Atualmente a procura por produtos sustentáveis têm-se mostrado cada vez mais frequente e promissora. Em espécies de importância comercial, procura-se obter a maior produtividade possível dentro de um curto espaço de tempo aliado à preservação do meio ambiente. Dentro disso, a transformação genética de plantas se mostra uma alternativa atrativa para a geração de variedades de cana-de-açúcar que gerem produtos de maneira mais eficaz. O sucesso da transformação genética está diretamente associada a cultura de tecidos de plantas que precisa ser adequada a cada genótipo e situação de cultivo, sendo a luminosidade um dos principais fatores para a produção de plantas vigorosas. Outro fator importante é a seleção das plantas transgênicas, que precisam ser submetidas a uma quantidade de agente seletivo suficiente para identificar as plantas modificadas geneticamente. Em cana-de-açúcar, a identificação de plantas transgênicas por PCR e a definição do número de cópias é um procedimento de difícil execução e muito oneroso. Isto se dá pois no processo transformação via biolística, a inserção de genes é aleatória, produzindo plantas com variados números de cópias. Em consideração a estes fatores envolvidos na eficiência de obtenção de plantas transgênicas de cana-de-açúcar, os objetivos deste trabalho foram o aperfeiçoamento do protocolo de cultura de tecidos, transformação genética da variedade SP803280 com os genes xth, AtDdm1, como também, definir genes de referência para a quantificação do número de cópias dos genes xth e AtDdm1 inseridos na variedade SP803280 e do gene neo na RB835089, análise de ploidia e tamanho de genoma dos eventos transgênicos comparado com as plantas controle. No estudo a respeito da melhor qualidade de luz durante o cultivo in vitro na fase de regeneração de plantas, tem-se que a luz branca e a junção das luzes LED e branca se mostraram melhores para regeneração e desenvolvimento das plantas enquanto que para plântulas, as luzes LED e branca separadamente foram mais efetivas no crescimento. Para a seleção das plantas uma concentração de geneticina entre 40 e 50 mgL-1 é recomendada. As taxas de sucesso nas transformações genéticas para o gene xth variaram entre 2,5 a 18,3% dependendo do experimento e para AtDdm1 foi de 2,2% em um bombardeamento.Não houveram alterações de ploidia e tamanho do genoma nos transgênicos das duas variedades em relação à planta selvagem. Os genes p4h e prr foram identificados como os melhores para a quantificação relativa de genes inseridos por PCR em tempo real na variedade SP803280 enquanto que para a RB835089 aprt e prr se mostraram mais eficazes. A análise do número de cópias inseridas em eventos transgênicos por PCR em tempo real foi possível através das duas metodologias de cálculo testados por este trabalho, com resultados que concordam com uma tendência nesta determinação de maneira simples e rápida. / Currently the demand for sustainable products has been shown to be frequent and promising. In species of commercial importance, there is an effort to obtain the highest possible productivity in a short time, along with the environment preservation. In this context, genetic transformation of plants appears as an attractive alternative for the development of sugarcane varieties able to generate products in a more effective way. The genetic transformation success is directly associated to plant tissue culture that requires specific condition for each genotype and cultivation process, in which, luminosity is one of the main factors that determines the production of vigorous plants. Another important factor is the selection of transgenic plants, that occur by exposing plants to a sufficient amount of selective agent in order to identify only genetic modified plants. In sugarcane, identification of transgenic plants by PCR and the definition of copy numbers is a difficult procedure to implement and usually is very costly. It is because in the process of genetic transformation by biolistic, the insertion of genes occurs randomly and also produce plants with varied copy numbers. In consideration of these factors directly involved in the efficiency to obtain sugarcane transgenic plants the objectives of this study were the improvement of a tissue culture protocol, the genetic transformation of the variety SP803280 with xth and AtDdm1 genes. Also, the studies include the definition of reference genes for determining the number of copies inserted of xth and AtDdm1 genes into the variety SP803280 and neo gene in RB835089, ploidy analysis and genome size of the transgenic events compared to control plants. In the study related to the best light quality for in vitro plant regeneration, white light and the combination of LED and white lights proved to be better for plants regeneration and development while for seedlings, LED and white light separately were more effective for growth. In order to obtain selection of transgenic plants, geneticin concentration between 40 and 50 mg L-1 is recommended. Success rates in xth genetic transformation ranged from 2.5 to 18.3% depending on the experiment, and for AtDdm1 was only 2.2% in just one biolistic bombardment. There were no changes in ploidy and genome size in transgenic events related to their wild type plant. The genes p4h and prr were defined to be the best for determining the copy number of transgenic events by real time PCR in SP803280 variety, while for RB835089, the genes aprt and prr were the most effective. The analysis of the number of inserted copies was possible using the two calculation methodologies tested by this work, with results that agree with a tendency in a simple and fast quantification methodology.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-22T12:13:15Z No. of bitstreams: 1 daniellelucianaaurorasoaresdoamaral.pdf: 933775 bytes, checksum: ab2892397c2895f9047b1f683dec1351 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-08-07T19:20:42Z (GMT) No. of bitstreams: 1 daniellelucianaaurorasoaresdoamaral.pdf: 933775 bytes, checksum: ab2892397c2895f9047b1f683dec1351 (MD5) / Made available in DSpace on 2017-08-07T19:20:42Z (GMT). No. of bitstreams: 1 daniellelucianaaurorasoaresdoamaral.pdf: 933775 bytes, checksum: ab2892397c2895f9047b1f683dec1351 (MD5) Previous issue date: 2014-03-07 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Desde a domesticação das plantas para a utilização humana, as doenças vêm causando grandes perdas na produção. Fungos fitopatogênicos tais como Sclerotium rolfsii, Botrytis cinerea, Fusarium oxysporum e Sclerotinia sclerotiorum são capazes de infectar diferentes espécies de plantas. A infecção por estes fungos leva a perdas consideráveis na época da colheita. A fase inicial da infecção envolve a produção e o acúmulo de grande quantidade de ácido oxálico (AO), que parece ser um dos maiores determinantes da patogenicidade. Fusarium oxysporum é a espécie mais comum do gênero e causa murcha vascular em diferentes espécies de plantas. Esse fungo causa perdas severas em muitas lavouras, como algodão, fumo, banana, café, morango e cana de açúcar. Genes que conferem resistência a fitopatógenos tornam-se de importância agronômica como recursos para melhoramento. Dentre esses, destacamos o da enzima oxalato descarboxilase (OXDC), capaz de catalizar a degradação do AO em ácido fórmico e dióxido de carbono, diminuindo a capacidade de infecção do fungo. Na geração T0 de fumo transformado com gene da OXDC, foram obtidas quatro linhagens resistentes ao fungo, estas foram analisadas na T1. O objetivo deste trabalho foi avaliar a segregação do transgene OXDC para a geração T1 de fumo e avaliar se a geração T1 de plantas transformadas é capaz de resistir ao fitopatógeno Fusarium oxysporum. Trinta plantas de cada linhagem T1 de fumo transformado com OXDC foram avaliadas, por PCR, quanto a presença do HPTII. Estas quatro linhagens foram analisadas apresentaram proporção de segregação de 3:1. Uma planta PCR positiva de cada linhagem foi submetida a bioensaios para verificar a resistência ao fungo e ao AO. No ensaio de resistência ao fungo Fusarium oxysporum, este não foi capaz de infectar as linhagens transgênicas, mostrando um aumento da resistência da T1 em relação a T0 quando os resultados foram comparados. Os níveis de expressão do transgene foram avaliados por RT-PCR. As linhagens T1, T4 e T6 mostraram níveis de expressão semelhantes, já a linhagem T2 apresentou menor nível de expressão que as demais linhagens, de maneira que este resultado pode ser correlacionado com menor resistência ao AO. Com base nestes resultados pode-se concluir que a enzima Oxalato Descarboxilase demonstrou ser eficiente no combate ao patógeno Fusarium oxysporum e potencialmente eficiente no combate a outros fungos que também utilizem AO no processo de infecção. / Since the domestication of plants for human use, the diseases are causing major production losses. Pathogenic fungi such as Sclerotium rolfsii, Botrytis cinerea, Sclerotinia sclerotiorum and Fusarium oxysporum are capable of infecting various plant species. Infection by these fungi leads to considerable losses at harvest. The initial phase of the infection involves the production and accumulation of large amounts of oxalic acid (OA), which seems to be one of the biggest determinants of pathogenicity. Fusarium oxysporum is the most common species of the genus and causes vascular wilt in different plant species. This fungus causes severe losses in many crops such as cotton, tobacco, bananas, coffee, strawberry and sugar cane. Genes that confer resistance to pathogens become of agronomic importance as resources for improvement. Among these we highlight the enzyme oxalate decarboxylase (OXDC) capable of catalyzing the degradation of OA in formic acid and carbon dioxide, decreasing the infectivity of the fungus. In the T0 generation of tobacco transformed with OXDC gene four resistant fungal strains were obtained, they were analyzed in T1. The objective of this study was to evaluate the segregation of the transgene OXDC for T1 generation of smoke and assess whether the T1 generation of transformed plants are able to resist the pathogen Fusarium oxysporum. Thirty T1 plants of each line of tobacco transformed with OXDC were evaluated by PCR for the presence of HPTII. These four strains were analyzed showed a segregation ratio of 3:1. A positive PCR plant of each strain was subjected to bioassays to verify resistance to the fungus and the OA. In the test of resistance to the fungus Fusarium oxysporum, this was not able to infect the transgenic lines , showing an increase of the resistance of T1 relative to T0 when the results were compared. The levels of transgene expression were assessed by RT-PCR. T1, T4 and T6 strains showed similar levels of expression, the T2 strain showed lower expression level than other strains , so that this result can be correlated with lower resistance to OA. Based on these results it can be concluded that the enzyme Oxalate Descarboxylase demonstrated to be effective in combating the pathogen Fusarium oxysporum and potentially efficient against other fungi which also use OA in the infection process.

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As pesquisas em ensino de Ciências têm buscado referenciais teóricos para lidar com a complexidade dos processos de ensino-aprendizagem. Esta pesquisa procura trazer uma contribuição para esta busca, ao acompanhar os processos de tomada de consciência de 46 estudantes durante um semestre. Trata-se de uma pesquisa de natureza quali-quantitativa, que utiliza diferentes instrumentos de análise: questionário, construção de mapas conceituais com uso do Cmap Tools, e filmagens. Os resultados são analisados com base na tomada de consciência, a partir da Epistemologia Genética, e referem-se a dois recortes: uma análise do questionário na categoria Implicação Significante, no primeiro momento da pesquisa; e uma análise diacrônica com 12 sujeitos, a partir do conjunto de dados nas categorias Implicação Significante e Todos, Alguns e Nenhum, que são generalizados aos 46 sujeitos pesquisados, após uma análise minuciosa das frequências presentes nos mapas conceituais. Em relação ao primeiro recorte, os resultados apontaram que os sujeitos apresentam um domínio de representação não estruturado acerca dos conhecimentos em Biotecnologia. Assim, evidenciamos formas de pensamento transdutivo, ou seja, quando o raciocínio dos alunos parte do particular e se conduz ao particular, sem atingir uma generalização. Já no segundo recorte, constatamos três níveis de conceituação: no nível um, há ausência de tomada de consciência da relação entre biotecnologia, clonagem e transgênicos. Na regulagem de Todos, Alguns e Nenhum, o sujeito não chega à quantificação das extensões. No nível dois (A), há tomada de consciência entre biotecnologia e clonagem e biotecnologia e transgênicos. Na regulagem de Todos, Alguns e Nenhum, o sujeito não chega à quantificação das extensões. No nível dois (A), há tomada de consciência entre biotecnologia e clonagem e biotecnologia e transgênicos. Na regulagem de Todos, Alguns e Nenhum, os sujeitos já consideram que os transgênicos podem ser micro-organismos, plantas ou animais, o que implica numa dimensão de generalização. No nível dois (B), os sujeitos chegam a uma quantificação positiva, admitindo que todos os transgênicos são OGM. No nível três (A), há tomada de consciência da relação entre biotecnologia, clonagem e transgênicos. Na regulagem de Todos, Alguns e Nenhum, os sujeitos já chegam a uma quantificação positiva e negativa, admitindo que todos os transgênicos são OGM, mas que nem todos OGM são transgênicos. No nível três (B), além de admitir Todos e Alguns, também reconhecem os organismos que não são OGM, como aqueles que se originam por processos naturais, tais como conjugação, transdução e transformação. / Investigations on Science teaching have been searching for theoretical references to deal with the complexity of teaching-learning processes. This study aims to contribute to this search by following the processes of awareness of 46 students during a semester. This is a quali-quantitive research that uses different assessment instruments: questionnaire, construction of conceptual maps, with the useof Cmap Tools, and video footages. The results will be analyzed based on awareness in Genetics Epistemology and refer to two research outlines: the first one analyzes questionnaires with regard to the category significant implication, in the initial stage of the research. The second one performs a diachronic analysis with 12 subjects, based on the data set obtained for the Significant Implication and All, Some and None categories, which was then generalized for the 46 subjects analyzed, after a meticulous analysis of the frequencies of the relationships present in the conceptual maps. As for the first outline, results showed that subjects had a domain of unstructured knowledge representation on Biotechnology. Thus, we found forms of transductive thinking, that is, when students’ reasoning go from particular to particular, without reaching a generalization. On the other hand, in the second outline we identified three levels of conceptualization. At level one, there is no awareness of the relationship between biotechnology, cloning and transgenics. When regulating All, Some and None categories, subjects are not able to quantify their extensions. At level two (A), there is awareness of the relationship between biotechnology and cloning and of biotechnology and transgenics. When regulating All, Some and None categories, subjects are able to consider that transgenics can be microorganisms, plants or animals, which implicates a generalization dimension. At level two (B), subjects are able to establish a positive quantification, acknowledging that all transgenics are GMOs. At level three (A), there is awareness of the relationship between biotechnology, cloning and transgenics. When regulating All, Some and None, subjects are now able to establish a positive and negative quantification, acknowledging that all transgenics are GMOs but not all GMOs are transgenics. At level three (B), besides acknowledging All and Some categories, subjects also acknowledge organisms that are not GMOs, such as those originated by natural processes like conjugation, transduction, and transformation. / La investigación en didáctica de las ciencias han tratado de marcos teóricos para abordar la complejidad de los procesos de enseñanza y aprendizaje. Esta investigación tiene como objetivo hacer una contribución a esta misión de acompañar los procesos de toma de conciencia de 46 estudiantes por un semestre. Esta es una encuesta de carácter cualitativo y cuantitativo utilizando diferentes instrumentos de análisis: cuestionario, construir mapas conceptuales utilizando el rodaje Cmap Tools. Los resultados se analizaron con base en el conocimiento de la epistemología genética y se refieren a dos recortes de investigación: la primera es un análisis de la implicación cuestionario significativo en la categoría, la primera vez de la encuesta. En el segundo, se realiza un análisis diacrónico de 12 sujetos, a partir del conjunto de datos en categorías: Implicación significativa y todas, algunas y Ninguno y luego se generaliza de los 46 sujetos estudiados, después de un análisis exhaustivo de las frecuencias relaciones presentes en los mapas conceptuales. En cuanto el primer cultivo, los resultados indicaron que los sujetos tienen una representación en el dominio de conocimientos estructurada sobre Biotecnología. Por lo tanto, se evidencia transdutivas maneras de pensar, es decir, cuando la parte del pensamiento de los estudiantes y conduce a lo particular concreto, sin llegar a una generalización. En el segundo corte, vemos tres niveles de conceptualización, y, en el nivel uno, hay una falta de conciencia de la relación entre la biotecnología, la clonación y los transgénicos. En la regulación de todos, algunos y ninguno, el sujeto no llega a la cuantificación de las extensiones. En el segundo nivel (A), hay una conciencia entre la biotecnología y la clonación y la biotecnología y transgénicos. En la regulación de todos, algunos y ninguno, los sujetos ya consideran que los OGM pueden ser microorganismos, plantas o animales, lo que implica una dimensión de la generalización. En el segundo nivel (B), los sujetos llegan a una cuantificación positivo, suponiendo que todos los OMG son genéticamente modificados. En el nivel tres (A), se tiene conocimiento de la relación entre la biotecnología, la clonación y transgénicos. En la regulación de todos, algunos y ninguno, los sujetos ya llegar a una cuantificación positivo y negativo el supuesto de que todos los OGM son genéticamente modificados, pero no todos los OGM son modificados genéticamente. En el nivel tres (B), además de admitir todos y algunos también reconocen que los organismos no son OGM, tales como los que surgen por procesos naturales, tales como conjugación, transducción y transformación.

Aggregations of fused in sarcoma (FUS), a multifunctional RNA processing protein, define a pathological subtype of both frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS), whilst mutations in the FUS gene are causative for ALS. To model the impact of FUS mutations, expression vectors containing the entire genomic sequence of FUS, up and downstream regions, and native promoter sequences have been generated. The constructs have been tagged with an mCherry fluorescent tag, and three separate pathological mutations (R244C, R521C, and P525L) have been separately inserted. Transgenic mice have been generated using the WT and P525L FUS vectors to provide a highly physiological model of FUS in disease. Within transfected HEK293 cells, insertion of the P525L and R521C FUS mutations leads to relocalisation of FUS from the nucleus to the cytoplasm. R521C and P525L mutant FUS incorporates into cytoplasmic aggregations of untranslated mRNA and RNA binding proteins known as stress granules. The strong relocalisation seen with P525L-FUS is associated with a gain of cytotoxicity. Reversal of this cytoplasmic relocalisation by demethylation of FUS rescues this cytotoxicity, suggesting a toxic gain of cytoplasmic function in the majority of FUS mutations. By contrast, insertion of the R244C mutation leads to neither relocalisation, stress granule association, nor cytotoxicity. Notably the R244C mutation, located away from the nuclear localization domain in which the majority of FUS mutations are found, leads to the presence of smaller FUS fragments in western blot analyses. These fragments appear not to be due to splicing defects in FUS but rather are due to post-translational modifications or aberrant protein cleavage. These data suggest an alternative pathway for FUS toxicity based upon a nuclear loss of function.

Overexpression of the NR2B subunit of the NMDA receptor in the forebrain has been shown to improve learning and memory in mice (Tang et al 1999), which provides exciting implications for the enhancement of human cognition. However, it was first essential to establish replicability, and since the Tang et al (1999) study used only male mice we wished to investigate possible sex differences. On the hidden platform watermaze, we found a trend for male NR2BOE mice to learn the task more quickly than male wildtype mice (as observed by Tang et al. 1999), but the opposite trend in female mice; female NR2BOE mice were slower to reach the hidden platform than female wildtype mice. This pattern of results was also observed on the spatial reference Y memory task and open field task (for anxiety), although not on the spatial working memory T maze task (despite a sex difference). However, wildtype and NR2BOE mice performed at similar levels on the novel object recognition task, the spatial novelty preference task, visible platform watermaze and visual discrimination task. A battery of tests considering some species typical behaviours of mice demonstrated that wildtype and NR2BOE mice were comparable on tests of motor ability, strength, co-ordination, anxiety, burrowing and nesting. This suggests that our behavioural results are not due to a general impairment or enhancement of species typical behaviours. We considered the possibility that the difference between the results of Tang et al (1999) and those we observed may be caused by age differences; hence we attempted to replicate our results on the hidden platform watermaze, spatial reference Y maze and open field test in age matched mice. However, the second cohort of NR2BOE mice performed at similar levels to wildtype mice, and at significantly improved levels compared to the mice of the first cohort. We also considered the effects of knocking out the NR2B subunit on learning and memory, and NR1 subunit deletion within the hippocampus. On the spatial working memory T maze, these mouse strains performed similarly to their respective wildtype strains. Similarly, on a two beacon watermaze (with one indicating the platform position), mice lacking the NR2B subunit were able to locate the platform in a similar length of time. To ensure that the null results we had observed in the second cohort were not due to loss of the NR2B protein overexpression in the forebrain, we performed polymerase chain reactions (PCR), quantitative real-time PCR, and Western blots. We ascertained that the transgene was indeed present and that NR2B mRNA and protein levels were elevated in the hippocampi of the NR2BOE mice. In conclusion, it is unclear why the behaviours we observed in the NR2BOE mice are different to those published in the literature. It is possible that they may be due to differences in environmental enrichment, but the cause of the genotype by sex differences observed in the mice of cohort 1 is unclear. Nonetheless, we have advanced our knowledge of the effects of modifications in the levels of the NR2B subunit of the NMDA receptor on learning and behaviour.

I have sought to discover genetic causes of neuroanatomical defects by conducting N-ethyl-N-nitrosourea mutagenesis and transgenic knock out screens in mice. The rationale behind this is that mutations causal to structural defects will be informative about developmental neurobiology and the biological basis of behaviour. Direct screening for behavioural abnormalities in mice has historically been arduous and yielded few findings due to small effect sizes and limited statistical power. My approach sought to bypass these problems by screening for highly penetrant morphological phenotypes. This thesis details my screens and the histological, genetic and behavioural characterisation of lines of interest. These include models of hydrocephalous, pyramidal cell layer ectopia, abnormal neurogenesis, corpus callosum agenesis, hippocampal enlargement, elevated cell death and hypomyelination. Whilst N-ethyl-N-nitrosourea mutagenesis screening has been conducted since the twilight of the 20^th century, systematic transgenic knock out screening is currently in its infancy. By discovering gene-phenotype associations through both approaches, I have been able to compare the relative yields, strengths and weaknesses of the two screening methods. Additionally, I have discussed the significant of the gene-phenotype associations produced from both screens.

Desmosomes are intercellular junctions that anchor intermediate filaments to the sites of intercellular contacts. They are critical for maintaining the integrity of tissues that experience constant mechanical and structural stresses, like the skin and heart. Perturbation of desmosomal adhesion can lead to devastating epidermal and myocardial diseases. However, little is known about the regulators of desmosomes and the role of desmosomes in cell signalling events. Recent work has suggested that iASPP, an inhibitor of the p53 family of proteins, localises at the intercalated discs where desmosomes reside. However, its role at the desmosomes has remained elusive. Thus, in this thesis, it was investigated whether iASPP is a dual function protein that links desmosome adhesion to gene expression and if desmosome-related diseases develop in the absence of iASPP. iASPP was found to be a novel regulator of desmosomes, co-localising with them by physically interacting with the desmosomal components desmoplakin and K5 intermediate filaments. Loss of iASPP resulted in increased phosphorylation and solubilisation of desmoplakin, leading to the formation of K5 aggregates. This culminated in disrupted intercellular adhesion and enhanced cellular migration. Consistent with the role of iASPP in the maintenance of desmosomal adhesion integrity, focal palmoplantar keratoderma was observed in iASPP-deficient mice — a disorder often associated with desmosome dysfunction. This was accompanied by disrupted intracellular signalling, as exemplified by the disrupted expression of differentiation markers; an increase in the thickness of cell layers expressing differentiation marker K1 was noted, and K5 and K6 cells were ectopically expressed throughout the diseased palmoplantar epidermis. Impaired intercellular adhesion and migration had consequences for wound healing, as iASPP-deficient mice exhibited delayed wound closure. Furthermore, defects in eyelid closure in iASPP-deficient mice were found to be due to increased apoptosis. The localisation of apoptotic cells at the leading edge of the eyelid epidermis implied that apoptosis might have occurred due to a loss of cell-matrix or cell-cell contact, i.e. anoikis. Taken together, these results suggest that iASPP is involved in pathological (palmoplantar keratoderma), physiological (wound healing) and developmental processes (embryonic eyelid closure) through its regulation of desmosomes and their dynamics. Therefore, iASPP represents a new candidate gene in cutaneous disorders and could be implicated in a variety of epidermal and myocardial diseases.

En Argentine, la biotechnologie agricole, spécialement le soya transgénique, a été adoptée de façon fulgurante et elle a provoqué un fort choc dans l’économie nationale et dans la société. Actuellement, dû à la gravité des conséquences de ce phénomène, les médias, et la presse en particulier, ont fait écho du débat. Le but général de cette étude est d’analyser le débat de société sur ce phénomène dans la presse écrite argentine. Pour ce faire, trois objectifs spécifiques ont été retenus : dresser un portrait général du discours; comprendre le contexte politique et économique qui a permis l’insertion de la biotechnologie agricole en Argentine; et analyser les enjeux socioéthiques subjacents au problème des biotechnologies. Pour répondre à ces objectifs, on a effectué une analyse de contenu du discours social circonscrit à la presse écrite argentine entre les années 1999- 2006. La démarche privilégiée inclut la classification des articles de journaux par l’utilisation de mots-clés et l’assignation à des catégories thématiques avec l’assistance des techniques d’analyse de texte par ordinateur. Les résultats de cette étude signalent pour la période étudiée une importante couverture journalistique des biotechnologies agricoles, couverture qui, en général, a été favorable. La quantité d’articles augmente avec les années et montre un virage important des sujets commerciaux à des questions politiques. Le débat autour des conséquences environnementales et sociales de l’application du nouveau modèle agricole sont pauvrement représentées et montrent une apparition plus tardive dans les journaux argentins. Cependant, cela pourrait s’expliquer par un déplacement dans l’axe de la discussion des biotechnologies vers la sojisation qui devient l’enjeu central du débat autour du phénomène agricole. / In Argentina, agricultural biotechnology – especially transgenic soya – has been widely adopted causing a strong impact on the national economy and society. Today, because of its important impact, the media and the written press in particular have published substantial material on this phenomenon of agricultural biotechnology. The overall objective of this study is to analyze the social debate on this phenomenon in the Argentinean written press. To this end, three specific objectives were retained: to provide an overview of the discourse; to understand the political and economic context that permitted the inclusion of agricultural biotechnology in Argentina; and to analyze the socio-ethical issues underlying the integration of biotechnology into Argentinean agriculture. To meet these objectives, I conducted a content analysis of social discourse in the Argentinean press during the years 1999-2006. I classified articles using keywords and constructed thematic categories using computer-assisted text analysis techniques. The results of this study show a wide coverage of agricultural biotechnology with a generally positive presentation. The number of articles increases over time and shows a major shift from a discussion of economic to political issues. The debate over the environmental, social and ethical consequences of the implementation of this new agricultural model is poorly represented and has a late appearance in the press. However, this could be explained by a change in the focus of discussion from biotechnology to sojisation, which includes many of these issues and which has become the focus of debate about agriculture.