Deoxynivalenol: toxicological profile and potential for reducing cereal grain contamination using bacterial additives in fermented animal feed.

Deoxynivalenol (DON) contamination of grain destined for animal feeds is a major toxicological risk to monogastrics and is suspected of restricting productivity in ruminants. Whereas bacterial additives have been developed that can detoxify DON in the rumen and lower intestine, there are currently no commercial inoculants able to perform this task in crimped grain (CG) silage, a regionally important method of moist grain preservation based on homo- and heterofermentative lactic acid bacteria or chemical additives. Determining whether this ensiling process alongside the action of detoxifying bacteria has the potential to remove DON in CG prior to ingestion, was explored in mini-silo ensiling experiments. CG was heat treated (100 °C, 60 min) or ensiled fresh in triplicate 50 g silos, spiked with 5 mg/kg DON and inoculated with lactic acid bacteria derived from wild birds, natural epiphytic inoculants and commercially sourced silage additives (21 d). DON recovery was only significantly reduced (31.2 ± 14.4% recovery, p<0.001, n= 30) by heat treatment, as determined by IAC-RP-HPLC-UV. Bacterial assemblage analysis by 16S rRNA PCR-DGGE-SEQ identified Weissella cibaria, Pantoea agglomerans, Bacillus subtilis, B. licheniformis and Hafnia alvei as candidate detoxification agents, of which W. cibaria and H. alvei decreased DON recovery in vitro (11.3 and 6.2% recovery respectively, p<0.05, n = 18), which translated to inoculated W. cibaria yielding a decrease in DON recovery (67.2± 14.4%, 28 d) in naturally contaminated crimped wheat (13.5 ± 1.0 mg/kg, 35-40% moisture, p<0.05, n =15). As W. cibaria is a lactic acid bacteria already associated with fermented CG by default it has promise as a novel DON detoxification agent in CG silage. DON is however just one of many hepatotoxic co-contaminants. Retrorsine, a DNA-crosslinking pyrrolizidine alkaloid derived from Ragwort (Senecio sp.) was investigated for interactive toxicity with DON in an in vitro co-exposure experiment. HepG2 cells were exposed to Log10 multifactorial binary exposures for 48 h followed by a suite of assays to elucidate mechanisms of interactive cytotoxicity, genotoxicity and modulation of the proteome. Retrorsine was tentatively confirmed to form DNA/protein crosslinks in the comet, micronucleus and crosslinking assays, whilst DON was found to potently induce cytotoxicity and apoptosis. Co-exposure yielded a complex toxicity response, with low doses yielding antagonistic effects and high doses trending towards additive effects, although DON dose was generally the principle component. The difficulties associated with undertaking an interactive toxicity study where both toxins have multiple metabolic and cellular targets are highlighted

Sub-lethal effects of waterborne exposure to copper nanoparticles compared to copper sulphate on the shore crab ( Carcinus maenas )

publisher: Elsevier articletitle: Sub-lethal effects of waterborne exposure to copper nanoparticles compared to copper sulphate on the shore crab (Carcinus maenas) journaltitle: Aquatic Toxicology articlelink: http://dx.doi.org/10.1016/j.aquatox.2017.08.006 content_type: article copyright: © 2017 Elsevier B.V. All rights reserved

Genotoxic and Cytotoxic effects of Ti02, CdS and Ag2S nanoparticles on fish cells in vitro

The exponential increase in engineered nanoparticles (ENP) warrants the need for a battery of well-defined cytotoxicity and genotoxicity screening tests across several organisnn groups. This study aimed to evaluate these effects in vitro using the RTG-2 cell line as a prelude to further aquatic testing in vivo. Extensive characterisation of the Ti02 nanoparticles (NP) enabled the synthesis of an efficient dosing strategy in which exposure in PBS gave optimal ENP agglomeration effects when in contact with the cells. Furthermore, when UVillumination was applied there was a much reduced inherent photo-genotoxic activity with PBS than exposing cells in MEM (10% FBS, 1% NEAA). Only with a UVA co-exposure were any NP-associated increases in DNA strand breaks recorded, and only with a 4-24 hour exposure to 50mg 1"^. Supplementation with Fpg (bacterial endonuclease specific for oxidised purine bases) produced elevated strand breakage in all but the highest doses. Micronucleus incidence was not affected by a 48-hour incubation with the same dose in the dark. The neutral red retention assay results indicate significant cytotoxic effects with a 24-hour exposure to 50mg in the dark, but produced a shielding effect from excessive lysosomal damage caused by UVB irradiation. Cells observed using SEM following a 50mg T^exposure were comprehensively covered in NP. The effect of this extracellular distribution is discussed in terms of inhibited cytoplasmic movement, mitosis and cell-cell communication. Thiol-terminated methyl polyethylene glycol capped CdS and Ag2S NPs were found to be innocuous following a 4-hour exposure in the absence of UVillumination. Keywords: Nanoparticles, Genotoxicity, Cytotoxicity, Ptioto-genotoxicity, RTG-2Faculty of Science in collaboration with Cefas (Weymouth, UK)