Browsing by Author "Roelofs, Dick"
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- An integrative omics approach to unravel toxicity mechanisms of environmental chemicals: effects of a formulated herbicidePublication . Simões, Tiago; Novais, Sara C.; Natal-da-Luz, Tiago; Devreese, Bart; de Boer, Tjalf; Roelofs, Dick; Sousa, José P.; van Straalen, Nico M.; Lemos, Marco F.L.The use of integrative molecular approaches can aid in a comprehensive understanding of the effects of toxicants at different levels of biological organization, also supporting risk assessment. The present study aims to unravel the toxicity mechanisms of a widely used herbicide to the arthropod Folsomia candida exposed in a natural soil, by linking effects on reproduction, proteomics and genome-wide gene expression. The EC50 effects on reproduction over 4 weeks was 4.63 mg glyphosate/kg of soil. The formulation included a polyethoxylated tallowamine as an adjuvant, which at 50% effect on reproduction had an estimated concentration of 0.87-1.49 mg/kg of soil. No effects were observed on survival and reproduction when using the isolated active substance, pointing the toxicity of the formulated product to the co-formulant instead of the active ingredient, glyphosate. RNA sequencing and shotgun proteomics were applied to assess differential transcript and protein expressions between exposed and control organisms in time, respectively. Specific functional categories at protein and transcriptome levels were concordant with each other, despite overall limited correlations between datasets. The exposure to this formulation affected normal cellular respiration and lipid metabolism, inducing oxidative stress and leading to impairment in biological life cycle mechanisms such as molting and reproduction.
- Fate and effects of two pesticide formulations in the invertebrate Folsomia candida using a natural agricultural soilPublication . Simões, Tiago; Novais, Sara C.; Natal-da-Luz, Tiago; Leston, Sara; Rosa, João; Ramos, Fernando; Pouca, Ana Sofia Vila; Freitas, Andreia; Barbosa, Jorge; Roelofs, Dick; Sousa, José P.; Van Straalen, Nico M.; Lemos, Marco F. L.Degradation rates of two widely used pesticides were assessed, and acute and chronic effects on a standard invertebrate species investigated. An herbicide (Montana®) and fungicide (Bravo500®) formulations were investigated and results were compared to the isolated active substances of each formulation (glyphosate and chlorothalonil, respectively). Tests were performed using the invertebrate Folsomia candida as test species and an agricultural natural soil. Degradation rate tests were determined under aerobic conditions at 20 ± 2 °C, using an ecologically relevant concentration of 5 mg (a.i.) kg−1 of soil for both chemicals. Results demonstrated degradation half-lives (DT50) of 2.2 days for Montana® and 2.8 days when pure glyphosate was tested. Values of 1.1 and 2.9 days were registered for Bravo500® and its active substance chlorothalonil, respectively. There were no effects on survival for the tested concentrations of both forms of the herbicide (up to 17.3 mg kg−1). However, reproduction was affected, but only by the herbicide formulation, with an estimated EC50 value of 4.63 mg (a.i.) kg−1. Effects were most unlikely related to glyphosate. For chlorothalonil, both tested forms affected survival and reproduction. The estimated LC50 values were 117 mg (a.i.) kg−1 and 73.5 mg (a.i.) kg−1, and the EC50 41.3 mg (a.i.) kg−1 and 14.9 mg kg−1 for the formulation and the active ingredient, respectively. The effects of the active ingredient were significantly stronger, indicating the major influence of the active substance in the effects caused also by the formulation. Overall results demonstrate the importance of evaluating the effects of the formulated chemicals, as they are applied in the field, and not only their isolated active ingredients.
- Using time-lapse omics correlations to integrate toxicological pathways of a formulated fungicide in a soil invertebratePublication . Simões, Tiago; Novais, Sara C.; Natal-da-Luz, Tiago; Devreese, Bart; de Boer, Tjalf; Roelofs, Dick; Sousa, José P.; Van Straalen, Nico M.; Lemos, Marco F. L.The use of an integrative molecular approach can actively improve the evaluation of environmental health status and impact of chemicals, providing the knowledge to develop sentinel tools that can be integrated in risk assessment studies, since gene and protein expressions represent the first response barriers to anthropogenic stress. This work aimed to determine the mechanisms of toxic action of a widely applied fungicide formulation (chlorothalonil), following a time series approach and using a soil model arthropod, Folsomia candida. To link effects at different levels of biological organization, data were collected on reproduction, gene expression and protein levels, in a time series during exposure to a natural soil. Results showed a mechanistic mode of action for chlorothalonil, affecting pathways of detoxification and excretion, immune response, cellular respiration, protein metabolism and oxidative stress defense, causing irregular cell signaling (JNK and NOD ½ pathways), DNA damage and abnormal cell proliferation, leading to impairment in developmental features such as molting cycle and reproduction. The omics datasets presented highly significant positive correlations between the gene expression levels at a certain time-point and the corresponding protein products 2e3 days later. The integrated omics in this study has provided useful insights into pesticide mechanisms of toxicity, evidencing the relevance of such analyses in toxicological studies, and highlighting the importance of considering a time-series when integrating these datasets.