Physiological responses to cumulative ozone uptake in two white clover (**Trifolium repens** L. cv. Regal) clones with different ozone sensitivity

Critical ozone levels must be determined to assess ozone damage on plants, but the cumulative ozone exposure concept of 'AOT40' fails to consider actual ozone uptake via the stomata. While the use of ozone fluxes to assess ozone-induced plant responses is mechanistically appropriate, few studies have examined the relationship between cumulative ozone fluxes and physiological dysfunction. Physiological differences between a widely used ozone-sensitive (NC-S) and ozone-resistant (NC-R) bio-monitor clone of white clover (Trifolium repens L. cv. Regal) were studied and related to cumulative ozone fluxes (CUO3). Generally, no physiological effect of ozone uptake was detected in the NC-R clone, whereas there were negative responses in the NC-S clone for most leaf gas exchange parameters, including net photosynthesis (Asat) and carboxylation capacity (Vcmax). Stomatal conductance (gs) was not significantly different between clones in ozone-free conditions, but gs decreased significantly for the NC-S clone during ozone exposure. The NC-S clone showed higher electron transport rates but lower non-photochemical quenching under high photon flux densities and elevated ozone compared to NC-R clone. Our results suggest that avoiding ozone-induced damage depends on the ability of different genotypes to reduce O3 uptake through stomatal closure and on the capacity for non-photochemical quenching to scavenge reactive oxygen. Relating key physiological parameters to cumulative ozone fluxes contributes to refining flux-based ozone uptake models used in setting critical ozone levels to alleviate the detrimental impact of O3 exposure on vegetation

Evaluation of a screening system for obesogenic compounds : screening of endocrine disrupting compounds and evaluation of the PPAR dependency of the effect

Recently the environmental obesogen hypothesis has been formulated, proposing a role for endocrine disrupting compounds (EDCs) in the development of obesity. To evaluate this hypothesis, a screening system for obesogenic compounds is urgently needed. In this study, we suggest a standardised protocol for obesogen screening based on the 3T3-L1 cell line, a well-characterised adipogenesis model, and direct fluorescent measurement using Nile red lipid staining technique. In a first phase, we characterised the assay using the acknowledged obesogens rosiglitazone and tributyltin. Based on the obtained dose-response curves for these model compounds, a lipid accumulation threshold value was calculated to ensure the biological relevance and reliability of statistically significant effects. This threshold based method was combined with the well described strictly standardized mean difference (SSMD) method for classification of non-, weak- or strong obesogenic compounds. In the next step, a range of EDCs, used in personal and household care products (parabens, musks, phthalates and alkylphenol compounds), were tested to further evaluate the obesogenicity screening assay for its discriminative power and sensitivity. Additionally, the peroxisome proliferator activated receptor γ (PPARγ) dependency of the positive compounds was evaluated using PPARγ activation and antagonist experiments. Our results showed the adipogenic potential of all tested parabens, several musks and phthalate compounds and bisphenol A (BPA). PPARγ activation was associated with adipogenesis for parabens, phthalates and BPA, however not required for obesogenic effects induced by Tonalide, indicating the role of other obesogenic mechanisms for this compound

Citrinin Determination in Food and Food Supplements by LC-MS/MS: Development and Use of Reference Materials in an International Collaborative Study.

The development of incurred reference materials containing citrinin (CIT) and their successful application in a method validation study (MVS) in order to harmonize CIT determination in food and food supplements are demonstrated. CIT-contaminated materials made of red yeast rice (RYR), wheat flour, and leaves (GBL), as well as food supplements made of red yeast rice (FS-RYR) and leaves (FS-GBL), were manufactured in-house via fungal cultivation on collected raw materials. The homogeneity and stability from randomly selected containers were verified according to the ISO 13528. CIT was found to be homogenously distributed and stable in all contaminated materials, with no significant degradation during the timescale of the MVS when storage was performed up to +4 °C. Next, an MVS was organized with eighteen international laboratories using the provided standard operating procedure and 12 test materials, including three RYRs (blank, <50 µg/kg, <2000 µg/kg), two wheat flours (blank, <50 µg/kg), two GBL powders (blank, <50 µg/kg), three FS-RYRs (blank, <50 µg/kg, <2000 µg/kg), and two FS-GBLs (blank, <50 µg/kg). The results of seven CIT-incurred materials showed acceptable within-laboratory precision (RSDr) varying from 6.4% to 14.6% and between-laboratory precision (RSDR) varying from 10.2% to 37.3%. Evidenced by HorRat values < 2.0, the results of the collaborative trial demonstrated that the applied analytical method could be standardized. Furthermore, the appropriateness of producing CIT reference materials is an important step towards food and feed quality control systems and the organization of proficiency tests