Development and application of a ratiometric nanosensor for measuring pH inside the gastrointestinal tract of zooplankton

Davis, A. D.; Nasser, Fatima; Lead, Jamie R.; Shi, Zongbo

doi:10.1039/c9en01300h

Cited by 8 publications

(6 citation statements)

References 35 publications

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“…We employed an organic fluorogen with AIE features, tetraphenyl-ethenecyanine adduct (TPE-Cy), capable of mapping the pH in the whole gastrointestinal tract of D. magna. In the control group, the pH was significantly lower in the anterior section than in the posterior section (Figure a,b), consistent with earlier studies . All MNP particles at environmentally relevant concentration exposures played a previously unappreciated role in modulating pH in the gut of D.…”

Section: Resultssupporting

confidence: 79%

“…25 In the control group, the pH was significantly lower in the anterior section than in the posterior section (Figure 4a,b), consistent with earlier studies. 39 All MNP particles at environmentally relevant concentration exposures played a previously unappreciated role in modulating pH in the gut of D. magna. Specifically, the ingested MNPs could readily change the pH distribution after 1 h, with position of accumulated MNPs showing a decreasing trend of pH.…”

Section: Ph Esterase and Inflammation Responses In The Gutmentioning

confidence: 99%

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Accumulation Kinetics and Gut Microenvironment Responses to Environmentally Relevant Doses of Micro/Nanoplastics by Zooplankton Daphnia Magna

Wang

2023

Environ. Sci. Technol.

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Microplastics are emerging pollutants that have been widely reported in aquatic ecosystems. Based on the analysis of environmentally relevant concentrations of microplastics in global freshwater systems, herein, we employed aggregated-induced emission (AIE) microplastic fluorogens and imaged and quantified the bioaccumulation of differentially charged micro-(20 μm)/ nano-(200 nm) plastics (MNPs) in zooplankton Daphnia magna. We found that all particles of different sizes and charges were readily ingested, especially larger-sized and positively charged MNPs, with over 50% of the ingested particles accumulating in the gut. Bioaccumulation of MNPs reached 50% of steady-state condition within 1 h. The presence of algae inhibited the ingestion and depuration of MNPs. To further demonstrate the effects of such accumulation on gut health, we further applied the AIE probes for visualizing the pH and esterase in the digestive tract, as well as the gut inflammation. An accumulation of MNPs in D. magna significantly and rapidly induced the acidification of gut pH while inducing esterase activity. The NPs apparently induced gut inflammation in contrast to the MPs, demonstrating the size-dependent effects on oxidative stress. Our results highlighted that MNP exposure at environmentally relevant concentrations perturbed the microenvironments of zooplankton guts, which may significantly affect their digestion and assimilation of food materials as well as contaminant uptake.

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Section: Resultssupporting

confidence: 79%

Section: Ph Esterase and Inflammation Responses In The Gutmentioning

confidence: 99%

Accumulation Kinetics and Gut Microenvironment Responses to Environmentally Relevant Doses of Micro/Nanoplastics by Zooplankton Daphnia Magna

Wang

2023

Environ. Sci. Technol.

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“…The highest Au ion release in daphnids was detected for rod-shaped 50 × 100 nm Au-NMs, followed by spherical 100 nm NMs, which resulted in releases of 56% and 39% of the NM mass, respectively. The dissolution of the Au-NMs in the daphnids could have occurred in the gut, which has a lower pH (∼4) than the exposure medium 12 , 39 . Absorption of a biomolecule corona to the surface of NMs when they enter the daphnids can also accelerate the dissolution of the particles if there is a strongly Au-binding protein present or can slow dissolution by promoting sulfidation processes 40 .…”

Section: Resultsmentioning

confidence: 99%

Particle number-based trophic transfer of gold nanomaterials in an aquatic food chain

et al. 2021

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Analytical limitations considerably hinder our understanding of the impacts of the physicochemical properties of nanomaterials (NMs) on their biological fate in organisms. Here, using a fit-for-purpose analytical workflow, including dosing and emerging analytical techniques, NMs present in organisms are characterized and quantified across an aquatic food chain. The size and shape of gold (Au)-NMs are shown to control the number of Au-NMs attached to algae that were exposed to an equal initial concentration of 2.9 × 1011 particles mL−1. The Au-NMs undergo size/shape-dependent dissolution and agglomeration in the gut of the daphnids, which determines the size distribution of the NMs accumulated in fish. The biodistribution of NMs in fish tissues (intestine, liver, gills, and brain) also depends on NM size and shape, although the highest particle numbers per unit of mass are almost always present in the fish brain. The findings emphasize the importance of physicochemical properties of metallic NMs in their biotransformations and tropic transfers.

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“…For example, Nile red is often used as a stain to identify MP in environmental samples, but this dye is also widely used for lipid staining within Daphnia which can lead to overestimation of internalised MPs concentrations and retention. Furthermore, the change in internal biological conditions (such as pH) can affect the fluorescent signalling from the dye which can significantly impact the results or could further impact the dye leaching from the particles (Triebskorn et al, 2019;Davis et al, 2020).…”

Section: Bioaccumulation Of Nms In Aquatic Food Webs and Quantificati...mentioning

confidence: 99%

Daphnia as a model organism to probe biological responses to nanomaterials—from individual to population effects via adverse outcome pathways

et al. 2023

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The importance of the cladoceran Daphnia as a model organism for ecotoxicity testing has been well-established since the 1980s. Daphnia have been increasingly used in standardised testing of chemicals as they are well characterised and show sensitivity to pollutants, making them an essential indicator species for environmental stress. The mapping of the genomes of D. pulex in 2012 and D. magna in 2017 further consolidated their utility for ecotoxicity testing, including demonstrating the responsiveness of the Daphnia genome to environmental stressors. The short lifecycle and parthenogenetic reproduction make Daphnia useful for assessment of developmental toxicity and adaption to stress. The emergence of nanomaterials (NMs) and their safety assessment has introduced some challenges to the use of standard toxicity tests which were developed for soluble chemicals. NMs have enormous reactive surface areas resulting in dynamic interactions with dissolved organic carbon, proteins and other biomolecules in their surroundings leading to a myriad of physical, chemical, biological, and macromolecular transformations of the NMs and thus changes in their bioavailability to, and impacts on, daphnids. However, NM safety assessments are also driving innovations in our approaches to toxicity testing, for both chemicals and other emerging contaminants such as microplastics (MPs). These advances include establishing more realistic environmental exposures via medium composition tuning including pre-conditioning by the organisms to provide relevant biomolecules as background, development of microfluidics approaches to mimic environmental flow conditions typical in streams, utilisation of field daphnids cultured in the lab to assess adaption and impacts of pre-exposure to pollution gradients, and of course development of mechanistic insights to connect the first encounter with NMs or MPs to an adverse outcome, via the key events in an adverse outcome pathway. Insights into these developments are presented below to inspire further advances and utilisation of these important organisms as part of an overall environmental risk assessment of NMs and MPs impacts, including in mixture exposure scenarios.

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Development and application of a ratiometric nanosensor for measuring pH inside the gastrointestinal tract of zooplankton

Abstract: The pH in the anterior gut of Daphnia magna is more than 2 pH units lower than the cultural medium.

Cited by 8 publications

References 35 publications

Accumulation Kinetics and Gut Microenvironment Responses to Environmentally Relevant Doses of Micro/Nanoplastics by Zooplankton Daphnia Magna

Accumulation Kinetics and Gut Microenvironment Responses to Environmentally Relevant Doses of Micro/Nanoplastics by Zooplankton Daphnia Magna

Particle number-based trophic transfer of gold nanomaterials in an aquatic food chain

Daphnia as a model organism to probe biological responses to nanomaterials—from individual to population effects via adverse outcome pathways

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