Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / FundaÃÃo de Amparo à Pesquisa do Estado do Cearà / Water stress, induced by drought or salinity, is the major environmental restriction to plant survive and crop sustainability, specially in semi-arid areas, where they are often associated to high temperatures and high radiation rates. Part of the effects exerted by these abiotic stresses on plant metabolism is mediated by oxidative damage due to an increased production of active oxygen species (AOS). The present study aims to elucidate the interactions and the importance of the catalase (CAT) and ascorbate peroxidase (APX) enzymatic antioxidants systems in the protection of cowpea leaf tissues [Vigna unguiculata (L.) Walp.] against the oxidative damage induced by water deficit and salinity. The experimental approach adopted, involved 3 different experiments, using PEG-induced water stress or NaCl-induced salt stress, combined to the CAT inhibitor 3-Amino-1,2,4-trizole (3-AT) application. These experiments were conduced under two environmental conditions: in a growth chamber, under controlled conditions, and in a greenhouse, under the typical semiarid conditions of the Brazilian Northeast. PEG and NaCl treatments were applied to the nutritive solution for 72 h, while the 3-AT was daily sprayed in the shoot. The osmotic stress induced by PEG or NaCl caused acute declines in the transpiration rates, due to increase in stomatal resistance, as well as an intense growth reduction, in the plants cultivated in the greenhouse conditions. The osmotic stressed plants presented significant increases on lipid peroxidation and on the ascorbate content, in addition to a CAT activity reduction. The osmotic stress and 3-AT combination raised the APX activity levels that counteracted, at least in part, the CAT absence. The fall in the CAT activity was related to a strong mRNA expression restraint, followed by an up-regulation of the cytosolic APX mRNA. These results indicate the presence of a controlled synchrony between the expression and enzymatic activity of these antioxidant systems, in the regulation and detoxification of the AOS produced in plant cells, during environmental stresses situations. / O estresse hÃdrico induzido por seca ou salinidade à a principal restriÃÃo ambiental à sobrevivÃncia das plantas e sustentabilidade das culturas, principalmente nas regiÃes semiÃridas, onde estÃo frequentemente associados a altas temperaturas e taxas de luminosidade. Uma grande parte dos efeitos destes estresses ambientais no metabolismo das plantas à mediada por danos oxidativos devido ao aumento na produÃÃo de espÃcies ativas de oxigÃnio (AOS). O presente estudo se propÃs a estudar a interaÃÃo e a importÃncia dos sistemas antioxidantes enzimÃticos da catalase (CAT) e da peroxidase de ascorbato (APX) na proteÃÃo dos tecidos foliares de feijÃo caupi [Vigna unguiculata (L.) Walp.] contra os danos oxidativos induzidos por condiÃÃes de deficiÃncia hÃdrica e salinidade. Para isso, foi utilizada uma abordagem experimental envolvendo 3 experimentos, utilizando combinaÃÃes de estresse hÃdrico, induzido por polietilenoglicol (PEG), ou salino, induzido por NaCl, com a pulverizaÃÃo do inibidor de catalases 3-Amino-1,2,4-Triazol (3-AT). Estes experimentos foram, ainda, realizados em duas condiÃÃes ambientais: uma em cÃmara de crescimento sob condiÃÃes controladas e em casa de vegetaÃÃo, sob condiÃÃes tÃpicas do semi-Ãrido. O PEG e o NaCl foram aplicados na soluÃÃo nutritiva durante 72 h, e o 3-AT pulverizado diariamente na parte aÃrea. O estresse osmÃtico causado pela aplicaÃÃo de PEG ou de NaCl induziu uma forte reduÃÃo na transpiraÃÃo, associada a uma maior resistÃncia estomÃtica, e uma acentuada reduÃÃo no crescimento nas plantas submetidas as condiÃÃes de casa de vegetaÃÃo. Houve um considerÃvel aumento na peroxidaÃÃo de lipÃdeos e do conteÃdo do antioxidante ascorbato das plantas tratadas, bem como uma diminuiÃÃo da atividade de CAT. As plantas submetidas a uma combinaÃÃo de estresse osmÃtico e a aplicaÃÃo do 3-AT apresentaram um acentuado aumento da atividade da enzima APX, compensando, em parte a ausÃncia da atividade da enzima CAT. Esta diminuiÃÃo da atividade enzimÃtica de CAT foi acompanhada por uma forte repressÃo dos mRNAs para esta enzima, enquanto que houve uma induÃÃo dos mRNAs da APX citossÃlica. Estes resultados indicam que hà uma controlada sincronia entre a expressÃo e a atividade enzimÃtica destes dois sistemas, na regulaÃÃo e desintoxicaÃÃo das AOS produzidas na cÃlula vegetal, durante situaÃÃes de estresse ambiental.

The cranberry scare of 1959 was the first food scare in the United States involving food additives to have a national impact. It was also the first event to test the Delaney clause, part of a 1958 amendment to the 1938 Food, Drug and Cosmetics Act prohibiting cancer-causing chemicals in food. Although lasting only a few weeks, the scare significantly affected the cranberry industry and brought the regulation of chemical residues in food to the national stage. Generated by a complex interaction of legislation, technology, media, and science, the scare had far-reaching effects in all areas of the cranberry industry, food legislation, and the perception of the public toward additives and residues in their food. The ripples caused by the scare permanently altered the cranberry industry and, after numerous subsequent scares and challenges to the law, eventually resulted in the repeal of the Delaney clause. The goal of this investigation was to demonstrate how the social, scientific, and political climates in the United States interacted and led to such an event. It shows how science, politics, and contemporary social anxiety combined, with technology as a catalyst, and how the resulting scare left significant marks on the development of both legislation and industry. It also improves our understanding of this seminal event in American social history by exploring the events surrounding the scare, as well as by comparing the perspectives and reactions of the public, the Eisenhower administration, the cranberry industry, and other industries affected by the scare and its aftermath.