L'îlot génomique Salmonella Genomic Island 1 (SGI1) est un élément intégratif et mobilisable, support de nombreux gènes de résistance aux antibiotiques, et identifié chez de nombreux genres bactériens. Le transfert de SGI1 requiert spécifiquement la présence d'un plasmide conjugatif du groupe d'incompatibilité IncA/C. Les régulateurs globaux AcaCD des plasmides IncA/C activent l’excision de SGI1 qui, une fois sous forme d’un intermédiaire extrachromosomique circulaire, va pouvoir être transféré en utilisant la machinerie de conjugaison encodée par les plasmides IncA/C (mobilisation conjugative en trans). Depuis la description de SGI1, plusieurs études ont relaté une apparente stabilité de SGI1 au cours des générations bactériennes. Cependant, des observations préliminaires indiquaient des difficultés de cohabitation entre SGI1 et les plasmides IncA/C. L’objectif de ce travail était d’étudier la stabilité de SGI1 et sa compatibilité avec les plasmides conjugatifs IncA/C dont dépend sa mobilité. L’opéron putatif S026- S025 de SGI1 a été identifié comme constituant un système Toxine-Antitoxine (TA) qui a été appelé sgiAT. Le rôle de ce système TA dans la stabilité de SGI1 a été mis en évidence en présence d'un plasmide IncA/C. De plus, l’incompatibilité entre SGI1 et les plasmides IncA/C a été démontrée expérimentalement pour la première fois. La stabilité de SGI1 est liée à son intégration chromosomique. Cependant, lorsque SGI1 est excisé du chromosome et donc vulnérable (il peut être perdu), c’est-à-dire en présence d’un plasmide IncA/C, le système TA sgiAT joue un rôle important dans le maintien de SGI1 dans les populations bactériennes. / The multidrug resistance Salmonella Genomic Island 1 (SGI1) is an integrative mobilizable element identified in several enterobacterial pathogens. This chromosomal island requires specifically the presence of a conjugative IncA/C plasmid to be excised and transfered by conjugation (mobilization in trans). Preliminary observations suggest stable maintenance of SGI1 in the bacterial host but paradoxically also incompatibility between SGI1 and IncA/C plasmids. Here, using a Salmonella enterica serovar Agona clonal bacterial population as model, we demonstrate that a Toxin-Antitoxin (TA) system encoded by SGI1 plays a critical role in its stable host maintenance when an IncA/C plasmid is concomitantly present. This system, designated sgiAT for Salmonella genomic island 1 Antitoxin and Toxin respectively, thus seems to play a stabilizing role in a situation where SGI1 is susceptible to be lost through plasmid IncA/C-mediated excision. Moreover and for the first time, the incompatibility between SGI1 and IncA/C plasmids was experimentally confirmed.

abstract: Isolation-by-distance is a specific type of spatial genetic structure that arises when parent-offspring dispersal is limited. Many natural populations exhibit localized dispersal, and as a result, individuals that are geographically near each other will tend to have greater genetic similarity than individuals that are further apart. It is important to identify isolation-by-distance because it can impact the statistical analysis of population samples and it can help us better understand evolutionary dynamics. For this dissertation I investigated several aspects of isolation-by-distance. First, I looked at how the shape of the dispersal distribution affects the observed pattern of isolation-by-distance. If, as theory predicts, the shape of the distribution has little effect, then it would be more practical to model isolation-by-distance using a simple dispersal distribution rather than replicating the complexities of more realistic distributions. Therefore, I developed an efficient algorithm to simulate dispersal based on a simple triangular distribution, and using a simulation, I confirmed that the pattern of isolation-by-distance was similar to other more realistic distributions. Second, I developed a Bayesian method to quantify isolation-by-distance using genetic data by estimating Wright’s neighborhood size parameter. I analyzed the performance of this method using simulated data and a microsatellite data set from two populations of Maritime pine, and I found that the neighborhood size estimates had good coverage and low error. Finally, one of the major consequences of isolation-by-distance is an increase in inbreeding. Plants are often particularly susceptible to inbreeding, and as a result, they have evolved many inbreeding avoidance mechanisms. Using a simulation, I determined which mechanisms are more successful at preventing inbreeding associated with isolation-by-distance. / Dissertation/Thesis / Doctoral Dissertation Molecular and Cellular Biology 2015

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-03-31T13:42:09Z No. of bitstreams: 2 Dissertação - Elga de Fátima Almeida - 2014.pdf: 1529680 bytes, checksum: ee90611c2799a2036aadcc8089f3bef6 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-04-01T10:46:20Z (GMT) No. of bitstreams: 2 Dissertação - Elga de Fátima Almeida - 2014.pdf: 1529680 bytes, checksum: ee90611c2799a2036aadcc8089f3bef6 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-04-01T10:46:20Z (GMT). No. of bitstreams: 2 Dissertação - Elga de Fátima Almeida - 2014.pdf: 1529680 bytes, checksum: ee90611c2799a2036aadcc8089f3bef6 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2014-04-23 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The plant reproductive biology involves all the features (morphological, anatomical or physiological) of a species that participate in the reproduction of its individuals. The Fabaceae family is one of the most important of the Cerrado, the genus Bauhinia being one of the most diversified. Several studies with species of Bauhinia L. showed diversity in floral shapes, reproductive phenology, reproductive system and interactions with different groups of pollinators. In general, the Bauhinia species are outcrossing and have low reproductive efficiency. Bauhinia brevipes is common in the municipality of Goiás-GO and has floral features compatible with the syndrome chiropterophily: white flowers that release a strong odour overnight, producing large amounts of nectar with low sugar concentration. Flowers of B. brevipes may have reduced ovaries or anthers with low production of viable pollen, indicating that this species moves towards sexual separation in some flowers. Although the visit the bats to flowers were not seen, their flights over the plants were observed. A test of exclusion of diurnal pollinators showed the efficiency of nocturnal pollinators in B. brevipes. The flowers of B. brevipes not have herkogamy as the main factor to avoid inbreeding, but some flowers positioned above the anthers stigma were observed. The species present gametophytic selfincompatibility and therefore requires the pollinators visit to ensure pollinating pollen exchange among different and unrelated plants. Bauhinia brevipes has an average 20% of reproductive efficiency. In general, the species showed a high level of pollen limitation (0.73). The largest fruit production occurs in the middle position of the inflorescence. Most of fruit produced occurs in the median position of the inflorescence, when possibly the availability of pollen in the system is higher and resources are available for their development. / A biologia reprodutiva de plantas trata de diversos aspectos relacionados a mecanismos como o de polinização (e.g., morfologia e biologia floral, interação plantapolinizador), do sistema de reprodução (sistema sexual, de incompatibilidade, modos de reprodução – sexuada e assexuado-vegetativa), eficiência reprodutiva, dentre outros. A família Fabaceae é uma das mais importantes do Cerrado, sendo o gênero Bauhinia um dos mais diversificados. Diversos estudos realizados com espécies de Bauhinia L. mostraram a diversidade na fenologia, formas florais, sistema reprodutivo e interações com diferentes grupos de polinizadores. Embora aconteça autopolinização em algumas espécies do gênero, a xenogamia é a forma mais frequente de reprodução, e espécies autoincompatíveis são muito comuns. Bauhinia brevipes é comum no Cerrado da região do Município de Goiás-GO e possui características florais compatíveis com a síndrome da quiropterofilia: flores brancas que liberam odor forte durante a noite, produção de grande volume de néctar com baixa concentração de açúcar. Flores de B. brevipes podem apresentar ovário reduzido ou anteras com baixa produção de pólen viável, indicando que esta espécie caminha para separação sexual em algumas flores. Apesar de não serem visualizadas as visita dos morcegos às flores, que foram observados em sobrevoo na população, um teste de exclusão de polinizadores diurnos mostrou a eficiência dos polinizadores noturnos. As flores de B. brevipes não possuem hercogamia como principal fator para evitar a endogamia, porém existe na população uma porcentagem de flores com estigma posicionado acima do conjunto das anteras. A espécie apresenta autoincompatibilidade gametofítica e, portanto, necessita da visita de polinizadores para garantir a troca de pólen entre plantas diferentes e não aparentadas. Bauhinia brevipes apresenta uma eficiência reprodutiva em média de 20% das flores produzidas. De forma geral, a espécie apresentou um elevado índice de limitação polínica (0,73). A maior produção de fruto ocorre na posição mediana da inflorescência. As flores abertas nesta posição estão expostas, possivelmente, a uma alta disponibilidade de pólen no sistema, e os recursos maternos estão disponíveis em maior quantidade para o desenvolvimento de seus frutos.

Made available in DSpace on 2014-08-20T14:22:08Z (GMT). No. of bitstreams: 1 Dissertacao_Poliana_Francescatto.pdf: 2354601 bytes, checksum: f9edc628e12d95fd04503d6e3013ba1f (MD5) Previous issue date: 2009-06-12 / Quince has been used as an alternative of rootstock for pear trees because of its dwarfing effect which allows better tree vigor control, fruiting precocity and yield influence. However, highlighting the issue of rootstock versus cultivar, some combinations show severe problems regarding graft incompatibility. The main characteristics seen by incompatible combinations are cell necrosis and vascular discontinuity at the graft interface, leading to a rupture of the union or a slow tree decline. Therefore, the study aimed to evaluate the influence of different quince and Pyrus calleryana on vegetative growth of pear trees through combination performance, scion x rootstock. The work was carried out at the Centro Agropecuário da Palma in Capão do Leão, RS, from March 2007 to March 2009. The assessed cultivars were Carrick, Packham s Triumph and Williams, and the rootstocks were: P. calleryana and the quinces Adams, Alaranjado, Alongado, BA29, Berreckzi, Champion, D Angers, D Vranja, De Patras, Du Lot, Inta267, MC, Meliforme, Pineapple, Portugal and Smyrna. Tree height, increment of tree height; canopy volume; rootstock, union and scion diameters; diameters increment of rootstock, union and scion; fresh pruning weight and specific leaf area. The rootstock P. calleryana showed superior vigor for the three cultivars whether compared with all evaluated quince rootstocks. Incompatibility between plants is not individually defined only by the overgrowth at the graft union. Both observation and comparison of the all tree characteristics due scion/rootstock combination is of fundamental importance to diagnose incompatibility. Tree height, canopy volume and fresh pruning weight are the representative variables of pear tree vigor. The cultivar Carrick showed reduced vigor (64% in relation to P. calleryana) and compatibility with the quince rootstocks (in descending order of vigor): ‗Inta267 , ‗D Vranja , ‗BA29 , ‗Champion , ‗Portugal , ‗Pineapple , ‗Adams , ‗MC , ‗Berreckzi and ‗Meliforme . ‗Alaranjado and ‗Du Lot were incompatible with this cultivar. The cultivar Packham s showed reduced vigor (46.5% in relation to P. calleryana) and compatibility with the quince rootstocks (in descending order of vigor): ‗Smyrna , ‗D Angers and ‗Alongado . ‗Adams was incompatible with this cultivar. The cultivar Williams showed reduced vigor (60.4% in relation to P. calleryana) and compatibility only with the quince rootstocks (in descending order of vigor): 'Champion , ‗Meliforme and 'Du Lot . ‗BA29 , 'Smyrna , ‗Berreckzi , 'D Vranja , ‗De Patras and ‗MC were incompatible with this cultivar. / O marmeleiro é usado como uma alternativa de porta-enxerto para pereiras por possuir efeito ananizante, permitindo melhor controle do vigor da planta, e por induzir precocidade na frutificação e produtividade. No entanto, considerando o assunto porta-enxerto versus cultivar, algumas combinações apresentam sérios problemas de incompatibilidade de enxertia. As principais características mostradas pelas combinações incompatíveis são necrose celular e descontinuidade vascular na interface do enxerto, a qual leva a uma ruptura da união ou um lento declínio da planta. Neste contexto o projeto teve por objetivo avaliar a influência de diferentes porta-enxertos de marmeleiros e Pyrus calleryana sobre o crescimento vegetativo de plantas de pereira através do comportamento da respectiva combinação copa x porta-enxerto. O trabalho foi desenvolvido no Centro Agropecuário da Palma, Capão do Leão, RS, no período de março de 2007 a março de 2009. As cultivares testadas foram Carrick, Packham s Triumph e Williams, e os porta-enxertos: P. calleryana e os marmeleiros Adams, Alaranjado, Alongado, BA29, Berreckzi, Champion, D Angers, D Vranja, De Patras, Du Lot, Inta267, MC, Meliforme, Pineapple, Portugal e Smyrna. As variáveis avaliadas foram altura de planta; incremento de altura de planta; volume de copa; diâmetro de tronco do porta-enxerto, da cv. copa e do ponto de enxertia; incremento do diâmetro do tronco; massa verde de poda e área foliar específica. O porta-enxerto de pereira P. calleryana mostrou-se superior em vigor se comparado com todos os marmeleiros estudados para todas as cultivares. A incompatibilidade entre plantas não é definida, isoladamente, apenas pelo engrossamento na união de enxertia. A observação e comparação conjunta das características da planta, devido a combinação copa/porta-enxerto é de fundamental importância para diagnosticar incompatibilidade. Altura de planta, volume de copa e massa verde de poda foram as variáveis representativas de vigor de pereiras. A cultivar Carrick apresentou vigor reduzido (64% em relação a P. calleryana) e compatibilidade com os porta-enxertos de marmeleiros (em ordem decrescente de vigor): ‗Inta267 , ‗D Vranja , ‗BA29 , ‗Champion , ‗Portugal , ‗Pineapple , ‗Adams , ‗MC , ‗Berreckzi e ‗Meliforme . Os porta-enxertos ‗Alaranjado e ‗Du Lot foram incompatíveis com esta cultivar. A cultivar Packham s apresentou vigor reduzido (46,5% em relação a P. calleryana) e compatibilidade com os porta-enxertos de marmeleiros (em ordem decrescente de vigor): ‗Smyrna , ‗D Angers e ‗Alongado . O porta-enxerto ‗Adams foi incompatível com esta cultivar. A cultivar Williams apresentou vigor reduzido (60,4% em relação a P. calleryana) e compatibilidade apenas com os porta-enxertos de marmeleiros (em ordem decrescente de vigor): 'Champion , ‗Meliforme e 'Du Lot . Os porta-enxertos ‗BA29 , 'Smyrna , ‗Berreckzi , 'D Vranja , ‗De Patras e ‗MC foram incompatíveis com esta cultivar.

Model Driven Development (MDD) is considered as a powerful emerging paradigm for developing system software and services. MDD relies heavily on the models to generate part of the code for implementation. It is virtually inevitable that changes at the model level result in breaking the compatibility with the existing code base. The study presented in this thesis is performed in an industrial setting. Our industrial partner is involved in MDD and has experienced compatibility problems described above. The aim of this thesis is to identify the changes that can be made to UML class diagram and investigate what kind of negative impact they pose on the compatibility with already existing Java implementations. Apart from identifying possible model changes and assessing their negative impact the thesis provides suggestions and guidelines of how to perform such modifications so that their negative impact will be minimized. / +46 455-395070

Context: Scientific computing in the 21st century has evolved from fixed to distributed work environment. The current trend of Cloud Computing (CC) allows accessing business applications from anywhere just by connecting to the Internet. Evidence shows that, switching to CC organizations' annual expenditure and maintenance are being reduced to a greater extent. However, there are several challenges that come along with various benefits of CC. Among these include security aspects. Objectives: This thesis aims to identify security challenges for adapting cloud computing and their solutions from real world for the challenge that do not have any proper mitigation strategies identified through literature review. For this the objective is to identify existing cloud computing security challenges and their solutions. Identify the challenges that have no mitigation strategies and gather solutions/guidelines/practices from practitioners, for a challenge with more references but no mitigation strategies identified (in literature). Methods: This study presents a literature review and a snowball sampling to identify CC security challenges and their solutions/mitigation strategies. The literature review is based on search in electronic databases and snowball sample is based on the primary studies searched and selected from electronic databases. Using the challenges and their solutions identified form literature review, challenges with no mitigation strategies are identified. From these identified challenges with no mitigation strategies, a challenge with more references is identified. The surveys are employed in the later stages to identify the mitigation strategies for this challenge. Finally the results from the survey are discussed in a narrative fashion. Results: 43 challenges and 89 solutions are identified from literature review using snowball sampling. In addition to these mitigation strategies few guidelines are also identified. The challenge with more (i.e., more articles mentioning the challenge) and no mitigation identified is incompatibility. The responses identified for the three insecure areas of incompatibility (i.e., interoperability, migration and IDM integration with CC) in cloud computing security are mostly guidelines/practices opined by experienced practitioners. Conclusions: This study identifies cloud computing security challenges and their solutions. Where these (challenges and solutions) are common to cloud computing applications and cannot be generalized to either service or deployment models (viz. SaaS, PaaS, IaaS, etc.). The study also identifies that there are methods guidelines/practices identified from practitioners) to provide secure interoperability, migration and integration of on-premise authentication systems with cloud applications, but these methods are developed by individuals (practitioners/organization) specific to their context. The study also identifies the non-existence of global standards for any of these operations (providing interoperability/migration/IDM integration with cloud). This identified non-existence of global standards and guidelines could be help academics to know the state of practice and formulate better methods/standards to provide secure interoperability. The identified cloud computing security challenges (43) and solutions (89), can be referred by practitioners to understand which areas of security need to be concentrated while adapting/migrating to a cloud computing environment.

Cytoplasmic incompatibility (CI) is an intriguing, widespread, symbiont-induced reproductive failure that decreases offspring production of arthropods through crossing incompatibility of infected males with uninfected females or with females infected with a distinct symbiont genotype. For years, the molecular mechanism of CI remained unknown. Recent genomic, proteomic, biochemical, and cell biological studies have contributed to understanding of CI in the alphaproteobacterium Wolbachia and implicate genes associated with the WO prophage. Besides a recently discovered additional lineage of alphaproteobacterial symbionts only moderately related to Wolbachia, Cardinium (Bacteroidetes) is the only other symbiont known to cause CI, and genomic evidence suggests that it has very little homology with Wolbachia and evolved this phenotype independently. Here, we present the first transcriptomic study of the CI Cardinium strain cEper1, in its natural host, Encarsia suzannae, to detect important CI candidates and genes involved in the insect-Cardinium symbiosis. Highly expressed transcripts included genes involved in manipulating ubiquitination, apoptosis, and host DNA. Female-biased genes encoding ribosomal proteins suggest an increase in general translational activity of Cardinium in female wasps. The results confirm previous genomic analyses that indicated that Wolbachia and Cardinium utilize different genes to induce CI, and transcriptome patterns further highlight expression of some common pathways that these bacteria use to interact with the host and potentially cause this enigmatic and fundamental manipulation of host reproduction. IMPORTANCE The majority of insects carry maternally inherited intracellular bacteria that are important in their hosts' biology, ecology, and evolution. Some of these bacterial symbionts cause a reproductive failure known as cytoplasmic incompatibility (CI). In CI, the mating of symbiont-infected males and uninfected females produces few or no daughters. The CI symbiont then spreads and can have a significant impact on the insect host population. Cardinium, a bacterial endosymbiont of the parasitoid wasp Encarsia in the Bacteroidetes, is the only bacterial lineage known to cause CI outside the Alphaproteobacteria, where Wolbachia and another recently discovered CI symbiont reside. Here, we sought insight into the gene expression of a CI-inducing Cardinium strain in its natural host, Encarsia suzannae. Our study provides the first insights into the Cardinium transcriptome and provides support for the hypothesis that Wolbachia and Cardinium target similar host pathways with distinct and largely unrelated sets of genes.

De nombreuses substances chimiques sont susceptibles de mener à des phénomènes d'incompatibilité, lors de leur mise en contact avec d'autres produits ou matériaux. Pour maîtriser ces risques, une identification rapide et précise de ces incompatibilités est nécessaire. Elle est réalisée, jusqu’à présent, par des outils expérimentaux qui malgré leur incontestable importance, ne fournissent que des informations limitées. Pour les compléter et améliorer la compréhension des processus d'incompatibilité, ce travail de thèse, vise à étudier la réactivité du nitrate d'ammonium, produit très utilisé dans l'industrie, connu pour sa longue liste d'incompatibilités et impliqué dans des nombreux accidents majeurs (Toulouse 2001), à l'aide de la modélisation moléculaire. Une étude théorique approfondie, basée sur des calculs DFT, destinée à identifier les chemins réactionnels, les produits formés ainsi que la chaleur dégagée par les réactions a été menée.Après avoir caractérisé le mécanisme radicalaire de décomposition du nitrate d’ammonium pur en phase gaz, une étude détaillée de la réactivité du mélange du nitrate d’ammonium et du dichloroisocyanurate de sodium (DCCNa), a été réalisée. Un chemin réactionnel a été caractérisé, il s'agit de la réaction directe entre le nitrate d'ammonium et le DCCNa, en présence d'une molécule d'eau. Ensuite, ces méthodes théoriques ont été appliquées à d'autres systèmes d'incompatibilités chimiques avec le nitrate d'ammonium (NaNO2, substances chlorées) en focalisant sur les étapes limitantes des mécanismes afin de tester leur pertinence et potentiel en tant qu'outil de prédiction a priori du phénomène d'incompatibilité. Ce travail, pionnier dans l'étude microscopique des incompatibilités chimiques du nitrate d'ammonium, a permis de clarifier les mécanismes réactionnels lors de la décomposition du produit pur et en contact avec des contaminants. / Numerous chemical reactants tend to lead to undesired phenomena of incompatibility. In order to prevent the happening of those phenomena, a rapid and accurate identification of the incompatibilities is needed. Until now, experimental studies, which provide insightful, but limited information, were the only possible approach used for the study of incompatibilities. In this work a molecular modeling approach was used in order to complete and improve experimental results of incompatibility processes for the reactivity of ammonium nitrate. Ammonium nitrate is a widely used compound in the chemical industry, known for its long list of incompatibilities and often involved in major accidents (Toulouse, 2001).This theoretical work, based on Density Functional Theory (DFT) calculations, is intended to provide insights into the possible reaction pathways, enthalpies and products formed by incompatibility reaction between ammonium nitrate and other compounds. In this thesis the mechanism of the decomposition of pure ammonium nitrate in the gas phase was firstly characterized and then the reactivity of the mixture of ammonium nitrate – sodium dichloroisocyanurate (DCCNa) was considered. The results obtained suggest the existence of a reaction path, involving a direct reaction between the ammonium nitrate and DCCNa in the presence of a molecule of water.Furthermore, the theoretical approach was employed focusing on the study of the limiting steps of other chemical incompatibilities for ammonium nitrate systems (NaNO2, chlorinated substances). Those results were employed to understand the potentiality of the theoretical approach as a priori predicting tool for the incompatibility processes.In summary this work, pioneer in the microscopic study of chemical incompatibilities of ammonium nitrate, has clarified the reaction mechanisms involved in the decomposition of pure compounds, as well as in contact with other contaminants.

The aim of this study is an examination of the Southern African Development Community's (SADC) conflict resolution role (through multilateral mediation) in the Zimbabwe conflict and to determine how this role impacted on the development and outcome of the conflict. The underlying problem is not so much the intervention of SADC but the process and impact thereof. The primary research question is: Would the events in Zimbabwe and the outcome of the 'Zimbabwe-problem' have been substantially different without the involvement and conflict resolution role of SADC? This question is underpinned by two subsidiary questions: Firstly, what was the conflict management role, including that of conflict resolution, that SADC played? Secondly, did this role contribute to a positive outcome by overcoming limitations and how? In response the argument is that SADC, despite institutional limitations and operational constraints, played a positive role that prevented an escalation of the conflict and that contributed to a de-escalation thereof on account of its mediation. The study includes a framework for analysis to explore the conflict resolution role of a regional organisation in intra-state (domestic) conflict; a contextualisation of SADC's role with reference to the nature, scope and development of the 'Zimbabweproblem' as conflict; the analysis of the conflict resolution role through SADC mediation; and an evaluation of key findings as a basis for policy and research recommendations. The study is demarcated in conceptual, temporal and geopolitical terms. At a conceptual level, the key variables are conflict, conflict resolution and the role of international (regional) organisations. In terms of time-frame, the study covers the period from 2002 to 2014. The commencement year of 2002 is based on the constitutional and humanitarian crises that emerged and necessitated SADC intervention. The concluding year of 2014 marks the first full year since the end of the Global Political Agreement's (GPA) Government of National Unity (GNU) and allows for a retrospective assessment of the outcome(s) of SADC's role. The noncomparative case study focuses on Zimbabwe as the national-level and SADC as the regional-level (Southern African) units of analysis. The research design is that of a historical case study and entails a critical literature-documentary analysis. Although SADC's initial response and involvement was delayed and limited, it developed into a concerted mediation effort and a dedicated conflict resolution role. This role, despite limitations and constraints, overcame challenges and produced a settlement agreement. It is evident that events in Zimbabwe and the outcome of the 'Zimbabwe-problem' would have been substantially different and undeniably more detrimental (even disastrous) not only to Zimbabwe but also to the Southern African region without SADC's involvement and conflict resolution role. Its intervention contributed to the de-escalation of the conflict and to acceptable levels of stability (unstable peace) in the region and within the country. A retrospective and diachronic assessment confirms a relative improvement in political, economic and social conditions (if juxtaposed with the first decade of the 2000s. This, however, does not imply a termination of the conflict and the existence of stable peace. The residue of dissatisfaction produced by the GPA; the prevailing electoral and constitutional contestation; and the authoritarian and repressive regime trends still apparent in Zimbabwe attest to continued latent and manifest conflict. This confirms the tenet that intra-state conflict is never really terminated, seldom resolved but only managed in an effective manner to produce a minimally acceptable outcome of unstable peace. / Mini Dissertation (M Security Studies)--University of Pretoria, 2017. / Political Sciences / M Security Studies / Unrestricted

La entrada PI 126944 de S. peruvianum ha sido descrita como resistente a distintos estreses bióticos, entre ellos a la enfermedad del rizado amarillo del tomate (Tomato yellow leaf curl disease, TYLCD). En trabajos previos realizados en el Instituto Universitario para la Conservación y Mejora de la Agrodiversidad Valenciana (COMAV) se obtuvieron tres híbridos interespecíficos entre esta entrada y el tomate cultivado, empleando el rescate de semillas inmaduras. En trabajos posteriores se desarrollaron generaciones más avanzadas a partir de estos materiales, incluyendo hasta las generaciones pseudo-F6 y retrocruces hacia la especie cultivada de algunas de las generaciones pseudo-Fn. Con objeto de aprovechar estos materiales en la mejora del tomate cultivado se inició, en trabajos anteriores del grupo, el desarrollo de un conjunto de líneas de introgresión (Introgression lines, ILs) que contengan el genoma de la entrada PI 126944 en el fondo genético de S. lycopersicum. Para tener correctamente representado el genoma de la especie donante en el fondo genético del tomate es necesario obtener un gran número de descendientes, por lo que es necesario optimizar los protocolos. El primer objetivo de esta tesis fue el estudio de distintos factores implicados en la superación de las barreras de incompatibilidad, con objeto de conseguir un elevado número de descendientes y maximizar la probabilidad de introgresar el genoma de PI 126944 en el conjunto de ILs. Se llevaron a cabo tres ensayos de retrocruce, iniciados con diferentes plantas de las generaciones pseudo-F4, pseudo-F5 y pseudo-F6. El genotipo de los parentales resultó ser un factor determinante en la obtención de descendencia, por lo que se recomienda utilizar el máximo número de genotipos distintos, con objeto de maximizar la probabilidad de obtener progenie. Se llevó a cabo una prueba de medios de cultivo que permitió seleccionar la combinación más adecuada de auxinas y citoquininas para el cultivo de semillas inmaduras y posterior regeneración de plantas. También se estudió el efecto del número de días transcurridos desde la polinización hasta la recolección de los frutos. Tal y como se ha comentado anteriormente, esta colección del ILs presenta interés por la resistencia del parental donante a TYLCD. Una vez se complete la colección, se evaluará por su resistencia a esta enfermedad. Los estudios previos han mostrado que se trata probablemente de una resistencia poligénica, cuya expresión a menudo es más dependiente de las condiciones ambientales y de otros factores. En estos casos, el empleo de un solo testigo resistente y otro susceptible no es suficiente para determinar con exactitud el nivel de resistencia de los materiales en estudio. La disponibilidad de controles con distintos niveles de resistencia permitiría realizar un fenotipado más preciso. Un grupo de investigadores del "Volcani Center" desarrollaron una escala compuesta por siete líneas con diversos niveles de resistencia a TYLCD, introgresada a partir de distintas especies silvestres. En el marco de esta tesis se evaluó el comportamiento de esta escala en siete ensayos distintos, cuatro de ellos llevados a cabo en el COMAV-UPV y los otros tres en el Instituto Nacional de Ciencias Hortícolas de Cuba. Se compararon dos aislados de TYLCV (Tomato yellow leaf curl virus), una de las especies causantes de TYLCD, diferentes métodos de inoculación, dos estados de desarrollo de la planta y distintas condiciones ambientales. Los síntomas fueron más leves que los obtenidos en las condiciones ensayadas por los autores que desarrollaron la escala, si bien el orden de las líneas en la escala se mantuvo, con pocas excepciones. Sin embargo, en la mayor parte de las condiciones, la respuesta obtenida no correspondió a una escala gradual, ya que se observó una gran diferencia entre los valores de síntomas de las líneas susceptibles y las resistentes, siendo muy pequeñas las difer / Accession S. peruvianum PI 126944 has been reported as resistant to several biotic stresses, among them to Tomato yellow leaf curl disease, (TYLCD). In previous works carried out in the "Instituto Universitario para la Conservación y Mejora de la Agrodiversidad Valenciana" (COMAV) three interspecific hybrids between this accession and cultivated tomato were obtained, using immature seeds rescue. In subsequent works more advances generations from these materials were developed, including until the pseudo-F6 generations and backcrosses to the cultivated species of some of the pseudo-Fn generations. With the aim of taking advantage of these materials in the improvement of cultivated tomato, in previous works of the group, the development of a set of Introgression lines (ILs) that contain the genome of the accession PI 126944 in the genetic background of S. lycopersicum was initiated. The obtaining of a large number of descendants is necessary in order to have correctly represented the genome of the donor species, thus there is the need to optimize the protocols In this sense, the first aim of this work was the study of several factors involved in the overcoming of the incompatibility barriers, to obtain a high number of descendants and maximize the probability of introgressing the genome of PI 126944 in the set of ILs. Three backcross assays were carried out, initiated with different plants of the generations pseudo-F4, pseudo-F5 and pseudo-F6. The parental genotype resulted a determinant factor in the obtaining of descendants, so the recommendation is the use of the maximum number of different genotypes, in order to maximize the probability of obtaining progeny. A proof of different culture media was carried out, which allowed the selection of the better combination of auxins and cytokinins to grow immature seed and regenerate plants. The effect of the number of days from pollination to fruit harvest was also studied. As mentioned before, the collection of ILs results of interest, given the resistance of the donor parental to TYLCD, among others traits. Once the collection is completed, it will be evaluated for its resistance to this disease. The previous studies showed that it is probably a quantitative resistance, whose expression is often more dependent of the environmental conditions and of other factors. In these cases, the use of only one resistant and one susceptible control is not sufficient to determine with accuracy the level of resistance. Availability of controls with different levels of resistance would allow a more precise phenotyping. A group of researchers of the "Volcani Center" developed a scale that consisted of seven lines with different levels of resistance to TYLCD, introgressed from different wild species. In this work, the response of this scale in seven distinct assays was evaluated, four of them carried out in the COMAV-UPV and the others three in the "Instituto Nacional de Ciencias Hortícolas de Cuba". Two isolates of TYLCV (Tomato yellow leaf curl virus), one of the species causing TYLCD, different inoculation method, two development stages of the plant and several environmental conditions were evaluated. In general, the symptoms were more slight that the obtained in the conditions assayed by the authors that developed the scale, although the order of the lines in the scale were maintained, with few exceptions. However, in most of the conditions, the response obtained did not correspond to a graded scale, since there were high differences among the symptom scores of the susceptible and the resistant lines, with very small the differences among the resistant lines. These results suggest the possibility to reduce the number of lines to employ in each concrete condition, selecting the most susceptible, the most resistant and another with intermediate levels of resistance. / L'entrada PI 126944 de S. peruvianum ha sigut descrita com a resistent a diferents estresses biòtics, entre ells a la malaltia de l'arrissat groc de la tomaca (Tomato yellow leaf curl disease, TYLCD). En treballs previs realitzats en el "Instituto Universitario para la Conservación y Mejora de la Agrodiversidad Valenciana" (COMAV) es van obtenir tres híbrids interespecífics entre aquesta entrada i la tomaca cultivada, emprant el rescat de llavors immadures. En treballs posteriors, es van desenvolupar generacions més avançades a partir d'aquests materials, incloent fins a les generacions pseudo-F6 i retrocreuaments cap a l'espècie cultivada d'algunes de les generacions pseudo-Fn. A fi de aprofitar aquests materials en la millora de la tomaca cultivada es va iniciar, en treballs anteriors del grup, el desenvolupament d'un conjunt de línies d'introgressió (Introgression lines, ILs) que continguen el genoma de l'entrada PI 126944 en el fons genètic de S. lycopersicum. Per a tenir correctament representat el genoma de l'espècie donant en el fons genètic de la tomaca és necessari obtenir un gran nombre de descendents, per la qual cosa és necessari optimitzar els protocols. El primer objectiu d'aquesta tesi va ser l'estudi de diferents factors implicats en la superació de les barreres d'incompatibilitat, a fi d'aconseguir un elevat nombre de descendents i maximitzar la probabilitat d'introgressar el genoma de PI 126944 en el conjunt de ILs. Es van dur a terme tres assajos de retrocreuament, iniciats amb diferents plantes de les generacions pseudo-F4, pseudo-F5 i pseudo-F6. El genotip dels parentals va resultar un factor determinant en l'obtenció de descendència, per la qual cosa es recomana utilitzar el màxim nombre de genotips diferents, a fi de maximitzar la probabilitat d'obtenir descendència. Es va dur a terme una prova de medis de cultiu que va permetre seleccionar la combinació més adequada d'auxines i citoquinines per al cultiu de llavors immadures i posterior regeneració de plantes. Es va estudiar l'efecte del nombre de dies transcorreguts des de la pol·linització fins a la recol·lecció dels fruits, havent-se obtingut resultats diferents. Tal com s'ha comentat anteriorment, aquesta col·lecció de ILs presenta interès per la resistència del parental donant a TYLCD. Una vegada es complete la col·lecció, s'avaluarà per la seua resistència a aquesta malaltia. Els estudis previs han mostrat que es tracta probablement d'una resistència quantitativa, l'expressió de la qual sovint és més depenent de les condicions ambientals i d'altres factors. En aquests casos, l'utilització d'un sol control resistent i un altre susceptible no és suficient per a determinar amb exactitud el nivell de resistència dels materials en estudi. La disponibilitat de controls amb diferents nivells de resistència permetria realitzar un fenotipat més precís. Un grup d'investigadors del "Volcani Center" van desenvolupar una escala composta per set línies amb diversos nivells de resistència a TYLCD, introgressada a partir de diferents espècies silvestres. En el marc d'aquesta tesi es va avaluar el comportament d'aquesta escala en set assajos diferents, quatre d'ells duts a terme en el COMAV-UPV i els altres tres en el "Instituto Nacional de Ciencias Hortícolas de Cuba". Es van comparar dos aïllats deTYLCV (Tomato yellow leaf curl virus), una de les espècies causants de TYLCD, diferents mètodes d'inoculació, dos estats de desenvolupament de la planta i diferents condicions ambientals. Els símptomes van ser més lleus que els obtinguts en les condicions assajades pels autors que van desenvolupar l'escala, si ben l'ordre de les línies en l'escala es va mantenir, amb poques excepcions. No obstant açò, en la major part de les condicions, la resposta obtinguda no va correspondre a una escala gradual, ja que es va observar una gran diferència entre els valors de símptomes de les línies susceptibles i les resiste / Campos, GN. (2018). Aprovechamiento de las especies Solanum peruvianum en la mejora del tomate [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/100858 / TESIS