Amvm Soares | University of Aveiro (original) (raw)

Papers by Amvm Soares

Ecotoxicology and Environmental Safety, 2014

In aquatic ecosystems several stressors may act together and affect the life traits of organisms.... more In aquatic ecosystems several stressors may act together and affect the life traits of organisms. Pesticide runoffs are usually associated with high inputs of organic matter and depletion of oxygen in aquatic systems. This study aimed at combining anthropogenic stress (chemicals) and natural stress (food availability) and evaluates their joint effect to the life traits of Daphnia magna. The neonicotinoid insecticide imidacloprid and the heavy metal nickel chloride were used and a 21 d chronic test was carried out to obtain reproduction and growth data. The conceptual model Independent action, usually used for assessing response patterns in chemical mixtures, was used for data interpretation. Results showed an increase in the reproduction and growth pattern of D. magna as food levels increased. Both chemicals significantly impaired the reproduction as well as the somatic growth of the organism while the same happened with food concentrations lower than 3 Â 10 5 cells/mL. It was also observed that food availability did not change the toxicity of imidacloprid and nickel chloride when food levels were higher than 3 Â 10 5 cells/mL. When combined with low food levels, imidacloprid showed a slight increase in toxicity, showing that daphnids become more sensitive with reduced food availability, however in a non-significant way. However, toxicity of nickel appeared to be independent of the food level. Both chemicals induced mortality to the organisms exposed in the absence of food only at the end of the test.

Water, Air, & Soil Pollution, 2011

Energy intake and allocation are mainly used to maintain body functions, such as locomotion, grow... more Energy intake and allocation are mainly used to maintain body functions, such as locomotion, growth, and reproductive output. It has been observed that environmental pollutants can affect the energy allocation either due to a cost of handling toxicants or because the toxicant interacts with the storage processes within the organisms. Less than a handful of studies are available reporting the effect of toxicants on energy reserves in enchytraeids and no studies have dealt with the influence of nanomaterials. The present paper shows results on the basal energy reserves (lipids, carbohydrates, and proteins) in Enchytraeus albidus and the influence of copper (Cu) salt and Cu nanoparticles on these reserves for two exposure durations. The energy allocation levels follow what has been reported for other worm species, although lower carbohydrate levels were observed. There were clear differences between worms exposed to control soils and those exposed to Cu for 3 weeks, but no difference after 6 weeks exposure. There was no apparent difference between the impacts of the two Cu exposure forms.

Science of The Total Environment, 2000

Ž. This study was designed to investigate the effect of two surfactants, dodecyl benzyl sulfonate... more Ž. This study was designed to investigate the effect of two surfactants, dodecyl benzyl sulfonate DBS , sodium Ž. Ž. dodecyl sulfate SDS , and of a domestic detergent Y on the AChE activity of the crustacean cladoceran Daphnia magna. All the chemicals significantly inhibit the activity of the enzyme, both in vitro and in vivo conditions. In vitro Ž. Ž lowest observed effect concentration LOEC values ranged from 12.5 to 100 mgrl and correspondent IC 50% 50. inhibition concentration values ranged from 6.6 to 58.5 mgrl. In vivo LOEC values ranged from 2 to 11.9 mgrl, Ž. while EC 50% effect concentration values ranged from 11.4 to 56.7 mgrl. AChE inhibition by environmental 50 contaminants such as surfactants, detergents and metals may lead to false diagnostics and even wrong conclusions in biomonitoring studies based on the use of AChE as a specific biomarker for organophosphorous and carbamate compounds.

Nanotoxicology, 2013

The progressive practical applications of engineered nanoparticles results in their ever-increasi... more The progressive practical applications of engineered nanoparticles results in their ever-increasing release into the environment. Accurate assessment of their environmental and health risks requires the development of methods allowing their monitoring in different environmental compartments and the evaluation of their potential toxicity at different levels of organization. Toxic effects of third-generation (G3) and fourth-generation (G4) poly(amidoamine) dendrimers (ethylenediamine cored, imine-terminated) were assessed on zebrafish embryos during the first two days post-fertilization. Particle characterization by dynamic light scattering showed no tendency to form aggregates in the assay conditions. G3 particles showed somewhat a higher acute toxicity than G4 particles, with LC50 values of 1.8 and 2.3 mg/L, respectively. At sublethal concentrations, both particles affected the zebrafish transcriptome following similar patterns, suggesting a similar mode of action. About 700 transcripts were affected by at least one of the treatments, following a pattern with significant correlations to the effects of bacterial infection in zebrafish embryos. We concluded that the response to G3 and G4 dendrimers was consistent with the activation of the innate immune response, a still unreported potential effect of these particles. These data may contribute to the characterization of hazards of these nanomaterials for both human health and the environment.

PloS one, 2012

Over the last decades the inhibition of plasma cholinesterase (ChE) activity has been widely used... more Over the last decades the inhibition of plasma cholinesterase (ChE) activity has been widely used as a biomarker to diagnose organophosphate and carbamate exposure. Plasma ChE activity is a useful and non-invasive method to monitor bird exposure to anticholinesterase compounds; nonetheless several studies had shown that the ChE form(s) present in avian plasma may vary greatly among species. In order to support further biomonitoring studies and provide reference data for wildlife risk-assessment, plasma cholinesterase of the northern gannet (Morus bassanus), the white stork (Ciconia ciconia) and the grey heron (Ardea cinerea) were characterized using three substrates (acetylthiocholine iodide, propionylthiocholine iodide, and S-butyrylthiocholine iodide) and three ChE inhibitors (eserine sulphate, BW284C51, and iso-OMPA). Additionally, the range of ChE activity that may be considered as basal levels for non-exposed individuals was determined. The results suggest that in the plasma of...

Environmental Pollution, 2004

Toxicity of acid mine drainage was evaluated by macroinvertebrate bioassessment and a new on-line... more Toxicity of acid mine drainage was evaluated by macroinvertebrate bioassessment and a new on-line rapid behavioural toxicity test with Atyaephyra desmaresti (Crustacea).

Ecotoxicology and Environmental Safety, 2000

This paper describes the experimental results for optimizing isopod culture conditions for terres... more This paper describes the experimental results for optimizing isopod culture conditions for terrestrial ecotoxicity testing. The in6uence of animal density and food quality on growth and reproduction of Porcellio dilatatus was investigated. Results indicate that density in6uences isopod performance in a signi5cant way, with low-density cultures having a higher growth rate and better reproductive output than medium-or high-density cultures. Alder leaves, as a soft nitrogen-rich species, were found to be the best-quality diet; when compared with two other food mixtures, alder leaves induced the best results, particularly in terms of breeding success. Guidance regarding culture conditions of isopod species, especially in terms of culture density and diet, is given.

Ecotoxicology and Environmental Safety, 2001

The in vivo e4ects of parathion and endosulfan on the isopod Porcellio dilatatus were investigate... more The in vivo e4ects of parathion and endosulfan on the isopod Porcellio dilatatus were investigated. Feeding parameters (food consumption and assimilation rates), growth, and energy reserves (glycogen, lipid, and protein contents) of pesticide-exposed isopods were compared with those of control animals. Isopods were exposed to a wide range of concentrations of parathion or endosulfan (0.1, 1, 10, 25, 50, 100, 250, and 500 g/g of food) for 21 days. The route of uptake of the pesticides was through the diet (alder leaves). Results revealed that parathion induces a signi5cant depression of glycogen, lipid, and protein contents. However, no signi5cant e4ect was observed on either feeding parameters or growth. Animals fed endosulfan-contaminated food had smaller amounts of glycogen and lipid than control animals, while protein levels were similar in all treatments. Endosulfan also induced a signi5cant decrease in food consumption and assimilation rates at the highest concentrations tested. Growth rate was also signi5cantly a4ected by endosulfan. These results suggest that the isopod P. dilatatus is a suitable species for use in toxicity tests and that energy reserves could be used as e4ect criteria in both laboratory and 5eld studies. 2001 Academic Press

Ecotoxicology and Environmental Safety, 2011

In the present work a small-scale terrestrial ecosystem (STEM) containing a soil collected from a... more In the present work a small-scale terrestrial ecosystem (STEM) containing a soil collected from an agricultural field in Central Portugal was used to evaluate the effects of the combination of the herbicide glyphosate and the insecticide dimethoate. Earthworms (Eisenia andrei), isopods (Porcellionides pruinosus), turnip seeds (Brassica rapa), and bait-lamina strips were placed in the STEM. The results showed that the application of the recommended field dose of both pesticides did not cause any effect on the weight variation of earthworms and growth of the plants. The application of the herbicide, even at 5 and 10 times the field dose, increased feeding activity in soil (bait-lamina test), although the application of dimethoate led to a decrease in feeding activity in all concentrations tested. The binary mixtures performed showed that according to the Independent Action model, synergism (higher effect than expected from the single exposures) was observed in both the shoot length and fresh weight of B. rapa at 5 times the field dose, but antagonism was observed at 10 times the field dose. Regarding the germination success, synergism was observed at the field dose, but antagonism was detected at 5 times and 10 times the field dose. There was a decrease on the earthworm's weight in all concentrations tested, although no statistical differences were observed in any of the treatments made. Regarding depth distribution of E. andrei, worms were found in the upper layer more than it was predicted for all concentrations. In the mixtures with the field and 5 times the field dose there was a decrease in the feeding activity (bait-lamina consumption) by the soil fauna. From the four biomarkers assessed on the isopods (Catalase, Acetylcholinesterase, Glutathione-S-transferase, and Lipid peroxidation), only a significant decrease in the Acetylcholinesterase activity upon dimethoate and the binary mixtures exposures performed with the field dose was observed and on Lipid peroxidation at the field doses of single and binary exposures.

Comparative Biochemistry and Physiology Part C: Toxicology & Pharmacology, 2012

Despite increased utilization of copper (Cu) nanoparticles, their behaviour and effect in the env... more Despite increased utilization of copper (Cu) nanoparticles, their behaviour and effect in the environment is largely unknown. Enchytraeids are extensively used in studies of soil ecotoxicology. Ecotoxicogenomic tools have shown to be valuable in nanotoxicity interpretation. A cDNA microarray for Enchytraeus albidus has recently been developed, which was used in this study. We compared the gene expression profiles of E. albidus when exposed to Cu-salt (CuCl 2) and Cu-nanoparticles (Cu-NP) spiked soil. Exposure time was 48 h with a concentration range of 400 to 1000 mg Cu/kg. There were more down-regulated than up-regulated genes. The number of differently expressed genes (DEG) decreased with increasing concentration for CuCl 2 exposure, whereas for Cu-NP, the number did not change. The number of common DEG decreased with increasing concentration. Differences were mainly related to transcripts involved in energy metabolism (e.g. monosaccharide transporting ATPase, NADH dehydrogenase subunit 1, cytochrome c). Overall, our results indicated that Cu-salt and Cu-NP exposure induced different gene responses. Indirect estimates of Cu-NP related ion-release indicated little or no free Cu 2+ activity in soil solutions. Hence, it was concluded that the Cu-NP effects were probably caused by the nanoparticles themselves and not by released ions.

Chemosphere, 2011

Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has ... more Cadmium is a non-essential toxic metal that is able to bioaccumulate in both flora fauna and has the potential to biomagnify in some food chains. However, the form in which cadmium is presented to consumers can alter the bioavailability and possibly the internal distribution of assimilated Cd. Previous studies in our laboratory highlighted differences in Cd assimilation among isopods when they were provided with a plant-based food with either Cd biologically incorporated into plant tissue or superficially amended with ionic Cd(2+). Cd is known for its high affinity for sulphur ligands in cysteine residues which form the basis for metal-binding proteins such as metallothionein. This study compares Cd assimilation efficiency (AE) in Porcellio dilatatus fed with food amended with either cadmium cysteinate or cadmium nitrate in an examination of the influence of Cd speciation on metal bioavailability followed by an examination of the sub-cellular distribution using a centrifugal fractionation protocol. As hypothesized the AE of Cd among isopods fed with Cd(NO(3))(2) (64%, SE=5%) was higher than AE for isopods fed with Cd(Cys)(2) (20%, SE=3%). The sub-cellular distribution also depended on the Cd species provided. Those isopods fed Cd(Cys)(2) allocated significantly more Cd to the cell debris and organelles fractions at the expense of allocation to metal-rich granules (MRG). The significance of the difference in sub-cellular distribution with regard to toxicity is discussed. This paper demonstrates that the assimilation and internal detoxification of Cd is dependent on the chemical form of Cd presented to the isopod.

Chemosphere, 2009

The water flea Daphnia magna belongs to the cyclical parthenogenic species, which can reproduce b... more The water flea Daphnia magna belongs to the cyclical parthenogenic species, which can reproduce by either parthenogenesis or sexual reproduction. Recent studies have reported the involvement of the methylfarnesoate hormone, in male sex determination of D. magna. The aim of this study was to evaluate the juvenoid and anti-juvenoid activity of atrazine, endosulfan sulphate, and chlorpyrifos. To assess the juvenoid activity we exposed maternal daphnids to several concentrations of the respective pesticides, using the percentage of male production as endpoint. Fenoxycarb (1microgL(-1)) was used as a positive control. The anti-juvenoid activity was assessed using a similar bioassay after the addition of fenoxycarb (1microgL(-1)) to all test solutions. Fenoxycarb is an insect growth regulator that mimics the action of methylfarnesoate, and promoted the production of 95% of male offspring at the given concentration. Weak juvenoid-agonist activity was detected for endosulfan sulphate, with a significant increase of the percentage of male daphnids detected through logistic regression. In addition, atrazine and endosulfan sulphate antagonized the juvenoid activity of fenoxycarb. These results also corroborate the hypothesis that weak juvenoid agonists can simultaneously act as juvenoid antagonists as it has been observed in other hormonal systems.

Archives of Environmental Contamination and Toxicology, 1995

Stressors can induce specific responses in enzyme function and energetic equilibrium. The hypothe... more Stressors can induce specific responses in enzyme function and energetic equilibrium. The hypothesis is tested that there are metabolic responses to stress, measured by a change in specific activity of piruvate kinase (PK) and malate dehydrogenase (MDH). Individual D. magna clones were exposed to 3,4-dichloroaniline for 7, 14, or 21 days. Other performed experiments persued the probable adaptation of the organisms borne under stress vs unstressed conditions. PK and MDH activity levels were inhibited after 7 days of 3,4-DCA exposure, whereas 14 and 21 day exposures induced enzyme activities. Enzymatic activities of individuals born under 3,4-DCA stress and reared in a DCA-free medium were compared with enzyme activities from individuals born and reared under control-M4 conditions. The inhibition of MDH at 7 and 21 days in these animals is similar to the responses of stressed animals in the initial phase of increased production. There was no significant effect on fecundity in DCA-tolerant animals. However, when the first generation of parents (under stress) were compared to DCA-tolerant animals (offsprings grown under normal culture conditions), a significant increase in fecundity was observed. This agrees with the decreased respiration under non-toxic conditions, hence, lower metabolic costs result during unstressed conditions, which may be an adaptative response to an environment free of stress.

Aquatic Toxicology, 2011

The toxicological assessment of chemical compounds released to the environment is more accurate w... more The toxicological assessment of chemical compounds released to the environment is more accurate when mixtures of chemicals and/or interactions between chemicals and natural stressors are considered. Ultraviolet radiation can be taken as a natural stressor since the levels of UV are increasing due to the decrease of its natural filter, the stratospheric ozone concentration. Therefore, a combination of chemical exposures and increasing UV irradiance in aquatic environments is likely to occur. In the current study, combined effects of carbendazim and ultraviolet radiation were evaluated, using selected life traits as endpoints on Daphnia magna. To design combined exposures, first single chemical and natural stressor bioassays were performed: a reproduction test with carbendazim and a reproduction, feeding inhibition and Energy budget test with ultraviolet radiation. Following single exposures, the combinations of stressors included exposures to UV radiation and carbendazim for a maximum exposure time of 4 h, followed by a post-exposure period in chemically contaminated medium for a maximum of 15 days, depending on the endpoint, where the effects of the combined exposures were investigated. Statistical analyses of the data set were performed using the MixTox tool and were based on the conceptual model of Independent Action (IA) and possible deviations to synergism or antagonism, dose-ratio or dose-level response pattern. Both ultraviolet radiation and carbendazim as single stressors had negative impacts on the measured life traits of daphnids, a decrease on both feeding rates and reproduction was observed. Feeding rates and reproduction of D. magna submitted to combined exposures of ultraviolet radiation and carbendazim showed a dose-ratio deviation from the conceptual model as the best description of the data set, for both endpoints. For feeding inhibition, antagonism was observed when the UV radiation was the dominant item in combination, and for reproduction, synergism was observed when UV radiation dominated the exposure. From these results, the combined exposure of ultraviolet radiation and chemical compounds should also be considered for risk assessment as this study has shown that more severe effect than expected by single chemical assessment might be observed.

Ecotoxicology, 2004

During spring and summer 1999 a ring-test and field-validation study with an open, intact Terrest... more During spring and summer 1999 a ring-test and field-validation study with an open, intact Terrestrial Model Ecosystem (TME) was conducted at four different European sites

… in standardization of …, 1993

CHAPTER 4 Reducing Variability in Daphnia Toxicity Tests A Case for Further Standardization Mair... more CHAPTER 4 Reducing Variability in Daphnia Toxicity Tests A Case for Further Standardization Mairead C. Bradley, Caroline Naylor, Peter Calow, Donald J. Baird, Ian Barber, and Amadeu MVM Scares ABSTRACT Problems associated with reproducibility of Daphnia toxicity ...