Hernandez-Prieto M.A.,University of Algarve
G3 (Bethesda, Md.) | Year: 2012
Iron is an essential cofactor in many metabolic reactions. Mechanisms controlling iron homeostasis need to respond rapidly to changes in extracellular conditions, but they must also keep the concentration of intracellular iron under strict control to avoid the generation of damaging reactive oxygen species. Due to its role as a redox carrier in photosynthesis, the iron quota in cyanobacteria is about 10 times higher than in model enterobacteria. The molecular details of how such a high quota is regulated are obscure. Here we present experiments that shed light on the iron regulatory system in cyanobacteria. We measured time-resolved changes in gene expression after iron depletion in the cyanobacterium Synechocystis sp. PCC 6803 using a comprehensive microarray platform, monitoring both protein-coding and non-coding transcripts. In total, less than a fifth of all protein-coding genes were differentially expressed during the first 72 hr. Many of these proteins are associated with iron transport, photosynthesis, or ATP synthesis. Comparing our data with three previous studies, we identified a core set of 28 genes involved in iron stress response. Among them were genes important for assimilation of inorganic carbon, suggesting a link between the carbon and iron regulatory networks. Nine of the 28 genes have unknown functions and constitute key targets for further functional analysis. Statistical and clustering analyses identified 10 small RNAs, 62 antisense RNAs, four 5'UTRs, and seven intragenic elements as potential novel components of the iron regulatory network in Synechocystis. Hence, our genome-wide expression profiling indicates an unprecedented complexity in the iron regulatory network of cyanobacteria.
Nunes C.A.,University of Algarve
European Journal of Plant Pathology | Year: 2012
Postharvest decay in harvested fruit causes considerable economical losses. Fungicides are the primary means to control these losses. Public concern in food safety and environmental issues and the increase of pathogen resistant populations have enhanced the interest in developing alternative methods to fungicides to control postharvest fruit decay. During the last two decades a huge information and advances concerning the selection of antagonists, mode of action, different approaches to enhance biocontrol activity, formulation and production have been achieved, and some biofungicides are already in the market. It is likely that several more products will enter the market in the near future, as the result of the biological control research programs worldwide. Nonetheless, it is necessary to continue finding new potential microorganisms, better understanding the mode of action, and pathogen, antagonist and host interactions, to increase the potential of biocontrol helping to become a real alternative to synthetic postharvest fungicides. This article presents an overview of postharvest biological control approaches and explores new research possibilities to improve biocontrol activity. © 2011 KNPV.
Potting R.,University of Algarve
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012
We consider field-theoretic models, one consisting purely of scalars, the other also involving fermions, that couple to a set of constant background coupling coefficients transforming as a symmetric observer Lorentz two-tensor. We show that the exact propagators can be cast in the form of a Källén-Lehmann representation. We work out the resulting form of the Feynman propagators and the equal-time field commutators, and derive sum rules for the spectral density functions. © 2012 American Physical Society.
Miguel M.G.,University of Algarve
Flavour and Fragrance Journal | Year: 2010
Antioxidant properties have been attributed to the essential oils but a great diversity of results has been reported, mainly attributed to the chemical composition of the essential oils and the diversity of tests used. In fact, several in vitro assays for the determination of antioxidant ability have been used. They can be divided into two main groups: those that evaluate lipid peroxidation and that those that measure free radical scavenging ability. In the present study, a brief description of the mechanism involved in the majority of techniques used for the evaluation of antioxidant activity of essential oils is given. At the same time, the antioxidant activities of some essential oils, measured through several methodologies, are presented and compared. © 2009 John Wiley & Sons, Ltd.
Miguel M.G.,University of Algarve
Molecules | Year: 2010
Essential oils are complex mixtures isolated from aromatic plants which may possess antioxidant and anti-inflammatory activities of interest in thye food and cosmetic industries as well as in the human health field. In this work, a review was done on the most recent publications concerning their antioxidant and anti-inflammatory activities. At the same time a survey of the methods generally used for the evaluation of antioxidant activity and some of the mechanisms involved in the anti-inflammatory activities of essential oils are also reported. © 2010 by the authors; licensee MDPI, Basel, Switzerland.