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[
Cell,
2017]
The microbiome has emerged as a major determinant of the functioning of host organisms, affecting both health and disease. Here, Han etal. use the workhorse of aging research, C.elegans, to identify specific mechanisms by which gut bacteria influence mitochondrial dynamics and aging, a first steptoward analogous manipulations to modulate human aging.
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[
Rejuvenation Res,
2010]
Due to its many advantages, the nematode worm Caenorhabditis elegans (C. elegans) is commonly employed as a convenient model for aging studies as well as for testing life span effects of chemical compounds. However, some challenges exist in the context of such life span studies, particularly in relation to generation and maintenance of synchronized cohorts, and these challenges are not always fully appreciated. Here we discuss the impact of incomplete control of nematode proliferation on life span studies and suggest some solutions to minimize these artefacts.
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[
Antioxid Redox Signal,
2015]
SIGNIFICANCE: The nematode Caenorhabditis elegans is a widely used model organism for research into aging. However, nematodes diverged from other animals between 600 and 1300 million years ago. Beyond the intuitive impression that some aspects of aging appear to be universal, is there evidence that insights into the aging process of nematodes may be applicable to humans? RECENT ADVANCES: There have been a number of results in nematodes that appear to contradict long-held beliefs about mechanisms and causes of aging. For example, ablation of several key antioxidant systems has often failed to result in lifespan shortening in C. elegans. CRITICAL ISSUES: While it is clear that some central signaling pathways controlling lifespan are broadly conserved across large evolutionary distances, it is less clear to what extent downstream molecular mechanisms of aging are conserved. In this review we discuss the biology of C. elegans and mammals in the context of aging and age-dependent diseases. We consider evidence from studies that attempt to investigate basic, possibly conserved mechanisms of aging especially in the context of the free radical theory of aging. Practical points, such as the need for blinding of lifespan studies and for appropriate biomarkers, are also considered. FUTURE DIRECTIONS: As data on the aging process(es) in different organisms increase, it is becoming increasingly clear that there are both conserved (public) and private aspects to aging. It is important to explore the dividing lines between these two aspects and to be aware of the large gray areas in-between.
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[
FEBS Lett,
2009]
The nematode worm Caenorhabditis elegans (C. elegans) is increasingly popular as a model organism for aging studies as well as for testing antioxidants and other compounds for effects on longevity. However, results in the literature are sometimes confusing and contradictory. This review introduces C. elegans as a model organism, discusses aspects that make it attractive for aging and antioxidant research, and addresses some problems and potential artifacts.
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[
Ann N Y Acad Sci,
2007]
Resveratrol is a naturally occurring polyphenolic compound commonly found in plant-derived products, including red wine. A large number of beneficial effects including anticarcinogenic action and protection from atherosclerotic disease have been attributed to resveratrol. Increased resveratrol intake has been suggested as an explanation for the beneficial effects of moderate red wine consumption. Resveratrol also consistently extends the mean and maximum life span in model organisms including nematode worms. It has been suggested that resveratrol exerts its life-span-extending effect through calorie restriction or hormesis mimetic effects. We have characterized the effect of resveratrol on stress resistance, developmental rate, growth, and fecundity in the nematode worm Caenorhabditis elegans in order to determine whether the beneficial effects of resveratrol on life span are associated with trade-offs in terms of early life fitness in nematodes. We find that resveratrol treatment increases stress resistance, specifically to oxidative stress, and causes a small but significant decrease in fecundity early in life without affecting overall fecundity. Resveratrol increased mean and maximum life span by delaying the onset of the exponential increase in mortality characterizing the "dying phase" in C. elegans, but did not affect the dying phase itself, suggesting that it did not act by directly affecting metabolism.
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Shui G, Fong S, Cheong WF, Koh SA, Halliwell B, Gruber J, Chen CB, Wenk MR, Schaffer S, Ng LF, Wong YT
[
PLoS One,
2011]
One of the most popular damage accumulation theories of ageing is the mitochondrial free radical theory of ageing (mFRTA). The mFRTA proposes that ageing is due to the accumulation of unrepaired oxidative damage, in particular damage to mitochondrial DNA (mtDNA). Within the mFRTA, the "vicious cycle" theory further proposes that reactive oxygen species (ROS) promote mtDNA mutations, which then lead to a further increase in ROS production. Recently, data have been published on Caenorhabditis elegans mutants deficient in one or both forms of mitochondrial superoxide dismutase (SOD). Surprisingly, even double mutants, lacking both mitochondrial forms of SOD, show no reduction in lifespan. This has been interpreted as evidence against the mFRTA because it is assumed that these mutants suffer from significantly elevated oxidative damage to their mitochondria. Here, using a novel mtDNA damage assay in conjunction with related, well established damage and metabolic markers, we first investigate the age-dependent mitochondrial decline in a cohort of ageing wild-type nematodes, in particular testing the plausibility of the "vicious cycle" theory. We then apply the methods and insights gained from this investigation to a mutant strain for C. elegans that lacks both forms of mitochondrial SOD. While we show a clear age-dependent, linear increase in oxidative damage in WT nematodes, we find no evidence for autocatalytic damage amplification as proposed by the "vicious cycle" theory. Comparing the SOD mutants with wild-type animals, we further show that oxidative damage levels in the mtDNA of SOD mutants are not significantly different from those in wild-type animals, i.e. even the total loss of mitochondrial SOD did not significantly increase oxidative damage to mtDNA. Possible reasons for this unexpected result and some implications for the mFRTA are discussed.
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[
Bio Protoc,
2019]
Mitochondrial function and dysfunction are at the core of aging and involved in many age-dependent diseases. Rate of oxygen consumption is a measure of mitochondrial function and energy production rate. The nematode <i>Caenorhabditis elegans (C. elegans</i>) offers an opportunity to study "living" mitochondria without the need for mitochondrial extraction, purification and associated artifacts. Oxygen consumption rate (OCR) is traditionally measured using single-chamber Clark electrodes with or without the addition of metabolic modulators. More recently, multi-well oxygen electrodes with automated injection system have been developed to enable rapid measurement of OCR under different conditions. Here, we describe a detailed protocol that we have adapted from existing protocols to measure coupled and uncoupled mitochondrial respiration (with and without metabolic modulators) in live respiring nematodes using a Seahorse XFe96 extracellular flux analyzer. We present details on our protocol, including preparation of nematode culture, use of metabolic modulators, execution of Seahorse XF assay as well as post-experimental data analysis. As a reference, we provide results of a series of experiments in which the metabolic activity of N2 wild-type nematodes was compared to N2 nematode treated with paraquat, a compound that generates reactive oxygen species (ROS), thus causing oxidative damage and mitochondrial dysfunction. These data illustrate the kind of insights that can be obtained even using a low number of nematodes (10 animals only per well).
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[
International Worm Meeting,
2017]
Many genes, drugs and environmental interventions have been reported to extend lifespan. However, compared to lifespan effects seen with genetic perturbations, the effect size of pharmacological interventions, are typically smaller. Furthermore, simultaneous genetic alteration of two or more pathways has been shown to extend lifespan synergistically. However, it is not clear whether combination of pro-longevity drugs would also have synergistic lifespan extension. Here, we first identified a set of well characterized and evolutionarily conserved ageing pathways. We then identified drugs which targets these pathways and extends lifespan in one or more model organisms. We then systematically explored the efficacy in terms of lifespan extension of all pairs of drugs, identifying two synergistic interactions. Finally, we explored selected triple drug combinations based on the two initial synergistic pairs. Our best triple combination results in doubling of median lifespan with similarly improved healthspan and without any evidence for fitness costs or developmental tradeoffs. To the best of our knowledge this is the largest reported lifespan effect for any pharmacological intervention in C. elegans. To explore the nature of the synergistic mechanism of lifespan extension we employed two approaches. First, we followed a paradigm-driven approach by determined lifespan efficacy of single and combined drugs in different mutants. Second, we used a data driven approach based on transcriptome profile for single drugs and drug combinations. Interestingly, we showed that both the paradigm approach and data driven approach agrees to explain the reason behind drug synergy. Moreover, we showed that TFG-beta signaling pathway is commonly enriched in all synergistic drug combinations but not in non-synergistic combinations. This may indicates that TGF-beta is required for the synergistic lifespan extension. Interestingly, drug combinations fail to show synergistic lifespan extension in TGF-beta downstream mutants. Hence, we believe that tools might be developed to predict synergistic interactions based on transcriptome profiles without the need of time-consuming combinatorial lifespan studies. Furthermore, the synergistic effect of our best combination is quantatively preserved in Drosophila Melanogaster, suggesting evolutionary conservation of this synergy.
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[
Biochemistry,
1987]
The major intestinal esterase from the nematode Caenorhabditis elegans has been purified to essential homogeneity. Starting from whole worms, the overall purification is 9000-fold with a 10% recovery of activity. The esterase is a single polypeptide chain of Mr 60,000 and is stoichiometrically inhibited by organophosphates. Substrate preferences and inhibition patterns classify the enzyme as a carboxylesterase (EC 3.1.1.1), but the physiological function is unknown. The sequence of 13 amino acid residues at the esterase N- terminus has been determined. This partial sequence shows a surprisingly high degree of similarity to the N-terminal sequence of two carboxylesterases recently isolated from Drosophila mojavensis [Pen, J., van Beeumen, J., & Beintema, J. J. (1986) Biochem. J. 238, 691-699].
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[
Curr Biol,
1999]
In this Brief Communication, which appeared in the 14 September 1998 issue of Current Biology, the UV dose was reported erroneously. The dose reported was 20 J/m2 but the actual dose used was 0.4 J/cm2. Also, the gene formally referred to as
tkr-1 has since been renamed
old-1 (overexpression longevity determination).