ORCID Profile
0000-0003-0879-9470
Current Organisation
University of Aveiro
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Publisher: Wiley
Date: 12-2008
DOI: 10.1897/08-154.1
Abstract: The present study examined how subcellular partitioning of Cd in plants with different strategies to store and detoxify Cd may affect trophic transfer of Cd to the isopod Porcellio dilatatus. The plant species used were Lactuca sativa, a horticultural metal accumulator species Thlaspi caerulescens, a herbaceous hyperaccumulator species and the nonaccumulator, T. arvense. Taking into account that differences in subcellular distribution of Cd in plants might have an important role in the bioavailability of Cd to a consumer, a differential centrifugation technique was adopted to separate plant leaf tissues into four different fractions: cell debris, organelles, heat-denatured proteins, and heat-stable proteins (metallothionein-like proteins). Plants were grown in replicate hydroponic systems and were exposed for 7 d to 100 microM Cd spiked with 109Cd. After a 14-d feeding trial, net assimilation of Cd in isopods following consumption of T. caerulescens and T. arvense leaves reached 16.0 +/- 2.33 and 21.9 +/- 1.94 microg/g animal, respectively. Cadmium assimilation efficiencies were significantly lower in isopods fed T. caerulescens (10.0 +/- 0.92%) than in those fed T. arvense (15.0 +/- 1.03%). In further experiments, Cd assimilation efficiencies were determined among isopods provided with purified subcellular fractions of the three plants. On the basis of our results, Cd bound to heat-stable proteins was the least bioavailable to isopods (14.4-19.6%), while Cd bound to heat-denatured proteins was the most trophically available to isopods (34.4-52.8%). Assimilation efficiencies were comparable in isopods fed purified subcellular fractions from different plants, further indicating the importance of subcellular Cd distribution in the assimilation. These results point to the ecological relevance of the subcellular Cd distribution in plants, which directly influence the trophic transfer of Cd to the animal consumer.
Publisher: Public Library of Science (PLoS)
Date: 30-04-2015
Publisher: Wiley
Date: 12-2006
DOI: 10.1897/06-141R.1
Abstract: Apart from analyses for elemental contaminants in field-collected specimens, very little is known about the assimilation and accumulation of inorganic contaminants in reptiles. Recent dietary studies with reptiles (and some other vertebrates and invertebrates) have taken care to incorporate the principles of trophic transfer by pre-exposing prey items to the elemental contaminant of interest. However, there are conflicting data in the literature as to whether biologically incorporated metals are more bioavailable to consumers in a food chain than simple salts added to the diet, and this study examines this issue in a lacertid lizard. Adult in iduals of Podarcis carbonelli were exposed to cadmium (Cd) in a 21-week dietary study to determine whether the form in which the Cd is provided influences assimilation efficiency for this metal. Lizards were provided with Cd that had either been biologically incorporated into crickets or as Cd(NO3)2 added superficially to crickets just prior to feeding. Radiospectrometric analysis for 109Cd in animal tissues and fecal material was used to follow Cd accumulation over the duration of exposure. The highest levels of accumulation were found within the gut. This, combined with the observation of higher rates of assimilation over the first five weeks, strongly suggests a rapid accumulation of Cd within the gut tissue followed by a slower redistribution to other tissues. No statistically different levels of Cd assimilation efficiency were detected between the two treatment groups, nor were there any statistically significant differences between the two treatment groups in relation to the proportional distribution to the gut, liver, or kidneys.
Publisher: Public Library of Science (PLoS)
Date: 24-09-2014
Publisher: Elsevier BV
Date: 07-2007
DOI: 10.1016/J.CHEMOSPHERE.2007.03.021
Abstract: Apart from analyses for elemental contaminants in field collected specimens, very little is known about the assimilation, accumulation and toxic effects of inorganic contaminants in reptiles. This study examined the chronic accumulation of Cd in a European lacertid lizard (Podarcis carbonelli) following dietary provision of an environmentally realistic concentration of Cd for 21 weeks. Lizards were provided with Cd that had either been biologically incorporated into crickets, or as Cd(NO3)2 added superficially to crickets just prior to feeding. Among both treatment groups Cd accumulated in tissues in the following order of concentration: gut>liver>kidney>carcass. The majority of the Cd was retained within the gut, and transfer to internal organs was low. Morphological indices, brain and plasma cholinesterase activities, gut and liver metallothionein content, and standard metabolic rate were measured as biomarkers of exposure and effect however, no differences between control lizards and Cd-treated lizards were observed.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.ECOENV.2008.08.002
Abstract: Laboratory and field studies have provided encouraging insights into the capacity of plants to act as biomonitors of environmental quality through the use of biomarkers. However, a better understanding of the overall process of Cd-induced senescence, describing the cascade of Cd effects in plants is needed for a selection of relevant biomarkers of Cd stress. In order to approach this, 5-week old Lactuca sativa L. were exposed for 14 days to 100muM Cd(NO(3))(2) and harvested at days 0, 1, 3, 7 and 14. The parameters measured included classical endpoints (shoot and root growth) and biochemical endpoints related to photosynthesis, nutrients content, and oxidative stress. Cadmium-exposed plants displayed nutrient imbalances in leaves and roots. Photosynthetic efficiency was significantly decreased and lipid peroxidation was enhanced. Antioxidant enzymes were significantly altered during exposure-catalase was inhibited by the end of exposure and peroxidase was induced at day 1 in young leaves. These alterations culminated in a decrease in shoot growth after 14-days exposure to Cd. Biochemical alterations could be used in integrative approaches with classical endpoints in ecotoxicological tests for Cd and after further testing in real scenarios conditions, they could form the basis of a plant biomarkers battery for monitoring and predicting early effects of exposure to Cd.
Publisher: Elsevier BV
Date: 09-2010
DOI: 10.1016/J.ECOENV.2010.06.020
Abstract: Cadmium (Cd) is a widespread environmental contaminant, strongly mutagenic and known to cause DNA damage in plants. In this work, flow cytometry (FCM) was applied to determine if in vivo exposure to Cd would induce genotoxic effects at the genome level. The hyper-accumulator Thlaspi caerulescens (J. & C. Presl), the related non-accumulator Thlaspi arvense L. and the accumulator crop species Lactuca sativa L. were germinated in distilled water and grown in modified Hoagland's medium with increasing concentrations of Cd(NO3)2 (0, 1, 10 and 100 microM). After 28 days of exposure, shoot and root growth was recorded and the tissues were harvested for Cd and FCM analysis. In general, roots from treated plants contained higher content of Cd than leaves and growth inhibition was observed in the treated plants. Nuclear DNA content was estimated and the G0/G1 full peak coefficient of variation (FPCV), as an indicator of clastogenic damage, was recorded. In T. arvense and T. caerulescens no significant differences were detected between control and exposed plants. Leaves of L. sativa exposed to 10 microM Cd presented a statistically significant increase in FPCV values in comparison with the control group. Furthermore, roots exposed to 100 microM Cd presented a reduction in nuclear DNA content and an increase in FPCV when compared to the control. FCM data indicates that no major DNA damage was induced on both Cd-exposed Thlaspi species and L. sativa leaves. On the contrary, results obtained with L. sativa roots suggests clastogenic damage in these organs exposed to 100 microM of Cd.
Publisher: Wiley
Date: 17-08-2012
DOI: 10.1002/ETC.1955
Abstract: In Europe, reptiles have been recently included in environmental risk-assessment processes for registration of plant-protection products. However, data on toxicity effects of most compounds are lacking. Chlorpyrifos is the most commonly used organophosphorus insecticide worldwide. In the present study, the authors exposed a lacertid lizard, Podarcis bocagei, to sublethal concentrations of chlorpyrifos. In iduals were exposed through spiked food for a period of 20 d (low dose 0.12 mg/kg/d, high dose 1.57 mg/kg/d). After exposure, various biomarkers of exposure and effect were evaluated, including the activities of glutathione S-transferase and enzymes involved in the glutathione redox cycle, glutathione concentrations, activities of esterases, liver and testes histopathologies, as well as locomotory and predatory behavior. The results indicate that sublethal, subchronic exposure to chlorpyrifos can affect P. bocagei in a dose-dependent manner. Adverse effects occurred at both the subin idual and in idual levels, including inhibition of carboxylesterases and cholinesterases (ChEs), liver histopathological changes, and altered predatory behaviors. Animals exposed to chlorpyrifos took more time to capture and subdue prey items. The results suggest a link between effects at subin idual levels of organization with those observed at the whole in idual level after exposure to environmentally realistic dosages of chlorpyrifos.
Publisher: Elsevier BV
Date: 11-2020
Publisher: Springer Science and Business Media LLC
Date: 18-12-2010
Publisher: Wiley
Date: 02-11-2016
DOI: 10.1111/GEB.12532
Publisher: Elsevier BV
Date: 2009
DOI: 10.1016/J.MRGENTOX.2008.10.012
Abstract: Cadmium (Cd) is a cytotoxic, mutagenic and carcinogenic metal. Mutagenesis is indicative of genetic instability and can be assayed by use of microsatellite markers (simple sequence repeats, SSRs). These are tandem-repeated tracts of DNA composed of units that are 1-6 base pairs (bp) long, spread throughout the genome and highly polymorphic. SSRs can be used in the detection of genomic DNA damage and/or mutational events (e.g. deletions, insertions, point mutations). In order to study chronic exposure to cadmium, Lactuca sativa L. seeds were germinated in distilled water and grown on modified Hoagland's medium, both supplemented with 0, 10 and 100microM Cd(NO(3))(2). After 28 days of exposure, the plants were harvested to assess shoot and root length and accumulation of cadmium. DNA was extracted from young and expanded leaves and roots in order to analyse microsatellite instability (MSI). Mutagenic effects of cadmium were evaluated on nine microsatellite loci. No MSI was found in leaves, but a 2-bp deletion in one lettuce root SSR was detected among the SSRs that were analysed. Thus, SSR analyses may provide a complementary tool in the assessment of different genotoxic effects of compounds on plants.
Publisher: Elsevier BV
Date: 07-2005
Publisher: Wiley
Date: 10-2015
DOI: 10.1002/ECE3.1723
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.AQUATOX.2017.10.017
Abstract: Increased variability in water temperature is predicted to impose disproportionally greater fitness costs than mean increase in temperature. Additionally, water contaminants are currently a major source of human-induced stress likely to produce fitness costs. Global change models forecast an increase in these two human-induced stressors. Yet, in spite the growing interest in understanding how organisms respond to global change, the joint fitness effects of water pollution and increased variability in temperature remain unclear. Here, using a multigenerational design, we test the hypothesis that exposure to high concentrations of fluoxetine, a human medicine commonly found in freshwater systems, causes increased lifetime fitness costs, when associated with increased variability in temperature. Although fluoxetine and variability in temperature elicited some fitness cost when tested alone, when both stressors acted together the costs were disproportionally greater. The combined effect of fluoxetine and variability in temperature led to a reduction of 37% in lifetime reproductive success and a 17.9% decrease in population growth rate. Interestingly, fluoxetine and variability in temperature had no effect on the probability of survival. Freshwater systems are among the most imperilled ecosystems, often exposed to multiple human-induced stressors. Our results indicate that organisms face greater fitness risk when exposed to multiple stressors at the same time than when each stress acts alone. Our study highlights the importance of using a multi-generational approach to fully understand in idual environmental tolerance and its responses to a global change scenario in aquatic systems.
Publisher: Elsevier BV
Date: 07-2007
Publisher: Springer Science and Business Media LLC
Date: 10-11-2012
DOI: 10.1007/S10646-012-1012-2
Abstract: Pesticide exposure has been related with thyroid disrupting effects in different vertebrate species. However, very little is known about the effects of these compounds in reptiles. In the Mediterranean area, lacertid lizards are the most abundant vertebrate group in agroecosystems, and have been identified as potential model species for reptile ecotoxicology. The aim of this study was to understand if the herbicides applied in corn fields have thyroid disruptive effects in the lizard Podarcis bocagei. Adult male lizards were captured in north-western Portugal in corn fields treated with herbicides (exposed sites), and in organic agricultural fields (reference sites). Thyroid and male gonad morphology and functionality, and testosterone levels were investigated through histological, immunohistochemical and biochemical techniques. Lizards from exposed locations displayed thyroid follicular lumens with more reabsorption vacuoles and significantly larger follicular area than those from reference fields. Furthermore, testes of lizards from exposed locations had significantly larger seminiferous tubule diameters, significantly higher number of spermatogenic layers and displayed an up-regulation of thyroid hormone receptors when compared with lizards from reference areas. These findings strongly suggest that the complex mixture of herbicides that lizards are exposed to in agricultural areas have thyroid disrupting effects which ultimately affect the male reproductive system. Alachlor, which has demonstrated thyroid effects in mammals, may be largely responsible for the observed effects.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.CHEMOSPHERE.2012.01.048
Abstract: As part of a wider study examining the impacts of corn pesticides on lacertid lizards in north-western Portugal, we examined various physiological, biochemical, and histological biomarkers of exposure and effect among field populations of Podarcis bocagei. Biomarkers included body condition index, standard metabolic rate, locomotor performance, parasitization, glutathione oxidative pathways and related enzyme activity, lipid peroxidation and liver and testis histology. Few of the various biomarkers investigated provided statistically significant evidence of toxic effect. However, using a weight of evidence approach, we conclude that pesticides are affecting lizards living in the vicinity of pesticide exposed corn agriculture sites. Lizards from these locations present a profile of animals under metabolic stress with reduced condition indices, increased standard metabolic rate, lower incidence of hepatocyte vacuolation, altered iron metabolism, increased activation of GSH oxidation pathways, and even increased prevalence of hemoparasites.
Publisher: Elsevier BV
Date: 05-2012
DOI: 10.1016/J.CHEMOSPHERE.2011.12.075
Abstract: At the European level, lacertid lizards have been proposed as potential model species for reptile ecotoxicology. We studied demographic and morphological aspects of natural field subpopulations of Podarcis bocagei inhabiting similar agricultural habitats which were either regularly exposed to pesticides, or not. Parameters examined in this study included population size and density, sex ratio, adult body size, fluctuating asymmetry in femoral pores and parasite prevalence. In general, we detected few statistically significant differences between the exposed and reference subpopulations. Although field situations are ecologically complex and factors other than pesticides may be acting, the absence of observable effects on field subpopulations is probably indicative that lizards are coping or compensating for this level of exposure.
Publisher: Wiley
Date: 25-01-2019
DOI: 10.1111/ECOG.04117
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Amadeu Soares.