scholarly journals Lifespan extension in Caenorhabditis elegans insulin/IGF-1 signalling mutants is supported by non-vertebrate physiological traits

Nematology ◽  
2017 ◽  
Vol 19 (5) ◽  
pp. 499-508
Author(s):  
Bart P. Braeckman ◽  
Ineke Dhondt
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Genetic Model ◽  
Causal Relation ◽  
Glyoxylate Cycle ◽  
Protein Carbonyls ◽  
Lifespan Extension ◽  
Turnover Rates ◽  
C Elegans ◽  
Trehalose Synthesis

The insulin/IGF-1 signalling (IIS) pathway connects nutrient levels to metabolism, growth and lifespan in eukaryotes ranging from yeasts to humans, including nematodes such as the genetic model organismCaenorhabditis elegans. The link between ageing and the IIS pathway has been thoroughly studied inC. elegans; upon reduced IIS signalling, a genetic survival program is activated resulting in a drastic lifespan extension. One of the components of this program is the upregulation of antioxidant activity but experiments failed to show a clear causal relation to longevity. However, oxidative damage, such as protein carbonyls, accumulates at a slower pace in long-livedC. elegansmutants with reduced IIS. This is probably not achieved by increased macroautophagy, a process that sequesters cellular components to be eliminated as protein turnover rates are slowed down in IIS mutants. The IIS mutantdaf-2, bearing a mutation in the insulin/IGF-1 receptor, recapitulates the dauer survival program, including accumulation of fat and glycogen. Fat can be converted into glucose and glycogenviathe glyoxylate shunt, a pathway absent in vertebrates. These carbohydrates can be used as substrates for trehalose synthesis, also absent in mammals. Trehalose, a non-reducing homodimer of glucose, stabilises intracellular components and is responsible for almost half of the lifespan extension in IIS mutants. Hence, the molecular mechanisms by which lifespan is extended under reduced IIS may differ substantially between phyla that have an active glyoxylate cycle and trehalose synthesis, such as ecdysozoans and fungi, and vertebrate species such as mammals.

scholarly journals Caenorhabditis elegans as an in vivo Model to Assess Amphetamine Tolerance

2021 ◽  
pp. 1-9
Author(s):  
Dayana Torres Valladares ◽  
Sirisha Kudumala ◽  
Murad Hossain ◽  
Lucia Carvelli
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Drugs Of Abuse ◽  
Genetic Model ◽  
In Vivo Model ◽  
C Elegans ◽  
Hyperactivity Disorder ◽  
In Vitro Data

Amphetamine is a potent psychostimulant also used to treat attention deficit/hyperactivity disorder and narcolepsy. In vivo and in vitro data have demonstrated that amphetamine increases the amount of extra synaptic dopamine by both inhibiting reuptake and promoting efflux of dopamine through the dopamine transporter. Previous studies have shown that chronic use of amphetamine causes tolerance to the drug. Thus, since the molecular mechanisms underlying tolerance to amphetamine are still unknown, an animal model to identify the neurochemical mechanisms associated with drug tolerance is greatly needed. Here we took advantage of a unique behavior caused by amphetamine in <i>Caenorhabditis elegans</i> to investigate whether this simple, but powerful, genetic model develops tolerance following repeated exposure to amphetamine. We found that at least 3 treatments with 0.5 mM amphetamine were necessary to see a reduction in the amphetamine-induced behavior and, thus, to promote tolerance. Moreover, we found that, after intervals of 60/90 minutes between treatments, animals were more likely to exhibit tolerance than animals that underwent 10-minute intervals between treatments. Taken together, our results show that <i>C. elegans</i> is a suitable system to study tolerance to drugs of abuse such as amphetamines.

The Effect of Mianserin on Lifespan of Caenorhabditis elegans is Abolished by Glucose

2021 ◽  
Vol 13 ◽  
Author(s):  
Abdullah Almotayri ◽  
Jency Thomas ◽  
Mihiri Munasinghe ◽  
Markandeya Jois
Keyword(s):  
Caenorhabditis Elegans ◽  
Scaffolding Protein ◽  
Lifespan Extension ◽  
Wild Type ◽  
E Coli ◽  
C Elegans ◽  
Risk Of Death ◽  
Increased Risk ◽  
Antidepressant Use ◽  
Extension Effect

Background: The antidepressant mianserin has been shown to extend the lifespan of Caenorhabditis elegans (C. elegans), a well-established model organism used in aging research. The extension of lifespan in C. elegans was shown to be dependent on increased expression of the scaffolding protein (ANK3/unc-44). In contrast, antidepressant use in humans is associated with an increased risk of death. The C. elegans in the laboratory are fed Escherichia coli (E. coli), a diet high in protein and low in carbohydrate, whereas a typical human diet is high in carbohydrates. We hypothesized that dietary carbohydrates might mitigate the lifespan-extension effect of mianserin. Objective: To investigate the effect of glucose added to the diet of C. elegans on the lifespan-extension effect of mianserin. Methods: Wild-type Bristol N2 and ANK3/unc-44 inactivating mutants were cultured on agar plates containing nematode growth medium and fed E. coli. Treatment groups included (C) control, (M50) 50 μM mianserin, (G) 73 mM glucose, and (M50G) 50 μM mianserin and 73 mM glucose. Lifespan was determined by monitoring the worms until they died. Statistical analysis was performed using the Kaplan-Meier version of the log-rank test. Results: Mianserin treatment resulted in a 12% increase in lifespan (P<0.05) of wild-type Bristol N2 worms but reduced lifespan by 6% in ANK3/unc-44 mutants, consistent with previous research. The addition of glucose to the diet reduced the lifespan of both strains of worms and abolished the lifespan-extension by mianserin. Conclusion: The addition of glucose to the diet of C. elegans abolishes the lifespan-extension effects of mianserin.

scholarly journals Oscillatory Ca2+ Signaling in the Isolated Caenorhabditis elegans Intestine

2005 ◽  
Vol 126 (4) ◽  
pp. 379-392 ◽  
Author(s):  
Maria V. Espelt ◽  
Ana Y. Estevez ◽  
Xiaoyan Yin ◽  
Kevin Strange
Keyword(s):  
Caenorhabditis Elegans ◽  
Intestinal Epithelium ◽  
Oscillation Frequency ◽  
Gene Networks ◽  
Molecular Mechanisms ◽  
Apical Cell ◽  
Intestinal Cell ◽  
C Elegans ◽  
Contrast Gain ◽  
Behavioral Rhythm

Defecation in the nematode Caenorhabditis elegans is a readily observable ultradian behavioral rhythm that occurs once every 45–50 s and is mediated in part by posterior body wall muscle contraction (pBoc). pBoc is not regulated by neural input but instead is likely controlled by rhythmic Ca2+ oscillations in the intestinal epithelium. We developed an isolated nematode intestine preparation that allows combined physiological, genetic, and molecular characterization of oscillatory Ca2+ signaling. Isolated intestines loaded with fluo-4 AM exhibit spontaneous rhythmic Ca2+ oscillations with a period of ∼50 s. Oscillations were only detected in the apical cell pole of the intestinal epithelium and occur as a posterior-to-anterior moving intercellular Ca2+ wave. Loss-of-function mutations in the inositol-1,4,5-trisphosphate (IP3) receptor ITR-1 reduce pBoc and Ca2+ oscillation frequency and intercellular Ca2+ wave velocity. In contrast, gain-of-function mutations in the IP3 binding and regulatory domains of ITR-1 have no effect on pBoc or Ca2+ oscillation frequency but dramatically increase the speed of the intercellular Ca2+ wave. Systemic RNA interference (RNAi) screening of the six C. elegans phospholipase C (PLC)–encoding genes demonstrated that pBoc and Ca2+ oscillations require the combined function of PLC-γ and PLC-β homologues. Disruption of PLC-γ and PLC-β activity by mutation or RNAi induced arrhythmia in pBoc and intestinal Ca2+ oscillations. The function of the two enzymes is additive. Epistasis analysis suggests that PLC-γ functions primarily to generate IP3 that controls ITR-1 activity. In contrast, IP3 generated by PLC-β appears to play little or no direct role in ITR-1 regulation. PLC-β may function instead to control PIP2 levels and/or G protein signaling events. Our findings provide new insights into intestinal cell Ca2+ signaling mechanisms and establish C. elegans as a powerful model system for defining the gene networks and molecular mechanisms that underlie the generation and regulation of Ca2+ oscillations and intercellular Ca2+ waves in nonexcitable cells.

scholarly journals The Actin-Binding Protein UNC-115/abLIM Controls Formation of Lamellipodia and Filopodia and Neuronal Morphogenesis in Caenorhabditis elegans

2005 ◽  
Vol 25 (12) ◽  
pp. 5158-5170 ◽  
Author(s):  
Yieyie Yang ◽  
Erik A. Lundquist
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Binding Protein ◽  
Phosphorylation Site ◽  
Serine Phosphorylation ◽  
Actin Binding ◽  
Axon Pathfinding ◽  
Neuronal Morphogenesis ◽  
Actin Binding Protein ◽  
C Elegans

ABSTRACT The roles of actin-binding proteins in development and morphogenesis are not well understood. The actin-binding protein UNC-115 has been implicated in cytoskeletal signaling downstream of Rac in Caenorhabditis elegans axon pathfinding, but the cellular role of UNC-115 in this process remains undefined. Here we report that UNC-115 overactivity in C. elegans neurons promotes the formation of neurites and lamellipodial and filopodial extensions similar to those induced by activated Rac and normally found in C. elegans growth cones. We show that UNC-115 activity in neuronal morphogenesis is enhanced by two molecular mechanisms: when ectopically driven to the plasma membrane by the myristoylation sequence of c-Src, and by mutation of a putative serine phosphorylation site in the actin-binding domain of UNC-115. In support of the hypothesis that UNC-115 modulates actin cytoskeletal organization, we show that UNC-115 activity in serum-starved NIH 3T3 fibroblasts results in the formation of lamellipodia and filopodia. We conclude that UNC-115 is a novel regulator of the formation of lamellipodia and filopodia in neurons, possibly in the growth cone during axon pathfinding.

scholarly journals Stochastic left–right neuronal asymmetry in Caenorhabditis elegans

2016 ◽  
Vol 371 (1710) ◽  
pp. 20150407 ◽  
Author(s):  
Amel Alqadah ◽  
Yi-Wen Hsieh ◽  
Rui Xiong ◽  
Chiou-Fen Chuang
Keyword(s):  
Caenorhabditis Elegans ◽  
Molecular Mechanisms ◽  
Neurological Diseases ◽  
Calcium Signalling ◽  
Model Organism ◽  
Brain Asymmetry ◽  
C Elegans ◽  
Left And Right ◽  
Left Right Asymmetry ◽  
Neuronal Asymmetry

Left–right asymmetry in the nervous system is observed across species. Defects in left–right cerebral asymmetry are linked to several neurological diseases, but the molecular mechanisms underlying brain asymmetry in vertebrates are still not very well understood. The Caenorhabditis elegans left and right amphid wing ‘C’ (AWC) olfactory neurons communicate through intercellular calcium signalling in a transient embryonic gap junction neural network to specify two asymmetric subtypes, AWC OFF (default) and AWC ON (induced), in a stochastic manner. Here, we highlight the molecular mechanisms that establish and maintain stochastic AWC asymmetry. As the components of the AWC asymmetry pathway are highly conserved, insights from the model organism C. elegans may provide a window onto how brain asymmetry develops in humans. This article is part of the themed issue ‘Provocative questions in left–right asymmetry’.

scholarly journals Piceatannol, a Natural Stilbene, Extends the Lifespan of Caenorhabditis elegans Under Fasting Through Inhibition of Lipolysis

2020 ◽  
Vol 4 (Supplement_2) ◽  
pp. 38-38
Author(s):  
Jang Miran ◽  
Zhang Yuan ◽  
Bai Juan ◽  
Jun-Bae An ◽  
Park Yeonhwa ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Caenorhabditis Elegans ◽  
Negative Energy ◽  
Hormone Sensitive Lipase ◽  
Pcr Analysis ◽  
Lifespan Extension ◽  
Mrna Levels ◽  
Free Glycerol ◽  
C Elegans ◽  
Glycerol Level

Abstract Objectives Lipolysis is the catabolic process that hydrolyzes triglyceride (TG) to free fatty acids (FFAs) and glycerol under negative energy balance such as fasting. In adipocytes, adipose TG lipase (ATGL), hormone-sensitive lipase (HSL), and monoglyceride lipase play key roles in a series of TG hydrolysis reactions in mammals. However, overly activated adipose lipolysis is believed to contribute to link between obesity and systemic inflammation and oxidative stress. We previously demonstrated that piceatannol (PIC), a natural resveratrol analogue, inhibits adipogenesis in cultured adipocytes and lipogenesis in Caenorhabditis elegans. Furthermore, we showed that PIC extends the lifespan of C. elegans via the insulin/IGF-1 signaling. However, the effects of PIC on lipid metabolism during fasting state is unknown. Methods We conducted Oil-Red-O assay, Enzyme assay (TG and Free glycerol contents), PCR analysis and lifespan assay. Results In this study, we demonstrated that PIC-treated C. elegans exhibited suppressed lipolysis under fasting as judged by increased lipid accumulation and TG levels with decreased free glycerol level. Consistent with these findings, PIC treatment resulted in decreased mRNA levels of genes involved lipolysis such as atgl-1, hosl-1 and aak-2 in fasted C. elegans. Also, PIC treatment augmented fasting-induced lifespan of C. elegans by an increased daf-16 gene expression. However, such effect was abolished when atgl-1, aak-2, and daf-16 mutants were treated with PIC. In addition, we also found that autophagy is required for PIC-induced lifespan in C. elegans during fasting since autophagy inhibitor treatments and autophagy gene deficient worms resulted in blunting the lifespan extension effect of PIC. Conclusions Collectively, our results indicate that PIC contributes to lifespan extension in C. elegans during fasting possibly through regulating lipolysis- and/or autophagy-dependent lipid metabolism. Funding Sources 1. The National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (2019R1A2C1086146) and (2019R1A6A3A03033878) 2. The Rural Development Administration of the Republic of Korea.

scholarly journals Inducible Systemic RNA Silencing in Caenorhabditis elegans

2003 ◽  
Vol 14 (7) ◽  
pp. 2972-2983 ◽  
Author(s):  
Lisa Timmons ◽  
Hiroaki Tabara ◽  
Craig C. Mello ◽  
Andrew Z. Fire
Keyword(s):  
Rna Interference ◽  
Caenorhabditis Elegans ◽  
Rna Silencing ◽  
Molecular Mechanisms ◽  
Normal Animal ◽  
Cell Types ◽  
Animal Cells ◽  
Tissue Specific ◽  
C Elegans ◽  
Systemic Rna

Introduction of double-stranded RNA (dsRNA) can elicit a gene-specific RNA interference response in a variety of organisms and cell types. In many cases, this response has a systemic character in that silencing of gene expression is observed in cells distal from the site of dsRNA delivery. The molecular mechanisms underlying the mobile nature of RNA silencing are unknown. For example, although cellular entry of dsRNA is possible, cellular exit of dsRNA from normal animal cells has not been directly observed. We provide evidence that transgenic strains of Caenorhabditis elegans transcribing dsRNA from a tissue-specific promoter do not exhibit comprehensive systemic RNA interference phenotypes. In these same animals, modifications of environmental conditions can result in more robust systemic RNA silencing. Additionally, we find that genetic mutations can influence the systemic character of RNA silencing in C. elegans and can separate mechanisms underlying systemic RNA silencing into tissue-specific components. These data suggest that trafficking of RNA silencing signals in C. elegans is regulated by specific physiological and genetic factors.

scholarly journals CAENORHABDITIS ELEGANS AS A MODEL OF AIR POLLUTION TOXICITY DURING DEVELOPMENT AND LIFESPAN

2019 ◽  
Vol 3 (Supplement_1) ◽  
pp. S97-S97
Author(s):  
Amin Haghani ◽  
Hans M Dalton ◽  
Nikoo Safi ◽  
Farimah Shirmohammadi ◽  
Constantinos Sioutas ◽  
...  
Keyword(s):  
Air Pollution ◽  
Caenorhabditis Elegans ◽  
Mouse Models ◽  
High Throughput ◽  
Molecular Mechanisms ◽  
Cultured Cells ◽  
Exposure Model ◽  
C Elegans ◽  
Biological Responses ◽  
Short Term Exposure

Abstract Air pollution (AirPoll) is among the leading human mortality risk factors and yet little is known about the molecular mechanisms of this global environmental toxin. Our recent studies using mouse models even showed genetic variation and sex can alter biological responses to air pollution. To expand genetic studies of AirPoll toxicity throughout the lifespan, we introduced Caenorhabditis elegans as a new AirPoll exposure model which has a short lifespan, high throughput capabilities and shared longevity pathways with mammals. Acute exposure of C. elegans to airborne nanosized AirPoll matter (nPM) caused similar gene expression changes to our prior findings in cell culture and mouse models. Initial C. elegans responses to nPM included antioxidant, inflammatory and Alzheimer homolog genes. The magnitude of changes was dependent on the developmental stage of the worms. Even short term exposure of C. elegans to nPM altered developmental and lifespan hormetic effects, with pathways that included skn-1/Nrf family antioxidant responses. We propose C. elegans as a new and complementary model for mouse and cultured cells to study AirPoll across the lifespan. Future chronic nPM exposure and high throughput genetic screening of C. elegans can identify other major regulators of the developmental and lifespan effects of air pollution. This work was supported by grants R01AG051521 (CEF); R21AG05020 (CEF); Cure Alzheimer’s Fund (CEF); R01GM109028 (SPC), F31AG051382 (HMD) and T32AG000037 (HMD), T32AG052374 (AH).

scholarly journals The Na+-K+-ATPase is needed in glia of touch receptors for responses to touch in C. elegans

2020 ◽  
Vol 123 (5) ◽  
pp. 2064-2074 ◽  
Author(s):  
Christina K. Johnson ◽  
Jesus Fernandez-Abascal ◽  
Ying Wang ◽  
Lei Wang ◽  
Laura Bianchi
Keyword(s):  
Caenorhabditis Elegans ◽  
Avoidance Behavior ◽  
Molecular Mechanisms ◽  
C Elegans ◽  
Data Support ◽  
Accessory Cells ◽  
Touch Avoidance ◽  
Neuronal Output

Increasing evidences support that accessory cells in mechanosensors regulate neuronal output; however, the glial molecular mechanisms that control this regulation are not fully understood. We show here in Caenorhabditis elegans that specific glial Na+-K+-ATPase genes are needed for nose touch-avoidance behavior. Our data support the requirement of these Na+-K+-ATPases for homeostasis of Na+ and K+ in nose touch receptors. Our data add to our understanding of glial regulation of mechanosensors.

scholarly journals Evolution of sperm competition: Natural variation and genetic determinants of Caenorhabditis elegans sperm size

2018 ◽  
Author(s):  
Clotilde Gimond ◽  
Anne Vielle ◽  
Nuno Silva-Soares ◽  
Stefan Zdraljevic ◽  
Patrick T. McGrath ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Sperm Competition ◽  
Natural Variation ◽  
Competitive Ability ◽  
Molecular Mechanisms ◽  
Genetic Determinants ◽  
Heritable Variation ◽  
C Elegans ◽  
Male Sperm ◽  
Sperm Size

ABSTRACTSperm morphology is critical for sperm competition and thus for reproductive fitness. In the male-hermaphrodite nematode Caenorhabditis elegans, sperm size is a key feature of sperm competitive ability. Yet despite extensive research, the molecular mechanisms regulating C. elegans sperm size and the genetic basis underlying its natural variation remain unknown. Examining 97 genetically distinct C. elegans strains, we observe significant heritable variation in male sperm size but genome-wide association mapping did not yield any QTL (Quantitative Trait Loci). While we confirm larger male sperm to consistently outcompete smaller hermaphrodite sperm, we find natural variation in male sperm size to poorly predict male fertility and competitive ability. In addition, although hermaphrodite sperm size also shows significant natural variation, male and hermaphrodite sperm size do not correlate, implying a sex-specific genetic regulation of sperm size. To elucidate the molecular basis of intraspecific sperm size variation, we focused on recently diverged laboratory strains, which evolved extreme sperm size differences. Using mutants and quantitative complementation tests, we demonstrate that variation in the gene nurf-1 – previously shown to underlie the evolution of improved hermaphrodite reproduction – also explains the evolution of reduced male sperm size. This result illustrates how adaptive changes in C. elegans hermaphrodite function can cause the deterioration of a male-specific fitness trait due to a sexually antagonistic variant, representing an example of intralocus sexual conflict with resolution at the molecular level. Our results further provide first insights into the genetic determinants of C. elegans sperm size, pointing at an involvement of the NURF chromatin remodelling complex.

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