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Nielsen PY, Jensen MK, Mitarai N, Bhatt S. The Gompertz Law emerges naturally from the inter-dependencies between sub-components in complex organisms. Sci Rep 2024; 14:1196. [PMID: 38216698 PMCID: PMC10786855 DOI: 10.1038/s41598-024-51669-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 01/08/2024] [Indexed: 01/14/2024] Open
Abstract
Understanding and facilitating healthy aging has become a major goal in medical research and it is becoming increasingly acknowledged that there is a need for understanding the aging phenotype as a whole rather than focusing on individual factors. Here, we provide a universal explanation for the emergence of Gompertzian mortality patterns using a systems approach to describe aging in complex organisms that consist of many inter-dependent subsystems. Our model relates to the Sufficient-Component Cause Model, widely used within the field of epidemiology, and we show that including inter-dependencies between subsystems and modeling the temporal evolution of subsystem failure results in Gompertizan mortality on the population level. Our model also provides temporal trajectories of mortality-risk for the individual. These results may give insight into understanding how biological age evolves stochastically within the individual, and how this in turn leads to a natural heterogeneity of biological age in a population.
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Affiliation(s)
- Pernille Yde Nielsen
- Department of Applied Mathematics and Computer Science, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
| | - Majken K Jensen
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Namiko Mitarai
- Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - Samir Bhatt
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College London, London, UK
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2
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Viguier C, Bullich S, Botella M, Fasseu L, Alfonso A, Rekik K, Gauzin S, Guiard BP, Davezac N. Impact of physical activity on brain oxidative metabolism and intrinsic capacities in young swiss mice fed a high fat diet. Neuropharmacology 2023; 241:109730. [PMID: 37758019 DOI: 10.1016/j.neuropharm.2023.109730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 09/22/2023] [Accepted: 09/23/2023] [Indexed: 10/03/2023]
Abstract
Type 2 diabetes and obesity characterized by hallmarks of insulin resistance along with an imbalance in brain oxidative metabolism would impair intrinsic capacities (ICs), a new concept for assessing mental and physical functioning. Here, we explored the impact of physical activity on antioxidant responses and oxidative metabolism in discrete brain areas of HFD or standard diet (STD) fed mice but also its consequences on specific domains of ICs. 6-week-old Swiss male mice were exposed to a STD or a HFD for 16 weeks and half of the mice in each group had access to an activity wheel and the other half did not. As expected HFD mice displayed peripheral insulin resistance but also a persistent inhibition of aconitase activity in cortices revealing an increase in mitochondrial reactive oxygen species (ROS) production. Animals with access to the running wheel displayed an improvement of insulin sensitivity regardless of the diet factor whereas ROS production remained impaired. Moreover, although the access of the running wheel did not influence mitochondrial biomass, in the oxidative metabolism area, it produced a slight decrease in brain SOD1 and catalase expression notably in HFD fed mice. At the behavioural level, physical exercise produced anxiolytic/antidepressant-like responses and improved motor coordination in both STD and HFD fed mice. However, this non-pharmacological intervention failed to enhance cognitive performance. These findings paint a contrasting landscape about physical exercise as a non-pharmacological intervention for positively orienting the aging trajectory.
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Affiliation(s)
- Clémence Viguier
- Remember Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France
| | - Sébastien Bullich
- Remember Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France
| | - Marlene Botella
- Minding Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France; INSPIRE Consortium, France
| | - Laure Fasseu
- Minding Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France; INSPIRE Consortium, France
| | - Amélie Alfonso
- Remember Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France; INSPIRE Consortium, France
| | - Khaoula Rekik
- Remember Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France
| | - Sébastien Gauzin
- Remember Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France; INSPIRE Consortium, France
| | - Bruno P Guiard
- Remember Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France; INSPIRE Consortium, France.
| | - Noélie Davezac
- Minding Team, Research Center on Animal Cognition (CRCA), Center of Integrative Biology (CBI), CNRS - University of Toulouse, CNRS, UPS, 31 067, Toulouse, France; INSPIRE Consortium, France.
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3
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The Role of SOX Transcription Factors in Ageing and Age-Related Diseases. Int J Mol Sci 2023; 24:ijms24010851. [PMID: 36614288 PMCID: PMC9821406 DOI: 10.3390/ijms24010851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/27/2022] [Accepted: 12/28/2022] [Indexed: 01/05/2023] Open
Abstract
The quest for eternal youth and immortality is as old as humankind. Ageing is an inevitable physiological process accompanied by many functional declines that are driving factors for age-related diseases. Stem cell exhaustion is one of the major hallmarks of ageing. The SOX transcription factors play well-known roles in self-renewal and differentiation of both embryonic and adult stem cells. As a consequence of ageing, the repertoire of adult stem cells present in various organs steadily declines, and their dysfunction/death could lead to reduced regenerative potential and development of age-related diseases. Thus, restoring the function of aged stem cells, inducing their regenerative potential, and slowing down the ageing process are critical for improving the health span and, consequently, the lifespan of humans. Reprograming factors, including SOX family members, emerge as crucial players in rejuvenation. This review focuses on the roles of SOX transcription factors in stem cell exhaustion and age-related diseases, including neurodegenerative diseases, visual deterioration, chronic obstructive pulmonary disease, osteoporosis, and age-related cancers. A better understanding of the molecular mechanisms of ageing and the roles of SOX transcription factors in this process could open new avenues for developing novel strategies that will delay ageing and prevent age-related diseases.
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4
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Role of Melatonin in Angiotensin and Aging. Molecules 2021; 26:molecules26154666. [PMID: 34361818 PMCID: PMC8347812 DOI: 10.3390/molecules26154666] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/27/2021] [Accepted: 07/29/2021] [Indexed: 12/19/2022] Open
Abstract
The cellular utilization of oxygen leads to the generation of free radicals in organisms. The accumulation of these free radicals contributes significantly to aging and several age-related diseases. Angiotensin II can contribute to DNA damage through oxidative stress by activating the NAD(P)H oxidase pathway, which in turn results in the production of reactive oxygen species. This radical oxygen-containing molecule has been linked to aging and several age-related disorders, including renal damage. Considering the role of angiotensin in aging, melatonin might relieve angiotensin-II-induced stress by enhancing the mitochondrial calcium uptake 1 pathway, which is crucial in preventing the mitochondrial calcium overload that may trigger increased production of reactive oxygen species and oxidative stress. This review highlights the role and importance of melatonin together with angiotensin in aging and age-related diseases.
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5
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Multiple life-stage inbreeding depression impacts demography and extinction risk in an extinct-in-the-wild species. Sci Rep 2021; 11:682. [PMID: 33436770 PMCID: PMC7804286 DOI: 10.1038/s41598-020-79979-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Accepted: 12/09/2020] [Indexed: 11/13/2022] Open
Abstract
Inbreeding can depress individuals’ fitness traits and reduce population viability. However, studies that directly translate inbreeding depression on fitness traits into consequences for population viability, and further, into consequences for management choices, are lacking. Here, we estimated impacts of inbreeding depression (B, lethal equivalents) across life-history stages for an extinct-in-the-wild species, the sihek (Guam kingfisher, Todiramphus cinnamominus). We then projected population growth under different management alternatives with our B estimates incorporated, as well as without inbreeding depression (B = 0) or with a conventional default B. We found that inbreeding depression severely impacted multiple life-history stages, and directly translated into an effect on population viability under management alternatives. Simulations including our B estimates indicated rapid population decline, whereas projections without inbreeding depression or with default B suggested very gradual population decline. Further, our results demonstrate that incorporation of B across life-history stages can influence management decisions, as projections with our B estimates suggested a need to switch to increased breeding management to avoid species extinction and support wild releases. Our results demonstrate that magnitude of B across life-history stages can translate into demographic consequences, such that incorporation of multiple life-stage B into population models can be important for informed conservation management decision-making.
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6
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Kyriazis M. Aging as “Time-Related Dysfunction”: A Perspective. Front Med (Lausanne) 2020; 7:371. [PMID: 32850891 PMCID: PMC7397818 DOI: 10.3389/fmed.2020.00371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 06/17/2020] [Indexed: 11/13/2022] Open
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Fonseca Costa SS, Robinson-Rechavi M, Ripperger JA. Single-cell transcriptomics allows novel insights into aging and circadian processes. Brief Funct Genomics 2020; 19:343-349. [PMID: 32633783 PMCID: PMC7716582 DOI: 10.1093/bfgp/elaa014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/18/2020] [Accepted: 06/04/2020] [Indexed: 12/14/2022] Open
Abstract
Aging and circadian rhythms are two biological processes that affect an organism, although at different time scales. Nevertheless, due to the overlap of their actions, it was speculated that both interfere or interact with each other. However, to address this question, a much deeper insight into these processes is necessary, especially at the cellular level. New methods such as single-cell RNA-sequencing (scRNA-Seq) have the potential to close this gap in our knowledge. In this review, we analyze applications of scRNA-Seq from the aging and circadian rhythm fields and highlight new findings emerging from the analysis of single cells, especially in humans or rodents. Furthermore, we judge the potential of scRNA-Seq to identify common traits of both processes. Overall, this method offers several advantages over more traditional methods analyzing gene expression and will become an important tool to unravel the link between these biological processes.
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Affiliation(s)
- Sara S Fonseca Costa
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.,SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.,SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
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8
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Chai KC, Zhang YB, Chang KC. Regional Disparity of Medical Resources and Its Effect on Mortality Rates in China. Front Public Health 2020; 8:8. [PMID: 32117848 PMCID: PMC7011092 DOI: 10.3389/fpubh.2020.00008] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 01/10/2020] [Indexed: 11/13/2022] Open
Abstract
Objectives: The purpose of this study was two-fold. First, to empirically study the effects that medical resources (i.e., hospital, doctors, beds) have on the mortality rate in China. Second, to divide China into east, middle, and west regions, and empirically study the regional disparity of medical resources and its effect on mortality rates in China. Methodology and Data: This study utilized a panel data regression model to explore the effect medical resources have on the age-standardized mortality rate in China. The data came from the 2003-2017 China Statistical Yearbook compiled by the National Bureau of Statistics of China. Results: Nationwide, hospitals, doctors, and beds had a significant negative correlation with the mortality rate. In the western region, hospitals, beds, and doctors had a significant negative correlation with the mortality rate. In China's middle and eastern regions, hospitals, beds, and doctors had no significant effect on the mortality rate. In China, increased hospitals, doctors, and beds significantly reduced the mortality rate. The distribution of medical resources in eastern, middle, and western China was unequal. More hospitals, beds, and doctors in the less developed western regions can more effectively alleviate the local mortality rate. In the middle and east regions, hospitals, beds, and doctors had no significant impact on the local mortality rate. Conclusion: First, China's overall medical resources are still inadequate and improving medical resources throughout the country could reduce the mortality rate. Second, due to the imbalanced distribution of medical resources in China, the Chinese government should implement more supportive policies for medical resources in the western region. At the same time, we should also actively develop the western region by improving local per capita GDP and reducing unemployment, so as to fundamentally reduce the local mortality rate.
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Affiliation(s)
- Kuang-Cheng Chai
- Business School, Guilin University of Electronic Technology, Guilin, China
| | - Ying-Bin Zhang
- Business School, Guilin University of Electronic Technology, Guilin, China
| | - Ke-Chiun Chang
- School of Economic and Management, Wuhan University, Wuhan, China
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9
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Abstract
The past two centuries have witnessed an unprecedented rise in human life expectancy. Sustaining longer lives with reduced periods of disability will require an understanding of the underlying mechanisms of ageing, and genetics is a powerful tool for identifying these mechanisms. Large-scale genome-wide association studies have recently identified many loci that influence key human ageing traits, including lifespan. Multi-trait loci have been linked with several age-related diseases, suggesting shared ageing influences. Mutations that drive accelerated ageing in prototypical progeria syndromes in humans point to an important role for genome maintenance and stability. Together, these different strands of genetic research are highlighting pathways for the discovery of anti-ageing interventions that may be applicable in humans.
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10
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Rao RV. Ayurveda and the science of aging. J Ayurveda Integr Med 2018; 9:225-232. [PMID: 29276113 PMCID: PMC6148064 DOI: 10.1016/j.jaim.2017.10.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 10/13/2017] [Accepted: 10/16/2017] [Indexed: 02/01/2023] Open
Abstract
Since time immemorial, humanity has been concerned with developing and preserving youthful vigor, and extending longevity by stopping or delaying the aging process. By 2030, one in five of the world population will be over 65 years old. Longevity and old age are accompanied with a variety of health challenges and population studies indicate that the elderly will use between three to five times more healthcare services compared to the younger population. Modern medicine has made a great deal of progress in understanding the aging process and in controlling age-associated health issues including heart attacks, strokes, diabetes, cancer, senility, and arthritis. Thus, every individual is now looking forward to a youthful, productive lifespan of 100 or more years filled with unlimited health and opportunity. Research by aging experts is focused on ways to go against the natural order of the aging process in order to delay it. Interventions include among other things anti-aging pills, restricted food consumption and cloning body parts to stay young and delay biological aging. Ayurveda, one of the world's most authoritative mind-body-spirit medicinal systems, offers various concepts of the aging process. This system of medicine includes therapies for healthy aging so as to create an optimal health and lengthen an individual's healthspan by living in harmony with nature. This review will explore various aspects of aging and longevity by comparing the science of aging as defined by modern medicine with the Ayurvedic treatise of Jara and Vriddhavastha.
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Affiliation(s)
- Rammohan V Rao
- The Buck Institute for Research on Aging, 8001 Redwood Blvd, Novato, CA 94945, USA; Faculty, California College of Ayurveda, 700 Zion Street, Nevada City, CA 95959, USA.
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11
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Horváth B, Kalinka AT. The genetics of egg retention and fertilization success in Drosophila: One step closer to understanding the transition from facultative to obligate viviparity. Evolution 2018; 72:318-336. [PMID: 29265369 DOI: 10.1111/evo.13411] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Revised: 10/16/2017] [Accepted: 11/14/2017] [Indexed: 12/17/2022]
Abstract
Oviparous, facultative egg retention enables Drosophila females to withhold fertilized eggs in their reproductive tracts until circumstances favor oviposition. The propensity to retain fertilized eggs varies greatly between species, and is correlated with other reproductive traits, such as egg size and ovariole number. While previous studies have described the phenomenon, no study to date has characterized within-species variation or the genetic basis of the trait. Here, we develop a novel microscope-based method for measuring egg retention in Drosophila females and determine the range of phenotypic variation in mated female egg retention in a subset of 91 Drosophila Genetic Reference Panel (DGRP) lines. We inferred the genetic basis of egg retention using a genome-wide association study (GWAS). Further, the scoring of more than 95,000 stained, staged eggs enabled estimates of fertilization success for each line. We found evidence that ovary- and spermathecae-related genes as well as genes affecting olfactory behavior, male mating behavior, male-female attraction and sperm motility may play a crucial role in post-mating physiology. Based on our findings we also propose potential evolutionary routes toward obligate viviparity. In particular, we propose that the loss of fecundity incurred by viviparity could be offset by benefits arising from enhanced mate discrimination, resource specialization, or modified egg morphology.
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Affiliation(s)
- Barbara Horváth
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria.,Vienna Graduate School of Population Genetics, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria.,Current Address: Barbara Ellis, Institutionen för ekologi och genetik, Evolutionsbiologiskt Centrum (EBC), Norbyvägen 18D, 752 36 Uppsala, Sweden
| | - Alex T Kalinka
- Institut für Populationsgenetik, Veterinärmedizinische Universität Wien, Veterinärplatz 1, Vienna A-1210, Austria
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12
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Zsakai A, Sipos R, Takacs-Vellai K, Szabo A, Bodzsar EB. The relationship between reproductive and biochemical ageing at the time of the menopausal transition. Exp Gerontol 2017; 98:162-168. [PMID: 28843511 DOI: 10.1016/j.exger.2017.08.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 07/04/2017] [Accepted: 08/21/2017] [Indexed: 10/19/2022]
Abstract
The biochemical ageing status of women in the menopausal transition was studied using quantitative analysis of age- and autophagy-related gene activities (CDC42 and MAP1LC3 genes were selected as target genes). Free estradiol and progesterone levels in saliva were estimated. General linear models were used to determine the relationship between lifestyle, health status, socioeconomic factors and CDC42 and MAP1LC3 gene expression levels. Gene expression analysis revealed (1) an increasing expression of CDC42 gene after 45years in women, (2) expression level of CDC42 gene associated with menopausal status, (3) while endocrine status was found to associate with the expression of both of the studied age-related genes, (4) the "never used hormonal contraceptives" and "obese nutritional status" were the strongest factors for increased level of age-related gene expressions, and (5) changes in gene expression levels by ageing should be studied by considering not only chronological, but also biological ages. Gene expression profile of ageing has mostly been studied in model systems or human blood samples, but rarely in human saliva samples. The concordance of results between the present and former gene expression analyses, and the simplicity of saliva sample collection emphasizes the importance of saliva tissue samples in gene expression analyses especially in epidemiological surveys.
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Affiliation(s)
- Annamaria Zsakai
- Department of Biological Anthropology, Eotvos Lorand University, Pazmany P. 1/c, 1117 Budapest, Hungary.
| | - Rita Sipos
- Biomi Ltd, Szent-Gyorgyi Albert ut 4, 2100 Godollo, Hungary.
| | - Krisztina Takacs-Vellai
- Department of Biological Anthropology, Eotvos Lorand University, Pazmany P. 1/c, 1117 Budapest, Hungary
| | - Attila Szabo
- Department of Microbiology, Eotvos Lorand University, Pazmany P. 1/c, 1117 Budapest, Hungary
| | - Eva B Bodzsar
- Department of Biological Anthropology, Eotvos Lorand University, Pazmany P. 1/c, 1117 Budapest, Hungary.
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Fonseca Costa SS, Wegmann D, Ripperger JA. Normalisation against Circadian and Age-Related Disturbances Enables Robust Detection of Gene Expression Changes in Liver of Aged Mice. PLoS One 2017; 12:e0169615. [PMID: 28068403 PMCID: PMC5222604 DOI: 10.1371/journal.pone.0169615] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 12/08/2016] [Indexed: 12/29/2022] Open
Abstract
The expression of some genes is affected by age. To detect such age-related changes, their expression levels are related to constant marker genes. However, transcriptional noise increasing with advancing age renders difficult the identification of real age-related changes because it may affect the marker genes as well. Here, we report a selection procedure for genes appropriate to normalise the mouse liver transcriptome under various conditions including age. These genes were chosen from an initial set of 16 candidate genes defined based on a RNA-sequencing experiment and published literature. A subset of genes was selected based on rigorous statistical assessment of their variability using both RNA-sequencing and Nanostring hybridization experiments. The robustness of these marker genes was then verified by the analysis of 130 publicly available data sets using the mouse liver transcriptome. Altogether, a set of three genes, Atp5h, Gsk3β, and Sirt2 fulfilled our strict selection criteria in all assessments, while four more genes, Nono, Tprkb, Tspo, and Ttr passed all but one assessment and were included into the final set of marker genes to enhance robustness of normalisation against outliers. Using the geometric mean of expression of the genes to normalise Nanostring hybridization experiments we reliably identified age-related increases in the expression of Casein kinase 1δ and 1ϵ, and Sfpq, while the expression of the glucose transporter Glut2 decreased. The age-related changes were verified by real-time PCR and Western blot analysis. As conclusion, proper normalisation enhances the robustness of quantitative methods addressing age-related changes of a transcriptome.
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Affiliation(s)
| | - Daniel Wegmann
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- Swiss Institute of Bioinformatics, University of Lausanne, Lausanne, Switzerland
- * E-mail: (DW); (JAR)
| | - Jürgen A. Ripperger
- Department of Biology, University of Fribourg, Fribourg, Switzerland
- * E-mail: (DW); (JAR)
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14
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Aghaei S, Nilforoushzadeh MA, Aghaei M. The role of peroxisome proliferator-activated receptor-coactivator-1 gene in skin aging. JOURNAL OF RESEARCH IN MEDICAL SCIENCES 2016; 21:36. [PMID: 27904582 PMCID: PMC5122240 DOI: 10.4103/1735-1995.183999] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Revised: 12/23/2015] [Accepted: 03/31/2016] [Indexed: 01/09/2023]
Abstract
Skin aging is a continuous process that exhibits fine and deep wrinkles, thin and transparent skin, loss of underlying fat, dry skin and itch, following decreased collagen and elastin synthesis. Both extrinsic and intrinsic agents are considered in the pathogenesis on skin aging. Extrinsic factors such as sun exposure, windy and dry weather, nutrition, and lifestyle may induce premature aging, toxic-free radicals, and reactive oxygen species due to decreasing normal function of mitochondria which play the major intrinsic factors in premature skin aging. One of the major genetic factors in mitochondrial function is peroxisome proliferator-activated receptor-coactivator-1 (PGC-1) gene. This factor could delay skin aging by increasing the mitochondrial biogenesis and replication and oxidative phosphorylation and so may induce free radical scavenging. This review is focused on intrinsic skin aging and the role of PGC-1 protein in decreasing effect of aging causes.
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Affiliation(s)
- Shahrzad Aghaei
- Department of Genetics, Shahrekord University, Shahrekord, Iran
| | | | - Maryam Aghaei
- Skin Disease and Leishmaniasis Research Centre, Isfahan University of Medical Sciences, Isfahan, Iran
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15
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Sanz JJ, Moreno J. Delayed senescence in a southern population of the pied flycatcher (Ficedula hypoleuca). ECOSCIENCE 2016. [DOI: 10.1080/11956860.2000.11682567] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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On cognitive ecology and the environmental factors that promote Alzheimer disease: lessons from Octodon degus (Rodentia: Octodontidae). Biol Res 2016; 49:10. [PMID: 26897365 PMCID: PMC4761148 DOI: 10.1186/s40659-016-0074-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/12/2016] [Indexed: 12/15/2022] Open
Abstract
Cognitive ecologist posits that the more efficiently an animal uses information from the biotic and abiotic environment, the more adaptive are its cognitive abilities. Nevertheless, this approach does not test for natural neurodegenerative processes under field or experimental conditions, which may recover animals information processing and decision making and may explain, mechanistically, maladaptive behaviors. Here, we call for integrative approaches to explain the relationship between ultimate and proximate mechanisms behind social behavior. We highlight the importance of using the endemic caviomorph rodent Octodon degus as a valuable natural model for mechanistic studies of social behavior and to explain how physical environments can shape social experiences that might influence impaired cognitive abilities and the onset and progression of neurodegenerative disorders such as Alzheimer disease. We consequently suggest neuroecological approaches to examine how key elements of the environment may affect neural and cognitive mechanisms associated with learning, memory processes and brain structures involved in social behavior. We propose the following three core objectives of a program comprising interdisciplinary research in O. degus, namely: (1) to determine whether diet types provided after weaning can lead to cognitive impairment associated with spatial memory, learning and predisposing to develop Alzheimer disease in younger ages; (2) to examine if early life social experience has long term effects on behavior and cognitive responses and risk for development Alzheimer disease in later life and (3) To determine if an increase of social interactions in adult degu reared in different degree of social stressful conditions alter their behavior and cognitive responses.
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17
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Fonseca Costa SS, Ripperger JA. Impact of the circadian clock on the aging process. Front Neurol 2015; 6:43. [PMID: 25798127 PMCID: PMC4351613 DOI: 10.3389/fneur.2015.00043] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 02/19/2015] [Indexed: 12/11/2022] Open
Abstract
The increase of life expectancy and the decline of biological functions with advancing age are impending obstacles for our society. In general, age-related changes can be separated into two processes. Primary aging is based on programs governing gradual changes which are generally not harmful. On the other hand, secondary aging or senescence is more aleatory in nature and it is at this stage that the progressive impairment of metabolic, physiological, and neurological functions increases the risk of death. Exploiting genetic animal models, we obtain more and more information on the underlying regulatory networks. The aim of this review is to identify potential links between the output of the circadian oscillator and secondary aging. The reasons to suspect such links rely on the fact that the mouse models without functional circadian clocks sometimes exhibit reduced life expectancy. This may be due to their inability to properly control and synchronize energy expenditure, affecting, for example, the integrity of neurons in the brain. Hence, it is tempting to speculate that re-synchronization of metabolic and physiological functions by the circadian clock may slow down the aging process.
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Affiliation(s)
- Sara S Fonseca Costa
- Department of Biology/Biochemistry, University of Fribourg , Fribourg , Switzerland
| | - Jürgen A Ripperger
- Department of Biology/Biochemistry, University of Fribourg , Fribourg , Switzerland
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18
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Romain G, Opacka-Juffry J. Cerebral ageing-the role of insulin and insulin-like growth factor signalling: A review. World J Neurol 2014; 4:12-22. [DOI: 10.5316/wjn.v4.i3.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 11/11/2014] [Accepted: 12/01/2014] [Indexed: 02/07/2023] Open
Abstract
Cerebral ageing is a complex biological process associated with progressing cerebrovascular disease and neuronal death. It does not always, however, associate with a functional decline, as the ageing mammalian brain retains considerable functional plasticity which supports successful cerebral ageing where age-related cognitive decline is modest. On the contrary, pathological cerebral ageing results in memory impairment and cognitive deterioration, with Alzheimer’s disease (AD) being a florid example. Trophic/growth factors promote brain plasticity; among them are peptides which belong to the insulin family. Preclinical research suggests that the evolutionarily conserved brain insulin/insulin-like growth factor-1 (IGF-1) signalling system controls lifespan and protects against some features of AD such as neurodegeneration-related accumulation of toxic proteins and cognitive deficiencies, as observed in animal models. Insulin and IGF-1 activate cell signalling mechanisms which play protective and regenerative roles; abnormalities in the insulin/IGF-1 system may trigger a cascade of neurodegeneration in AD. AD patients show cerebral resistance to insulin which associates with IGF-I resistance and dysregulation of insulin/IGF-1 receptors as well as cognitive deterioration. This review is focused on the roles of the insulin/IGF-1 signalling system in cerebral ageing and its potential involvement in neurodegeneration in the human brain as seen against the background of preclinical evidence.
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Craig T, Smelick C, Tacutu R, Wuttke D, Wood SH, Stanley H, Janssens G, Savitskaya E, Moskalev A, Arking R, de Magalhães JP. The Digital Ageing Atlas: integrating the diversity of age-related changes into a unified resource. Nucleic Acids Res 2014; 43:D873-8. [PMID: 25232097 PMCID: PMC4384002 DOI: 10.1093/nar/gku843] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Multiple studies characterizing the human ageing phenotype have been conducted for decades. However, there is no centralized resource in which data on multiple age-related changes are collated. Currently, researchers must consult several sources, including primary publications, in order to obtain age-related data at various levels. To address this and facilitate integrative, system-level studies of ageing we developed the Digital Ageing Atlas (DAA). The DAA is a one-stop collection of human age-related data covering different biological levels (molecular, cellular, physiological, psychological and pathological) that is freely available online (http://ageing-map.org/). Each of the >3000 age-related changes is associated with a specific tissue and has its own page displaying a variety of information, including at least one reference. Age-related changes can also be linked to each other in hierarchical trees to represent different types of relationships. In addition, we developed an intuitive and user-friendly interface that allows searching, browsing and retrieving information in an integrated and interactive fashion. Overall, the DAA offers a new approach to systemizing ageing resources, providing a manually-curated and readily accessible source of age-related changes.
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Affiliation(s)
- Thomas Craig
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Chris Smelick
- University of North Carolina at Chapel Hill, NC, USA
| | - Robi Tacutu
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Daniel Wuttke
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Shona H Wood
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Henry Stanley
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | - Georges Janssens
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
| | | | - Alexey Moskalev
- Institute of Biology of Komi Science Center of RAS, Syktyvkar, Russia Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Robert Arking
- Department of Biological Sciences, Wayne State University, Detroit, MI, USA
| | - João Pedro de Magalhães
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Liverpool, UK
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20
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Sgrò CM, van Heerwaarden B, Kellermann V, Wee CW, Hoffmann AA, Lee SF. Complexity of the genetic basis of ageing in nature revealed by a clinal study of lifespan and methuselah, a gene for ageing, in Drosophila from eastern Australia. Mol Ecol 2014; 22:3539-51. [PMID: 23802551 DOI: 10.1111/mec.12353] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 03/12/2013] [Accepted: 03/16/2013] [Indexed: 11/29/2022]
Abstract
Clinal studies are a powerful tool for understanding the genetic basis of climatic adaptation. However, while clines in quantitative traits and genetic polymorphisms have been observed within and across continents, few studies have attempted to demonstrate direct links between them. The gene methuselah in Drosophila has been shown to have a major effect on stress response and longevity phenotypes based largely on laboratory studies of induced mutations in the mth gene. Clinal patterns in the most common mth haplotype and for lifespan (both increasing with latitude) have been observed in North American populations of D. melanogaster, implicating climatic selection. While these clinal patterns have led some to suggest that mth influences ageing in natural populations, limited evidence on the association between the two has so far been collected. Here, we describe a significant cline in the mth haplotype in eastern Australian D. melanogaster populations that parallel the cline in North America. We also describe a cline in mth gene expression. These findings further support the idea that mth is itself under selection. In contrast, we show that lifespan has a strong nonlinear clinal pattern, increasing southwards from the tropics, but then decreasing again from mid-latitudes. Furthermore, in association studies, we find no evidence for a direct link between mth haplotype and lifespan. Thus, while our data support a role for mth variation being under natural selection, we found no link to naturally occurring variation in lifespan and ageing in Australian populations of D. melanogaster. Our results indicate that the mth locus likely has genetic background and environment-specific effects.
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Affiliation(s)
- Carla M Sgrò
- Department of Biological Sciences, Monash University, Clayton, Vic., 3800, Australia.
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21
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Boehm AM, Rosenstiel P, Bosch TCG. Stem cells and aging from a quasi-immortal point of view. Bioessays 2013; 35:994-1003. [PMID: 24037777 DOI: 10.1002/bies.201300075] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Understanding aging and how it affects an organism's lifespan is a fundamental problem in biology. A hallmark of aging is stem cell senescence, the decline of functionality, and number of somatic stem cells, resulting in an impaired regenerative capacity and reduced tissue function. In addition, aging is characterized by profound remodeling of the immune system and a quantitative decline of adequate immune responses, a phenomenon referred to as immune-senescence. Yet, what is causing stem cell and immune-senescence? This review discusses experimental studies of potentially immortal Hydra which have made contributions to answering this question. Hydra transcription factor FoxO has been shown to modulate both stem cell proliferation and innate immunity, lending strong support to a role of FoxO as critical rate-of-aging regulator from Hydra to human. Constructing a model of how FoxO responds to diverse environmental factors provides a framework for how stem cell factors might contribute to aging.
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Affiliation(s)
- Anna-Marei Boehm
- Zoological Institute, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
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22
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A mathematical model of mortality dynamics across the lifespan combining heterogeneity and stochastic effects. Exp Gerontol 2013; 48:801-11. [DOI: 10.1016/j.exger.2013.05.054] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 03/28/2013] [Accepted: 05/15/2013] [Indexed: 11/23/2022]
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23
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Liu B, Yip RK, Zhou Z. Chromatin remodeling, DNA damage repair and aging. Curr Genomics 2013; 13:533-47. [PMID: 23633913 PMCID: PMC3468886 DOI: 10.2174/138920212803251373] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2012] [Revised: 06/19/2012] [Accepted: 07/25/2012] [Indexed: 01/26/2023] Open
Abstract
Cells are constantly exposed to a variety of environmental and endogenous conditions causing DNA damage, which is detected and repaired by conserved DNA repair pathways to maintain genomic integrity. Chromatin remodeling is critical in this process, as the organization of eukaryotic DNA into compact chromatin presents a natural barrier to all DNA-related events. Studies on human premature aging syndromes together with normal aging have suggested that accumulated damages might lead to exhaustion of resources that are required for physiological functions and thus accelerate aging. In this manuscript, combining the present understandings and latest findings, we focus mainly on discussing the role of chromatin remodeling in the repair of DNA double-strand breaks (DSBs) and regulation of aging.
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Affiliation(s)
- Baohua Liu
- Shenzhen Institute of Research and Innovation, The University of Hong Kong, Shenzhen, China ; Department of Biochemistry, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong
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Giaimo S. Are some conventional measures of the rate of ageing consistent with antagonistic pleiotropy? J Theor Biol 2013; 323:20-4. [PMID: 23295891 DOI: 10.1016/j.jtbi.2012.12.020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 12/24/2012] [Accepted: 12/26/2012] [Indexed: 02/02/2023]
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25
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Lebigre C, Arcese P, Reid JM. Decomposing variation in male reproductive success: age-specific variances and covariances through extra-pair and within-pair reproduction. J Anim Ecol 2013; 82:872-83. [DOI: 10.1111/1365-2656.12063] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 02/02/2013] [Indexed: 11/26/2022]
Affiliation(s)
| | - Peter Arcese
- Department of Forest and Conservation Science; Centre for Applied Conservation Research; University of British Columbia; Vancouver; BC V6T 1Z4; Canada
| | - Jane M. Reid
- Institute of Biological and Environmental Sciences; School of Biological Sciences; Zoology Building; University of Aberdeen; Aberdeen; AB24 2TZ; UK
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26
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Abstract
Ageing, also called as senescence, is one of the most complex, intrinsic, biological processes of growing older and resulting into reduced functional ability of the organism. Telomerase, environment, low calorie diets, free radicals, etc., are all believed to affect this ageing process. A number of genetic components of ageing have been identified using model organisms. Genes, mainly the sirtuins, regulate the ageing speed by indirection and controlling organism resistance to damages by exogenous and endogenous stresses. In higher organisms, ageing is likely to be regulated, in part, through the insulin/insulin-like growth factor 1 pathway. Besides this, the induction of apoptosis in stem and progenitor cells, increased p53 activity, and autophagy is also thought to trigger premature organismal ageing. Ageing has also been shown to upregulate expression of inflammatory mediators in mouse adipose tissue. The understanding of pathophysiology of ageing over the past few years has posed tremendous challenges for the development of anti-ageing medicine for targeted therapy. Future research areas must include targeted role of systemic inflammatory markers such as C-reactive protein and interleukin 6 and other biochemical and genetic studies including gene signaling pathways, gene microarray analysis, gene modulation, gene therapy, and development of animal/human models for potential therapeutic measures and evaluations.
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Affiliation(s)
- Anjana Nigam
- Department of Surgery, Pt. J. N. M. Medical College, Raipur, CG, India
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27
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Abstract
The ageing of the population is an issue in wealthy countries worldwide because of increasing costs for health care and welfare. Survival curves taken from demographic life tables may help shed light on the hypotheses that humans are living longer and that human populations are growing older. We describe a methodology that enables us to obtain separate measurements of scale and shape variances in survival curves. Specifically, 'living longer' is associated with the scale variance of survival curves, whereas 'growing older' is associated with the shape variance. We show how the scale and shape of survival curves have changed over time during recent decades, based on period and cohort female life tables for selected wealthy countries. Our methodology will be useful for performing better tracking of ageing statistics and it is possible that this methodology can help identify the causes of current trends in human ageing.
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Affiliation(s)
- Byung Mook Weon
- X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
| | - Jung Ho Je
- X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
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Smith AE, Ridding MC, Higgins RD, Wittert GA, Pitcher JB. Cutaneous afferent input does not modulate motor intracortical inhibition in ageing men. Eur J Neurosci 2012; 34:1461-9. [PMID: 22034977 DOI: 10.1111/j.1460-9568.2011.07869.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Afferent input has been shown to be a powerful modulator of cortical inhibition. Such modulation is likely to be important for the control of ongoing movement, but may also play a role in facilitating neuroplastic reorganisation. Human motor control and neuroplasticity both decline with ageing, whereas the efficacy of short-interval intracortical inhibition (SICI) appears not to. We examined if ageing alters the efficacy of afferent modulation of SICI. Previously, electrical cutaneous stimulation of a finger has been shown to reduce SICI in the motor cortices of young adults. Paired-pulse transcranial magnetic stimulation was used to assess SICI in the cortical representation of the first dorsal interosseous muscle. SICI was assessed separately under two conditions: with and without prior afferent input from electrical cutaneous stimulation of the index finger. Fifteen 'young' (20.1 ± 2.1 years) and 15 'old' male humans (65.5 ± 3.9 years) were studied. SICI did not differ when young and old males were compared. However, when preceded by electrical cutaneous finger stimulation, SICI was reduced in young men but not old men. Reflex testing indicated preservation of the afferent volley to the cortex. These findings suggest that a contributing factor in the decline of motor function, and possibly neuroplasticity, with ageing is loss of SICI modulation, probably due to altered cortical sensorimotor integration of afferent input.
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Affiliation(s)
- Ashleigh E Smith
- Robinson Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Adelaide, South Australia, Australia
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29
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Weon BM, Je JH. Plasticity and rectangularity in survival curves. Sci Rep 2011; 1:104. [PMID: 22355622 PMCID: PMC3216589 DOI: 10.1038/srep00104] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 09/09/2011] [Indexed: 01/12/2023] Open
Abstract
Living systems inevitably undergo a progressive deterioration of physiological function with age and an increase of vulnerability to disease and death. To maintain health and survival, living systems should optimize survival strategies with adaptive interactions among molecules, cells, organs, individuals, and environments, which arises plasticity in survival curves of living systems. In general, survival dynamics in a population is mathematically depicted by a survival rate, which monotonically changes from 1 to 0 with age. It would be then useful to find an adequate function to describe complicated survival dynamics. Here we describe a flexible survival function, derived from the stretched exponential function by adopting an age-dependent shaping exponent. We note that the exponent is associated with the fractal-like scaling in cumulative mortality rate. The survival function well depicts general features in survival curves; healthy populations exhibit plasticity and evolve towards rectangular-like survival curves, as examples in humans or laboratory animals.
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Affiliation(s)
- Byung Mook Weon
- X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
| | - Jung Ho Je
- X-ray Imaging Center, Department of Materials Science and Engineering, Pohang University of Science and Technology, San 31, Hyoja-dong, Pohang, 790-784, Korea
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30
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Carnes BA, Riesch R, Schlupp I. The delayed impact of parental age on offspring mortality in mice. J Gerontol A Biol Sci Med Sci 2011; 67:351-7. [PMID: 21835807 DOI: 10.1093/gerona/glr116] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The certitude of death makes reproduction the foundation upon which all life-history strategies are based. Plasticity in the reproductive biology of organisms is an essential adaptive response to the capricious and hazardous environments of earth. In this article, we use data from a breeding colony for laboratory mice to examine the mortality risks of offspring born at the outer boundaries of their Dam's reproductive plasticity. Our results suggest that the mortality/survival characteristics of offspring are affected by both litter parity and offspring gender. Females born to young Dams have consistently longer life spans than females born to older Dams. Conversely, males are either not affected by parental age or have longer life spans when born to older Dams.
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Affiliation(s)
- Bruce A Carnes
- Reynolds Department of Geriatric Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
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31
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Uranga RM, Bruce-Keller AJ, Morrison CD, Fernandez-Kim SO, Ebenezer PJ, Zhang L, Dasuri K, Keller JN. Intersection between metabolic dysfunction, high fat diet consumption, and brain aging. J Neurochem 2010; 114:344-61. [PMID: 20477933 PMCID: PMC2910139 DOI: 10.1111/j.1471-4159.2010.06803.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Deleterious neurochemical, structural, and behavioral alterations are a seemingly unavoidable aspect of brain aging. However, the basis for these alterations, as well as the basis for the tremendous variability in regards to the degree to which these aspects are altered in aging individuals, remains to be elucidated. An increasing number of individuals regularly consume a diet high in fat, with high-fat diet consumption known to be sufficient to promote metabolic dysfunction, although the links between high-fat diet consumption and aging are only now beginning to be elucidated. In this review we discuss the potential role for age-related metabolic disturbances serving as an important basis for deleterious perturbations in the aging brain. These data not only have important implications for understanding the basis of brain aging, but also may be important to the development of therapeutic interventions which promote successful brain aging.
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Affiliation(s)
- Romina M. Uranga
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina
| | | | - Christopher D. Morrison
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Sun Ok Fernandez-Kim
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Philip J. Ebenezer
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Le Zhang
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Kalavathi Dasuri
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
| | - Jeffrey N. Keller
- Pennington Biomedical Research Center/Louisiana State University System, Baton Rouge, LA, USA
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Risher JF, Todd GD, Meyer D, Zunker CL. The elderly as a sensitive population in environmental exposures: making the case. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2010; 207:95-157. [PMID: 20652665 DOI: 10.1007/978-1-4419-6406-9_2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The US population is aging. CDC has estimated that 20% of all Americans will be 65 or older by the year 2030. As a part of the aging process, the body gradually deteriorates and physiologic and metabolic limitations arise. Changes that occur in organ anatomy and function present challenges for dealing with environmental stressors of all kinds, ranging from temperature regulation to drug metabolism and excretion. The elderly are not just older adults, but rather are individuals with unique challenges and different medical needs than younger adults. The ability of the body to respond to physiological challenge presented by environmental chemicals is dependent upon the health of the organ systems that eliminate those substances from the body. Any compromise in the function of those organ systems may result in a decrease in the body's ability to protect itself from the adverse effects of xenobiotics. To investigate this issue, we performed an organ system-by-organ system review of the effects of human aging and the implications for such aging on susceptibility to drugs and xenobiotics. Birnbaum (1991) reported almost 20 years ago that it was clear that the pharmacokinetic behavior of environmental chemicals is, in many cases, altered during aging. Yet, to date, there is a paucity of data regarding recorded effects of environmental chemicals on elderly individuals. As a result, we have to rely on what is known about the effects of aging and the existing data regarding the metabolism, excretion, and adverse effects of prescription medications in that population to determine whether the elderly might be at greater risk when exposed to environmental substances. With increasing life expectancy, more and more people will confront the problems associated with advancing years. Moreover, although proper diet and exercise may lessen the immediate severity of some aspects of aging, the process will continue to gradually degrade the ability to cope with a variety of injuries and diseases. Thus, the adverse effects of long-term, low-level exposure to environmental substances will have a longer time to be manifested in a physiologically weakened elderly population. When such exposures are coupled with concurrent exposure to prescription medications, the effects could be devastating. Public health officials must be knowledgeable about the sensitivity of the growing elderly population, and ensure that the use of health guidance values (HGVs) for environmental contaminants and other substances give consideration to this physiologically compromised segment of the population.
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Affiliation(s)
- John F Risher
- Agency for Toxic Substances and Disease Registry, Division of Toxicology (F-32), Toxicology Information Branch, 1600 Clifton Road, Atlanta, GA 30333, USA.
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SCANNAPIECO ALEJANDRAC, SAMBUCETTI PABLO, NORRY FABIANM. Direct and correlated responses to selection for longevity in Drosophila buzzatii. Biol J Linn Soc Lond 2009. [DOI: 10.1111/j.1095-8312.2009.01223.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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35
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Berman M, Gaillard JM, Weimerskirch H. Contrasted patterns of age-specific reproduction in long-lived seabirds. Proc Biol Sci 2009; 276:375-82. [PMID: 18832060 PMCID: PMC2674342 DOI: 10.1098/rspb.2008.0925] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 09/09/2008] [Accepted: 09/15/2008] [Indexed: 11/12/2022] Open
Abstract
While the number of studies providing evidence of actuarial senescence is increasing, and covers a wide range of taxa, the process of reproductive senescence remains poorly understood. In fact, quite high reproductive output until the last years of life has been reported in several vertebrate species, so that whether or not reproductive senescence is widespread remains unknown. We compared age-specific changes of reproductive parameters between two closely related species of long-lived seabirds: the small-sized snow petrel Pagodroma nivea, and the medium-sized southern fulmar Fulmarus glacialoides. Both are sympatric in Antarctica. We used an exceptional dataset collected over more than 40 years to assess age-specific variations of both breeding probability and breeding success. We found contrasted age-specific reproductive patterns between the two species. Reproductive senescence clearly occurred from 21 years of age onwards in the southern fulmar, in both breeding probability and success, whereas we did not report any decline in the breeding success of the snow petrel, although a very late decrease in the proportion of breeders occurred at 34 years. Such a contrasted age-specific reproductive pattern was rather unexpected. Differences in life history including size or migratory behaviour are the most likely candidates to account for the difference we reported in reproductive senescence between these sympatric seabird species.
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Affiliation(s)
- M. Berman
- Centre d'Etudes Biologiques de Chizé, Centre National de la Recherche Scientifique79360 Villiers en Bois, Deux-Sèvres, France
| | - J.-M. Gaillard
- Unité Mixte de Recherche 5558, ‘Biométrie et Biologie Evolutive’ Université Claude Bernard Lyon 143 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex, France
| | - H. Weimerskirch
- Centre d'Etudes Biologiques de Chizé, Centre National de la Recherche Scientifique79360 Villiers en Bois, Deux-Sèvres, France
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36
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Asymptotic properties of infinite Leslie matrices. J Theor Biol 2009; 256:157-63. [PMID: 18950643 DOI: 10.1016/j.jtbi.2008.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 09/16/2008] [Accepted: 09/16/2008] [Indexed: 11/20/2022]
Abstract
The stable population theory is classically applicable to populations in which there is a maximum age after which individuals die. Demetrius [1972. On an infinite population matrix. Math. Biosci. 13, 133-137] extended this theory to infinite Leslie matrices, in which the longevity of individuals is potentially infinite. However, Demetrius had to assume that the survival probability per time step tends to 0 with age. We generalise here the conditions of application of the stable population theory to infinite Leslie matrix models and apply these results to two examples, including or not senescence.
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37
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Keller LF, Reid JM, Arcese P. Testing evolutionary models of senescence in a natural population: age and inbreeding effects on fitness components in song sparrows. Proc Biol Sci 2008; 275:597-604. [PMID: 18211879 PMCID: PMC2366077 DOI: 10.1098/rspb.2007.0961] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mutation accumulation (MA) and antagonistic pleiotropy (AP) have each been hypothesized to explain the evolution of ‘senescence’ or deteriorating fitness in old age. These hypotheses make contrasting predictions concerning age dependence in inbreeding depression in traits that show senescence. Inbreeding depression is predicted to increase with age under MA but not under AP, suggesting one empirical means by which the two can be distinguished. We use pedigree and life-history data from free-living song sparrows (Melospiza melodia) to test for additive and interactive effects of age and individual inbreeding coefficient (f) on fitness components, and thereby assess the evidence for MA. Annual reproductive success (ARS) and survival (and therefore reproductive value) declined in old age in both sexes, indicating senescence in this short-lived bird. ARS declined with f in both sexes and survival declined with f in males, indicating inbreeding depression in fitness. We observed a significant age×f interaction for male ARS (reflecting increased inbreeding depression as males aged), but not for female ARS or survival in either sex. These analyses therefore provide mixed support for MA. We discuss the strengths and limitations of such analyses and therefore the value of natural pedigreed populations in testing evolutionary models of senescence.
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Affiliation(s)
- L F Keller
- Zoological Museum, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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Density dependence, lifespan and the evolutionary dynamics of longevity. Theor Popul Biol 2008; 75:46-55. [PMID: 19027031 DOI: 10.1016/j.tpb.2008.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Revised: 09/12/2008] [Accepted: 10/21/2008] [Indexed: 12/30/2022]
Abstract
Longevity is a life-history trait that is shaped by natural selection. Evolution will shape mortality trajectories and lifespans, but until now the evolutionary analysis of longevity is based principally on a density-independent (Euler-Lotka) framework. The effects of density dependence on the evolution of lifespan and mortality remain largely unexplored. We investigate the influence of different population demographies on the evolution of longevity, and show how these can be linked to adaptive radiations. We present a range of models to explore the intraspecific and interspecific density effects on longevity and, consequently, diversification. We show how the magnitude, type, and timing of mutation can also affect fitness, invasion and diversification. We argue that fitness of alternative strategies under a range of different demographic structures leads to flat, as opposed to rugged, landscapes and that these flat fitness surfaces are important in the evolution of lifespan and senescence.
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Kawasaki N, Brassil CE, Brooks RC, Bonduriansky R. Environmental effects on the expression of life span and aging: an extreme contrast between wild and captive cohorts of Telostylinus angusticollis (Diptera: Neriidae). Am Nat 2008; 172:346-57. [PMID: 18710341 DOI: 10.1086/589519] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Most research on life span and aging has been based on captive populations of short-lived animals; however, we know very little about the expression of these traits in wild populations of such organisms. Because life span and aging are major components of fitness, the extent to which the results of many evolutionary studies in the laboratory can be generalized to natural settings depends on the degree to which the expression of life span and aging differ in natural environments versus laboratory environments and whether such environmental effects interact with phenotypic variation. We investigated life span and aging in Telostylinus angusticollis in the wild while simultaneously estimating these parameters under a range of conditions in a laboratory stock that was recently established from the same wild population. We found that males live less than one-fifth as long and age at least twice as rapidly in the wild as do their captive counterparts. In contrast, we found no evidence of aging in wild females. These striking sex-specific differences between captive and wild flies support the emerging view that environment exerts a profound influence on the expression of life span and aging. These findings have important implications for evolutionary gerontology and, more generally, for the interpretation of fitness estimates in captive populations.
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Affiliation(s)
- Noriyoshi Kawasaki
- Evolution and Ecology Research Centre and School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney 2052, New South Wales, Australia
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Nussey DH, Coulson T, Festa-Bianchet M, Gaillard JM. Measuring senescence in wild animal populations: towards a longitudinal approach. Funct Ecol 2008. [DOI: 10.1111/j.1365-2435.2008.01408.x] [Citation(s) in RCA: 308] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Escobar JS, Jarne P, Charmantier A, David P. Outbreeding Alleviates Senescence in Hermaphroditic Snails as Expected from the Mutation-Accumulation Theory. Curr Biol 2008; 18:906-10. [DOI: 10.1016/j.cub.2008.04.070] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2008] [Revised: 03/21/2008] [Accepted: 04/21/2008] [Indexed: 10/22/2022]
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Scannapieco AC, Sørensen JG, Loeschcke V, Norry FM. Heat-induced hormesis in longevity of two sibling Drosophila species. Biogerontology 2006; 8:315-25. [PMID: 17160437 DOI: 10.1007/s10522-006-9075-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2006] [Accepted: 11/14/2006] [Indexed: 12/24/2022]
Abstract
Previous work showed that mild-heat stress induces longevity hormesis in a model organism, D. melanogaster. Here we compared the possible heat-induced hormesis in longevity of other species of Drosophila, D. buzzatii and its sibling species D. koepferae, in a single-sex environment. Possible correlations between longevity and heat-stress resistance were also tested by measuring longevity, heat-knockdown resistance and the heat-induced Hsp70 expression for each species in a common environment. D. buzzatii was longer lived than D. koepferae at benign temperature. Knockdown resistance to heat stress was positively correlated to longevity within species. However, the shorter-lived species was more resistant to knockdown by heat stress than the longer-lived species. The heat-induced Hsp70 expression was similar between species. A heat-shock treatment (37 degrees C for 1 h at 4 days of age) extended mean longevity in the longer lived species but not in the shorter lived species. In D. koepferae, the demographic rate of senescence decreased but the baseline mortality rate increased by heat-shock, resulting in no extension of mean longevity. Sympatric populations of closely related species can be differentially sensitive to temperature and exhibit different patterns of 37 degrees C-induced hormesis in demographic senescence and longevity. The results also show that positive correlations between stress resistance and life span within species can shift in sign across closely related species. Finally, this study shows that heat-induced hormesis in longevity can be found across different Drosophila species, as hormetic effects are not limited to the previously studied D. melanogaster.
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Affiliation(s)
- Alejandra C Scannapieco
- Departamento de Ecología, Genética y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, 1428, Argentina
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Alonso-Alvarez C, Bertrand S, Devevey G, Prost J, Faivre B, Chastel O, Sorci G. AN EXPERIMENTAL MANIPULATION OF LIFE-HISTORY TRAJECTORIES AND RESISTANCE TO OXIDATIVE STRESS. Evolution 2006. [DOI: 10.1111/j.0014-3820.2006.tb00534.x] [Citation(s) in RCA: 172] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Norry FM, Sambucetti P, Scannapieco AC, Loeschcke V. Altitudinal patterns for longevity, fecundity and senescence in Drosophila buzzatii. Genetica 2006; 128:81-93. [PMID: 17028942 DOI: 10.1007/s10709-005-5537-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2005] [Accepted: 11/28/2005] [Indexed: 11/28/2022]
Abstract
We tested for variation in longevity, senescence rate and early fecundity of Drosophila buzzatii along an elevational transect in Argentina, using laboratory-reared flies in laboratory tests performed to avoid extrinsic mortality. At 25 degrees C, females from lowland populations lived longer and had a lower demographic rate of senescence than females from highland populations. Minimal instead of maximal temperature at the sites of origin of population best predicted this cline. A very different pattern was found at higher test temperature. At 29.5 degrees C, longevity of males increased with altitude of origin of population. No clinal trend was apparent for longevity of females at 29.5 degrees C. There was evidence for a trade-off between early fecundity and longevity at non-stressful temperature (25 degrees C) along the altitudinal gradient. This trait association is consistent with evolutionary theories of aging. Population-by-temperature and sex-by-temperature interactions indicate that senescence patterns are expressed in environment specific ways.
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Affiliation(s)
- F M Norry
- Departamento de Ecología y Evolución, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, (C-1428-EHA), Buenos Aires, Argentina.
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Bonsall MB. Longevity and ageing: appraising the evolutionary consequences of growing old. Philos Trans R Soc Lond B Biol Sci 2006; 361:119-35. [PMID: 16553312 PMCID: PMC1626542 DOI: 10.1098/rstb.2005.1738] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Senescence or ageing is an increase in mortality and/or decline in fertility with increasing age. Evolutionary theories predict that ageing or longevity evolves in response to patterns of extrinsic mortality or intrinsic damage. If ageing is viewed as the outcome of the processes of behaviour, growth and reproduction then it should be possible to predict mortality rate. Recent developments have shown that it is now possible to integrate these ecological and physiological processes and predict the shape of mortality trajectories. By drawing on the key exciting developments in the cellular, physiological and ecological process of longevity the evolutionary consequences of ageing are reviewed. In presenting these ideas an evolutionary demographic framework is used to argue how trade-offs in life-history strategies are important in the maintenance of variation in longevity within and between species. Evolutionary processes associated with longevity have an important role in explaining levels of biological diversity and speciation. In particular, the effects of life-history trait trade-offs in maintaining and promoting species diversity are explored. Such trade-offs can alleviate the effects of intense competition between species and promote species coexistence and diversification. These results have important implications for understanding a number of core ecological processes such as how species are divided among niches, how closely related species co-occur and the rules by which species assemble into food-webs. Theoretical work reveals that the proximate physiological processes are as important as the ecological factors in explaining the variation in the evolution of longevity. Possible future research challenges integrating work on the evolution and mechanisms of growing old are briefly discussed.
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Affiliation(s)
- Michael B Bonsall
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK.
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Bonduriansky R, Brassil CE. Reproductive ageing and sexual selection on male body size in a wild population of antler flies (Protopiophila litigata). J Evol Biol 2006; 18:1332-40. [PMID: 16135128 DOI: 10.1111/j.1420-9101.2005.00957.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Little is known about the importance of trade-offs between ageing and other life history traits, or the effects of ageing on sexual selection, particularly in wild populations suffering high extrinsic mortality rates. Life history theory suggests that trade-offs between reproduction and somatic maintenance may constrain individuals with higher initial reproductive rates to deteriorate more rapidly, resulting in reduced sexual selection strength. However, this trade-off may be masked by increased condition dependence of reproductive effort in older individuals. We tested for this trade-off in males in a wild population of antler flies (Protopiophila litigata). High mating rate was associated with reduced longevity, as a result of increased short-term mortality risk or accelerated ageing in traits affecting viability. In contrast, large body size was associated with accelerated ageing in traits affecting mating success, resulting in reduced sexual selection for large body size. Thus, ageing can affect sexual selection and evolution in wild populations.
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Affiliation(s)
- R Bonduriansky
- Department of Zoology, University of Toronto, Toronto, ON, Canada.
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Alonso-Alvarez C, Bertrand S, Devevey G, Prost J, Faivre B, Chastel O, Sorci G. AN EXPERIMENTAL MANIPULATION OF LIFE-HISTORY TRAJECTORIES AND RESISTANCE TO OXIDATIVE STRESS. Evolution 2006. [DOI: 10.1554/05-644.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Maklakov AA, Kremer N, Arnqvist G. Adaptive male effects on female ageing in seed beetles. Proc Biol Sci 2005; 272:2485-9. [PMID: 16271973 PMCID: PMC1599781 DOI: 10.1098/rspb.2005.3240] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2005] [Accepted: 06/28/2005] [Indexed: 02/04/2023] Open
Abstract
Selection can favour the evolution of a high reproductive rate early in life even when this results in a subsequent increase in the rate of mortality, because selection is relatively weak late in life. However, the optimal reproductive schedule of a female may be suboptimal to any one of her mates, and males may thus be selected to modulate female reproductive rate. Owing to such sexual conflict, coevolution between males and females may contribute to the evolution of senescence. By using replicated beetle populations selected for reproduction at an early or late age, we show that males evolve to affect senescence in females in a manner consistent with the genetic interests of males. 'Late' males evolved to decelerate senescence and increase the lifespan of control females, relative to 'early' males. Our findings demonstrate that adaptive evolution in one sex may involve its effects on senescence in the other, showing that the evolution of optimal life histories in one sex may be either facilitated or constrained by genes expressed in the other.
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Affiliation(s)
- Alexei A Maklakov
- Uppsala University Animal Ecology/Department of Ecology and Evolution Norbyvägen 18D, 752 36 Uppsala, Sweden.
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Mangel M, Munch SB. A life-history perspective on short- and long-term consequences of compensatory growth. Am Nat 2005; 166:E155-76. [PMID: 16475079 DOI: 10.1086/444439] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2004] [Accepted: 06/23/2005] [Indexed: 11/03/2022]
Abstract
Compensatory or catch-up growth (CG) is widely observed following periods of resource deprivation. Because of this commonness, it is generally assumed that compensatory growth is adaptive, but most theory to date has explicitly ignored considerations of fitness. Following a period of deprivation, when resources become plentiful again, individuals may not respond at all and continue on a "normal" trajectory from a smaller size at age, may exhibit faster-than-normal growth immediately following the end of the period, or may adopt a growth strategy that involves faster-than-normal growth at some later time. Compensating individuals may also overtake control individuals who have been growing normally throughout. We hypothesize that the key to understanding CG is that growth leads to the accumulation of damage at the cellular level that is expressed (and thus must be modeled) at the level of the organism. We show that a life-history model incorporating the mortality consequences of both size and damage provides a framework for understanding compensatory growth. We use the theory to classify physiological and life-history characteristics for which CG is predicted to be the optimal response to deprivation.
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Affiliation(s)
- Marc Mangel
- Center for Stock Assessment Research, Department of Applied Mathematics and Statistics, University of California, Santa Cruz, California 95064, USA.
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Yearsley JM, Kyriazakis I, Gordon IJ, Johnston SL, Speakman JR, Tolkamp BJ, Illius AW. A life history model of somatic damage associated with resource acquisition: damage protection or prevention? J Theor Biol 2005; 235:305-17. [PMID: 15882693 DOI: 10.1016/j.jtbi.2005.01.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 01/19/2005] [Accepted: 01/19/2005] [Indexed: 11/26/2022]
Abstract
A resource acquisition-allocation model is developed to examine the trade-off between reproduction and somatic protection. Unlike previous studies, resource intake is not assumed to be constrained: instead, resource intake is free to vary, with increased intake being associated with an increased risk of somatic damage. This gives rise to an optimal resource intake as well as an optimal allocation strategy. This paper studies the relative importance of acquisition and allocation strategies in regulating acquisition-related mortality. Under the optimal allocation strategy mortality rate increases with age, in accordance with the disposable soma theory of aging. Contrary to the usual interpretation of the disposable soma theory, this increase in mortality can arise from an increase in the resource acquisition effort rather than a decrease in the resources allocated to protection. At early ages resource acquisition is found to be the primary path for regulating life history costs, whilst allocating resources to protection becomes more important later in life. Models for targeted and non-targeted damage repair are considered and the robustness of our results to the structure and parameterization of the model is discussed. The results from our models are discussed in light of published data. Resource acquisition is shown to be a potentially important mechanism for controlling somatic damage which deserves further study.
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