Machine learning and materials modelling interpretation of in vivo toxicological response to TiO2 nanoparticles library (UV and non-UV exposure)

Assessing the risks of nanomaterials/nanoparticles (NMs/NPs) under various environmental conditions requires a more systematic approach, including the comparison of effects across many NMs with identified different but related characters/descriptors. Hence, there is an urgent need to provide coherent (eco)toxicological datasets containing comprehensive toxicity information relating to a diverse spectra of NPs characters. These datasets are test benches for developing holistic methodologies with broader applicability. In the present study we assessed the effects of a custom design Fe-doped TiO2 NPs library, using the soil invertebrate Enchytraeus crypticus (Oligochaeta), via a 5-day pulse via aqueous exposure followed by a 21-days recovery period in soil (survival, reproduction assessment). Obviously, when testing TiO2, realistic conditions should include UV exposure. The 11 Fe-TiO2 library contains NPs of size range between 5-27 nm with varying þ (enabling the photoactivation of TiO2 at energy wavelengths in the visible-light range). The NPs were each described by 122 descriptors, being a mixture of measured and atomistic model descriptors. The data were explored using single and univariate statistical methods, combined with machine learning and multiscale modelling techniques. An iterative pruning process was adopted for identifying automatically the most significant descriptors. TiO2 NPs toxicity decreased when combined with UV. Notably, the short-term water exposure induced lasting biological responses even after longer-term recovery in clean exposure. The correspondence with Fe-content correlated with the band-gap hence the reduction of UV oxidative stress. The inclusion of both measured and modelled materials data benefitted the explanation of the results, when combined with machine learning

Enchytraeus albidus Microarray: Enrichment, Design, Annotation and Database (EnchyBASE)

Enchytraeus albidus (Oligochaeta) is an ecologically relevant species used as standard test organisms for risk assessment. Effects of stressors in this species are commonly determined at the population level using reproduction and survival as endpoints. The assessment of transcriptomic responses can be very useful e.g. to understand underlying mechanisms of toxicity with gene expression fingerprinting. In the present paper the following is being addressed: 1) development of suppressive subtractive hybridization (SSH) libraries enriched for differentially expressed genes after metal and pesticide exposures; 2) sequencing and characterization of all generated cDNA inserts; 3) development of a publicly available genomic database on E. albidus. A total of 2100 Expressed Sequence Tags (ESTs) were isolated, sequenced and assembled into 1124 clusters (947 singletons and 177 contigs). From these sequences, 41% matched known proteins in GenBank (BLASTX, e-value≤10-5) and 37% had at least one Gene Ontology (GO) term assigned. In total, 5.5% of the sequences were assigned to a metabolic pathway, based on KEGG. With this new sequencing information, an Agilent custom oligonucleotide microarray was designed, representing a potential tool for transcriptomic studies. EnchyBASE (http://bioinformatics.ua.pt/enchybase/) was developed as a web freely available database containing genomic information on E. albidus and will be further extended in the near future for other enchytraeid species. The database so far includes all ESTs generated for E. albidus from three cDNA libraries. This information can be downloaded and applied in functional genomics and transcription studies

Gene Expression Responses Linked to Reproduction Effect Concentrations (EC10,20,50,90) of Dimethoate, Atrazine and Carbendazim, in Enchytraeus albidus

BACKGROUND: Molecular mechanisms of response to pesticides are scarce and information on such responses from soil invertebrates is almost inexistent. Enchytraeus albidus (Oligochaeta) is a standard soil ecotoxicology model species for which effects of many pesticides are known on survival, reproduction and avoidance behaviour. With the recent microarray development additional information can be retrieved on the molecular effects. METHODOLOGY/PRINCIPAL FINDINGS: Experiments were performed to investigate the transcription responses of E. albidus when exposed to three pesticides - dimethoate (insecticide), atrazine (herbicide) and carbendazim (fungicide) - in a range of concentrations that inhibited reproduction by 10%, 20%, 50% and 90% (EC(10), EC(20), EC(50) and EC(90), respectively). The goal of this study was to further identify key biological processes affected by each compound and if dose-related. All three pesticides significantly affected biological processes like translation, regulation of the cell cycle or general response to stress. Intracellular signalling and microtubule-based movement were affected by dimethoate and carbendazim whereas atrazine affected lipid and steroid metabolism (also by dimethoate) or carbohydrate metabolism (also by carbendazim). Response to DNA damage/DNA repair was exclusively affected by carbendazim. CONCLUSIONS: Changes in gene expression were significantly altered after 2 days of exposure in a dose-related manner. The mechanisms of response were comparable with the ones for mammals, suggesting across species conserved modes of action. The present results indicate the potential of using gene expression in risk assessment and the advantage as early markers

Predicted No Effect Concentration (PNEC) for triclosan to terrestrial species (invertebrates and plants)

Triclosan (TCS) is an antimicrobial agent which is used as a broad-spectrum bacteriostatic and found in personal care products, and due to this it is spread in the environment. Aquatic toxicity studies have been reported, but little data is available for its toxicity to terrestrial organisms. The main purpose of this study was to assess the toxicity of TCS in the terrestrial environment, using a battery of soil species, belonging to different taxonomic levels. The species included the invertebrates Eisenia andrei, Enchytraeus albidus and Folsomia candida and the plants Triticum aestivum (monocotyledonous) and Brassica rapa (dicotyledonous). For the invertebrate species the reproduction EC(10)s were 0.6 (E. andrei), 2 (E. albidus) and 7 (F. candida) mg TCS/kg soil dry weight (DW). For plants' emergence EC(10)s are 0.1 (B. rapa) and 142 (T. aestivum) TCS/kg soil DW. The calculated PNEC (Predicted No Effect Concentration) ranged between 0.0008 and 0.004 mg TCS/kg (95% certainty) and between 0.04 and 0.2 mg TCS/kg soil DW (50% certainty) when using the SSD (Species Sensitivity Distribution) approach: applying a safety factor to the lowest EC(10) resulted in a PNEC of 0.06 mg TCS/kg soil DW. (C) 2010 Elsevier Ltd. All rights reserved

Biochemical characterization of cholinesterases in Enchytraeus albidus and assessment of in vivo and in vitro effects of different soil properties, copper and phenmedipham

Enchytraeus albidus are important organisms of the soil biocenosis, used as standard test species in environmental risk assessment. The inhibition of cholinesterases (ChE) activity of several species has been widely used to assess the exposure and effects of anti-cholinesterase environmental contaminants. Several studies have shown the association between ChE activity inhibition and adverse effects on behaviour and survival. Extensive studies addressing survival and behavioural endpoints, as well as other biomarkers, have been done in E. albidus with different types of soil contaminants. The main objectives of this study were: (1) to characterize biochemically the ChE present in the soluble post-mitochondrial fraction of E. albidus whole body homogenates, using different substrates and selective inhibitors; (2) to assess the in vivo effects of copper, phenmedipham and different soil properties (pH, organic matter, clay) on the ChE activity; (3) to assess the in vitro effects of copper and phenmedipham on the ChE activity. The results suggest the presence of one ChE in the soluble post-mitochondrial fraction of E. albidus whole body homogenates, which displays properties of both acetylcholinesterase and pseudocholinesterase considering the typical mammalian enzymes. It is also shown that ChE activity is not inhibited by exposure to different soil properties and that copper and phenmedipham inhibited ChE activity both in in vivo and in in vitro conditions and therefore ChE inhibition seems to be a robust biomarker for this herbicide and this heavy metal. This study showed that ChE activity in E. albidus might be correlated to previously determined higher level effects like survival and reproduction, as well as avoidance behaviour

Ultra-high Throughput TRANScryptOME Sequencing of Enchytraeus crypticus - Innovative Tool for Stress Response Assessment

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