Fent, Karl

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Fent, Karl

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2016 - 20195
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Autor:in: Faltermann, Susanne ×

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  • Vorschaubild nicht verfügbar
    Publikation
    Physiological and Transcriptional Effects of Mixtures of Environmental Estrogens, Androgens, Progestins, and Glucocorticoids in Zebrafish
    (American Chemical Society, 12.12.2019) Willi, Raphael; Furia, Nathan; Fent, Karl; Faltermann, Susanne; Mastroianni, Sarah [in: Environmental Science & Technology]
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Environmental 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
  • Vorschaubild nicht verfügbar
    Publikation
    Cytotoxicity and molecular effects of biocidal disinfectants (quaternary ammonia, glutaraldehyde, poly(hexamethylene biguanide) hydrochloride PHMB) and their mixtures in vitro and in zebrafish eleuthero-embryos
    (Elsevier, 2017) Christen, Verena; Faltermann, Susanne; Fent, Karl; Brun, Nadja [in: Science of the Total Environment]
    Frequently used biocidal disinfectants, including quaternary ammonium compounds (QAC), glutaraldehyde and poly(hexamethylene biguanide) hydrochloride (PHMB), occur in the aquatic environment but their potential effects in fish are poorly known, in particular when occurring as mixtures. To investigate their joint activity, we assessed the cytotoxicity of three QACs (BAC, barquat and benzalkonium chloride), glutaraldehyde andPHMB by the MTT assay individually, followed by assessing binary and ternary mixtures in zebrafish liver cells (ZFL) and human liver cells (Huh7). We also analysed molecular effects by quantitative PCR in vitro and in zebrafish eleuthero-embryos employing a targeted gene expression approach. QACs displayed strong cytotoxicity in both cell lines with EC50 values in the low μg/ml range, while glutaraldehyde and PHMB were less cytotoxic. Most of the binary and both ternary mixtures showed synergistic activity at all equi-effective concentrations. A mixture containing all five compounds mixed at their no observed effect concentrations showed strong cytotoxicity, suggesting a synergistic interaction. Additionally, we determined transcriptional alterations of target genes related to endoplasmatic reticulum (ER) stress, general stress, inflammatory action and apoptosis. Induction of ER stress genes occurred at non-cytotoxic concentrations of barquat, glutaraldehyde and BAC in ZFL cells. Barquat and BAC induced tumor necrosis factor alpha (tnf-α). Similar transcriptional alterations were found in vivo upon exposure of zebrafish eleuthero-embryos for 120 h. Glutaraldehyde led to induction of ER stress genes and tnf-α, while BAC additionally induced genes indicative of apoptosis, which was also the case with benzalkonium chloride at the highest concentration. We demonstrated strong cytotoxicity of QACs, and synergistic activity of binary, ternary and quintuple mixtures. Barquat and BAC let to induction of ER stress and inflammation in vitro, and BAC and glutaraldehyde at non-toxic concentrations in vivo, while benzalkonium chloride induced expression of tnf-α only.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Anti-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
  • Vorschaubild nicht verfügbar
    Publikation
    Comparative effects of nodularin and microcystin-LR in zebrafish: 1. Uptake by organic anion transporting polypeptide Oatp1d1 (Slco1d1)
    (Elsevier, 02/2016) Faltermann, Susanne; Prétôt, René; Pernthaler, Jakob; Fent, Karl [in: Aquatic Toxicology]
    Microcystin-LR (MC-LR) and nodularin are hepatotoxins produced by several cyanobacterial species. Their toxicity is based on active cellular uptake and subsequent inhibition of protein phosphatases PP1/2A, leading to hyperphosphorylation and cell death. To date, uptake of MC-LR and nodularin in fish is poorly understood. Here, we investigated the role of the organic anion transporting polypeptide Oatp1d1 in zebrafish (drOatp1d1, Slco1d1) in cellular uptake in zebrafish. We stably transfected CHO and HEK293 cell lines expressing drOatp1d1. In both transfectants, uptake of MC-LR and nodularin was demonstrated by competitive inhibition of uptake with fluorescent substrate lucifer yellow. Direct uptake of MC-LR was demonstrated by immunostaining, and indirectly by the high cytotoxicity in stable transfectants. By means of a synthesized fluorescent labeled MC-LR derivative, direct uptake was further confirmed in HEK293 cells expressing drOatp1d1. Additionally, uptake and toxicity was investigated in the permanent zebrafish liver cell line ZFL. These cells had only a low relative abundance of drOatp1d1, drOatp2b1 and drOatp1f transcripts, which correlated with the lack of MC-LR induced cytotoxicity and transcriptional changes of genes indicative of endoplasmic reticulum stress, a known effect of this toxin. Our study demonstrates that drOatp1d1 functions as an uptake transporter for both MC-LR and nodularin in zebrafish.
    01A - Beitrag in wissenschaftlicher Zeitschrift