Neurotoxicity Evaluation of Nanomaterials Using C. elegans: Survival, Locomotion Behaviors, and Oxidative Stress

Abstract

Nanomaterials are broadly used in a variety of industries and consumer products. However, studies have demonstrated that many nanomaterials, including metal-containing nanoparticles and nanoplastics, have neurotoxic effects. Caenorhabditis elegans (C. elegans) is a widely used model organism with numerous advantages for research, including transparency, short life span, wellcharacterized nervous system, complete connectome, available genome, and numerous genetic tools. C. elegans has been extensively used to assess the neurotoxicity of multiple chemicals via survival assays, behavioral tests, neuronal morphology studies, and various molecular and mechanistic analyses. However, detailed protocols describing general assays in C. elegans to examine the neurotoxic effects of nanomaterials are limited. Here, we describe protocols for assessing nanomaterial neurotoxicity in C. elegans. We describe the steps for exposure and subsequent evaluation of survival, locomotion behavior, and oxidative stress. Survival and locomotion behavior are measured in wild-type N2 strains to assess acute neurotoxicity. Oxidative stress is used as an endpoint here since it is one of the most predominant and common changes induced by nanomaterials. VP596 nematodes, which express GFP upon activation of skn-1 (the worm homolog of Nrf2), are evaluated for assays of oxidative stress in response to test nanomaterials. These assays can be readily used to quickly examine the neurotoxicity of nanomaterials in vivo, laying the foundation for mechanistic studies of nanomaterials and their impacts on health and physiology.

Charge-regulated fluorescent anchors enable high-fidelity tracking of plasma membrane dynamics during biological events

“…Locomotion behaviors such as body bending and head thrashing were thus measured to reect the functional state of motor neurons. 40 We found that CSP-DBO up to 40 mM did not signicantly affect body bend or head thrash of the worms (Fig. S12 †), indicating that CSP-DBO had no obvious neurotoxic effect in C. elegans.…”

Silica Nanoparticles Disclose a Detailed Neurodegeneration Profile throughout the Life Span of a Model Organism

“…The somata of HSN neurons were located close to the vulva, whereas dendritic processes extended along the ventral nerve cord to the head (Figure 1A; inset 3). After exposition to silica NPs, the fluorescent signal of all dendritic processes changed to dotted patterns (Figure 1B; insets [4][5][6] that usually indicate dendritic beading and neurodegeneration. Quantification in young and middle-aged C. elegans showed that nano silica-induced a significant age-related increase in neurodegeneration in the serotonergic neurons ADF, HSN and NSM compared to mock-exposed controls and reporter nematodes that were exposed to BULK silica particles with a larger diameter (Figure 1C).…”

“…As beading precedes the retraction of dendrites to the soma and usually heralds neuronal death, early and specific beading of dopaminergic PDE neurons may serve as a disease model that mimics the death of specific dopaminergic neurons in PD [7,17]. The insets show blow-ups of the ADF dendrites, the NSM processes and the HSN axons (1)(2)(3)(4)(5)(6). A discontinuous punctate fluorescence pattern was categorized as neurodegeneration.…”

“…Nano silica has turned out as a reliable tool to induce the degeneration of defined dopaminergic and serotonergic neurons in the animal model Caenorhabditis elegans ( C. elegans ). A short life span of 2–3 weeks as an adult hermaphrodite and only 302 neurons that constitute a simple but representative nervous system enables the investigation of the schedule of neurodegeneration in young, middle-aged and old nematodes, e.g., over the entire adult life [ 3 , 4 ]. Neural signaling via dopaminergic, serotonergic or cholinergic neurotransmitters is conserved between C. elegans and higher organisms, including mammals [ 5 ].…”

Comprehensive Neurotoxicity of Lead Halide Perovskite Nanocrystals in Nematode Caenorhabditis elegans

“…Moreover, C. elegans has been applied as a valuable model to evaluate the neurotoxicity of various chemicals because of the conservation of the biocharacteristics of neurotransmitters of the human in the worm. [29,31,[41][42][43][44] Thus, we employed C. elegans as the model organism for the neurotoxicology evaluation of SA-CsPbBr 3 PeQDs. The array of endpoints consisting of locomotive behaviors, forging behavior, pharyngeal pumping, brood size, and lifespan was performed to provide information on the potential risks of PeQDs in the neural system.…”