Maria José Amaral

Publications (4) View all

• Article: Thyroid disruption in the lizard Podarcis bocagei exposed to a mixture of herbicides: a field study.

  Rita C Bicho, Maria José Amaral, Augusto M R Faustino, Deborah M Power, Alexandra Rêma, Miguel A Carretero, Amadeu M V M Soares, Reinier M Mann
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  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.
  Ecotoxicology 11/2012; · 2.36 Impact Factor
• Source

  Available from: Amadeu M V M Soares

  Article: Biomarkers of exposure and effect in a lacertid lizard (Podarcis bocagei Seoane) exposed to chlorpyrifos.

  Maria José Amaral, Juan C Sanchez-Hernandez, Rita C Bicho, Miguel A Carretero, Ricardo Valente, Augusto M R Faustino, Amadeu M V M Soares, Reinier M Mann
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  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. Individuals 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 subindividual and individual 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 subindividual levels of organization with those observed at the whole individual level after exposure to environmentally realistic dosages of chlorpyrifos. Environ. Toxicol. Chem. 2012; 31: 2345-2353. © 2012 SETAC.
  Environmental Toxicology and Chemistry 07/2012; 31(10):2345-53. · 2.81 Impact Factor
• Source

  Available from: Reinier M Mann

  Article: The use of a lacertid lizard as a model for reptile ecotoxicology studies--part 1 field demographics and morphology.

  Maria José Amaral, Miguel A Carretero, Rita C Bicho, Amadeu M V M Soares, Reinier M Mann
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  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.
  Chemosphere 02/2012; 87(7):757-64. · 3.21 Impact Factor
• Article: The use of a lacertid lizard as a model for reptile ecotoxicology studies: Part 2 – Biomarkers of exposure and toxicity among pesticide exposed lizards

  Maria José Amaral, Rita C. Bicho, Miguel A. Carretero, Juan C. Sanchez-Hernandez, Augusto M. R. Faustino, Amadeu M. V. M. Soares, Reinier M. Mann
  Chemosphere. 87(7):765-774.