Laura Sigg

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Sigg

First Name

Laura

ORCID

0000-0002-2210-2951

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Publications 1 - 4 of 4

Toxicity and translocation of Ag, CuO, ZnO and TiO2 nanoparticles upon exposure to fish intestinal epithelial cells
Geppert, Mark; Sigg, Laura; Schirmer, Kristin (2021)
Environmental Science: Nano
Understanding the ability of fish intestinal cells to act as a barrier for nanoparticle (NP) uptake and their effects is of significance from an environmental perspective as well as for human health, for which fish serves as an important nutrient source. We used an in vitro intestinal barrier model, based on rainbow trout intestinal (RTgutGC) cells, to elaborate the toxicity and translocation of five types of metal-based NPs. The NPs were polyvinylpyrrolidone (PVP)-coated Ag NPs, uncoated Ag NPs, CuO NPs, ZnO NPs and TiO2 NPs. In conventional monolayers on impermeable supports, cell viability declined according to classical sigmoidal dose–response curves with EC50 values between 0.28 mg L−1 and >100 mg L−1 in the following rank order, from the most toxic (lowest EC50) to the least toxic (highest EC50): PVP–Ag NPs < uncoated Ag NPs < CuO NPs < ZnO NPs < TiO2 NPs. When cells were cultured on permeable membranes to mimic an intestinal lumen and a blood-facing side, however, a much higher resistance of the cells towards NP-induced stress was noted with little to no impact on cell viability or barrier integrity. Yet, increased levels of Ag, Cu and Zn but not Ti were measured in the blood-side mimicking (basolateral) compartment, indicating translocation of Ag, Cu, and Zn-based NPs or ions liberated from them through the epithelial cell layer. Since especially CuO NPs appeared to be translocated as intact particles, they were investigated in more detail. A time- and temperature-dependent analysis, involving different endocytosis inhibitors, suggested that CuO NPs were translocated through the epithelium by apical caveolae-mediated endocytosis followed by delayed export onto the basolateral side. These data give valuable insights into NP uptake by, and translocation through, the fish intestinal epithelium and will be of value for future research on the molecular mechanisms of NPs that enter the fish via this critical uptake route.
Characterization of extracellular polymeric substances (EPS) from periphyton using liquid chromatography-organic carbon detection–organic nitrogen detection (LC-OCD-OND)
Stewart, Theodora J.; Traber, Jacqueline; Kroll, Alexandra; et al. (2013)
Environmental Science and Pollution Research
A protocol was developed to extract, fractionate, and quantitatively analyze periphyton extracellular polymeric substances (EPS), which obtains both information on the molecular weight (M r) distribution and protein and polysaccharide content. The EPS were extracted from freshwater periphyton between July and December 2011. Organic carbon (OC) compounds from different EPS extracts were analyzed using liquid chromatography-organic carbon detection–organic nitrogen detection (LC-OCD-OND), and total protein and polysaccharide content were quantified. Four distinct OC fractions, on the basis of M r, were identified in all extracts, corresponding to high M r biopolymers (≥80–4 kDa), degradation products of humic substances (M r not available), low M r acids (10–0.7 kDa), and small amphiphilic/neutral compounds (3–0.5 kDa). Low C/N ratios (4.3 ± 0.8) were calculated for the biopolymer fractions, which represented 16–38 % of the measured dissolved organic carbon (DOC), indicating a significant presence of high M r proteins in the EPS. Protein and polysaccharide represented the two major components of EPS and, when combined, accounted for the measured DOC in extracts. Differences in specific OC fractions of EPS extracts over the course of the study could be quantified using this method. This study suggests that LC-OCD-OND is a new valuable tool in EPS characterization of periphyton.
Aerobic methane oxidation under copper scarcity in a stratified lake
Guggenheim, Carole; Brand, Andreas; Bürgmann, Helmut; et al. (2019)
Scientific Reports
Aerobic methane-oxidizing bacteria (MOB) substantially reduce methane fluxes from freshwater sediments to the atmosphere. Their metalloenzyme methane monooxygenase (MMO) catalyses the first oxidation step converting methane to methanol. Its most prevalent form is the copper-dependent particulate pMMO, however, some MOB are also able to express the iron-containing, soluble sMMO under conditions of copper scarcity. So far, the link between copper availability in different forms and biological methane consumption in freshwater systems is poorly understood. Here, we present high-resolution profiles of MOB abundance and pMMO and sMMO functional genes in relation to copper, methane and oxygen profiles across the oxic-anoxic boundary of a stratified lake. We show that even at low nanomolar copper concentrations, MOB species containing the gene for pMMO expression are present at high abundance. The findings highlight the importance of copper as a micronutrient for MOB species and the potential usage of copper acquisition strategies, even under conditions of abundant iron, and shed light on the spatial distribution of these microorganisms.
Interaction of silver nanoparticles with algae and fish cells: a side by side comparison
Yue, Yang; Li, Xiaomei; Sigg, Laura; et al. (2017)
Journal of Nanobiotechnology
Background Silver nanoparticles (AgNP) are widely applied and can, upon use, be released into the aquatic environment. This raises concerns about potential impacts of AgNP on aquatic organisms. We here present a side by side comparison of the interaction of AgNP with two contrasting cell types: algal cells, using the algae Euglena gracilis as model, and fish cells, a cell line originating from rainbow trout (Oncorhynchus mykiss) gill (RTgill-W1). The comparison is based on the AgNP behavior in exposure media, toxicity, uptake and interaction with proteins. Results (1) The composition of exposure media affected AgNP behavior and toxicity to algae and fish cells. (2) The toxicity of AgNP to algae was mediated by dissolved silver while nanoparticle specific effects in addition to dissolved silver contributed to the toxicity of AgNP to fish cells. (3) AgNP did not enter into algal cells; they only adsorbed onto the cell surface. In contrast, AgNP were taken up by fish cells via endocytic pathways. (4) AgNP can bind to both extracellular and intracellular proteins and inhibit enzyme activity. Conclusion Our results showed that fish cells take up AgNP in contrast to algal cells, where AgNP sorbed onto the cell surface, which indicates that the cell wall of algae is a barrier to particle uptake. This particle behaviour results in different responses to AgNP exposure in algae and fish cells. Yet, proteins from both cell types can be affected by AgNP exposure: for algae, extracellular proteins secreted from cells for, e.g., nutrient acquisition. For fish cells, intracellular and/or membrane-bound proteins, such as the Na+/K+-ATPase, are susceptible to AgNP binding and functional impairment.

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Laura Sigg

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