ESTM - Artigos em revistas internacionais
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- Reproductive toxicity of the endocrine disrupters vinclozolin and bisphenol A in the terrestrial isopod Porcellio scaber (Latreille, 1804)Publication . Lemos, M. F. L.; van Gestel, C. A. M.; Soares, A. M. V. M.Endocrine Disruptor Compounds (EDCs) have been largely studied concerning their effects on vertebrates. Nevertheless, invertebrates as targets for these chemicals have been neglected and few studies are available. Specifically for edaphic invertebrates, data concerning the effects of EDCs is residual. Influences of EDCs on the reproduction systems of these organisms, with consequences at the population level, are expected but have not been confirmed. This work aimed to study the effects of bisphenol A (BPA) and vinclozolin (Vz) on the reproduction of the terrestrial isopod Porcellio scaber. Isopods were coupled and exposed to increasing concentrations of Vz and BPA and the females' reproductive cycle followed for 56 d. Both compounds elicited reproductive toxicity. Vz and BPA decreased female reproductive allocation. Vz reduced pregnancy duration; increased the abortion percentage; decreased the number of pregnancies; and decreased the number of juveniles per female while BPA increased abortions at the lowest and highest test concentrations. The reproductive endpoints presented in here are indicative of the possible impact that this type of compounds might have on isopod population dynamics, which may eventually lead to population decline.
- Protein differential expression induced by endocrine disrupting compounds in a terrestrial isopodPublication . Lemos, Marco F. L.; Esteves, Ana Cristina; Samyn, Bart; Timperman, Isaak; van Beeumen, Jozef; Correia, António; van Gestel, Cornelis A. M.; Soares, Amadeu M. V. M.Endocrine disrupting compounds (EDCs) have been studied due to their impact on human health and increasing awareness of their impact on wildlife species. Studies concerning the organ-specific molecular effects of EDC in invertebrates are important to understand the mechanisms of action of this class of toxicants but are scarce in the literature. We have used a dose/response approach to unravel the protein expression in different organs of isopods exposed to bisphenol A (BPA) and vinclozolin (Vz) and assess their potential use as surrogate species. Male isopods were exposed to a range of Vz or of BPA concentrations. After animal dissection, proteins were extracted from gut, hepatopancreas and testes. Protein profiles were analysed by electrophoresis and differentially expressed proteins were identified by MALDI mass spectrometry. EDCs affected proteins involved in the energy metabolism (arginine kinase), proteins of the heat shock protein family (Hsp70 and GRP78) and most likely microtubule dynamics (tubulin). Different proteins expressed at different concentrations in different organs are indicative of the organ-specific effects of BPA and Vz. Additionally, several proteins were up-regulated at lower but not higher BPA or Vz concentrations, bringing new data to the non-monotonic response curve controversy. Furthermore, our findings suggest that some common responses to EDCs in both vertebrates and invertebrates may exist.
- Feeding habits of Solea senegalensis in earthen ponds in Sado estuaryPublication . Castelo Branco, Maria Ana; Arruda, Marco A.; Gamito, SofiaThe senegale sole, Solea senegalensis Kaup, 1858, is a commercially valuable fish and it is beginning to be cultured in a semi-intensive way in fish farms in southern European countries. The present study was initiated to investigate the diet of S. senegalensis under semi-extensive conditions. The feeding habits of sole were studied in two earthen ponds of a fish farm in the Sado estuary. In one earthen pond, artificial fish ration was given. S. senegalensis feeds on few prey items, its diet is mainly composed of insect larvae (Chironomus salinarus) and polychaeta (Hediste diversicolor). The diet composition of this species suggests feeding specialization, by consuming mainly annelids and insect larvae and by avoiding other items, extremely abundant in the environment, such as gastropods. In the water reservoir where ration was given, some fish consumed simultaneously benthic organism together with ration. However, benthic organisms seem to be the most important component of S. senegalensis diet.
- Resilience of an isopod population (Cyathura carinata) to multiple stress factors in a temperate estuarine systemPublication . Bordalo, M. D.; Ferreira, Susana; Cardoso, P. G.; Leston, S.; Pardal, M. A.The Mondego Estuary (Portugal) underwent major modifications in the late 1980s, because of eutrophication, for which it was developed a restoration programme that has been effective in recovering seagrass beds. Recently, this system has been affected by successive weather extremes: floods, droughts, and heat waves. The effect of these multiple stressors on a Cyathura carinata (Isopoda) population has been evaluated, through a long-term data series (16 years) in a seagrass bed, an intermediate area, and a sand flat. A well age-structured and abundant population of C. carinata was observed in the sand flat, in contrast with the seagrass bed and intermediate area. After introducing the restoration measures, C. carinata’s abundance increased even in the stations where it was formerly scarce. This recovery was compromised by successive extreme events. C. carinata declined severely in terms of total abundance and growth production during the 2003 summer heat wave, at the sand flat, also endangering its reproductive success. Floods and droughts affected dispersion of the individuals, which was reflected in the population’s density and production. Nevertheless, this isopod had great resilience, recovering successfully after disturbances. In contrast, the population of C. carinata had less resilience in the seagrass bed and intermediate area, being unable to recover after a succession of disturbances, which may threaten the success of this species in the system. Because the frequency and intensity of weather extremes are expected to continue to increase in a scenario of global climate change, their repercussions will affect such populations, which will have difficulty surviving. This will have severe implications on the functioning of the whole ecosystem.
- On the Use of the Gompertz Model to Predict Microbial Thermal Inactivation Under Isothermal and Non-Isothermal ConditionsPublication . Gil, Maria M.; Miller, Fátima A.; Brandão, Teresa R. S.; Silva, Cristina L. M.Food processes should be designed to provide an adequate margin of safety against microbiological risk of food poisoning and food spoilage throughout shelf life. In this field, the use of mathematical models that describe the microorganisms’ kinetics in such conditions is an important tool for convenient design, control and optimization of efficient processes. If those models are accurate and precise, one can extract the best aiming at predictive purposes. The Gompertz equation is commonly applied to describe sigmoidal kinetics. Besides the proven adequacy of the model in those kinetics descriptions, most of the reported works do not use Gompertz equation in the most convenient form, and insightful information could be obtained with re-parameterized forms. This work aims at reviewing the use of the Gompertz model to describe inactivation, as well as re-parameterized forms that include parameters related to the survival curve features. Microbial survival often presents a shoulder prior to inactivation, followed by a linear phase (corresponding to a maximum inactivation rate) and a tail residual population. The versatility of the Gompertz model in describing kinetics with different shapes, varying from a log-linear tendency till a complete sigmoidal shape, makes it attractive for predictive purposes, both under static and dynamic temperature conditions. Drawbacks and critical features of the model, when it is applied to microbial responses, will be overview.
- Proteins in ecotoxicology – How, why and why not?Publication . Lemos, Marco F.L.; Soares, Amadeu M. V. M.; Correia, António C.; Esteves, Ana C.The growing interest in the application of proteomic technologies to solve toxicology issues and its relevance in ecotoxicology research has resulted in the emergence of "ecotoxicoproteomics". There is a general consensus that ecotoxicoproteomics is a powerful tool to spot early molecular events involved in toxicant responses, which are responsible for the adverse effects observed at higher levels of biological organization, thus contributing to elucidate the mode of action of stressors and to identify specific biomarkers. Ultimately, early-warning indicators can then be developed and deployed in "in situ" bioassays and in environmental risk assessment. The number of field experiments or laboratory trials using ecologically relevant test-species and involving proteomics has been, until recently, insufficient to allow a critical analysis of the real benefits of the application of this approach to ecotoxicology. This article intends to present an overview on the applications of proteomics in the context of ecotoxicology, focusing mainly on the prospective research to be done in invertebrates. Although these represent around 95% of all animal species and in spite of the key structural and functional roles they play in ecosystems, proteomic research in invertebrates is still in an incipient stage. We will review applications of ecotoxicoproteomics by evaluating the technical methods employed, the organisms and the contexts studied, the advances achieved until now and lastly the limitations yet to overcome will be discussed.
- Trace Elements in Edible Rocky Shore Species: Effect of Sewage Discharges and Human Health Risk ImplicationsPublication . Cabral-Oliveira, Joana; Pratas, João; Mendes, Susana; Pardal, Miguel A.Sewage pollution is a worldwide concern and can result in increasing levels of trace elements in the environment that can pose serious risks both to wildlife and human health. This highlights the importance of studying the role of sewage discharges in the contamination of aquatic systems, especially in rocky shores, since part of our food resources is directly collected from coastal waters. For this purpose, the accumulation of trace elements (Cu, Zn, Pb, Ni, Co, Cd, Fe, Mn, and As) by edible molluscs (Mytilus galloprovincialis, Patella ulyssiponensis, and Phorcus lineatus) was compared between one sewage-impacted area and two reference areas. This study suggests that the concentrations of trace elements in the soft tissues of the selected molluscs can be affected by the presence of sewage discharges, and that limpets seem to be the best bioindicator. Moreover, the sewage pollution increased the concentrations of As in the mollusc species, emphasizing its potential damaging effects on natural systems and on edible species.
- Tryptophan Depletion and Formation of α-Aminoadipic and γ-Glutamic Semialdehydes in Porcine Burger Patties with Added Phenolic-Rich Fruit ExtractsPublication . Ganhão, Rui; Morcuende, David; Estévez, MarioThe effect of added fruit extracts on the oxidation of muscle proteins in porcine burger patties subjected to cooking and chill storage was studied. Extracts from arbutus berries (Arbutus unedo L., AU), common hawthorns (Crataegus monogyna L., CM), dog roses (Rosa canina L., RC), and elmleaf blackberries (Rubus ulmifolius Schott, RU) were prepared, characterized, added to burger patties (3% of total weight), and evaluated as inhibitors of protein oxidation. Negative (no added extract, C) and positive control (added quercetin, 230 mg/kg, Q) groups were also included in the design. Protein oxidation was assessed by means of tryptophan loss using fluorescence spectroscopy (FS) and formation of the specific protein carbonyls αaminoadipic (AAS) and y-glutamic semialdehyde (GGS) using liquid chromatography and mass spectroscopy (LC-MS). Both advanced methodologies (FS and LC-MS) were found to be reliable and specific protein oxidation measurements that allow us to gain chemical insight into protein oxidation. The mechanisms likely involved In the oxidative reactions affecting proteins during cooking and storage of burger patties are profusely discussed. Phenolic-rich fruit extracts protected tryptophan residues against oxidation and Inhibited the formation of both semialdehydes In burger patties during cooking and subsequent chill storage. In general, RC, RU, and AU were the most effective inhibitors of protein oxidation, with this effect being more intense than that of pure polyphenols like quercetin. These fruit extracts could be considered functional ingredients as their antioxidant actions contribute to the enhancement of the nutritional value of the meat products.
- Protein oxidation in emulsified cooked burger patties with added fruit extracts: Influence on colour and texture deterioration during chill storagePublication . Ganhão, Rui; Morcuende, David; Estévez, MarioThe influence of protein oxidation, as measured by the dinitrophenylhydrazine (DNPH) method, on colour and texture changes during chill storage (2. °C, 12. days) of cooked burger patties was studied. Extracts from arbutus-berries (Arbutus unedo L., AU), common hawthorns (Crataegus monogyna L., CM), dog roses (Rosa canina L., RC) and elm-leaf blackberries (Rubus ulmifolius Schott., RU) were prepared, added to burger patties (3% of total weight) and evaluated as inhibitors of protein oxidation and colour and texture changes. Negative (no added extract, C) and positive control (added quercetin; 230. mg/kg, Q) groups were also considered. The significant increase of protein carbonyls during chill storage of control burger patties reflect the intense oxidative degradation of the muscle proteins. Concomitantly, an intense loss of redness and increase of hardness was found to take place in burger patties throughout refrigerated storage. Most fruit extracts as well as Q significantly reduced the formation of protein carbonyls and inhibited colour and texture deterioration during chill storage. Likely mechanisms through which protein oxidation could play a major role on colour and texture changes during chill storage of burger patties are discussed. Amongst the extracts, RC was most suitable for use as a functional ingredient in processed meats since it enhanced oxidative stability, colour and texture properties of burger patties with no apparent drawbacks.
- Optimization in the immobilization of penicillin G acylase by entrapment in xerogel particles with magnetic propertiesPublication . Bernardino, Susana; Estrela, Nídia; Ochoa-Mendes, Vanessa; Fernandes, Pedro; Fonseca, Luís P.Biocatalysis presents a sound alternative to chemical synthesis in the field of drug production, given the highly selective nature of biological catalysts. Penicillin G Acylase (PGA) from E. coli is currently used to hydrolyze penicillin G (PG) and catalyzes the synthesis of β-lactam antibiotics. In this work, particular emphasis is given to recent developments in penicillin G acylase immobilization, by entrapment simultaneously with nano-magnetic particles in a silica matrix. The sol-gel biocatalytic particles were prepared either by a conventional method (crushed powder) or by a more recent approach, based in an emulsion system using 150 mM AOT/isooctane, which allowed for the formation of spherical micro- and nanobeads. The effects on PGA activity of different sol-gel precursors, additives, enzyme concentration, aging, drying conditions and mechanical stability were evaluated. After these optimization studies, a mechanically stable carrier based on porous xerogels silica matrixes, starting from tetramethoxysilane (TMOS) with 65-67% PGA activity yield in these carriers allowed an immobilization yield of 74 mg protein g dry sol-gel -1 and 930 Ug dry sol-gel -1 for specific activity were obtained.