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Diferenças do efeito do ácido salicílico em dois lotes de sementes de Glycine Max
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Em plantas existem enzimas mitocondrias alternativas ao transporte de electrões (oxidase alternativa AOX e NADH desidrogenases alternativas) e de protões (proteínas desacopladoras) que, actuando ao nível do metabolismo respiratório, conferem flexibilidade na resposta a alterações funcionais metabólicas. Estas enzimas têm sido associadas aos mecanismos de defesa em situações desfavoráveis à planta. O presente trabalho tem como base dois estudos realizados anteriormente no laboratório de acolhimento (Centro de Engenharia Biológica, Faculdade de Ciências da Universidade de Lisboa, CEB/FCUL) nos quais se analisou a resposta de mitocôndrias de hipocótilos de plântulas de soja (Glycine max cv. cresir) ao tratamento com ácido salicílico (SA) 1 mM (Matos et al., 2005; Mendes et al., 2006), em que se utilizaram dois lotes de sementes designados por 2005 e 2006 . Uma vez que se obtiveram resultados diferentes nos dois trabalhos, pretendeu-se investigar a causa de tais diferenças. Nos trabalhos anteriores, verificou-se que, em amostras de 2005, o SA estimulou a capacidade da AOX e diminuiu a oxidação de NADH, e em amostras de 2006 o SA não teve efeito sobre a capacidade da AOX, mas provocou um aumento da capacidade das NADH desidrogenases. A nível da composição das membranas biológicas o SA apenas provocou uma diminuição de ácido linolénico, nas amostras de 2005. No presente trabalho, extraíram-se mitocondrias de hipocótilos de plântulas de soja e quantificou-se por Blotting o teor proteico de AOX e das NADH desidrogenases interna e externa (NDA e NDB). Em amostras de 2005, o SA provocou a acumulação de AOX2b mas não afectou a quantidade de NDA nem de NDB. Em amostras de 2006, o SA não provocou alterações no teor proteico de nenhuma das 3 enzimas. Adicionalmente, não se verificou indução de morte celular (estudada por imunodetecção do citocromo c). Extraíram-se também os RNA de hipocótilos de plântulas de
In plants, there are mitochondrial enzymes alternative to the electron transport chain (alternative oxidase AOX and alternative NADH dehydrogenases) and to the protons transport (uncoupling proteins) that act in the respiratory metabolism and provide flexibility in the response to metabolic modifications. These enzymes have been associated to defence processes in stress situations. The present work is based in two previous studies carried out in the laboratories of the Centro de Engenharia Biológica, Faculdade de Ciências da Universidade de Lisboa, CEB/FCUL, in which it was analyzed the soybean (Glycine max cv. cresir) hypocotyls mitochondria response to 1 mM of salicylic acid (Matos et al., 2005; Mendes et al., 2006) using two different seed bunch, named 2005 and 2006 . Since different results were obtained, the aim of this study is to investigate the causes of such differences. In the previous works, in samples 2005, the SA has stimulated the AOX capacity and has decreased the NADH oxidation rate. However, in samples 2006, the SA didn't affect the AOX capacity but has increased the NADH dehydrogenase capacity. Concerning biological membrane composition, only in the samples 2005 has the SA led to a decrease in the linolenic acid. In the present work, mitochondria from soybean hypocotyls were extracted and the amount of AOX and internal and external NADH dehydrogenases (NAD and NDB) was measured by blotting. We observed that the SA led to an accumulation of AOX2b but didn't affect the NADH dehydrogenases amount in samples 2005. However, in samples 2006, we didn't observe any modifications in the amount of these three proteins in the presence of SA. Moreover, the SA didn't induce the cellular death. We extracted the RNA from soybean hypocotyls and we studied the expression of genes that encode mitochondrial respiration related proteins (Aox1, Aox2a, Aox2b, Nda1, Ndb, UCP1a e COXII) and the expression of a SA-specific gene (PR1a). In sa
In plants, there are mitochondrial enzymes alternative to the electron transport chain (alternative oxidase AOX and alternative NADH dehydrogenases) and to the protons transport (uncoupling proteins) that act in the respiratory metabolism and provide flexibility in the response to metabolic modifications. These enzymes have been associated to defence processes in stress situations. The present work is based in two previous studies carried out in the laboratories of the Centro de Engenharia Biológica, Faculdade de Ciências da Universidade de Lisboa, CEB/FCUL, in which it was analyzed the soybean (Glycine max cv. cresir) hypocotyls mitochondria response to 1 mM of salicylic acid (Matos et al., 2005; Mendes et al., 2006) using two different seed bunch, named 2005 and 2006 . Since different results were obtained, the aim of this study is to investigate the causes of such differences. In the previous works, in samples 2005, the SA has stimulated the AOX capacity and has decreased the NADH oxidation rate. However, in samples 2006, the SA didn't affect the AOX capacity but has increased the NADH dehydrogenase capacity. Concerning biological membrane composition, only in the samples 2005 has the SA led to a decrease in the linolenic acid. In the present work, mitochondria from soybean hypocotyls were extracted and the amount of AOX and internal and external NADH dehydrogenases (NAD and NDB) was measured by blotting. We observed that the SA led to an accumulation of AOX2b but didn't affect the NADH dehydrogenases amount in samples 2005. However, in samples 2006, we didn't observe any modifications in the amount of these three proteins in the presence of SA. Moreover, the SA didn't induce the cellular death. We extracted the RNA from soybean hypocotyls and we studied the expression of genes that encode mitochondrial respiration related proteins (Aox1, Aox2a, Aox2b, Nda1, Ndb, UCP1a e COXII) and the expression of a SA-specific gene (PR1a). In sa
Descrição
Tese de mestrado em Biologia Celular e Biotecnologia, apresentada à Universidade de Lisboa, através da Faculdadede Ciências, 2007
Palavras-chave
Biotecnologia Biologia celular Teses de Mestrado