Dissertation (MInt (Prof))--University of Pretoria, 2010. / Architecture / unrestricted

Philosophiae Doctor - PhD / The tripartite symbiosis between Phaseolus vulgaris, arbuscular-mycorrhiza and the nodule bacteria, Rhizobia have been the focus of many studies ranging over a number of decades, however these studies have failed to answer certain questions relating the role of the symbionts in regard to host nutrition and the subsequent influence of these symbionts on the host C- economy. There is little doubt over the synergistic benefits involved in the dual inoculation of bean plants, as well as the resultant C-costs of maintaining the 2 symbionts, yet the specific contribution of the individual symbionts to the hosts overall nutrient and C-economy remain to be clarified. Thus the aim of this thesis is to help clarify these points by determining the symbiont induced photosynthetic, respiratory and nutritional changes taking place in the host. This was achieved by a series of experiments in which nodulated bean plants were split into two categories-those with and without AM colonized roots. These plants were then exposed to a range of growing conditions, including hi and low P, and a series of N treatments, ranging from zero N through to 3 mM NH/. Under these differing nutrient conditions growth, photosynthetic, respiratory, nutrient and amino acid responses were monitored, thus allowing for the determination of the symbionts influence on the host and the hosts reliance on the respective symbionts. Host reliance was noted most strongly under nutrient limiting conditions. Under low P treatment AM was the dominant symbiont as far as host C was concerned, allowing for the early establishment of the AM, thus ensuring the uptake of P for both host and nodule development. High P affected AM colonization to a greater extent than it did nodule dry weight and conversely the addition of N~ + led to a greater decrease in nodule dry weight than it did AM colonization. In spite of this decline, AM benefited the host by improving host N nutrition and relieving N-feedback inhibition of the export amino acid asparagine on BNF. These AM induced benefits did come at a cost to the host though, the dual inoculated plants had higher below ground respiratory costs and subsequently higher photosynthetic rates to compensate for the increased demand for C. The higher photosynthetic rates associated with dual inoculation were as a result of symbiont induced sink stimulation and not due to the improved nutrition of the host, as shown by the photosynthetic and nutrient response ratios. However, the respiratory costs associated with the uptake of soil nutrients were lower in AM colonized roots, thus showing an increased efficiency in nutrient gain by AM colonized roots. This improvement in host N nutrition as a result of AM colonization, coupled with the lower respiratory costs of AM nutrition led to the conclusion that under certain growing conditions nodules can become redundant and possibly parasitic.