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[
Nat Protoc,
2016]
Mitochondrial dysfunction is at the core of many diseases ranging from inherited metabolic diseases to common conditions that are associated with aging. Although associations between aging and mitochondrial function have been identified using mammalian models, much of the mechanistic insight has emerged from Caenorhabditis elegans. Mitochondrial respiration is recognized as an indicator of mitochondrial health. The Seahorse XF96 respirometer represents the state-of-the-art platform for assessing respiration in cells, and we adapted the technique for applications involving C. elegans. Here we provide a detailed protocol to optimize and measure respiration in C. elegans with the XF96 respirometer, including the interpretation of parameters and results. The protocol takes 2 d to complete, excluding the time spent culturing C. elegans, and it includes (i) the preparation of C. elegans samples, (ii) selection and loading of compounds to be injected, (iii) preparation and execution of a run with the XF96 respirometer and (iv) postexperimental data analysis, including normalization. In addition, we compare our XF96 application with other existing techniques, including the eight-well Seahorse XFp. The main benefits of the XF96 include the limited number of worms required and the high throughput capacity due to the 96-well format.
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[
Methods Mol Biol,
2019]
Caenorhabditis elegans is widely used to investigate biological processes related to health and disease. Multiple C. elegans models for human neurodegenerative diseases do exist, including those expressing human -synuclein. Even though these models do not feature all pathological and molecular hallmarks of the disease they mimic, they allow for the identification and dissection of molecular pathways that are involved. In line with this, genetic screens have yielded multiple modifiers of proteotoxicity in C. elegans models for neurodegenerative diseases. Here, we describe a set of common screening approaches and tools that can be used to study synucleinopathies and other neurodegenerative diseases in C. elegans. RNA interference and mutagenesis screens can be used to find genes that affect proteotoxicity, while relatively simple molecular, cellular (fractionation studies), metabolic (respiration studies), and behavioral (thrashing and crawling) readouts can be used to study the effects of disease proteins and modifiers more closely.
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[
MicroPubl Biol,
2023]
Transactive response DNA binding-protein 43 (TDP-43) is a conserved RNA/DNA-binding protein with a role in RNA metabolism and homeostasis. Aberrant TDP-43 functioning has been considered a major culprit in amyotrophic lateral sclerosis (ALS). <i>Caenorhabditis elegans</i> can be used to phenocopy ALS <i>in vivo</i> . Since disrupted locomotion is a strong readout of toxicity, we examined multiple motor phenotypes of a <i>C. elegans</i> model expressing human wild-type <i>TDP-43</i> ( <i>hTDP-43</i> ) pan-neuronally. Our data reveal that impaired locomotion includes more than the common deficits in crawling capacity and the presence of early-onset paralysis. We show that reduced thrashing, abnormal coiling, and decreased pharyngeal pumping are also observed, in a temperature-dependent fashion.
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[
BMC Biol,
2021]
BACKGROUND: Optogenetics allows the experimental manipulation of excitable cells by a light stimulus without the need for technically challenging and invasive procedures. The high degree of spatial, temporal, and intensity control that can be achieved with a light stimulus, combined with cell type-specific expression of light-sensitive ion channels, enables highly specific and precise stimulation of excitable cells. Optogenetic tools have therefore revolutionized the study of neuronal circuits in a number of models, including Caenorhabditis elegans. Despite the existence of several optogenetic systems that allow spatial and temporal photoactivation of light-sensitive actuators in C. elegans, their high costs and low flexibility have limited wide access to optogenetics. Here, we developed an inexpensive, easy-to-build, modular, and adjustable optogenetics device for use on different microscopes and worm trackers, which we called the OptoArm. RESULTS: The OptoArm allows for single- and multiple-worm illumination and is adaptable in terms of light intensity, lighting profiles, and light color. We demonstrate OptoArm's power in a population-based multi-parameter study on the contributions of motor circuit cells to age-related motility decline. We found that individual components of the neuromuscular system display different rates of age-dependent deterioration. The functional decline of cholinergic neurons mirrors motor decline, while GABAergic neurons and muscle cells are relatively age-resilient, suggesting that rate-limiting cells exist and determine neuronal circuit ageing. CONCLUSION: We have assembled an economical, reliable, and highly adaptable optogenetics system which can be deployed to address diverse biological questions. We provide a detailed description of the construction as well as technical and biological validation of our set-up. Importantly, use of the OptoArm is not limited to C. elegans and may benefit studies in multiple model organisms, making optogenetics more accessible to the broader research community.
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[
MicroPubl Biol,
2023]
Cytoplasmic inclusions consisting of transactive response DNA-binding protein 43 (TDP-43) are a key hallmark of TDP-43 proteinopathies like amyotrophic lateral sclerosis (ALS). Caenorhabditis elegans is considered a useful model for studying the molecular mechanisms underlying TDP-43 toxicity in vivo . Here, we assessed different neuronal systems through established behavioral assays and extended the phenotypic characterisation of a C. elegans model expressing wildtype human TDP-43 ( hTDP-43 ) pan-neuronally. Our data show that neuronal expression of hTDP-43 in C. elegans disrupts chemotaxis and decreases fecundity. The basal slowing response, on the other hand, appears to be preserved in the presence of hTDP-43.
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Brown AEX, Nollen EAA, Janssen L, Koopman M, Wardenaar R, Hogewerf W, Gungordu L, Seinstra RI, Okerlund N, Richmond JE, Jorgensen EM, Islam P
[
Cell Rep,
2024]
Amyotrophic lateral sclerosis can be caused by abnormal accumulation of TAR DNA-binding protein 43 (TDP-43) in the cytoplasm of neurons. Here, we use a C.&#
xa0;elegans model for TDP-43-induced toxicity to identify the biological mechanisms that lead to disease-related phenotypes. By applying deep behavioral phenotyping and subsequent dissection of the neuromuscular circuit, we show that TDP-43 worms have profound defects in GABA neurons. Moreover, acetylcholine neurons appear functionally silenced. Enhancing functional output of repressed acetylcholine neurons at the level of, among others, G-protein-coupled receptors restores neurotransmission, but inefficiently rescues locomotion. Rebalancing the excitatory-to-inhibitory ratio in the neuromuscular system by simultaneous stimulation of the affected GABA- and acetylcholine neurons, however, not only synergizes the effects of boosting individual neurotransmitter systems, but instantaneously improves movement. Our results suggest that interventions accounting for the altered connectome may be more efficient in restoring motor function than those solely focusing on diseased neuron populations.
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[
Nat Protoc,
2020]
Caenorhabditis elegans is a valuable model organism in biomedical research that has led to major discoveries in the fields of neurodegeneration, cancer and aging. Because movement phenotypes are commonly used and represent strong indicators of C. elegans fitness, there is an increasing need to replace manual assessments of worm motility with automated measurements to increase throughput and minimize observer biases. Here, we provide a protocol for the implementation of the improved wide field-of-view nematode tracking platform (WF-NTP), which enables the simultaneous analysis of hundreds of worms with respect to multiple behavioral parameters. The protocol takes only a few hours to complete, excluding the time spent culturing C. elegans, and includes (i) experimental design and preparation of samples, (ii) data recording, (iii) software management with appropriate parameter choices and (iv) post-experimental data analysis. We compare the WF-NTP with other existing worm trackers, including those having high spatial resolution. The main benefits of WF-NTP relate to the high number of worms that can be assessed at the same time on a whole-plate basis and the number of phenotypes that can be screened for simultaneously.
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[
MicroPubl Biol,
2023]
Inclusions consisting of transactive response DNA-binding protein 43 (TDP-43) are a characteristic feature of amyotrophic lateral sclerosis (ALS). <i>Caenorhabditis elegans</i> has been instrumental in studying the underlying mechanisms of TDP-43 pathology. Here, we extend the possibilities of previous studies by examining a <i>C. elegans</i> model expressing human wild-type <i>TDP-43</i> ( <i>hTDP-43</i> ) pan-neuronally. We show that disease-related (hyper)phosphorylation and cytosolic localisation of hTDP-43 are present in hTDP-43 worms and that these features can be enhanced by adjusting the environmental temperature.
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[
Biochemistry,
2012]
Decapping scavenger (DcpS) enzymes catalyze the cleavage of a residual cap structure following 3' 5' mRNA decay. Some previous studies suggested that both m(7)GpppG and m(7)GDP were substrates for DcpS hydrolysis. Herein, we show that mononucleoside diphosphates, m(7)GDP (7-methylguanosine diphosphate) and m(3)(2,2,7)GDP (2,2,7-trimethylguanosine diphosphate), resulting from mRNA decapping by the Dcp1/2 complex in the 5' 3' mRNA decay, are not degraded by recombinant DcpS proteins (human, nematode, and yeast). Furthermore, whereas mononucleoside diphosphates (m(7)GDP and m(3)(2,2,7)GDP) are not hydrolyzed by DcpS, mononucleoside triphosphates (m(7)GTP and m(3)(2,2,7)GTP) are, demonstrating the importance of a triphosphate chain for DcpS hydrolytic activity. m(7)GTP and m(3)(2,2,7)GTP are cleaved at a slower rate than their corresponding dinucleotides (m(7)GpppG and m(3)(2,2,7)GpppG, respectively), indicating an involvement of the second nucleoside for efficient DcpS-mediated digestion. Although DcpS enzymes cannot hydrolyze m(7)GDP, they have a high binding affinity for m(7)GDP and m(7)GDP potently inhibits DcpS hydrolysis of m(7)GpppG, suggesting that m(7)GDP may function as an efficient DcpS inhibitor. Our data have important implications for the regulatory role of m(7)GDP in mRNA metabolic pathways due to its possible interactions with different cap-binding proteins, such as DcpS or eIF4E.