Nanoparticle-Biological Interactions in a Marine Benthic Foraminifer

Abstract

The adverse effects of engineered nanomaterials (ENM) in marine environments have recently attracted great attention although their effects on marine benthic organisms such as foraminifera are still largely overlooked. Here we document the effects of three negatively charged ENM, different in size and composition, titanium dioxide (TiO2), polystyrene (PS) and silicon dioxide (SiO2), on a microbial eukaryote (the benthic foraminifera Ammonia parkinsoniana) using multiple approaches. This research clearly shows the presence, within the foraminiferal cytoplasm, of metallic (Ti) and organic (PS) ENM that promote physiological stress. Specifically, marked increases in the accumulation of neutral lipids and enhanced reactive oxygen species production occurred in ENM-treated specimens regardless of ENM type. This study indicates that ENM represent ecotoxicological risks for this microbial eukaryote and presents a new model for the neglected marine benthos by which to assess natural exposure scenarios.

Behavior and Bio-Interactions of Anthropogenic Particles in Marine Environment for a More Realistic Ecological Risk Assessment

“…Under controlled laboratory conditions, TiO 2 stock suspensions are extensively sonicated prior to use to ensure a good dispersion in the exposure media, as described by Brunelli et al (2013). Once in NSW, TiO 2 NPs have been shown to quickly agglomerate, reaching micrometric sizes and wide size distribution within the first minutes after the preparation of the colloidal suspensions (Della Torre et al, 2015b;Hu et al, 2018;Ciacci et al, 2019). The same behavior has been observed in standard marine algal culture (F/2) medium, characterized by high salt content (Morelli et al, 2018).…”

“…The measurement of ζ-potential (mV) by EM can be used as an indicator of the NP surface charge and, thus, colloidal stability in the medium, with low absolute values usually associated with the screening of NP surface charge (Mourdikoudis et al, 2018). DLS and EM techniques are usually coupled with scanning or transmission electron microscopy (SEM/TEM), which allow to display the agglomeration state of colloidal suspensions and also the specific interactions occurring at the biological surfaces, such as bacteria (Gupta et al, 2016;Fu et al, 2018), microalgae (e.g., Chen et al, 2011;Wang et al, 2016;Bergami et al, 2017;González-Fernández et al, 2019;Seoane et al, 2019), and invertebrate cells (e.g., Canesi et al, 2016a,b;Ciacci et al, 2019). The limit of these techniques is the high concentration of the sample required (usually in the range of µg ml −1 ) (Ribeiro et al, 2017), which often do not reflect PECs for the anthropogenic NPs, in the range of µg L −1 for TiO 2 NPs and ng L −1 for PS NPs (da Silva et al, 2011;Gottschalk et al, 2013).…”

Assessing the Cadmium Effects on the Benthic Foraminifer Ammonia cf. parkinsoniana: An Acute Toxicity Test

“…parkinsoniana were placed on Petri dishes covered with NSW. This taxon was chosen to have a comparison with previous published papers [25,26,28]. In fact, this taxon has been selected, in previous studies, to test the effects of lead [25], mercury [26] and a set of nanoparticles (titanium dioxide, polystyrene and silicon dioxide) [28].…”

“…Polar lipids (i.e., phospholipids), which are mostly present in membranes, fluoresce red (emission >590 nm) whereas lipids fluoresce yellow (570-590 nm) [33,34]. The specimens were treated, observed and imaged following the methodology of [26,28]. The NR mean fluorescence intensity (MFI) analyses were performed using ImageJ software (NIH, Bethesda, MD, USA) by imaging specimens at the same level of magnification, and determining the MFI of all the selected pixels.…”

“…Heavy metals are known to induce assemblages' (e.g., [19,45,46]) as well as physiological alteration and ultrastructure changes in benthic foraminifera (e.g., [22,26,45]). At ultrastructural level, these changes include the thickening of the organic lining, mitochondrial degeneration, proliferation of degradation vacuoles, lysosomes, residual bodies and the increased production of neutral lipids and of reactive oxygen species (i.e., [20,28]). Nile Red is a probe widely used to distinguish neutral from polar lipids.…”