Aschner M et al. (2017) Metallomics "Imaging metals in Caenorhabditis elegans."

Bornhorst J, Sperling M, Schwerdtle T, Karst U, Palinski C, Aschner M

[Metallomics, 2017]

Systemic trafficking and storage of essential metal ions play fundamental roles in living organisms by serving as essential cofactors in various cellular processes. Thereby metal quantification and localization are critical steps in understanding metal homeostasis, and how their dyshomeostasis might contribute to disease etiology and the ensuing pathologies. Furthermore, the amount and distribution of metals in organisms can provide insight into their underlying mechanisms of toxicity and toxicokinetics. While in vivo studies on metal imaging in mammalian experimental animals are complex, time- and resource-consuming, the nematode Caenorhabditis elegans (C. elegans) provides a suitable comparative and complementary model system. Expressing homologous genes to those inherent to mammals, including those that regulate metal homeostasis and transport, C. elegans has become a powerful tool to study metal homeostasis and toxicity. A number of recent technical advances have been made in the development and application of analytical methods to visualize metal ions in C. elegans. Here, we briefly summarize key findings and challenges of the three main techniques and their application to the nematode, namely sensing fluorophores, microbeam synchrotron radiation X-ray fluorescence as well as laser ablation (LA) coupled to inductively coupled plasma-mass spectrometry (ICP-MS).

Aschner M et al. (2010) Neurotoxicology "Gene-environment interactions: neurodegeneration in non-mammals and mammals."

Helmcke KJ, Ponnoru P, Avila DS, Forsby A, Sunol C, Connor JR, Ali RH, Upchurch L, Linney E, Sledge D, Donerly S, Levin ED, Olopade JO, Aschner M

[Neurotoxicology, 2010]

The understanding of how environmental exposures interact with genetics in central nervous system dysfunction has gained great momentum in the last decade. Seminal findings have been uncovered in both mammalian and non-mammalian model in large result of the extraordinary conservation of both genetic elements and differentiation processes between mammals and non-mammalians. Emerging model organisms, such as the nematode and zebrafish have made it possible to assess the effects of small molecules rapidly, inexpensively, and on a miniaturized scale. By combining the scale and throughput of in vitro screens with the physiological complexity and traditional animal studies, these models are providing relevant information on molecular events in the etiology of neurodegenerative disorders. The utility of these models is largely driven by the functional conservation seen between them and higher organisms, including humans so that knowledge obtained using non-mammalian model systems can often provide a better understanding of equivalent processes, pathways, and mechanisms in man. Understanding the molecular events that trigger neurodegeneration has also greatly relied upon the use of tissue culture models. The purpose of this summary is to provide-state-of-the-art review of recent developments of non-mammalian experimental models and their utility in addressing issues pertinent to neurotoxicity (Caenorhabditis elegans and Danio rerio). The synopses by Aschner and Levin summarize how genetic mutants of these species can be used to complement the understanding of molecular and cellular mechanisms associated with neurobehavioral toxicity and neurodegeneration. Next, studies by Sunol and Olopade detail the predictive value of cultures in assessing neurotoxicity. Sunol and colleagues summarize present novel information strategies based on in vitro toxicity assays that are predictive of cellular effects that can be extrapolated to effects on individuals. Olopade and colleagues describe cellular changes caused by sodium metavanadate (SMV) and demonstrate how rat primary astrocyte cultures can be used as predicitive tools to assess the neuroprotective effects of antidotes on vanadium-induced astrogliosis and demyelination.

Aschner M et al. (2009) J Toxicol Environ Health B Crit Rev "Toxicity studies on depleted uranium in primary rat cortical neurons and in Caenorhabditis elegans: what have we learned?"

Jiang GC, Aschner M

[J Toxicol Environ Health B Crit Rev, 2009]

Depleted uranium (DU) is the major by-product of the uranium enrichment process for its more radioactive isotopes, retaining approximately 60% of its natural radioactivity. Given its properties as a pyrophoric and dense metal, it has been extensively used in armor and ammunitions. Questions have been raised regarding the possible neurotoxic effects of DU in humans based on follow-up studies in Gulf War veterans, where a decrease in neurocognitive behavior in a small population was noted. Additional studies in rodents indicated that DU readily traverses the blood-brain barrier, accumulates in specific brain regions, and results in increased oxidative stress, altered electrophysiological profiles, and sensorimotor deficits. This review summarizes the toxic potential of DU with emphasis on studies on thiol metabolite levels, high-energy phosphate levels, and isoprostane levels in primary rat cortical neurons. Studies in Caenorhabditis elegans detail the role of metallothioneins, small thiol-rich proteins, in protecting against DU exposure. In addition, recent studies also demonstrate that only one of the two forms, metallothionein-1, is important in the accumulation of uranium in worms.

Au C et al. (2008) Neurotoxicology "Manganese transport in eukaryotes: the role of DMT1."

Au C, Benedetto A, Aschner M

[Neurotoxicology, 2008]

Manganese (Mn) is a transition metal that is essential for normal cell growth and development, but is toxic at high concentrations. While Mn deficiency is uncommon in humans, Mn toxicity is known to be readily prevalent due to occupational overexposure in miners, smelters and possibly welders. Excessive exposure to Mn can cause Parkinson''s disease-like syndrome; patients typically exhibit extrapyramidal symptoms that include tremor, rigidity and hypokinesia [Calne DB, Chu NS, Huang CC, Lu CS, Olanow W. Manganism and idiopathic parkinsonism: similarities and differences. Neurology 1994;44(9):1583-6; Dobson AW, Erikson KM, Aschner M. Manganese neurotoxicity. Ann NY Acad Sci 2004;1012:115-28]. Mn-induced motor neuron diseases have been the subjects of numerous studies; however, this review is not intended to discuss its neurotoxic potential or its role in the etiology of motor neuron disorders. Rather, it will focus on Mn uptake and transport via the orthologues of the divalent metal transporter (DMT1) and its possible implications to Mn toxicity in various categories of eukaryotic systems, such as in vitro cell lines, in vivo rodents, the fruitfly, Drosophila melanogaster, the honeybee, Apis mellifera L., the nematode, Caenorhabditis elegans and the baker''s yeast, Saccharomyces cerevisiae.

Colonnello A et al. (2020) Neurotox Res "Correction to: Comparing the Neuroprotective Effects of Caffeic Acid in Rat Cortical Slices and Caenorhabditis elegans: Involvement of Nrf2 and SKN-1 Signaling Pathways."

Tunez I, Rubio-Lopez LC, Aguilera-Portillo G, Silva-Palacios A, Evaristo-Priego Y, Santamaria A, Galvan-Arzate S, Cortez-Nunez S, Aschner M, Rangel-Lopez E, Chen P, Colonnello A, Robles-Banuelos B, Garcia-Contreras R

[Neurotox Res, 2020]

One of the authors has incorrect family name spelling in the original article_. Michael Ashner should read as Michael Aschner.

Caito SW et al. (2015) Curr Protoc Toxicol "Quantification of Glutathione in Caenorhabditis elegans."

Caito SW, Aschner M

[Curr Protoc Toxicol, 2015]

Glutathione (GSH) is the most abundant intracellular thiol with diverse functions from redox signaling, xenobiotic detoxification, and apoptosis. The quantification of GSH is an important measure for redox capacity and oxidative stress. This protocol quantifies total GSH from Caenorhabditis elegans, an emerging model organism for toxicology studies. GSH is measured using the 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) cycling method originally created for cell and tissue samples but optimized for whole worm extracts. DTNB reacts with GSH to from a 5'-thio-2-nitrobenzoic acid (TNB) chromophore with maximum absorbance of 412 nm. This method is both rapid and sensitive, making it ideal for studies involving a large number of transgenic nematode strains.

Lee KH et al. (2016) Curr Protoc Toxicol "A Simple Light Stimulation of Caenorhabditis elegans."

Aschner M, Lee KH

[Curr Protoc Toxicol, 2016]

Response via noxious stimulus can be an important indicator of sensory neuron function and overall health of an organism. If the stimulation is quick and simple, and the animal can be rescued afterwards, such a method not only allows for assays pertaining to changed sensory ability after various treatments, but also increases the reliability of the statistical relationships that are established. This protocol demonstrates a stimulation assay in Caenorhabditis elegans, using blue light from common laboratory equipment: the fluorescent microscope. The nematode detects blue light using a set of amphid ciliary sensory neurons, and blue light is detrimental to its overall health after a prolonged exposure. However, under brief exposure, blue light stimulation provides a rapid and easy method for quantifying sensory functions and health without harming the animal. 2016 by John Wiley & Sons, Inc.

Pinkas A et al. (2016) Chem Res Toxicol "AGEs/RAGE-related neurodegeneration: daf-16 as a mediator, insulin as an ameliorant and C. elegans as an expedient research model."

Pinkas A, Aschner M

[Chem Res Toxicol, 2016]

Advanced glycation end-products (AGEs) are non-enzymatically glycated proteins, lipids and nucleic acids. These compounds both originate exogenously and are formed endogenously, and are associated, along with one of their receptors - RAGE, with a variety of pathologies and neurodegeneration. Some of their deleterious effects include affecting insulin signaling and FOXO-related pathways in both receptor-dependent and -independent manner. A potential ameliorating agent for these effects is insulin, which is being studied in several in vivo and in vitro models; one of these models is C. elegans, whose maintenance, genetic malleability and well-described longevity-related pathways make it an optimal complementary model for assessing these objectives. In the realm of neuroscience, this model is currently being used only for general assessment of neurodegeneration and shortened lifespan; We suggest that characterization of a) the effects of AGEs/RAGE on specific neurotransmitter systems, b) the role of the daf-2/daf-16 pathway in these neurodegenerative processes and c) the amending properties of insulin would greatly contribute to a more comprehensive understanding of AGEs-related neurodegeneration and, potentially, would lead to developing efficient therapeutic strategies.

Nguyen TT et al. (2014) Curr Protoc Toxicol "F3-Isoprostanes as a Measure of in vivo Oxidative Damage in Caenorhabditis elegans."

Aschner M, Nguyen TT

[Curr Protoc Toxicol, 2014]

Oxidative stress has been implicated in the development of a wide variety of disease processes, including cardiovascular disease, cancer, and neurodegenerative diseases, as well as progressive and normal aging processes. Isoprostanes (IsoPs) are prostaglandin-like compounds that are generated in vivo from lipid peroxidation of arachidonic acid (AA, C20:4, -6) and other polyunsaturated fatty acids (PUFA). Since the discovery of IsoPs by Morrow and Roberts in 1990, quantification of IsoPs has been shown to be an excellent source of biomarkers of in vivo oxidative damage. Eicosapentaenoic acid (EPA, C20:5, -3) is the most abundant PUFA in Caenorhabditis elegans and gives rise to F3-IsoPs upon nonenzymatic free-radical-catalyzed lipid peroxidation. The protocol presented is the current methodology that our laboratory uses to quantify F3-IsoPs in C. elegans using gas chromatography/mass spectrometry (GC/MS). The methods described herein have been optimized and validated to provide the best sensitivity and selectivity for quantification of F3-IsoPs from C. elegans lysates.

Pinkas A et al. (2016) Chem Res Toxicol "Advanced glycation end-products and their receptors: related pathologies, recent therapeutic strategies and a potential model for future neurodegeneration studies."

Pinkas A, Aschner M

[Chem Res Toxicol, 2016]

Advanced glycation end products (AGEs) are the result of a non-enzymatic reaction between sugars and either proteins, lipids or nucleic acids. AGEs are both consumed and endogenously formed; their accumulation is accelerated under hyperglycemic and oxidative stress conditions, and they are associated with the onset and complication of many diseases, such as cardiovascular diseases, diabetes and Alzheimer's disease. AGEs exert their deleterious effects by either accumulating in the circulation and tissues, or by receptor-mediated signal transduction. Several receptors bind AGEs: some are specific and contribute to clearance of AGEs, while some - like the RAGE receptor - are non-specific, associated with inflammation and oxidative stress and are considered as the mediators of the aforementioned AGEs-related diseases. While several anti-AGEs compounds have been studied, understanding the underlying mechanisms of RAGE and targeting it as a therapeutic strategy is becoming increasingly desirable; In order to achieve these goals efficiently and expeditiously the C. elegans model suggested. This model is already used for studying several human diseases and by expressing RAGE could also be used to study RAGE-related pathways and pathologies and to facilitate the development of novel therapeutic strategies.