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Maximum Lifespan (maximum + lifespan)
Selected AbstractsA long-term record of Nothofagus dominance in the southern Andes, ChileAUSTRAL ECOLOGY, Issue 1 2005William Pollmann Abstract The general model of regeneration dynamics in Nothofagus forests of southern South America could have value in community ecology if predictive relationships between disturbance history, functional traits and site attributes could be identified. Examined here is the proposal that on favourable sites shade-intolerant Nothofagus are likely not to survive in competition with shade-tolerant, broad-leaved evergreen taxa of temperate rain forests, and persistence, thus, is dependent on periodic coarse-scale disturbance. Comparison of stand dynamics of three old-growth Nothofagus forests at different elevations in the southern Andes, Chile where deciduous Nothofagus alpina dominates the upper canopy, and examination of the life history trade-offs of this variation were made. Stem density of all stems ,5.0 cm d.b.h. was 233,303 stems per hectare, and basal area was 123.9,171.0 m2ha,1. Maximum lifespan of N. alpina was found to be greater than ca 640 years, exceeding all previously reported ages for this species in the region. Forests had a stable canopy composition for this long-term, but some appeared to lack effective regeneration of N. alpina in recent years. Regeneration of N. alpina was generally greater in disturbed stands and higher elevation than in undisturbed stands and at lower elevation. Recruitment emerged to be strongly affected by competitive over- and understorey associates. There was a gradient of increasing dependence of N. alpina on disturbance towards the more productive end of the environment gradients, and hence less dependence of N. alpina on disturbance for its regeneration towards higher elevation. The study confirms that changes in forest composition may be explained by processes occurring in accordance with the predictions of the existing model of Nothofagus regeneration dynamics, providing stronger evidence specifically directed at mid-tolerant N. alpina, and by factoring out regeneration dynamics on favourable sites. Thus, for N. alpina, trait differences probably contribute to the competitive advantage over its associates in productive habitats, and may be linked to small-to-intermediate-sized disturbances which inevitably occur as older trees die, enabling N. alpina to persist in forests and therefore maintain species coexistence for the long-term. [source] Caloric restriction for longevity: I. Paradigm, protocols and physiological findings in animal researchEUROPEAN EATING DISORDERS REVIEW, Issue 5 2004Kelly M. Vitousek Abstract The initial article in this series reviews basic findings in the field of caloric restriction for longevity (CRL). To eating disorder specialists, the data are disconcerting. The chronic dieting and subnormal weight we endeavour to prevent and treat in humans appear highly beneficial when imposed on animals. In the laboratory, organisms from nematodes to monkeys thrive when forced to undereat, as long as they receive sufficient micronutrients. The most remarkable results are obtained through the most extreme measures: mice, for example, do best if limited to a third of expected caloric intake, beginning soon after weaning and continuing throughout adulthood. Deprivation can be achieved through an ,anorexic' protocol of steady underconsumption or a ,bulimic' pattern in which periods of fasting alternate with bouts of binge eating. The benefits of such regimens include delayed senescence, postponement and/or attenuation of age-related disease and dramatic increases in average and maximum lifespan. Although some biological functions are impaired (including growth, reproduction and perhaps resistance to certain stressors), the cost/benefit ratio clearly favours CRL when calculated on the basis of physical outcomes in late age. Advocacy of comparable regimens for people, however, is ill-considered. Enthusiasm for CRL can be sustained only by detaching deprivation from the context of daily life, ignoring psychological effects, and dismissing data on human semi-starvation and eating disorders. The experiences of participants in Biosphere 2 and individuals with anorexia nervosa suggest that the price of CRL is unacceptably high when a wider range of outcome variables is examined. Copyright © 2004 John Wiley & Sons, Ltd and Eating Disorders Association. [source] Reactive Oxygen Species as Mediators of Cellular SenescenceIUBMB LIFE, Issue 4-5 2005Renata Colavitti Abstract Aging has often been viewed as a random process arising from the accumulation of both genetic and epigenetic changes. Increasingly, the notion that aging is a stochastic process is being supplanted by the concept that maximum lifespan of an organism is tightly regulated. This knowledge has led to a growing overlap between classical signal transduction paradigms and the biology of aging. We review certain specific examples where these seemingly disparate disciplines intersect. In particular, we review the concept that intracellular reactive oxygen species function as signalling molecules and that oxidants play a central role as mediators of cellular senescence. IUBMB Life, 57: 277-281, 2005 [source] Longevity is not influenced by prenatal programming of body sizeAGING CELL, Issue 4 2010Cheryl A. Conover Summary Insulin-like growth factor (IGF) signaling is essential for achieving optimal body size during fetal development, whereas, in the adult, IGFs are associated with aging and age-related diseases. However, it is unclear as to what extent lifespan is influenced by events that occur during development. Here, we provide direct evidence that the exceptional longevity of mice with altered IGF signaling is not linked to prenatal programming of body size. Mice null for pregnancy-associated plasma protein-A (PAPP-A), an IGF-binding protein proteinase that increases local IGF bioavailability, are 60,70% the size of their wild-type littermates at birth and have extended median and maximum lifespan of 30,40%. In this study, PAPP-A,/, mice whose body size was normalized during fetal development through disruption of IgfII imprinting did not lose their longevity advantage. Adult-specific moderation of IGF signaling through PAPP-A inhibition may present a unique opportunity to improve lifespan without affecting important aspects of early life physiology. [source] Low complex I content explains the low hydrogen peroxide production rate of heart mitochondria from the long-lived pigeon, Columba liviaAGING CELL, Issue 1 2010Adrian J. Lambert Summary Across a range of vertebrate species, it is known that there is a negative association between maximum lifespan and mitochondrial hydrogen peroxide production. In this report, we investigate the underlying biochemical basis of the low hydrogen peroxide production rate of heart mitochondria from a long-lived species (pigeon) compared with a short-lived species with similar body mass (rat). The difference in hydrogen peroxide efflux rate was not explained by differences in either superoxide dismutase activity or hydrogen peroxide removal capacity. During succinate oxidation, the difference in hydrogen peroxide production rate between the species was localized to the ,pH-sensitive superoxide producing site within complex I. Mitochondrial ,pH was significantly lower in pigeon mitochondria compared with rat, but this difference in ,pH was not great enough to explain the lower hydrogen peroxide production rate. As judged by mitochondrial flavin mononucleotide content and blue native polyacrylamide gel electrophoresis, pigeon mitochondria contained less complex I than rat mitochondria. Recalculation revealed that the rates of hydrogen peroxide production per molecule of complex I were the same in rat and pigeon. We conclude that mitochondria from the long-lived pigeon display low rates of hydrogen peroxide production because they have low levels of complex I. [source] Relative longevity and field metabolic rate in birdsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2008A. P. MØLLER Abstract Metabolism is a defining feature of all living organisms, with the metabolic process resulting in the production of free radicals that can cause permanent damage to DNA and other molecules. Surprisingly, birds, bats and other organisms with high metabolic rates have some of the slowest rates of senescence begging the question whether species with high metabolic rates also have evolved mechanisms to cope with damage induced by metabolism. To test whether species with the highest metabolic rates also lived the longest I determined the relationship between relative longevity (maximum lifespan), after adjusting for annual adult survival rate, body mass and sampling effort, and mass-specific field metabolic rate (FMR) in 35 species of birds. There was a strongly positive relationship between relative longevity and FMR, consistent with the hypothesis. This conclusion was robust to statistical control for effects of potentially confounding variables such as age at first reproduction, latitude and migration distance, and similarity in phenotype among species because of common phylogenetic descent. Therefore, species of birds with high metabolic rates senesce more slowly than species with low metabolic rates. [source] N,3 polyunsaturated fatty acids impair lifespan but have no role for metabolismAGING CELL, Issue 1 2007Teresa G. Valencak Summary Although generally considered as beneficial components of dietary fats, polyunsaturated fatty acids (PUFA) have been suspected to compromise maximum lifespan (MLSP) in mammals. Specifically, high amounts of phospholipid PUFAs are thought to impair lifespan due to an increase in the susceptibility of membranes to lipid peroxidation and its damaging effect on cellular molecules. Also, there is evidence from in vitro studies suggesting that highly unsaturated PUFAs elevate basal metabolic rate (BMR). Previous comparative studies in this context were based on small sample sizes, however, and, except for one study, failed to address possible confounding influences of body weight and taxonomic relations between species. Therefore, we determined phospholipid membrane composition in skeletal muscle from 42 mammalian species to test for a relation with published data on MLSP, and with literature data on BMR (30 species). Using statistical models that adjust for the effects of body weight and phylogeny, we found that among mammals, MLSP indeed decreases as the ratio of n,3 to n,6 PUFAs increases. In contrast to previous studies, we found, however, no relation between MLSP and either membrane unsaturation (i.e. PUFA content or number of double bonds) or to the very long-chain, highly unsaturated docosahexaenoic acid (DHA). Similarly, our data set gave no evidence for any notable relation between muscle phospholipid fatty acid composition and BMR, or MLSP and BMR in mammals. These results contradict the ,membrane pacemaker theory of aging', that is, the concept of a direct link between high amounts of membrane PUFAs, elevated BMR, and thus, impaired longevity. [source] Temperature affects longevity and age-related locomotor and cognitive decay in the short-lived fish Nothobranchius furzeriAGING CELL, Issue 3 2006Dario R. Valenzano Summary Temperature variations are known to modulate aging and life-history traits in poikilotherms as different as worms, flies and fish. In invertebrates, temperature affects lifespan by modulating the slope of age-dependent acceleration in death rate, which is thought to reflect the rate of age-related damage accumulation. Here, we studied the effects of temperature on aging kinetics, aging-related behavioural deficits, and age-associated histological markers of senescence in the short-lived fish Nothobranchius furzeri. This species shows a maximum captive lifespan of only 3 months, which is tied with acceleration in growth and expression of aging biomarkers. These biological peculiarities make it a very convenient animal model for testing the effects of experimental manipulations on life-history traits in vertebrates. Here, we show that (i) lowering temperature from 25 °C to 22 °C increases both median and maximum lifespan; (ii) life extension is due to reduction in the slope of the age-dependent acceleration in death rate; (iii) lowering temperature from 25 °C to 22 °C retards the onset of age-related locomotor and learning deficits; and (iv) lowering temperature from 25 °C to 22 °C reduces the accumulation of the age-related marker lipofuscin. We conclude that lowering water temperature is a simple experimental manipulation which retards the rate of age-related damage accumulation in this short-lived species. [source] Annual fishes of the genus Nothobranchius as a model system for aging researchAGING CELL, Issue 5 2005Tyrone Genade Summary Aging research in vertebrates is hampered by the lack of short-lived models. Annual fishes of the genus Nothobranchius live in East African seasonal ponds. Their life expectancy in the wild is limited by the duration of the wet season and their lifespan in captivity is also short. Nothobranchius are popular aquarium fishes and many different species are kept as captive strains, providing rich material for comparative studies. The present paper aims at reviving the interest in these fishes by reporting that: (1) Nothobranchius can be cultured, and their eggs stored dry at room temperature for months or years, offering inexpensive methods of embryo storage; (2) Nothobranchius show accelerated growth and expression of aging biomarkers at the level of histology and behaviour; (3) the species Nothobranchius furzeri has a maximum lifespan of only 3 months and offers the possibility to perform investigations thus far unthinkable in a vertebrate, such as drug screening with life-long pharmacological treatments and experimental evolution; (4) when the lifespan of different species is compared, a general correlation is found between wet season duration in their natural habitat and longevity in captivity; and (5) vertebrate aging-related genes, such as p66Shc and MTP, can be easily isolated in Nothobranchius by homology cloning. These fishes can become excellent models for aging studies. They can be employed to test the effects of experimental manipulation on aging at a pace comparable with that of Drosophila and to probe the effects of natural selection on the evolution of aging-related genes. [source] | ||||||||||