Jafari, Gholamali et al. (2015) International Worm Meeting "Hyperoxia effects on development and reproduction."

Li, Zhongyu, Jafari, Gholamali, Kaeberlein, Matt, Ayon, Daniela, Pitt, Jason

[International Worm Meeting, 2015]

While hyperoxia is toxic to most organisms, C. elegans is resistant to long-term exposure to 100% (90 kPa). Oxygen toxicity results from the formation of Reactive Oxygen Species (ROS) within the mitochondria as superoxide anion and then hydrogen peroxide, which damages lipids, proteins, and nucleic acids. Superoxide dismutase and catalase protect the cells against normal levels of ROS. We sought to find other pathways that are involved in C. elegans hyperoxia tolerance. As previously shown, the superoxide dismutase pathway was involved in the defense against hyperoxia. We found that the previously described hyperoxia chemosensory circuit (npr-1, gcy-35, and gcy-36) did not affect survival or development in hyperoxia. Surprisingly, we found that the hypoxia (low oxygen) response pathway was required for hyperoxia tolerance through the egl-9 and hif-1 axis. hif-1 mutants could not reproduce in hyperoxia and showed a deformed pale body and a severe movement defect. Curiously, egl-9 mutants (that have elevated HIF-1 levels) have an even more severe phenotype, arresting during early larval development in hyperoxia. We conclude that in addition to its role in hypoxia, the HIF-1 pathway functions during hyperoxia to maintain the proper redox balance in the worm.

Blue, Ben W. et al. (2019) International Worm Meeting "Longevity Over the Counter: Investigating the Effects of Common Dietary Supplements on Aging."

Berry, Faith, Estes, Raja, Blue, Ben W., Pitt, Jason, Kim, Young-Woo, Vayndorf, Elena, Nikjoo, Arash, Kaeberlein, Matt, Pothan, Lincoln

[International Worm Meeting, 2019]

C. elegans has been a workhorse within the field of aging biology due to its short lifespan, easy culturing, and robust genetic tools. However, one major limiting factor in using C. elegans has been that throughput was constrained by the time and effort needed to manually check each worm for signs of life during longitudinal studies. By using the WormBot, a high-throughput robotic image capture platform, we were able to accurately and quickly screen a wide array of compounds for their effects on C. elegans lifespan. A single WormBot can monitor 144 individual experiments at once and, when coupled with an image analysis package, allows for accurate time of death calls. Here we present data generated with the WormBot that includes a screen of compounds from a wide array of natural and synthetic products. Supplements and multivitamin/minerals (MVMs) were a ~36 billion dollar industry in 2014 but are not subject to the same regulatory standards that FDA-approved drugs are. In order to better examine the effects of these widely-used compounds upon the aging process we examined longevity in a wildtype strain of C. elegans (N2) as well as an engineered strain (GMC101) that expresses human A? protein in the body wall muscle. The age-related pathogenesis of the A?-expressing strain is a progressive paralysis. As such, we screened our battery of compounds to determine which compounds have a significant effect on delaying GMC101's A?-associated paralysis. Lastly, using the WormBot's ability to capture video recording alongside time-lapse photography, we examine how each compound affects the healthspan of the different genetic models by using the WormBot's ability to capture high-resolution videos and then analyzing animal motility.

Yamei Wang et al. (2005) International Worm Meeting "Regulation of life span by a C. elegans SIR2"

Yamei Wang, Heidi A Tissenbaum

[International Worm Meeting, 2005]

In C. elegans, overexpression of sir-2.1, the closest homolog to yeast Sir2p and human SIRT1, extends life span (Tissenbaum and Guarente, 2001). Similarly, overexpression of yeast SIR2 extends yeast life span (Kaeberlein et al., 1999). In C. elegans, lifespan extension by sir-2.1 overexpression is dependent on the forkhead transcription factor, daf-16 (Tissenbaum and Guarente, 2001). We have done extensive genetic analysis with sir-2.1(ok434), a null mutant of C. elegans sir-2.1. sir-2.1(ok434) mutants show a slight decrease in life span as well as sensitivity to several stresses when compared to wild-type. Our genetic analysis suggests that sir-2.1 is also required for life span extension by caloric restriction; independent of the insulin-like signaling pathway. Finally, expression analysis of sir-2.1 shows sir-2.1 is expressed in many neurons, a tissue critical for life span regulation. Therefore, to date, analysis from both deletion and overexpression strains, indicates that sir-2.1 functions in both the insulin-like signaling pathway and caloric restriction pathway for life span regulation.

Malene Hansen et al. (2006) European Worm Meeting "Ribosomal Proteins are New Longevity Determinants in C. elegans"

Cynthia Kenyon., Malene Hansen

[European Worm Meeting, 2006]

Malene Hansen and Cynthia Kenyon. Multiple longevity pathways and genes have been identified in C. elegans. One example is the conserved DAF-2/insulin/IGF-1 pathway, which modulates lifespan through the downstream transcription factor DAF-16. Other processes, including dietary restriction, affect lifespan in daf-16 independent ways. The molecular mechanism by which dietary restriction works is largely unknown; however, experiments from other model organisms suggest the involvement of the nutrient sensor TOR (Kapahi et al., 2004, Kaeberlein et al., 2005).. Through an RNAi screen, we found that RNAi clones for ribosomal proteins (RPs) significantly extend lifespan in a daf-16 independent fashion. Knockdown of RPs belonging to both the small and the large ribosomal subunits increased lifespan, but only when RPs were inhibited during adulthood. Collectively, these observations reveal a longevity function for ribosomal proteins in adult C. elegans. Interestingly, deletion mutants of several ribosomal proteins in yeast have recently been reported to increase lifespan (Kaeberlein et al., 2005), indicating that the function of RP in lifespan modulation is conserved.. One major regulator of ribosomal biogenesis and translation is the kinase TOR, which, like RPs, influences C. elegans lifespan in a daf-16 independent fashion (Vellai et al., 2003). We have therefore begun to investigate a potential mechanistic overlap among RPs, TOR, and some of its putative effectors (including S6 kinase and several translation initiation factors).. We expected that this group of molecules collectively involved in translation would behave similarly to influence longevity. We were therefore surprised to find significant differences in how these molecules affect lifespan. Most importantly, our genetic analysis suggests that TOR affects lifespan by a dietary restriction-like mechanism in C. elegans, whereas RPs may function by an as yet unidentified mechanism. TOR''s role in dietary restriction might therefore involve TOR-regulated processes other than translation per se. We are currently investigating this hypothesis in more detail.

Corkins, Mark et al. (2009) International Worm Meeting "Osmotic stress extends C. elegans lifespan."

Somers, Gerard, Hart, Anne C., Anderson, Edward N., Corkins, Mark

[International Worm Meeting, 2009]

Moderate levels of environmental stress, such as oxidative stress, dietary restriction, or heat shock, can cause organisms to live longer. In S. cerevisiae, osmotic stress has been shown to cause lifespan extension, and this extension is regulated by sirtuins via the NAD salvage pathway. (Kaeberlein et al. 2002). We find that moderate osmotic stress can increase the lifespan of C. elegans. The major osmolyte in NGM media is NaCl. Wild type animals reared on NGM containing increased NaCl live longer than those reared on standard 51 mM NaCl. This increased lifespan extension is dose-dependant, and maximal lifespan is observed at roughly 300 mM NaCl with approximately 30% lifespan extension. Increased longevity is likely not due to a developmental change, animals shifted at the L4 stage to 300 mM NaCl have a lifespan similar to those reared from birth on 300 mM media. Currently, we are assessing the contribution of genes known to extend lifespan in this paradigm. Osmotic stress induced lifespan extension is prevented by loss of the FOXO transcription factor daf-16, but is unaffected by loss of the AMP kinase aak-2. Osmotic lifespan extension is not further extended by the eat-2 model of dietary restriction. Overall, our results suggest that osmotic stress can increase longevity and that a subset of conserved pathways are critical for this lifespan extension.

Anderson, Edward N. et al. (2011) International Worm Meeting "Osmotic stress and loss of Notch ligands extend C. elegans lifespan via FOXO and sirtuins."

Corkins, Mark, Sinclair, David, Anderson, Edward N., Hart, Anne C.

[International Worm Meeting, 2011]

Moderate environmental stress, such as oxidative stress, dietary restriction, or heat shock, can increase the lifespan of many species. In S. cerevisiae, moderate osmotic stress causes lifespan extension, and this extension requires sirtuin function in the NAD salvage pathway. (Kaeberlein et al. 2002). We find that moderate osmotic stress increases the lifespan of C. elegans. NGM contains 51 mM NaCl as the major osmolyte. Wild type animals reared on NGM with increased NaCl live longer than those reared on standard 51 mM NaCl. This lifespan extension occurs with other osmolytes and is dose-dependent. Maximal lifespan extension of 30% is observed at 300 mM NaCl. Osmotic stress starting after the L4 stage is sufficient to extend lifespan. Currently, we are investigating the underlying genetic pathways. Osmotic stress induced lifespan extension requires members of the sirtuin family and the FOXO transcription factor daf-16. We also find a partial requirement for pnc-1, a component of the NAD salvage pathway. Loss of Notch co-ligands osm-7 and osm-11 mimics osmotic stress and extends lifespan in a daf-16 dependent manner. Dietary restriction by eat-2 does not further extend lifespan under osmotic stress conditions. Overall, our results suggest that osmotic stress likely extends lifespan by activating conserved pathways.

Heidi A Tissenbaum et al. (2002) East Coast Worm Meeting "A new genetic screen to identify genes that regulate life span"

Nenad Svrzikapa, Heidi A Tissenbaum, Christian Grove

[East Coast Worm Meeting, 2002]

To identify new genes, that affect life span, we did a genetic screen looking for genes that extend life span when increased in gene dosage. We reasoned that increasing the dosage of any gene whose activity is rate limiting for the aging process should extend the life span of the worm. We increased gene dosage by analyzing duplication strains where the dosage of genes covered by the duplication is increased by 50% compared to wild type. Therefore, our genetic screen was a life span survey of duplication strains. The initial survey of duplications covered approximately 50% of the C. elegans genome from a total of 35 strains tested for life span (Tissenbaum and Guarente 2001). From this survey, we identified a new gene in the insulin-like signaling pathway, sir-2.1 (Tissenbaum and Guarente 2001). This gene is the C. elegans homolog to yeast SIR2. In yeast, SIR2 also regulates life span by gene dosage (Kaeberlein, McVey et al. 1999). We have obtained duplication strains covering the rest of the genome. Currently, we have tested an additional 40 duplication strains for life span and we have three new regions that extend the mean life span. We are now narrowing down the region responsible for the life span extension as well as continuing the screen to cover the rest of the genome. * these two authors contributed equally to this project

Gidalevitz T et al. (2013) BMC Biol "Natural genetic variation determines susceptibility to aggregation or toxicity in a C. elegans model for polyglutamine disease."

Alexander-Floyd J, Deravaj T, Wang N, Gidalevitz T, Morimoto RI

[BMC Biol, 2013]

BACKGROUND: Monogenic gain-of-function protein aggregation diseases, including Huntington's disease, exhibit substantial variability in age of onset, penetrance, and clinical symptoms, even between individuals with similar or identical mutations. This difference in phenotypic expression of proteotoxic mutations is proposed to be due, at least in part, to the variability in genetic background. To address this, we examined the role of natural variation in defining the susceptibility of genetically diverse individuals to protein aggregation and toxicity, using the Caenorhabditis elegans polyglutamine model. RESULTS: Introgression of polyQ40 into three wild genetic backgrounds uncovered wide variation in onset of aggregation and corresponding toxicity, as well as alteration in the cell-specific susceptibility to aggregation. To further dissect these relationships, we established a panel of 21 recombinant inbred lines that showed a broad range of aggregation phenotypes, independent of differences in expression levels. We found that aggregation is a transgressive trait, and does not always correlate with measures of toxicity, such as early onset of muscle dysfunction, egg-laying deficits, or reduced lifespan. Moreover, distinct measures of proteotoxicity were independently modified by the genetic background. CONCLUSIONS: Resistance to protein aggregation and the ability to restrict its associated cellular dysfunction are independently controlled by the natural variation in genetic background, revealing important new considerations in the search for targets for therapeutic intervention in conformational diseases. Thus, our C. elegans model can serve as a powerful tool to dissect the contribution of natural variation to individual susceptibility to proteotoxicity.Please see related commentary by Kaeberlein, http://www.biomedcentral.com/1741-7007/11/102.

Laura Gallo et al. (2003) International Worm Meeting "A genetic approach to identify meiotic-specific chromosome segregation factors"

Kathleen St. John, Diane C Shakes, Laura Gallo, Erica Stewart, Ken Donohue

[International Worm Meeting, 2003]

During the normal process of eukaryotic cell division, chromosomes replicate during S-phase, undergo ordered compaction during prophase, and align in a central plate during metaphase. As cells subsequently transition from metaphase to anaphase, the replicated and aligned chromosomes separate and segregate into each of the two daughter cells. During anaphase, defects in any step of this multi-step process result in chromosome breakage and/or mis-segregation, problems that ultimately result in birth defects, cell death, and/or malignant transformations. Recent studies in a variety of eukaryotes suggest that the basic molecular mechanisms of chromosome segregation have been conserved both across species and between the related but distinctive processes of mitosis and meiosis. At the same time, the meiotic-specific process of homolog separation requires at least a few meiotic specific components, and chromosome segregation on anastral, acentriolar spindles is similarly expected to require at least a few oocyte-specific components. To identify the combination of unique and cell-type specific genes required for proper anaphase chromosome segregation in C. elegans, we are screening through a large collection of temperature-sensitive maternal mutants originally isolated by Matt Wallenfang and Geraldine Seydoux. Our overall strategy is to identify those with obvious defects in oocyte meiotic chromosome segregation and then to secondarily determine which of these also have defects in spermatocyte meiosis and/or germline mitosis. Using this approach, we expect to not only identify genes required during different stages of chromosome segregation but also those that differ in their cell-type specificity including those with general (mitosis and meiosis); meiosis-specific; and oocyte-specific defects. To date, subclasses of oocyte defects include problems in meiotic metaphase alignment, homolog separation, and meiotic cell cycle progression. Genetic mapping studies of these mutants as well as a comparative analysis of their oocyte, spermatocyte, and germline defects are currently in progress.

McGee MD et al. (2011) Aging Cell "Loss of intestinal nuclei and intestinal integrity in aging C. elegans."

Hall DH, McGee MD, Weber D, Vitelli C, Crippen D, Melov S, Herndon LA, Day N

[Aging Cell, 2011]

The roundworm C. elegans is widely used as an aging model, with hundreds of genes identified that modulate aging (Kaeberlein etal., 2002. Mech. Ageing Dev.123, 1115-1119). The development and bodyplan of the 959 cells comprising the adult have been well described and established for more than 25 years (Sulston and Horvitz, 1977. Dev. Biol.56, 110-156; Sulston et al., 1983. Dev. Biol.100, 64-119.). However, morphological changes with age in this optically transparent animal are less well understood, with only a handful of studies investigating the pathobiology of aging. Age-related changes in muscle (Herndon etal., 2002. Nature419, 808-814), neurons (Herndon etal., 2002), intestine and yolk granules (Garigan etal., 2002. Genetics161, 1101-1112; Herndon etal., 2002), nuclear architecture (Haithcock etal., 2005. Proc. Natl Acad. Sci. USA102, 16690-16695), tail nuclei (Golden etal., 2007. Aging Cell6, 179-188), and the germline (Golden etal., 2007) have been observed via a variety of traditional relatively low-throughput methods. We report here a number of novel approaches to study the pathobiology of aging C. elegans. We combined histological staining of serial-sectioned tissues, transmission electron microscopy, and confocal microscopy with 3D volumetric reconstructions and characterized age-related morphological changes in multiple wild-type individuals at different ages. This enabled us to identify several novel pathologies with age in the C. elegans intestine, including the loss of critical nuclei, the degradation of intestinal microvilli, changes in the size, shape, and cytoplasmic contents of the intestine, and altered morphologies caused by ingested bacteria. The three-dimensional models we have created of tissues and cellular components from multiple individuals of different ages represent a unique resource to demonstrate global heterogeneity of a multicellular organism.