The objective of this project was to gain information on toxicokinetic behaviour and in vivo genotoxicity of alternariol (AOH) in NMRI mice. Therefore, commercially available AOH was purified using a preparative HPLC-method. Initial dose-range finding proved AOH to be nontoxic after single or repeated oral application of up to 2000 mg/kg (limit dose). Subsequently, an in vivo oral toxicokinetic study (OECD guideline 417) was performed with 200 and 1000 mg/kg radiolabelled AOH. The study revealed low systemic absorption, with about 90 % of the total dose excreted via faeces and up to 9 % via urine. Blood levels did not exceed 0.06 % of the administered dose during the first 24 h after administration. Thus, target organ toxicity would most likely be restricted to the gastrointestinal tract. Metabolism of AOH was then investigated in a toxicokinetic study with non-radiolabelled AOH. Three dosage schemes were used: 200 and 2000 mg/kg (single dose) and 3 x 2000 mg/kg (0, 24 and 45 h). Whole blood (LC-MS/MS analysis) and urine (GC-MS in SIM mode) were analysed for AOH and its hydroxy-metabolites. Four metabolites (8-hydroxy-AOH, 4-hydroxy-AOH, 10-hydroxy-AOH, 2-hydroxy-AOH) were detected and ID was confirmed by NMR and mass spectrometry. Results also pointed to low systemic absorption, but mean blood levels (0.5 µM AOH, 3 h after the last of three applications) was considered sufficient to justify performance of a combined bone marrow micronucleus test (OECD 474) and in vivo alkaline comet assay (stomach, gut, liver). Therefore, 3 x 2000 mg/kg AOH were applied in corn oil (at 0, 24, and 45 h) and animals were sacrificed 48 h after the first application. The micronucleus assay revealed no toxic or genotoxic effect of AOH in bone marrow and the comet assay with liver tissue also did not indicate systemic genotoxicicity. © Schuchardt S, Ziemann C, Hansen T, 2014

The contrasting effects of the invasive Marenzelleria viridis and the native Nereis diversicolor on benthic metabolism, partitioning of reaction pathways and distribution of inorganic porewater (C and N) solutes in homogenized sandy sediment were investigated experimentally over a period of 1 mo. The 2 species were studied separately and in combination to observe possible effects and interactions. Benthic O 2 uptake and total CO 2 (TCO 2 ) release were affected similarly by M. viridis, N. diversicolor and the two in combination, with roughly a doubling after 1 to 2 wk compared to defaunated sediment. Sulfate reduction after 1 mo, on the other hand, was more than twice as high in sediment inhabited by M. viridis alone than in any other treatment, even when combined with N. diversicolor. Denitrification estimated from benthic TCO 2 release, porewater reaction stoichiometry and nutrient fluxes was largely unaffected by the presence of fauna. Accordingly, the partitioning of reaction pathways after 1 mo revealed that M. viridis stimulated sulfate reduction at the expense of aerobic respiration. Most of the oxygen uptake in M. viridis sediment was apparently due to enhanced oxidation resulting from an upward drifting front of sulfide as indicated by low redox and the appearance of Beggiatoa sp. near the surface. Porewater solute profiles showed that M. viridis was capable of stronger and deeper irrigation than N. diversicolor despite ~10 times higher burrow ventilation by the latter species. This effect was caused by percolation of return water in the deep (> 20 cm) I-or J-shaped burrows of M. viridis compared to the flushing of the more shallow (6 to 8 cm) U-shaped burrows of N. diversicolor. A replacement of the native N. diversicolor with the invasive M. viridis as the dominant burrow-dwelling polychaete in shallow coastal sediments will probably affect the biogeochemical functioning and ecological stability of the ecosystem. Among other things, organisms tolerant to sulfide are likely to be favored at the expense of more sensitive species.

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1 Primary porcine hepatocytes and enterocytes were isolated and cultured in Williams' E medium for up to 10 days to investigate potential organ di erences in the metabolism of the immunosuppressive compound tacrolimus (FK 506) and of two investigational drugs (KC11346 and KC12291). Using LC-MS (FK506) and HPLC-FL (KC 11346/12291) a number of metabolites with identical mass and/or identical retention time could be detected. 2 In the case of tacrolimus hepatocytes and enterocytes produced the same spectrum of metabolites, e.g. bisdemethyl-tacrolimus, demethyl-tacrolimus, demethyl-hydroxy-tacrolimus and hydroxy-tacrolimus, albeit at varying intensities. 3 Treatment of enterocyte cultures with dexamethasone increased the overall metabolite formation very signi®cantly (up to 36 fold). 4 The metabolism of tacrolimus was also studied with preparations of insect cells, that express speci®cally high levels of individual human cytochrome P450 (CYP) isoenzymes. All metabolites could be generated with microsomal preparations speci®cally expressing CYP3A4, but hydroxytacrolimus was exclusively produced by CYP3A5. 5 In the case of the investigational drugs KC 11346 and KC 12291 only three metabolites were formed by cultured enterocytes whereas hepatocytes produced 10 and 20 metabolites, respectively. 6 When assessed at the protein level CYP1A and CYP3A were expressed in cultures of porcine enterocytes for up to 10 days but porcine hepatocytes expressed additionally CYP2C9/10. 7 In conclusion, primary enterocytes and hepatocytes can be successfully cultured for several days while maintaining mono-oxygenase activity and may therefore be used as a tool for studying intestinal and hepatic metabolism.