Hettich, Timm
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Hettich, Timm
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- PublikationEnvironmental glucocorticoids corticosterone, betamethasone and flumethasone induce more potent physiological than transcriptional effects in zebrafish embryos(Elsevier, 01.07.2019) Willi, Raffael Alois; Faltermann, Susanne; Hettich, Timm; Fent, Karl [in: Science of the Total Environment]Many glucocorticoids occur in the aquatic environments but their adverse effects to fish are poorly known. Here we investigate effects of the natural glucocorticoid corticosterone and the synthetic glucocorticoids betamethasone and flumethasone in zebrafish embryos. Besides studying the effects of each steroid, we compared effects of natural with synthetic glucocorticoids, used as drugs. Exposure at concentrations of 1 μg/L and higher led to concentration-related decrease in spontaneous muscle contractions at 24 h post fertilization (hpf) and increase in heart rate at 48 hpf. Betamethasone showed a significant increase at 0.11 μg/L in heart rate. Corticosterone also accelerated hatching at 60 hpf at 0.085 μg/L. Transcription of up to 24 genes associated with different pathways showed alterations at 96 and 120 hpf for all glucocorticoids, although with low potency. Corticosterone caused transcriptional induction of interleukin-17, while betamethasone caused transcriptional down-regulation of the androgen receptor, aromatase and hsd11b2, indicating an effect on the sex hormone system. Furthermore, transcripts encoding proteins related to immune system regulation (irg1l, gilz) and fkbp5 were differentially expressed by corticosterone and betamethasone, while flumethasone caused only little effects, mainly alteration of the irg1l transcript. Our study shows that these glucocorticoids caused more potent physiological effects in early embryos than transcriptional alterations in hatched embryos, likely due to increased metabolism in later developmental stages. Thus, these glucocorticoids may be of concern for early stages of fish embryos in contaminated aquatic environments.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationA vitellogenin antibody in honey bees (Apis mellifera ): Characterization and application as potential biomarker for insecticide exposure(Wiley, 02/2019) Christen, Verena; Fent, Karl; Hettich, Timm [in: Environmental Toxicology and Chemistry]The insect yolk precursor vitellogenin is a lipoglycoprotein synthesized and stored in the fat body and secreted into the hemolymph. In honey bees, vitellogenin displays crucial functions in hormone signaling, behavioral transition of nurse bees to foragers, stress resistance, and longevity in workers. Plant protection products such as neonicotinoids, pyrethroids, and organophosphates alter the transcriptional expression of vitellogenin. To assess plant protection product‐induced alterations on the protein level, we developed a rabbit polyclonal vitellogenin antibody. After characterization, we assessed its specificity and vitellogenin levels in different tissues of worker bees. The vitellogenin antibody recognized full‐length 180‐kDa vitellogenin and the lighter fragment of 150 kDa in fat body, hemolymph, and brain. In hemolymph, a band of approximately 75 kDa was detected. Subsequent mass spectrometric analysis (liquid chromatography–mass spectrometry) confirmed the 180‐ and 150‐kDa bands as vitellogenin. Subsequently, we evaluated vitellogenin expression in brain, fat body, and hemolymph on 24‐h exposure of bees to 3 ng/bee to the neonicotinoid clothianidin. Full‐length vitellogenin was upregulated 3‐fold in the fat body, and the 150‐kDa fragment was upregulated in the brain of exposed honey bees, whereas no alteration occurred in the hemolymph. Upregulation of the vitellogenin protein by the neonicotinoid clothianidin is in line with the previously shown induction of its transcript. We conclude that vitellogenin might serve as a potential biomarker for neonicotinoid and other pesticide exposure in bees. Environ Toxicol Chem 2019;00:1–10. © 2019 SETAC01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationBiodegradation of sulfamethoxazole by a bacterial consortium of Achromobacter denitrificans PR1 and Leucobacter sp. GP(Springer, 12/2018) Reis, Ana C.; Cvancarova Småstuen, M.; Liu, Ying; Lenz, Markus; Hettich, Timm; Kolvenbach, Boris; Corvini, Philippe; Nunes, Olga C. [in: Applied Microbiology and Biotechnology]In the last decade, biological degradation and mineralization of antibiotics have been increasingly reported feats of environmental bacteria. The most extensively described example is that of sulfonamides that can be degraded by several members of Actinobacteria and Proteobacteria. Previously, we reported sulfamethoxazole (SMX) degradation and partial mineralization by Achromobacter denitrificans strain PR1, isolated from activated sludge. However, further studies revealed an apparent instability of this metabolic trait in this strain. Here, we investigated this instability and describe the finding of a low-abundance and slow-growing actinobacterium, thriving only in co-culture with strain PR1. This organism, named GP, shared highest 16S rRNA gene sequence similarity (94.6–96.9%) with the type strains of validly described species of the genus Leucobacter. This microbial consortium was found to harbor a homolog to the sulfonamide monooxygenase gene (sadA) also found in other sulfonamide-degrading bacteria. This gene is overexpressed in the presence of the antibiotic, and evidence suggests that it codes for a group D flavin monooxygenase responsible for the ipso-hydroxylation of SMX. Additional side reactions were also detected comprising an NIH shift and a Baeyer–Villiger rearrangement, which indicate an inefficient biological transformation of these antibiotics in the environment. This work contributes to further our knowledge in the degradation of this ubiquitous micropollutant by environmental bacteria.01A - Beitrag in wissenschaftlicher Zeitschrift
- PublikationAnti-Inflammatory Activity of Cyanobacterial Serine Protease Inhibitors Aeruginosin 828A and Cyanopeptolin 1020 in Human Hepatoma Cell Line Huh7 and Effects in Zebrafish (Danio rerio)(MDPI, 14.07.2016) Faltermann, Susanne; Hutter, Simon; Christen, Verena; Hettich, Timm; Fent, Karl [in: Toxins]Intensive growth of cyanobacteria in freshwater promoted by eutrophication can lead to release of toxic secondary metabolites that may harm aquatic organisms and humans. The serine protease inhibitor aeruginosin 828A was isolated from a microcystin-deficient Planktothrix strain. We assessed potential molecular effects of aeruginosin 828A in comparison to another cyanobacterial serine protease inhibitor, cyanopeptolin 1020, in human hepatoma cell line Huh7, in zebrafish embryos and liver organ cultures. Aeruginosin 828A and cyanopeptolin 1020 promoted anti-inflammatory activity, as indicated by transcriptional down-regulation of interleukin 8 and tumor necrosis factor α in stimulated cells at concentrations of 50 and 100 µmol·L−1 aeruginosin 828A, and 100 µmol·L−1 cyanopeptolin 1020. Aeruginosin 828A induced the expression of CYP1A in Huh7 cells but did not affect enzyme activity. Furthermore, hatched zebrafish embryos and zebrafish liver organ cultures were exposed to aeruginosin 828A. The transcriptional responses were compared to those of cyanopeptolin 1020 and microcystin-LR. Aeruginosin 828A had only minimal effects on endoplasmic reticulum stress. In comparison to cyanopeptolin 1020 our data indicate that transcriptional effects of aeruginosin 828A in zebrafish are very minor. The data further demonstrate that pathways that are influenced by microcystin-LR are not affected by aeruginosin 828A.01A - Beitrag in wissenschaftlicher Zeitschrift