LINKEDIN - LINKING EFFECTS AT DIFFERENT LEVELS OF BIOLOGICAL ORGANIZATION: INSIGHTS INTO MECHANISMS OF PESTICIDE TOXICITY

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Argan oil as a rich source of linoleic fatty acid for dietetic structured lipids production

Publication . Simões, Tiago; Ferreira, Jessica; Lemos, Marco F.L.; Augusto, Ana; Félix, Rafael; Silva, Susana F.J.; Ferreira-Dias, Suzana; Tecelão, Carla

Argan oil is rich in long-chain unsaturated fatty acids (FA), mostly oleic and linoleic, and natural antioxidants. This study addresses the production of low-calorie structured lipids by acidolysis reaction, in a solvent-free system, between caprylic (C8:0; system I) or capric (C10:0; system II) acids and argan oil, used as triacylglycerol (TAG) source. Three commercial immobilized lipases were tested: Novozym® 435, Lipozyme® TL IM, and Lipozyme® RM IM. Higher incorporation degree (ID) was achieved when C10:0 was used as acyl donor, for all the lipases tested. Lipozyme® RM IM yielded the highest ID for both systems (28.9 +- 0.05 mol.% C10:0, and 11.4 +- 2.2 mol.% C8:0), being the only catalyst able to incorporate C8:0 under the reaction conditions for biocatalyst screening (molar ratio 2:1 FA/TAG and 55ºC). The optimal conditions for Lipozyme® RM IM in system II were found by response surface methodology (66ºC; molar ratio FA/TAG of 4:1), enabling to reach an ID of 40.9 mol.% of C10:0. Operational stability of Lipozyme® RM IM in system II was also evaluated under optimal conditions, after eight consecutive 24 h-batches, with biocatalyst rehydration between cycles. The biocatalyst presented a half-life time of 103 h.

2021Journal article

Open access

Fate and effects of two pesticide formulations in the invertebrate Folsomia candida using a natural agricultural soil

Publication . 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.

2019-04Journal article

Restricted access

Using time-lapse omics correlations to integrate toxicological pathways of a formulated fungicide in a soil invertebrate

Publication . 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.

2019-02Journal article

Restricted access