Alterations in isozyme patterns induced by different levels of iron, manganese and boron on white lupin

Tremoceiros brancos, quando cultivados em soluções nutritivas com vários níveis de ferro, manganês ou boro, apresentaram perfis isoenzimáticos diferentes, de aspartato-aminotransferases, fosfatases ácidas e carboxilesterases. Concentrações elevadas de ferro ou manganês induziram a síntese de novas isoenzimas com actividade de aspartato-aminotransferase. Estas apresentaram mobilidades electroforéticas menores do que as das enzimas normalmente presentes. Altas concentrações de ferro também inibiram a actividade de uma carboxilesterase. Uma fosfatase ácida foi estimulada nas folhas, por altos níveis de manganês. A falta de ferro na solução nutritiva conduziu à inibição de uma fosfatase ácida e a de manganês à de uma carboxilesterase. Elevados níveis de boro inibiram a actividade de todas as aspartato- aminotransferases normalmente presentes nas raízesinfo:eu-repo/semantics/publishedVersio

A técnica ELISA (Enzyme-linked immunosorbent assay)

No presente trabalho faz-se uma descrição da técnica ELISA (Enzyme- -Linked Immunosorbent Assay). Referem-se os vários parâmetros de execução desta técnica, as possibilidades de conservação das amostras e das placas sensibilizadas e de reutilização das placas e dos conjugados. Apresenta-se a relação existente entre a concentração de vírus e os valores do teste ELISA e mostra-se um exemplo de aplicação dessa relaçãoinfo:eu-repo/semantics/publishedVersio

Detection of CM 112 latent grapevine virus by the passive haemagglutinantion test (PHT)

A Técnica de Hemaglutinação Passiva (PHT) foi utilizada para detectar c Vírus CM 112 da Videira directamente de folhas infectadas de videira (Vitis vinifera L. cv Borraçal). Determinaram-se as condições de extracção, volumes de amostra, concentração de eritrócitos e de y-globulina. Foram detectados 25ng.ml-1 de vírus, em preparações purificadas diluídas em tampão, e 50ng.ml-1 em presença de extractos brutos de videira sãinfo:eu-repo/semantics/publishedVersio

Use of Hydrophilic Insoluble Polymers in the Restoration of Metal-Contaminated Soils

To develop cost-effective techniques that contribute to phytostabilization of severely metal-contaminated soils is a necessary task in environmental research. Hydrophilic insoluble polymers have been used for some time in diapers and other hygienic products and to increase the water-holding capacity of coarse-textured soils. These polymers contain groups, such as carboxyl groups, that are capable of forming bonds with metallic cations, thereby decreasing their bioavailability in soils. The use of polyacrylate polymers as soil amendments to restore metal-contaminated soils has been investigated in the Technical University of Lisbon since the late nineties. Plant growth and plant nutrients concentrations, extractable levels of metals in soil, and soil enzyme activities were used to monitor the improvement in soil quality following the application of these polymers. In contaminated soils, hydrophilic insoluble polymers can create microcosms that are rich in water and nutrients (counterions) but only contain small concentrations of toxic elements; the conditions of these microenvironments are favorable to roots and microorganisms. In this paper we described the most relevant information available about this topic

Avaliação da tolerância à clorose férrica de porta-enxertos de citrinos em solução nutritiva

4 Pags.- 3 Figs.Um dos principais factores indutores da clorose férrica em solos calcários é o ião bicarbonato cuja acção parece afectar diversos processos metabólicos nas raízes e nas folhas, diminuindo a disponibilidade de Fe no interior da planta. Nestas condições, quando a absorção de Fe é baixa, os genótipos Fe-eficientes desencadeiam mecanismos de resposta ao nível da parte aérea e/ou radicular que incluem alterações fisiológicas, bioquímicas e morfológicas (Schmidt, 1999). Ao nível da parte aérea, o ferro é um elemento essencial para a formação das membranas dos tilacóides e para a biossíntese clorofilina (Abadía, 1992). Consequentemente, a eficiência de conversão da energia fotossintética é afectada pela clorose férrica e pode ser avaliada pelos parâmetros de fluorescência da clorofila a (Abadía et al., 1999). Neste ensaio em solução nutritiva pretendeu-se caracterizar a tolerância de três porta-enxertos de citrinos à clorose férrica com base em diversos parâmetros e processos fisiológicos da planta.Peer reviewe

The root ferric-chelate reductase of Ceratonia siliqua (L.) and Poncirus trifoliata (L.) Raf. responds differently to a low level of iron

Iron (Fe) deficiency is a common nutritional disorder in several crops grown in calcareous soils, but some species are well adapted to these conditions. A hydroponic experiment was conducted to compare the response of a calcicole species Ceratonia siliqua L. (carob) and of Poncirus trifoliata (L.) Raf., a citrus rootstock very sensitive to Fe deficiency. Rootstocks from both species were grown in nutrient solutions without Fe (0 M Fe), with 1 M Fe, and with 10 M Fe (carob) or 40 M Fe (P. trifoliata). A low level of Fe or its absence in the nutrient solution led to a significant decrease in P. trifoliata vegetative growth and in SPAD readings. The root activity of ferric-chelate reductase (FC-R), a key enzyme in Fe uptake, was low in the absence or with high levels of Fe. Its highest values were in roots exposed to a low level of Fe as described in several sensitive species. In contrast, the activity of FC-R was very high in carob in the absence of Fe and was decreased sharply even when only a low level of Fe was present in the nutrient solution. Plant growth and SPAD readings in the leaves of carob were similar in all treatments. Carob seems to maintain a large activity of root FC-R that may ensure enough Fe to satisfy plant demand. The fact that it presents a slow growing pattern may also contribute to the tolerance of this species to low levels of external Fe

Utilização de Lolium Perenne L. na fitoestabilização controlada de solos degradados por actividades mineiras

Foi estudada a utilização de Lolium perenne L. e de diferentes resíduos orgânicos (RO) na fitoestabilização controlada de solos degradados por atividades mineiras (Mina de Aljustrel, Faixa Piritosa Ibérica). Apesar da aplicação dos RO ter permitido a imobilização de Cu, Pb e Zn no solo, baixando a fracção efetivamente disponível, os teores foliares destes elementos não diminuíram significativamente. Os factores de acumulação (FA) obtidos, FA(Cu) e FA(Pb) <<1 e FA(Zn) <1, permitem considerar esta espécie adequada para a fitoestabilização deste tipo de solos. Os teores foliares de Pb e Cu atingiram níveis considerados tóxicos, indicando risco de entrada destes metais na cadeia alimentar humana. Métodos estatísticos multivariados evidenciaram a lama residual urbana como o RO com maior capacidade para corrigir a acidez do solo e para melhorar as características deste, seguida do composto de resíduos sólidos urbanos. Porém,observou-se um crescimento reduzido por aplicação do nível mais elevado (100 Mg ha-1) destes RO. Todos os níveis do composto de resíduos verdes foram insuficientes para corrigir as principais restrições do solo ao crescimento vegetal

Consequences of iron deficiency on fruit quality in citrus and stawberry

Proceedings of the International Conference “Environmentally friendly and safe technologies for quality of fruit and vegetables”, held in Universidade do Algarve, Faro, Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924.Iron deficiency (iron chlorosis) is an important nutritional disorder in several plants, including fruit trees and strawberry. Iron chlorosis does not result from a small level of iron in soils but rather from impaired acquisition and use of this metal by plants. Calcium carbonate, present in great amounts in calcareous soils, and the resulting large levels of bicarbonate ions, are the main causes of iron deficiency. Countries in southern Europe, such as Portugal, Spain, Italy and Greece, have large areas of calcareous soils with established orchards, where iron chlorosis is a major factor that limits yield and profit for the farmer. Iron chlorosis affects several metabolic processes and leads to nutrient imbalances in sensitive plants. Decreased yield and poor quality of fruit resulting from the iron deficiency justify the development of methods to diagnose and correct this disorder. No single approach has been found to solve iron chlorosis satisfactorily, making it one of the most complex nutritional deficiencies known. In this chapter we describe some aspects of the effects of iron availability on quality of strawberry and citrus fruit

A study on As, Cu, Pb and Zn (bio)availability in an abandoned mine area (São Domingos, Portugal) using chemical and ecotoxicological tools

The aim of this study was to relate the results obtained by chemical methods, used to assess environmental (bio)availability, with the ecotoxic response and bioaccumulation of trace elements (TE) by the earthworm Eisenia fetida exposed to field-contaminated, metal-polluted soils from a sulphide mine. The extracting solution 0.5 M NH4CH3COO, 0.5 M CH3COOH and 0.02 M EDTA (pH 4.7), was able to predict environmental bioavailability of TE to E. fetida. However, the toxicological bioavailability could not be predicted from the results of the chemical extractions or from the bioaccumulation results: E. fetida reproduction was higher in soils where environmental bioavailability of TE and bioaccumulation values were also higher. In this study, the toxic response of the organism seemed to be more influenced by the overall nutritional status of the soil (e.g. pH, organic matter, plant nutrient availability and cation exchange capacity) than by its TE contamination. In the case of anthropogenic multi-contaminated sites, the different soil characteristics exert an important and confounding influence in the toxic response and the relationship between different bioavailable fractions cannot be easily established, emphasising the need to combine results from chemical methods with those from bioassays when evaluating the bioavailability of TE in these soils