Brood pouch-mediated polystyrene nanoparticle uptake during Daphnia magna embryogenesis

Abstract

Nanoplastic debris is currently expected to be ubiquitously distributed in aquatic environments and an emerging environmental issue affecting organisms across trophic levels. While ingestion of particles receives most attention, other routes of uptake and cellular accumulation remain unexplored. Here, the planktonic filter feeder Daphnia magna was used to track routes of uptake and target tissues of polystyrene nanoparticles (PSNPs). A sublethal concentration of 5 mg L À1 fluorescent PSNPs (25 nm) was used to monitor accumulation in adult animals as well as their embryos in the open brood pouch. A time series throughout embryonic development within the brood pouch revealed accumulation of PSNP in or on lipophilic cells in the early stages of embryonic development while the embryo is still surrounded by a chorion and before the beginning of organogenesis. In contrast, PSNP particles were neither detected in the gut epithelium nor in lipid droplets in adults. An ex vivo exposure of embryos to PSNP demonstrated a similar accumulation of PSNP in or on lipophilic cells, illustrating the likelihood of brood pouch-mediated PSNP uptake by embryos. By demonstrating embryo PSNP uptake via the brood pouch, data presented here give novel insights in bioaccumulation of nanoparticles and likely other lipophilic contaminants. Since this uptake route can occur within a diverse array of aquatic organisms, this study warrants consideration of brood pouch-mediated accumulation in efforts studying the hazards and risks of nanoparticle contamination. ARTICLE HISTORY

When Fluorescence Is not a Particle: The Tissue Translocation of Microplastics in Daphnia magna Seems an Artifact

“…However, this was rare and always in the context of a damaged gut, which was probably caused by the sample handling. Brun et al () made a similar observation in daphnids exposed to 25 nm polystyrene beads and attributed particles outside the gut to damage during sample preparation.…”

“…When exposing Daphnia galeata to 5 mg L -1 of 51 nm green fluorescent polystyrene beads, Cui et al (2017) showed fluorescence inside embryos and lipid droplets and concluded that there is a link to the observed toxicity. Brun et al (2017) investigated the brood pouch of D. magna as a potential exposure pathway for embryos, a mechanism proposed by Rosenkranz et al (2009). They © 2019 SETAC wileyonlinelibrary.com/ETC FIGURE 3: Identical Daphnia magna individuals exposed to 1000 nm polystyrene particles for 24 h before (A) and after (B) 60 min of confocal laser scanning microscopy imaging.…”

The choreography of chemicals in nature; beyond ecotoxicological limits

“…These then shot into the blood flow and we found them throughout the body, in fatty organs and tissues and even in the eyes (Van Pomeren et al, 2017). The neonates within the brood pouch of pregnant water fleas were shown to be covered by fluorescently dyed nanoparticles (Brun et al, 2017). From another study (Cui et al, 2017) it could be concluded that when a pregnant female is exposed to nanomaterials, the offspring get off to a difficult start in life.…”

Quantitative Structural Analysis of Polystyrene Nanoparticles Using Synchrotron X-ray Scattering and Dynamic Light Scattering

“…In particular, particle size is known as a crucial factor to govern the properties and performance [13][14][15][16][17][18][19][20]. To measure nanoparticle size, dynamic light scattering is currently used most widely because of the experimental simplicity and automatized data analysis scheme using the instruments developed in compact type [21][22][23][24][25][26]. However, dynamic light scattering very often provides unrealistically large size and distribution [27][28][29][30][31][32][33][34].…”