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1.
Nat Commun ; 11(1): 5076, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033264

RESUMO

Proper threat-reward decision-making is critical to animal survival. Emerging evidence indicates that the motor system may participate in decision-making but the neural circuit and molecular bases for these functions are little known. We found in C. elegans that GABAergic motor neurons (D-MNs) bias toward the reward behavior in threat-reward decision-making by retrogradely inhibiting a pair of premotor command interneurons, AVA, that control cholinergic motor neurons in the avoidance neural circuit. This function of D-MNs is mediated by a specific ionotropic GABA receptor (UNC-49) in AVA, and depends on electrical coupling between the two AVA interneurons. Our results suggest that AVA are hub neurons where sensory inputs from threat and reward sensory modalities and motor information from D-MNs are integrated. This study demonstrates at single-neuron resolution how motor neurons may help shape threat-reward choice behaviors through interacting with other neurons.


Assuntos
Caenorhabditis elegans/fisiologia , Neurônios GABAérgicos/metabolismo , Locomoção/fisiologia , Neurônios Motores/metabolismo , Animais , Aprendizagem da Esquiva , Viés , Proteínas de Caenorhabditis elegans/metabolismo , Quimiotaxia , Fenômenos Eletrofisiológicos , Junções Comunicantes/metabolismo , Glicerol/farmacologia , Interneurônios/metabolismo , Optogenética , Concentração Osmolar , Receptores Colinérgicos/metabolismo , Sinapses/metabolismo
2.
Ecotoxicol Environ Saf ; 203: 111001, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888585

RESUMO

Environmental nanomaterials contamination is a great concern for organisms including human. Copper oxide nanoparticles (CuO NPs) are widely used in a huge range of applications which might pose potential risk to organisms. This study investigated the in vivo transgenerational toxicity on development and reproduction with parental CuO NPs exposure in the nematode Caenorhabditis elegans. The results showed that CuO NPs (150 mg/L) significantly reduced the body length of parental C. elegans (P0). Only about 1 mg/L Cu2+ (~0.73%) were detected from 150 mg/L CuO NPs in 0.5X K-medium after 48 h. In transgenerational assays, CuO NPs (150 mg/L) parental exposure significantly induced developmental and reproductive toxicity in non-exposed C. elegans progeny (CuO NPs free) on body length (F1) and brood size (F1 and F2), respectively. In contrast, parental exposure to Cu2+ (1 mg/L) did not cause transgenerational toxicity on growth and reproduction. This suggests that the transgenerational toxicity was mostly attributed to the particulate form of CuO NPs. Moreover, qRT-PCR results showed that the mRNA levels of met-2 and spr-5 genes were significantly decreased at P0 and F1 upon only maternal exposure to CuO NPs (150 mg/L), suggesting the observed transgenerational toxicity was associated with possible epigenetic regulation in C. elegans.


Assuntos
Caenorhabditis elegans/efeitos dos fármacos , Cobre/toxicidade , Epigênese Genética/efeitos dos fármacos , Nanopartículas/toxicidade , Animais , Caenorhabditis elegans/genética , Caenorhabditis elegans/crescimento & desenvolvimento , Caenorhabditis elegans/fisiologia , Feminino , Humanos , Exposição Materna/efeitos adversos , Reprodução/efeitos dos fármacos , Reprodução/genética
4.
Adv Exp Med Biol ; 1207: 681-688, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32671785

RESUMO

Senescence is a progressive process of degeneration that occurs when cells and organisms mature. Many studies have shown that autophagy is closely related to senescence. Autophagy gradually decreases with the senescence activity of cells, and vice versa. Therefore, moderate autophagy can protect the body and inhibit cell senescence. The inactivation of genes encoding nematode insulin-like tyrosine kinase receptor (daf-2) inhibited the activity of type I PI3K (age-1), Akt molecules (akt1, akt2), PDK (pdk-1), and TOR, and increased the lifespan and autophagy of Caenorhabditis elegans.


Assuntos
Envelhecimento/efeitos dos fármacos , Autofagia/efeitos dos fármacos , Animais , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/fisiologia , Humanos , Longevidade/efeitos dos fármacos
5.
PLoS Comput Biol ; 16(7): e1008002, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32692770

RESUMO

Ageing affects a wide range of phenotypes at all scales, but an objective measure of ageing remains challenging, even in simple model organisms. To measure the ageing process, we characterized the sequence of alterations of multiple phenotypes at organismal scale. Hundreds of morphological, postural, and behavioral features were extracted from high-resolution videos. Out of the 1019 features extracted, 896 are ageing biomarkers, defined as those that show a significant correlation with relative age (age divided by lifespan). We used support vector regression to predict age, remaining life and lifespan of individual C. elegans. The quality of these predictions (age R2 = 0.79; remaining life R2 = 0.77; lifespan R2 = 0.72) increased with the number of features added to the model, supporting the use of multiple features to quantify ageing. We quantified the rate of ageing as how quickly animals moved through a phenotypic space; we quantified health decline as the slope of the declining predicted remaining life. In both ageing dimensions, we found that short lived-animals aged faster than long-lived animals. In our conditions, for isogenic wild-type worms, the health decline of the individuals was scaled to their lifespan without significant deviation from the average for short- or long-lived animals.


Assuntos
Caenorhabditis elegans/fisiologia , Longevidade , Fenótipo , Algoritmos , Animais , Comportamento Animal , Biomarcadores/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Biologia Computacional , Simulação por Computador , Mutação , Estresse Oxidativo , Prognóstico , Análise de Regressão , Reprodutibilidade dos Testes , Estresse Mecânico , Fatores de Tempo , Gravação em Vídeo
6.
Chemosphere ; 260: 127627, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32673864

RESUMO

Nickel is the most prevailing metal allergen with the highest sensitization rate among the "TOP 25" contact allergens and can affect about 15% of the human population. It is an essential trace metal in plants, animals, and humans. However, the environmental levels of nickel are considerably higher than what is needed for human life. Exposure to high levels of nickel can lead to skin allergies, lung fibrosis, and carcinogenesis. Few existing studies have closely examined the toxicity of nickel, let alone investigated the effective detoxification pathways. Here, we developed a high-throughput screening platform to comprehensively evaluate the nickel toxicity in wild-type C. elegans and explore the underlying detoxification mechanisms in transgenic nematodes. We demonstrated that nickel exerted multiple toxic effects on growth, brood size, feeding, and locomotion in C. elegans. Of which, brood size is the most sensitive endpoint. Nickel was found to first bind to phytochelatin (PC) after entering the worms' body and this PC-Ni complex was further transported by the ABC transporter, CeHMT-1, into the coelomocytes for further detoxification. Our study also demonstrated that the high-throughput screening platform is a promising system for evaluation and investigation of the ecological risks of heavy metals.


Assuntos
Caenorhabditis elegans/fisiologia , Níquel/metabolismo , Transportadores de Cassetes de Ligação de ATP/metabolismo , Animais , Transporte Biológico , Caenorhabditis elegans/metabolismo , Locomoção , Metais Pesados/toxicidade , Nematoides , Níquel/toxicidade , Fitoquelatinas/metabolismo
7.
PLoS Biol ; 18(6): e3000723, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32511224

RESUMO

Lymphatic filariasis (LF) afflicts over 60 million people worldwide and leads to severe pathological outcomes in chronic cases. The nematode parasites (Nematoda: Filarioidea) that cause LF require both arthropod (mosquito) intermediate hosts and mammalian definitive hosts for their propagation. The invasion and migration of filarial worms through host tissues are complex and critical to survival, yet little is known about the receptors and signaling pathways that mediate directed migration in these medically important species. In order to better understand the role of chemosensory signaling in filarial worm taxis, we employ comparative genomics, transcriptomics, reverse genetics, and chemical approaches to identify putative chemosensory receptor proteins and perturb chemotaxis phenotypes in filarial worms. We find that chemoreceptor family size is correlated with the presence of environmental (extrahost) stages in nematode life cycles, and that filarial worms contain compact and highly diverged chemoreceptor complements and lineage-specific ion channels that are predicted to operate downstream of chemoreceptor activation. In Brugia malayi, an etiological agent of LF, chemoreceptor expression patterns correspond to distinct parasite migration events across the life cycle. To interrogate the role of chemosensation in the migration of larval worms, arthropod and mammalian infectious stage Brugia parasites were incubated in nicotinamide, an agonist of the nematode transient receptor potential (TRP) channel OSM-9. Exposure of microfilariae to nicotinamide alters intramosquito migration, and exposure of L3s reduces chemotaxis toward host-associated cues in vitro. Nicotinamide also potently modulates thermosensory responses in L3s, suggesting a polymodal sensory role for Brugia osm-9. Reverse genetic studies implicate both Brugia osm-9 and the cyclic nucleotide-gated (CNG) channel subunit tax-4 in larval chemotaxis toward host serum, and these ion channel subunits partially rescue sensory defects in Caenorhabditis elegans osm-9 and tax-4 knock-out strains. Together, these data reveal genetic and functional diversification of chemosensory signaling proteins in filarial worms and encourage a more thorough investigation of clade- and parasite-specific facets of nematode sensory receptor biology.


Assuntos
Brugia Malayi/genética , Células Quimiorreceptoras/metabolismo , Culicidae/parasitologia , Filariose Linfática/parasitologia , Variação Genética , Animais , Caenorhabditis elegans/fisiologia , Quimiotaxia , Genoma , Proteínas de Helminto/metabolismo , Larva , Estágios do Ciclo de Vida , Interferência de RNA , RNA de Cadeia Dupla/metabolismo , Canais de Cátion TRPV/agonistas , Canais de Cátion TRPV/metabolismo , Temperatura
8.
PLoS One ; 15(6): e0233991, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497060

RESUMO

Neuropeptides are secreted molecules that have conserved roles modulating many processes, including mood, reproduction, and feeding. Dysregulation of neuropeptide signaling is also implicated in neurological disorders such as epilepsy. However, much is unknown about the mechanisms regulating specific neuropeptides to mediate behavior. Here, we report that the expression levels of dozens of neuropeptides are up-regulated in response to circuit activity imbalance in C. elegans. acr-2 encodes a homolog of human nicotinic receptors, and functions in the cholinergic motoneurons. A hyperactive mutation, acr-2(gf), causes an activity imbalance in the motor circuit. We performed cell-type specific transcriptomic analysis and identified genes differentially expressed in acr-2(gf), compared to wild type. The most over-represented class of genes are neuropeptides, with insulin-like-peptides (ILPs) the most affected. Moreover, up-regulation of neuropeptides occurs in motoneurons, as well as sensory neurons. In particular, the induced expression of the ILP ins-29 occurs in the BAG neurons, which were previously shown to function in gas-sensing. We also show that this up-regulation of ins-29 in acr-2(gf) animals is activity-dependent. Our genetic and molecular analyses support cooperative effects for ILPs and other neuropeptides in promoting motor circuit activity in the acr-2(gf) background. Together, this data reveals that a major transcriptional response to motor circuit dysregulation is in up-regulation of multiple neuropeptides, and suggests that BAG sensory neurons can respond to intrinsic activity states to feedback on the motor circuit.


Assuntos
Proteínas de Caenorhabditis elegans/genética , Caenorhabditis elegans/genética , Neuropeptídeos/genética , Receptores Nicotínicos/genética , Transcriptoma , Animais , Caenorhabditis elegans/fisiologia , Perfilação da Expressão Gênica , Neurônios Motores/metabolismo , Mutação , Células Receptoras Sensoriais/metabolismo
9.
PLoS One ; 15(6): e0235000, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32589676

RESUMO

Phoresy is a behavior in which an organism, the phoront, travels from one location to another by 'hitching a ride' on the body of a host as it disperses. Some phoronts are generalists, taking advantage of any available host. Others are specialists and travel only when specific hosts are located using chemical cues to identify and move (chemotax) toward the preferred host. Free-living nematodes, like Caenorhabditis elegans, are often found in natural environments that contain terrestrial isopods and other invertebrates. Additionally, the C. elegans wild strain PB306 was isolated associated with the isopod Porcellio scaber. However, it is currently unclear if C. elegans is a phoront of terrestrial isopods, and if so, whether it is a specialist, generalist, or developmental stage-specific combination of both strategies. Because the relevant chemical stimuli might be secreted compounds or volatile odorants, we used different types of chemotaxis assays across diverse extractions of compounds or odorants to test whether C. elegans is attracted to P. scaber. We show that two different strains-the wild isolate PB306 and the laboratory-adapted strain N2 -are not attracted to P. scaber during either the dauer or adult life stages. Our results indicate that C. elegans was not attracted to chemical compounds or volatile odorants from P. scaber, providing valuable empirical evidence to suggest that any associations between these two species are likely opportunistic rather than specific phoresy.


Assuntos
Caenorhabditis elegans/fisiologia , Interações Hospedeiro-Parasita/fisiologia , Isópodes/parasitologia , Animais , Caenorhabditis elegans/isolamento & purificação , Quimiotaxia/fisiologia , Isópodes/fisiologia , Estágios do Ciclo de Vida , Odorantes
10.
PLoS Genet ; 16(6): e1008829, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32502151

RESUMO

Ion channels are present at specific levels within subcellular compartments of excitable cells. The regulation of ion channel trafficking and targeting is an effective way to control cell excitability. The BK channel is a calcium-activated potassium channel that serves as a negative feedback mechanism at presynaptic axon terminals and sites of muscle excitation. The C. elegans BK channel ortholog, SLO-1, requires an endoplasmic reticulum (ER) membrane protein for efficient anterograde transport to these locations. Here, we found that, in the absence of this ER membrane protein, SLO-1 channels that are seemingly normally folded and expressed at physiological levels undergo SEL-11/HRD1-mediated ER-associated degradation (ERAD). This SLO-1 degradation is also indirectly regulated by a SKN-1A/NRF1-mediated transcriptional mechanism that controls proteasome levels. Therefore, our data indicate that SLO-1 channel density is regulated by the competitive balance between the efficiency of ER trafficking machinery and the capacity of ERAD.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Proteínas de Ligação a DNA/metabolismo , Degradação Associada com o Retículo Endoplasmático/genética , Canais de Potássio Ativados por Cálcio de Condutância Alta/metabolismo , Terminações Pré-Sinápticas/metabolismo , Fatores de Transcrição/metabolismo , Aldicarb/farmacologia , Animais , Animais Geneticamente Modificados , Caenorhabditis elegans/efeitos dos fármacos , Retículo Endoplasmático/metabolismo , Acoplamento Excitação-Contração/efeitos dos fármacos , Acoplamento Excitação-Contração/genética , Retroalimentação Fisiológica/efeitos dos fármacos , Proteínas de Membrana/metabolismo , Músculos/inervação , Terminações Pré-Sinápticas/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma , Isoformas de Proteínas/metabolismo , Ubiquitina-Proteína Ligases/metabolismo
11.
J Vis Exp ; (159)2020 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-32510480

RESUMO

Organisms are often exposed to fluctuating environments and changes in intracellular homeostasis, which can have detrimental effects on their proteome and physiology. Thus, organisms have evolved targeted and specific stress responses dedicated to repair damage and maintain homeostasis. These mechanisms include the unfolded protein response of the endoplasmic reticulum (UPRER), the unfolded protein response of the mitochondria (UPRMT), the heat shock response (HSR), and the oxidative stress response (OxSR). The protocols presented here describe methods to detect and characterize the activation of these pathways and their physiological consequences in the nematode, C. elegans. First, the use of pathway-specific fluorescent transcriptional reporters is described for rapid cellular characterization, drug screening, or large-scale genetic screening (e.g., RNAi or mutant libraries). In addition, complementary, robust physiological assays are described, which can be used to directly assess sensitivity of animals to specific stressors, serving as functional validation of the transcriptional reporters. Together, these methods allow for rapid characterization of the cellular and physiological effects of internal and external proteotoxic perturbations.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Proteínas de Fluorescência Verde/metabolismo , Resposta ao Choque Térmico , Estresse Oxidativo , Estresse Fisiológico , Resposta a Proteínas não Dobradas , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Retículo Endoplasmático/metabolismo , Proteínas de Fluorescência Verde/genética , Homeostase , Mitocôndrias/metabolismo
12.
PLoS Negl Trop Dis ; 14(6): e0008275, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32574217

RESUMO

Filarial nematodes can cause debilitating diseases in humans. They have complicated life cycles involving an insect vector and mammalian hosts, and they go through a number of developmental molts. While whole genome sequences of parasitic worms are now available, very little is known about transcription factor (TF) binding sites and their cognate transcription factors that play a role in regulating development. To address this gap, we developed a novel motif prediction pipeline, Emotif Alpha, that integrates ten different motif discovery algorithms, multiple statistical tests, and a comparative analysis of conserved elements between the filarial worms Brugia malayi and Onchocerca volvulus, and the free-living nematode Caenorhabditis elegans. We identified stage-specific TF binding motifs in B. malayi, with a particular focus on those potentially involved in the L3-L4 molt, a stage important for the establishment of infection in the mammalian host. Using an in vitro molting system, we tested and validated three of these motifs demonstrating the accuracy of the motif prediction pipeline.


Assuntos
Brugia Malayi/genética , Genes de Helmintos , Muda , Fatores de Transcrição/genética , Animais , Sequência de Bases , Brugia Malayi/fisiologia , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiologia , Perfilação da Expressão Gênica , Larva , Análise de Sequência com Séries de Oligonucleotídeos , Onchocerca volvulus/genética , Onchocerca volvulus/fisiologia , RNA de Helmintos/genética
13.
Nature ; 583(7816): 415-420, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32555456

RESUMO

Animals coexist in commensal, pathogenic or mutualistic relationships with complex communities of diverse organisms, including microorganisms1. Some bacteria produce bioactive neurotransmitters that have previously been proposed to modulate nervous system activity and behaviours of their hosts2,3. However, the mechanistic basis of this microbiota-brain signalling and its physiological relevance are largely unknown. Here we show that in Caenorhabditis elegans, the neuromodulator tyramine produced by commensal Providencia bacteria, which colonize the gut, bypasses the requirement for host tyramine biosynthesis and manipulates a host sensory decision. Bacterially produced tyramine is probably converted to octopamine by the host tyramine ß-hydroxylase enzyme. Octopamine, in turn, targets the OCTR-1 octopamine receptor on ASH nociceptive neurons to modulate an aversive olfactory response. We identify the genes that are required for tyramine biosynthesis in Providencia, and show that these genes are necessary for the modulation of host behaviour. We further find that C. elegans colonized by Providencia preferentially select these bacteria in food choice assays, and that this selection bias requires bacterially produced tyramine and host octopamine signalling. Our results demonstrate that a neurotransmitter produced by gut bacteria mimics the functions of the cognate host molecule to override host control of a sensory decision, and thereby promotes fitness of both the host and the microorganism.


Assuntos
Caenorhabditis elegans/microbiologia , Caenorhabditis elegans/fisiologia , Comportamento Alimentar/fisiologia , Intestinos/microbiologia , Neurotransmissores/metabolismo , Providencia/metabolismo , Olfato/fisiologia , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Caenorhabditis elegans/efeitos dos fármacos , Proteínas de Caenorhabditis elegans/metabolismo , Microbioma Gastrointestinal/fisiologia , Metabolômica , Mutação , Octanóis/farmacologia , Octopamina/biossíntese , Octopamina/metabolismo , Providencia/enzimologia , Providencia/fisiologia , Receptores de Amina Biogênica/metabolismo , Receptores Acoplados a Proteínas-G/metabolismo , Células Receptoras Sensoriais/metabolismo , Olfato/efeitos dos fármacos , Tiramina/biossíntese , Tiramina/metabolismo
14.
Nat Commun ; 11(1): 2099, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350248

RESUMO

Besides pro-inflammatory roles, the ancient cytokine interleukin-17 (IL-17) modulates neural circuit function. We investigate IL-17 signaling in neurons, and the extent it can alter organismal phenotypes. We combine immunoprecipitation and mass spectrometry to biochemically characterize endogenous signaling complexes that function downstream of IL-17 receptors in C. elegans neurons. We identify the paracaspase MALT-1 as a critical output of the pathway. MALT1 mediates signaling from many immune receptors in mammals, but was not previously implicated in IL-17 signaling or nervous system function. C. elegans MALT-1 forms a complex with homologs of Act1 and IRAK and appears to function both as a scaffold and a protease. MALT-1 is expressed broadly in the C. elegans nervous system, and neuronal IL-17-MALT-1 signaling regulates multiple phenotypes, including escape behavior, associative learning, immunity and longevity. Our data suggest MALT1 has an ancient role modulating neural circuit function downstream of IL-17 to remodel physiology and behavior.


Assuntos
Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/imunologia , Caenorhabditis elegans/fisiologia , Imunidade , Interleucina-17/metabolismo , Longevidade , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/metabolismo , Neurônios/metabolismo , Animais , Comportamento Animal , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Proteínas de Fluorescência Verde/metabolismo , Imunidade/efeitos dos fármacos , Interneurônios/efeitos dos fármacos , Interneurônios/fisiologia , Longevidade/efeitos dos fármacos , Modelos Biológicos , Neurônios/efeitos dos fármacos , Oxigênio/farmacologia , Transdução de Sinais/efeitos dos fármacos , Frações Subcelulares/metabolismo , Transgenes
15.
Nat Commun ; 11(1): 2073, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350270

RESUMO

Functional variomics provides the foundation for personalized medicine by linking genetic variation to disease expression, outcome and treatment, yet its utility is dependent on appropriate assays to evaluate mutation impact on protein function. To fully assess the effects of 106 missense and nonsense variants of PTEN associated with autism spectrum disorder, somatic cancer and PTEN hamartoma syndrome (PHTS), we take a deep phenotypic profiling approach using 18 assays in 5 model systems spanning diverse cellular environments ranging from molecular function to neuronal morphogenesis and behavior. Variants inducing instability occur across the protein, resulting in partial-to-complete loss-of-function (LoF), which is well correlated across models. However, assays are selectively sensitive to variants located in substrate binding and catalytic domains, which exhibit complete LoF or dominant negativity independent of effects on stability. Our results indicate that full characterization of variant impact requires assays sensitive to instability and a range of protein functions.


Assuntos
Doença/genética , Modelos Genéticos , Mutação de Sentido Incorreto/genética , PTEN Fosfo-Hidrolase/genética , Animais , Comportamento Animal , Caenorhabditis elegans/fisiologia , Células Cultivadas , Dendritos/fisiologia , Drosophila/genética , Drosophila/crescimento & desenvolvimento , Ensaios Enzimáticos , Células HEK293 , Humanos , Neoplasias/genética , Sistema Nervoso/crescimento & desenvolvimento , Fosforilação , Estabilidade Proteica , Proteínas Proto-Oncogênicas c-akt/metabolismo , Células Piramidais/metabolismo , Ratos Sprague-Dawley , Saccharomyces cerevisiae/metabolismo
16.
Nat Commun ; 11(1): 2076, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350283

RESUMO

Learning and memory are regulated by neuromodulatory pathways, but the contribution and temporal requirement of most neuromodulators in a learning circuit are unknown. Here we identify the evolutionarily conserved neuromedin U (NMU) neuropeptide family as a regulator of C. elegans gustatory aversive learning. The NMU homolog CAPA-1 and its receptor NMUR-1 are required for the retrieval of learned salt avoidance. Gustatory aversive learning requires the release of CAPA-1 neuropeptides from sensory ASG neurons that respond to salt stimuli in an experience-dependent manner. Optogenetic silencing of CAPA-1 neurons blocks the expression, but not the acquisition, of learned salt avoidance. CAPA-1 signals through NMUR-1 in AFD sensory neurons to modulate two navigational strategies for salt chemotaxis. Aversive conditioning thus recruits NMU signaling to modulate locomotor programs for expressing learned avoidance behavior. Because NMU signaling is conserved across bilaterian animals, our findings incite further research into its function in other learning circuits.


Assuntos
Aprendizagem da Esquiva/fisiologia , Proteínas de Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/fisiologia , Rede Nervosa/fisiologia , Neuropeptídeos/metabolismo , Transdução de Sinais , Cloreto de Sódio/efeitos adversos , Paladar/fisiologia , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados , Comportamento Animal , Proteínas de Caenorhabditis elegans/química , Cálcio/metabolismo , Alimentos , Modelos Biológicos , Mutação/genética , Filogenia , Células Receptoras Sensoriais/fisiologia
17.
Nat Commun ; 11(1): 2587, 2020 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-32444616

RESUMO

The gut microbiota metabolizes drugs and alters their efficacy and toxicity. Diet alters drugs, the metabolism of the microbiota, and the host. However, whether diet-triggered metabolic changes in the microbiota can alter drug responses in the host has been largely unexplored. Here we show that dietary thymidine and serine enhance 5-fluoro 2'deoxyuridine (FUdR) toxicity in C. elegans through different microbial mechanisms. Thymidine promotes microbial conversion of the prodrug FUdR into toxic 5-fluorouridine-5'-monophosphate (FUMP), leading to enhanced host death associated with mitochondrial RNA and DNA depletion, and lethal activation of autophagy. By contrast, serine does not alter FUdR metabolism. Instead, serine alters E. coli's 1C-metabolism, reduces the provision of nucleotides to the host, and exacerbates DNA toxicity and host death without mitochondrial RNA or DNA depletion; moreover, autophagy promotes survival in this condition. This work implies that diet-microbe interactions can alter the host response to drugs without altering the drug or the host.


Assuntos
Caenorhabditis elegans/efeitos dos fármacos , Floxuridina/toxicidade , Interações Alimento-Droga , Microbioma Gastrointestinal/efeitos dos fármacos , Serina/farmacologia , Animais , Caenorhabditis elegans/microbiologia , Caenorhabditis elegans/fisiologia , Suplementos Nutricionais , Escherichia coli/efeitos dos fármacos , Escherichia coli/metabolismo , Floxuridina/farmacocinética , Ácido Fólico/metabolismo , Microbioma Gastrointestinal/fisiologia , Timidina/análogos & derivados , Timidina/metabolismo , Timidina/farmacocinética , Timidina/farmacologia , Nucleotídeos de Uracila/metabolismo , Nucleotídeos de Uracila/farmacocinética
18.
PLoS One ; 15(5): e0232788, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32384109

RESUMO

High-speed imaging equipment can be an expensive investment, especially when certain applications require custom solutions. In this paper, we present a low-cost high-speed prototype camera built on a low-end Zynq-7000 System-on-Chip (SoC) platform and off-the-shelf components with the aim of removing the entry barrier into various high-speed imaging applications. The camera is standalone (does not require a host computer) and can achieve 211 frames per second (fps) at its maximum resolution of 1280x1024, and up to 2329 fps at a 256x256 resolution. With a current cost of only several hundred dollars and resource utilization of ~5%, the open-source design's modularity and customizability allows users with sufficient hardware or programming experience to modify the camera to suit their needs, potentially driving the cost lower. This can be done by utilizing the large remaining programmable logic for custom image processing algorithms, creating user interface software on the CPU, attaching extensions through the peripheral Module connections, or creating custom carrier or daughter boards. The development and design of the camera is described and a figure-of-merit is presented to provide a value assessment of some available commercial high-speed cameras against which our camera is competitive. Finally, the camera was tested to record low frequency spatial vibration and was found to be useful in investigating phenotypes associated with aging in a leading animal model, the nematode (worm) Caenorhabditis elegans.


Assuntos
Caenorhabditis elegans/anatomia & histologia , Processamento de Imagem Assistida por Computador/instrumentação , Software , Gravação em Vídeo/instrumentação , Animais , Caenorhabditis elegans/fisiologia , Desenho de Equipamento , Modelos Animais , Fenótipo , Gravação em Vídeo/economia
19.
PLoS One ; 15(5): e0233059, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32433687

RESUMO

Complex extracellular structures exist throughout phylogeny, but the dynamics of their formation and dissolution are often opaque. One example is the pharyngeal grinder of the nematode Caenorhabditis elegans, an extracellular structure that ruptures bacteria during feeding. During each larval transition stage, called lethargus, the grinder is replaced with one of a larger size. Here, we characterize at the ultrastructural level the deconstruction of the larval grinder and the construction of the adult grinder during the fourth larval stage (L4)-to-adult transition. Early in L4 lethargus, pharyngeal muscle cells trans-differentiate from contractile to secretory cells, as evidenced by the appearance of clear and dense core vesicles and disruptions in sarcomere organization. This is followed, within minutes, by the dissolution of the L4 grinder and the formation and maturation of the adult grinder. Components of the nascent adult grinder are deposited basally, and are separated from the dissolving larval grinder by a visible apical layer. The complete grinder is a lamellated extracellular matrix comprised of five layers. Following grinder formation, pharyngeal muscle cells regain ultrastructural contractile properties, and muscle contractions resume. Our findings add to our understanding of how complex extracellular structures assemble and dissemble.


Assuntos
Caenorhabditis elegans/fisiologia , Muda , Erupção Dentária , Animais , Caenorhabditis elegans/ultraestrutura , Proteínas de Caenorhabditis elegans/metabolismo , Larva , Metaloendopeptidases/metabolismo , Microscopia Eletrônica de Transmissão , Músculos Faríngeos/ultraestrutura , Sono , Imagem com Lapso de Tempo
20.
Nat Protoc ; 15(6): 2071-2106, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32433626

RESUMO

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.


Assuntos
Bioensaio/instrumentação , Caenorhabditis elegans/fisiologia , Movimento , Fenótipo , Animais
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