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Kargar M, Jamali H, Sadeghi M. Investigating Association of Human-Specific Derived Alleles of CD33 and Other Genes with Lifespan of Iranians. MEDICAL LABORATORY JOURNAL 2019. [DOI: 10.29252/mlj.13.5.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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Empirical verification of evolutionary theories of aging. Aging (Albany NY) 2017; 8:2568-2589. [PMID: 27783562 PMCID: PMC5115907 DOI: 10.18632/aging.101090] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/11/2016] [Indexed: 01/09/2023]
Abstract
We recently selected 3 long-lived mutant strains of Saccharomyces cerevisiae by a lasting exposure to exogenous lithocholic acid. Each mutant strain can maintain the extended chronological lifespan after numerous passages in medium without lithocholic acid. In this study, we used these long-lived yeast mutants for empirical verification of evolutionary theories of aging. We provide evidence that the dominant polygenic trait extending longevity of each of these mutants 1) does not affect such key features of early-life fitness as the exponential growth rate, efficacy of post-exponential growth and fecundity; and 2) enhances such features of early-life fitness as susceptibility to chronic exogenous stresses, and the resistance to apoptotic and liponecrotic forms of programmed cell death. These findings validate evolutionary theories of programmed aging. We also demonstrate that under laboratory conditions that imitate the process of natural selection within an ecosystem, each of these long-lived mutant strains is forced out of the ecosystem by the parental wild-type strain exhibiting shorter lifespan. We therefore concluded that yeast cells have evolved some mechanisms for limiting their lifespan upon reaching a certain chronological age. These mechanisms drive the evolution of yeast longevity towards maintaining a finite yeast chronological lifespan within ecosystems.
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Longevity extension by phytochemicals. Molecules 2015; 20:6544-72. [PMID: 25871373 PMCID: PMC6272139 DOI: 10.3390/molecules20046544] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 04/07/2015] [Accepted: 04/08/2015] [Indexed: 12/31/2022] Open
Abstract
Phytochemicals are structurally diverse secondary metabolites synthesized by plants and also by non-pathogenic endophytic microorganisms living within plants. Phytochemicals help plants to survive environmental stresses, protect plants from microbial infections and environmental pollutants, provide them with a defense from herbivorous organisms and attract natural predators of such organisms, as well as lure pollinators and other symbiotes of these plants. In addition, many phytochemicals can extend longevity in heterotrophic organisms across phyla via evolutionarily conserved mechanisms. In this review, we discuss such mechanisms. We outline how structurally diverse phytochemicals modulate a complex network of signaling pathways that orchestrate a distinct set of longevity-defining cellular processes. This review also reflects on how the release of phytochemicals by plants into a natural ecosystem may create selective forces that drive the evolution of longevity regulation mechanisms in heterotrophic organisms inhabiting this ecosystem. We outline the most important unanswered questions and directions for future research in this vibrant and rapidly evolving field.
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Schwarz F, Pearce OMT, Wang X, Samraj AN, Läubli H, Garcia JO, Lin H, Fu X, Garcia-Bingman A, Secrest P, Romanoski CE, Heyser C, Glass CK, Hazen SL, Varki N, Varki A, Gagneux P. Siglec receptors impact mammalian lifespan by modulating oxidative stress. eLife 2015; 4. [PMID: 25846707 PMCID: PMC4384638 DOI: 10.7554/elife.06184] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/08/2015] [Indexed: 12/12/2022] Open
Abstract
Aging is a multifactorial process that includes the lifelong accumulation of molecular damage, leading to age-related frailty, disability and disease, and eventually death. In this study, we report evidence of a significant correlation between the number of genes encoding the immunomodulatory CD33-related sialic acid-binding immunoglobulin-like receptors (CD33rSiglecs) and maximum lifespan in mammals. In keeping with this, we show that mice lacking Siglec-E, the main member of the CD33rSiglec family, exhibit reduced survival. Removal of Siglec-E causes the development of exaggerated signs of aging at the molecular, structural, and cognitive level. We found that accelerated aging was related both to an unbalanced ROS metabolism, and to a secondary impairment in detoxification of reactive molecules, ultimately leading to increased damage to cellular DNA, proteins, and lipids. Taken together, our data suggest that CD33rSiglecs co-evolved in mammals to achieve a better management of oxidative stress during inflammation, which in turn reduces molecular damage and extends lifespan. DOI:http://dx.doi.org/10.7554/eLife.06184.001 As we get older, we are more likely to become frail, be less mobile and develop heart disease, diabetes, and other age-related diseases. This is partly due to damage to tissues and organs that accumulates over the course of our lifetime. How quickly we age is controlled both by our genetics and by the environment we live in. It is thought that damage to DNA, proteins, and other molecules in the body caused by chemically active molecules called reactive oxygen species (ROS) can influence aging. ROS are produced during respiration, immune responses, and other important processes in cells, but in excessive amounts they can be extremely harmful. To avoid damage to DNA and other important molecules, cells have several ways to control the levels of ROS. One of the other hallmarks of aging is the development of chronic inflammation in tissues around the body, which is partly triggered by the immune system in response to cell damage. A group of genes called the CD33rSIGLEC genes are involved in controlling inflammation. The genomes of different mammal species carry different numbers of these genes, but it is not clear whether this alters the aging process in these animals. In this study, Schwarz et al. investigated whether the CD33rSIGLEC genes influence the lifespans of mammals. Species with a higher number of CD33rSIGLEC genes generally have a longer lifespan than those with fewer of these genes. Mice that were missing one of these genes and were subjected to inflammation early in life showed signs of accelerated aging and had shortened lifespans compared with normal mice. As predicted, these mice also had higher levels of ROS, which led to a greater amount of damage to the DNA and other molecules in their bodies. Schwarz et al.'s findings suggest that the CD33rSIGLECs co-evolved in mammals to help control the levels of ROS during inflammation, thereby reducing the damage to cells and extending the lifespan of the animals. Given that individual humans have different numbers of working CD33rSIGLEC genes, it would be interesting to see if this influences human lifespan. DOI:http://dx.doi.org/10.7554/eLife.06184.002
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Affiliation(s)
- Flavio Schwarz
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Oliver M T Pearce
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Xiaoxia Wang
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Annie N Samraj
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Heinz Läubli
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Javier O Garcia
- Department of Psychology, University of California, San Diego, San Diego, United States
| | - Hongqiao Lin
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, United States
| | - Xiaoming Fu
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, United States
| | - Andrea Garcia-Bingman
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Patrick Secrest
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Casey E Romanoski
- Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States
| | - Charles Heyser
- Department of Neurosciences, University of California, San Diego, San Diego, United States
| | - Christopher K Glass
- Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States
| | - Stanley L Hazen
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, United States
| | - Nissi Varki
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Ajit Varki
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Pascal Gagneux
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
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Gandhi M, Nikiforov YE. Suitability of animal models for studying radiation-induced thyroid cancer in humans: evidence from nuclear architecture. Thyroid 2011; 21:1331-7. [PMID: 22136268 PMCID: PMC3229820 DOI: 10.1089/thy.2011.0269] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Rat and mouse have been widely used to estimate the radiation risk and tumorigenic effects of radiation with extrapolating the findings to humans. RET/PTC is a characteristic genetic alteration frequently found in radiation-induced thyroid cancer in human populations. Recently, nuclear architecture and spatial proximity between recombinogenic genes have been implicated as important factors in the generation of RET/PTC and other chromosomal rearrangements in human cells. However, it is unknown whether the nuclear architecture in rodent thyroid cells is similar to that of human thyroid cells. The aim of this study was to test whether the proximity effects that are observed between loci involved in RET/PTC rearrangements in humans are conserved across different species. METHODS Using 3D fixation, fluorescence in situ hybridization, and confocal microscopy, we compared the distance between genes involved in RET/PTC rearrangement in normal thyroid cells from humans, mice, and rats. RESULTS While in humans, RET, NCOA4, and H4 are all located on the same chromosome (10q), in rodents these genes are located on separate chromosomes. In mouse, RET is located on chromosome 6F1, NCOA4 on 14B, and H4 on 10B5.3. In rat, RET is on chromosome 4q42, NCOA4 on 16p16, and H4 (TST1) on 9q36. We further observed that in human thyroid cells, mean distance between genes involved in two most common types of RET/PTC, that is, RET and NCOA4 (partners of RET/PTC3) and RET and H4 (partners of RET/PTC1), was 1.08±0.04 and 1.24±0.05 μm, respectively. In mouse thyroid cells, these distances were 3.21±0.1 and 3.43±0.1 μm, and in rat cells the values were 3.37±0.1 and 3.87±0.1 μm (p<0.001). Moreover, we found that in contrast to human thyroid cells, in rodent cells these genes were randomly positioned with respect to each other. CONCLUSIONS The differences in nuclear architecture and spatial positioning of genes involved in RET/PTC rearrangements between human and rodent thyroid cells raise a concern about suitability of animal models for assessing RET/PTC-driven thyroid carcinogenesis in humans.
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Affiliation(s)
- Manoj Gandhi
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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Levitis DA, Lackey LB. A measure for describing and comparing post-reproductive lifespan as a population trait. Methods Ecol Evol 2011; 2:446-453. [PMID: 22081792 DOI: 10.1111/j.2041-210x.2011.00095.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. While-classical life-history theory does not predict post-reproductive lifespan (PRLS), it has been detected in a great number of taxa, leading to the view that it is a broadly conserved trait, and attempts to reconcile theory with these observations. We suggest an alternative: the apparently wide distribution of significant PRLS is an artifact of insufficient methods.2. PRLS is traditionally measured in units of time between each individual's last parturition and death, after excluding those individuals for whom this interval is short. A mean of this measure is then calculated as a population value. We show this traditional population measure (which we denote PrT) to be inconsistently calculated, inherently biased, strongly correlated with overall longevity, uninformative on the importance of PRLS in a population's life-history, unable to use the most-commonly available form of relevant data and without a realistic null hypothesis. Using data altered to ensure that the null hypothesis is true, we find a false positive rate of 0.47 for PrT.3. We propose an alternative population measure, using life-table methods. Post-reproductive Representation (PrR) is the proportion of adult years lived which are post-reproductive. We briefly derive PrR and discuss its properties. We employ a demographic simulation, based on the null hypothesis of simultaneous and proportional decline in survivorship and fecundity, to produce a null distribution for PrR based on the age-specific rates of a population.4. In an example analysis, using data on 84 populations of human and non-human primates, we demonstrate the ability of PrR to represent the effects of artificial protection from mortality and of humanness on PRLS. PrR is found to be higher for all human populations under a wide range of conditions than for any non-human primate in our sample. A strong effect of artificial protection is found, but humans under the most-adverse conditions still achieve PrR of >0.3.5. PrT should not be used as a population measure, and should be used as an individual measure only with great caution. The use of PrR as an intuitive, statistically valid and intercomparable population life-history measure is encouraged.
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Affiliation(s)
- Daniel A Levitis
- Max Planck Institute for Demographic Research, Laboratory of Evolutionary Biodemography, Konrad-Zuse Strasse 1, 18057 Rostock Germany
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Abstract
ABSTRACTModel building in epidemiological-ecologic research on aging is hampered by the prevailing paradigm of standard empiricism, lack of knowledge about the biological origins and causes of aging and problems in differentiating the aging process from age-related diseases and disabilities. Consequently, the identification of associations or causal relations between risk factors, aging, diseases and disabilities suffers from a number of conceptual and methodological problems which sometimes can lead to research results which are absurd in the context of real life despite their formal correctness. The benefit of building theoretical models arises out of the necessity to construct an empirically sensible order of events which renders the research object intelligible. It is suggested that in the multifactorial epidemiological-ecologic aging research it might be useful to adopt and empirically test the concept of the “effective causal complex” instead of continuing, in many cases fruitless, attempts to define the effects of single risk factors on the associations between aging, physiological damage and disease and disability outcomes.
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Carey JR, Papadopoulos NT, Müller HG, Katsoyannos BI, Kouloussis NA, Wang JL, Wachter K, Yu W, Liedo P. Age structure changes and extraordinary lifespan in wild medfly populations. Aging Cell 2008; 7:426-37. [PMID: 18363903 PMCID: PMC2398686 DOI: 10.1111/j.1474-9726.2008.00390.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The main purpose of this study was to test the hypotheses that major changes in age structure occur in wild populations of the Mediterranean fruit fly (medfly) and that a substantial fraction of individuals survive to middle age and beyond (> 3-4 weeks). We thus brought reference life tables and deconvolution models to bear on medfly mortality data gathered from a 3-year study of field-captured individuals that were monitored in the laboratory. The average time-to-death of captured females differed between sampling dates by 23.9, 22.7, and 37.0 days in the 2003, 2004, and 2005 field seasons, respectively. These shifts in average times-to-death provided evidence of changes in population age structure. Estimates indicated that middle-aged medflies (> 30 days) were common in the population. A surprise in the study was the extraordinary longevity observed in field-captured medflies. For example, 19 captured females but no reference females survived in the laboratory for 140 days or more, and 6 captured but no reference males survived in the laboratory for 170 days or more. This paper advances the study of aging in the wild by introducing a new method for estimating age structure in insect populations, demonstrating that major changes in age structure occur in field populations of insects, showing that middle-aged individuals are common in the wild, and revealing the extraordinary lifespans of wild-caught individuals due to their early life experience in the field.
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Affiliation(s)
- James R Carey
- Department of Entomology, University of California, Davis, Davis, CA 95616, USA.
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Vaanholt L, Speakman J, Garland Jr. T, Lobley G, Visser G. Protein Synthesis and Antioxidant Capacity in Aging Mice: Effects of Long‐Term Voluntary Exercise. Physiol Biochem Zool 2008; 81:148-57. [DOI: 10.1086/525289] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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10
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Cheng C, Fabrizio P, Ge H, Wei M, Longo VD, Li LM. Significant and systematic expression differentiation in long-lived yeast strains. PLoS One 2007; 2:e1095. [PMID: 17971858 PMCID: PMC2039703 DOI: 10.1371/journal.pone.0001095] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2007] [Accepted: 10/09/2007] [Indexed: 01/30/2023] Open
Abstract
Background Recent studies suggest that the regulation of longevity may be partially conserved in many eukaryotes ranging from yeast to mammals. The three yeast mutants sch9Δ, ras2Δ, tor1Δ show extended chronological life span up to three folds. Our aim is to dissect the mechanisms that lead to the yeast life span extension. Methodology/Principal Findings We obtain gene expression profiles of sch9Δ, ras2Δ, tor1Δ as well as that for a wild type at day 2.5 in SDC medium using Affymetrix Yeast2.0 arrays. To accurately estimate the expression differentiation between the wild type and the long-lived mutants, we use sub-array normalization followed by a variant of the median-polishing summarization. The results are validated by the probe sets of S. pombe on the same chips. To translate the differentiation into changes of biological activities, we make statistical inference by integrating the expression profiles with biological gene subsets defined by Gene Ontology, KEGG pathways, and cellular localization of proteins. Other than subset-versus-other comparisons, we also make local comparisons between two directly-related gene subsets such as cytosolic and mitochondrial ribosomes. Our consensus is obtained by cross-examination of these inferences. The significant and systematic differentiation in the three long-lived strains includes: lower transcriptional activities; down-regulation of TCA cycle and oxidative phosphorylation versus up-regulation of the KEGG pathway Glycolysis/Gluconeogenesis; the overall reduction of mitochondrial activities. We also report some different expression patterns such as reduction of the activities relating to mitosis in ras2Δ. Conclusions/Significance The modification of energy pathways and modification of compartment activities such as down-regulation of mitochondrial ribosome proteins versus up-regulation of cytosolic ribosome proteins are directly associated with the life span extension in yeast. The results provide a new and systematic S. cerevisiae version of the free radical theory from the perspective of functional genomics.
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Affiliation(s)
- Chao Cheng
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Paola Fabrizio
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Huanying Ge
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Min Wei
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Valter D. Longo
- Andrus Gerontology Center and Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Lei M. Li
- Molecular and Computational Biology Program, Department of Biological Sciences, University of Southern California, Los Angeles, California, United States of America
- Department of Mathematics, University of Southern California, Los Angeles, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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Johnston S, Grune T, Bell L, Murray S, Souter D, Erwin S, Yearsley J, Gordon I, Illius A, Kyriazakis I, Speakman J. Having it all: historical energy intakes do not generate the anticipated trade-offs in fecundity. Proc Biol Sci 2006; 273:1369-74. [PMID: 16777725 PMCID: PMC1560301 DOI: 10.1098/rspb.2005.3456] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
An axiom of life-history theory, and fundamental to our understanding of ageing, is that animals must trade-off their allocation of resources since energy and nutrients are limited. Therefore, animals cannot "have it all"--combine high rates of fecundity with extended lifespans. The idea of life-history trade-offs was recently challenged by the discovery that ageing may be governed by a small subset of molecular processes independent of fitness. We tested the "trade-off" and "having it all" theories by examining the fecundities of C57BL/6J mice placed onto four different dietary treatments that generated caloric intakes from -21 to +8.6% of controls. We predicted body fat would be deposited in relation to caloric intake. Excessive body fat is known to cause co-morbidities that shorten lifespan, while caloric restriction enhances somatic protection and increases longevity. The trade-off model predicts that increased fat would be tolerated because reproductive gain offsets shortened longevity, while animals on a restricted intake would sacrifice reproduction for lifespan extension. The responses of body fat to treatments followed our expectations, however, there was a negative relationship between reproductive performance (fecundity, litter mass) and historical intake/body fat. Our dietary restricted animals had lower protein oxidative damage and appeared able to combine life-history traits in a manner contrary to traditional expectations by having increased fecundity with the potential to have extended lifespans.
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Affiliation(s)
- S.L Johnston
- Division of Energy Balance and Obesity, Rowett Research InstituteGreenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
- Aberdeen Centre for Energy Regulation and Obesity (ACERO)Aberdeen AB21 9SB, UK
| | - T Grune
- Research Institute for Environmental Medicine at the Heinrich Heine University Duesseldorf, Molecular Ageing ResearchAuf'm Hennekamp 50, 40225 Duesseldorf, Germany
| | - L.M Bell
- Division of Energy Balance and Obesity, Rowett Research InstituteGreenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
| | - S.J Murray
- Division of Energy Balance and Obesity, Rowett Research InstituteGreenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
| | - D.M Souter
- Division of Energy Balance and Obesity, Rowett Research InstituteGreenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
| | - S.S Erwin
- Division of Energy Balance and Obesity, Rowett Research InstituteGreenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
| | - J.M Yearsley
- Macaulay InstituteCraigiebuckler, Aberdeen AB15 8QH, UK
| | - I.J Gordon
- Macaulay InstituteCraigiebuckler, Aberdeen AB15 8QH, UK
- Sustainable Ecosystems, CSIRO—Davies LaboratoryPMB PO Aitkenvale, Queensland 4814, Australia
| | - A.W Illius
- School of Biological Sciences, Institute of Evolutionary BiologyUniversity of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK
| | - I Kyriazakis
- Animal Nutrition & Health Department, Scottish Agricultural CollegeKings Buildings, West Mains Road, Edinburgh EH9 3JG, UK
| | - J.R Speakman
- Division of Energy Balance and Obesity, Rowett Research InstituteGreenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
- School of Biological Sciences, University of AberdeenAberdeen AB24 2TZ, UK
- Aberdeen Centre for Energy Regulation and Obesity (ACERO)Aberdeen AB21 9SB, UK
- Author for correspondence ()
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Davis GE, Lowell WE. The Sun determines human longevity: teratogenic effects of chaotic solar radiation. Med Hypotheses 2004; 63:574-81. [PMID: 15324999 DOI: 10.1016/j.mehy.2004.03.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2004] [Accepted: 03/13/2004] [Indexed: 11/29/2022]
Abstract
An association between fertility and longevity has been known for many years, and considerable research has been focused on the mechanisms of ageing that ultimately determine longevity, which has remained essentially unchanged despite a near doubling of human life expectancy in the past 200 years. In this paper, the authors present evidence that the Sun determines the limits of longevity for the longest-living complex organisms. The Sun is a dynamical system and although solar cycles occur every 8-14 years (averaging approximately 11.1 years), the authors show that 28% of these cycles exhibit chaotic features and irregularly release up to 300% more ultraviolet radiation than usual. These chaotic solar cycles create an environment mutagenic to DNA that must be largely avoided in order to pass uncorrupted genes to the next generation. This requirement determines the limits of fertility, e.g., menarche and menopause in humans, and sets longevity to approximately 100 years.
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Affiliation(s)
- George E Davis
- Research Group, Psybernetics, Inc., 28 Eastern Ave., Augusta, Maine 04330, USA.
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13
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Ghirardi O, Cozzolino R, Guaraldi D, Giuliani A. Within- and between-strain variability in longevity of inbred and outbred rats under the same environmental conditions. Exp Gerontol 1995; 30:485-94. [PMID: 8557096 PMCID: PMC7134852 DOI: 10.1016/0531-5565(95)00002-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The analysis of 26 longevity curves of different populations of inbred (Fischer 344) and outbred (Sprague-Dawley) rats highlighted a remarkable between-populations variability in survival parameters. This variability is independent of the breeding characteristics of the strain. The two strains differed in the slope of the survival curves, with Fischer 344 rats showing a higher survival over the second year of life as well as a lower interindividual variability. A model-free approach based on principal component analysis allowed us to quantify these differences and to high-light some limitations of the classical Gompertzian approach.
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Affiliation(s)
- O Ghirardi
- Institute for Research on Senescence, Sigma-Tau S.p.A., Pomezia, Roma, Italy
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Ames BN, Shigenaga MK, Hagen TM. Oxidants, antioxidants, and the degenerative diseases of aging. Proc Natl Acad Sci U S A 1993; 90:7915-22. [PMID: 8367443 PMCID: PMC47258 DOI: 10.1073/pnas.90.17.7915] [Citation(s) in RCA: 3582] [Impact Index Per Article: 115.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Metabolism, like other aspects of life, involves tradeoffs. Oxidant by-products of normal metabolism cause extensive damage to DNA, protein, and lipid. We argue that this damage (the same as that produced by radiation) is a major contributor to aging and to degenerative diseases of aging such as cancer, cardiovascular disease, immune-system decline, brain dysfunction, and cataracts. Antioxidant defenses against this damage include ascorbate, tocopherol, and carotenoids. Dietary fruits and vegetables are the principal source of ascorbate and carotenoids and are one source of tocopherol. Low dietary intake of fruits and vegetables doubles the risk of most types of cancer as compared to high intake and also markedly increases the risk of heart disease and cataracts. Since only 9% of Americans eat the recommended five servings of fruits and vegetables per day, the opportunity for improving health by improving diet is great.
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Affiliation(s)
- B N Ames
- Division of Biochemistry and Molecular Biology, University of California, Berkeley 94720
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15
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Abstract
Longevity varies between and within species. The existence of species-specific limit to human life-span and its partial heritability indicate the existence of genetic factors that influence the ageing process. Insight into the nature of these genetic factors is provided by evolutionary studies, notably the disposable soma theory, which suggests a central role of energy metabolism in determining life-span. Energy is important in two ways. First, the disposable soma theory indicates that the optimum energy investment in cell maintenance and repair processes will be tuned through natural selection to provide adequate, but not excessive, protection against random molecular damages (e.g. to DNA, proteins). All that is required is that the organism remains in a sound condition through its natural expectation of life in the wild environment, where accidents are the predominant cause of mortality. Secondly, energy is implicated because of the intrinsic vulnerability of mitochondria to damage that may interfere with the normal supply of energy to the cell via the oxidative phosphorylation pathways. Oxidative phosphorylation produces ATP, and as a by-product also produces highly reactive oxygen radicals that can damage many cell structures, including the mitochondria themselves. Several lines of evidence link, on the one hand, oxidative damage to cell ageing, and on the other hand, energy-dependent antioxidant defences to the preservation of cellular homeostasis, and hence, longevity. Models of cellular ageing in vitro allow direct investigation of mechanisms, such as oxidative damage, that contribute to limiting human life-span. The genetic substratum of inter-individual differences in longevity may be unraveled by a two-pronged reverse genetics approach: sibling pair analysis applied to nonagenarian and centenarian siblings, combined with association studies of centenarians, may lead to the identification of genetic influences upon human longevity. These studies have become practicable thanks to recent progress in human genome mapping, especially to the development of microsatellite markers and the integration of genetic and physical maps.
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Affiliation(s)
- F Schächter
- Centre d'Etude du Polymorphisme Humain, Paris, France
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