Subcellular localization of gold nanoparticles in the estuarine bivalve Scrobicularia plana after exposure through the water

Abstract

Nanoparticles are extensively used particularly in biomedical and industrial applications. Because of their colloidal stability, gold nanoparticles (AuNPs) are suspected being persistent in aquatic ecosystem. Thus, the potential toxicity of gold nanoparticles is addressed by using a bivalve model Scrobicularia plana. Using AuNPs in a range of sizes (5, 15, and 40 nm), we examined their subcellular localization in gills and digestive gland. Clams were exposed to AuNPs stabilized with citrate buffer and then diluted in seawater at the concentration of 100 μgL −1 .After 16 days water-borne exposure, using transmission electron microscopy, few particles were observed in gills, distributed as free in the cytoplasm, or associated with vesicles. In the digestive gland, the most striking feature was the presence of individual or small aggregates 40 nm sized within the nuclei colocalized with DNA. Depending on the size, individual or small aggregates (40 nm AuNPs) or more aggregated NPs (5 and 15 nm) were observed, with at least one of the dimensions (40-50 nm) allowing the passage through nuclear pores. Disorganization of chromatin was marked with an increase in filamentous structures. In some parts no chromatin was visible. Moreover, the perinuclear space from nuclei was enlarged in contaminated clams when compared to controls.

Gold nanoparticles ingested by oyster larvae are internalized by cells through an alimentary endocytic pathway

“…While some aspects described here may can be considered peculiar to larval oysters, the larval digestive system is broadly similar to that reported for adult bivalves which feature a similar filter feeding alimentary strategy and intercellular digestion mechanism, allowing for NP cellular internalization at the digestive gland barrier (Koehler et al, 2008, Renault et al, 2008, Joubert et al, 2013. The main difference is that adult bivalves have a more complex open blood system, pre-and post-ingestive sorting processes and digestive apparatus than larvae (e.g.…”

“…hyperspectral imaging, confocal microscopy, near infrared fluorescence microscopy) typically cannot resolve individual particles and/or the cellular structures where the particle-associated signal is detected, leaving knowledge gaps on the transportation mechanisms employed and on the actual fate of NPs inside cells (Meyer et al, 2010, Unrine et al, 2010, Hull et al, 2011, Kwok et al, 2012, Ambrosone et al, 2014, Schultz et al, 2015. In contrast, the higher resolution transmission electron microscopy (TEM), which enables a detailed view of NP intracellular localization, is generally confined to a limited number of sections or samples, and may lack insight into the magnitude and the overall consistency of the permeation and translocation phenomenon, when applied to whole organism (Renault et al, 2008, Joubert et al, 2013, Schultz et al, 2015, Wray and Klaine, 2015.…”

Tissue specific responses to cadmium-based quantum dots in the marine mussel Mytilus galloprovincialis

“…Furthermore, QD aggregates/agglomerates can be broken by action of cilia in the gills (Joubert et al 2013;Katsumiti et al, 2014;Rocha et al, 2015b). Branchial epithelium is the first contact between the body surface and different Cd forms (QDs and or Cd 2+ ions released from QD core).…”

“…galloprovincialis (Joubert et al 2013;Katsumiti et al, 2014;Rocha et al, 2015b). In bivalve molluscs, digestive gland is the main site for metabolic regulation, detoxification and elimination of xenobiotics, besides participating in the regulation of homeostasis, immune defense and reproductive process (Gomes et al, 2012;Marigómez et al, 2012).…”

Introduction

“…Nanomaterials can have one (e.g., nanosheet), two (e.g., nanotube), or three dimensions (e.g., nanoparticle) in the nanoscale. However, recent studies carried out at much lower doses were able to reveal that all the nanoparticles tested were incorporated in the whole organisms but also enter the cells (Chapter 17) and even the nucleus (e.g., Joubert et al, 2013). An inventory of nanotechnology-based consumer products introduced on the market (http://www.nanotechproject.org/cpi/) reveals that the number of products exploded from 54 in 2005 to 1628 in October 2013, the main product categories being in the field of health and fitness (personal care, clothing, cosmetics, sporting goods, filtration), home and garden, automotive, food, and beverages.…”