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Seyed Alian R, Flasz B, Kędziorski A, Majchrzycki Ł, Augustyniak M. Concentration- and Time-Dependent Dietary Exposure to Graphene Oxide and Silver Nanoparticles: Effects on Food Consumption and Assimilation, Digestive Enzyme Activities, and Body Mass in Acheta domesticus. INSECTS 2024; 15:89. [PMID: 38392509 PMCID: PMC10888715 DOI: 10.3390/insects15020089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/23/2024] [Accepted: 01/25/2024] [Indexed: 02/24/2024]
Abstract
The advancement of nanotechnology poses a real risk of insect exposure to nanoparticles (NPs) that can enter the digestive system through contaminated food or nanopesticides. This study examines whether the exposure of model insect species-Acheta domesticus-to increasing graphene oxide (GO) and silver nanoparticle (AgNP) concentrations (2, 20, and 200 ppm and 4, 40, and 400 ppm, respectively) could change its digestive functions: enzymes' activities, food consumption, and assimilation. We noticed more pronounced alterations following exposure to AgNPs than to GO. They included increased activity of α-amylase, α-glucosidase, and lipase but inhibited protease activity. Prolonged exposure to higher concentrations of AgNPs resulted in a significantly decreased food consumption and changed assimilation compared with the control in adult crickets. A increase in body weight was observed in the insects from the Ag4 group and a decrease in body weight or no effects were observed in crickets from the Ag40 and Ag400 groups (i.e., 4, 40, or 400 ppm of AgNPs, respectively), suggesting that even a moderate disturbance in nutrient and energy availability may affect the body weight of an organism and its overall condition. This study underscores the intricate interplay between NPs and digestive enzymes, emphasizing the need for further investigation to comprehend the underlying mechanisms and consequences of these interactions.
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Affiliation(s)
- Reyhaneh Seyed Alian
- Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 40-007 Katowice, Poland
| | - Barbara Flasz
- Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 40-007 Katowice, Poland
| | - Andrzej Kędziorski
- Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 40-007 Katowice, Poland
| | - Łukasz Majchrzycki
- Institute of Physics, Faculty of Materials Engineering and Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
| | - Maria Augustyniak
- Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, 40-007 Katowice, Poland
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Mattioli CC, Takata R, de Oliveira Paes Leme F, Costa DC, Luz RK. Response of juvenile Lophiosilurus alexandri to osmotic and thermic shock. FISH PHYSIOLOGY AND BIOCHEMISTRY 2020; 46:51-61. [PMID: 31422544 DOI: 10.1007/s10695-019-00696-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
The objective of the present study was to evaluate the physiological responses of juvenile Lophiosilurus alexandri submitted to osmotic and thermic shock. Thirty juveniles were used for each test, of which 10 were not subjected to stress and remained in normal conditions (fresh water at 28.0 °C). The others were submitted to stress shock (saline water of 10.0 g of salt/L or water cooled to 18.0 °C). Blood samples were taken at 0 h (no exposure to the stress factor) and 1 h and 24 h after the tests. At 24 h, the survivorship was 100% in both tests. In both the osmotic and thermic shock tests, cortisol and glucose levels were higher at 1 h but then decreased after 24 h. Lactate dehydrogenase showed differences in the temperature test, but there was no difference between 1 and 24 h after exposure to osmotic shock (P > 0.05). The difference was recorded in blood gas variables (pH, PvCO2, PvO2, hemoglobin, sO2, BE, tCO2, HCO3-, and stHCO3-) and electrolytes (Na+, Ca++, nCa++, and K+) in both experiments. With regard to hematology and blood biochemistry, exposure to thermal shock did not affect (P > 0.05) ALP, total plasma protein, hematocrit, and ALT and AST at 1 h and 24 h. ALP and total protein in the blood of fish submitted to the osmotic shock were lowest (P < 0.05) at 24 h. Leukocyte and erythrocyte counts exhibited differences after osmotic shock, in contrast to erythrocyte counts of the temperature test, which did not change in 24 h (P > 0.05). Juveniles of L. alexandri were able to reestablish the main indicators of stress (cortisol, glucose), while the others (hematological, biochemical, and gasometric) varied in compensation for normal physiological reestablishment.
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Affiliation(s)
- Cristiano Campos Mattioli
- Departamento de Zootecnia, Laboratório de Aquacultura, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, no. 6627, Belo Horizonte, MG, CEP 30161-970, Brazil
| | - Rodrigo Takata
- Fundação Instituto de Pesca do Estado do Rio de Janeiro, Unidade de Pesquisa e Reprodução de Peixes, Av. Presidente Vargas, 197, Parque de Exposições, Cordeiro, RJ, CEP 28540-000, Brazil
| | - Fabiola de Oliveira Paes Leme
- Laboratório de apoio à pesquisa-LAPEQ, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, no. 6627, Belo Horizonte, MG, CEP 30161-970, Brazil
| | - Deliane Cristina Costa
- Departamento de Zootecnia, Laboratório de Aquacultura, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, no. 6627, Belo Horizonte, MG, CEP 30161-970, Brazil
| | - Ronald Kennedy Luz
- Departamento de Zootecnia, Laboratório de Aquacultura, Universidade Federal de Minas Gerais, Avenida Antônio Carlos, no. 6627, Belo Horizonte, MG, CEP 30161-970, Brazil.
- Laboratório de Aquacultura da Escola de Veterinária, Universidade Federal de Minas Gerais, Av. Antônio Carlos, 6627, Belo Horizonte, MG, CEP 31270-901, Brazil.
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Rodrigues ACM, Gravato C, Quintaneiro C, Bordalo MD, Barata C, Soares AMVM, Pestana JLT. Energetic costs and biochemical biomarkers associated with esfenvalerate exposure in Sericostoma vittatum. CHEMOSPHERE 2017; 189:445-453. [PMID: 28957762 DOI: 10.1016/j.chemosphere.2017.09.057] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 08/25/2017] [Accepted: 09/12/2017] [Indexed: 05/06/2023]
Abstract
Pyrethroid insecticides have been used for decades and their worldwide market continues to increase, despite their high toxicity to non-target insects. Recent studies reveal that it is essential to investigate the secondary mechanisms of action of type II pyrethroids to understand their cellular effects on invertebrates. The aim of this study was to evaluate the lethality, behaviour and physiological alterations and energetic costs in caddisfly larvae exposed to environmentally relevant concentrations of esfenvalerate (ESF). ESF caused both mortality and feeding inhibition of exposed caddisfly larvae: nominal ESF 96 h LC50 was 2.29 μg/L; feeding activity was impaired at concentrations equal or above 0.25 μg/L. At the cellular level, glutathione-S-transferase (GST) activity was increased on caddisfly larvae exposed to 0.25 and 0.5 μg/L ESF, which might contribute to prevent oxidative damage since levels of lipid peroxidation (LPO) were not altered. The energy budget of exposed caddisfly larvae was impaired by exposure to 0.25 μg/L ESF since sugar and protein contents decreased, while a decline of energy consumption was observed. The analysis of feeding, energy reserves and consumption data through structural equation modelling (SEM) allowed to quantify the direct and indirect effects of ESF exposure on bioenergetics of caddisfly larvae. SEM analysis showed a strong negative direct influence of ESF onto feeding activity, sugars content and energy consumption, highlighting a significant positive relationship between sugars and protein contents. These results show that energy expenditure is related to oxidative defense mechanisms induced by ESF stress that may lead to deleterious effects on growth and development.
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Affiliation(s)
- Andreia C M Rodrigues
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal; Department of Environmental Chemistry (IDAEA-CSIC), Jordi Girona, 18-26, 08034, Barcelona, Spain
| | - Carlos Gravato
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Carla Quintaneiro
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Maria D Bordalo
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - Carlos Barata
- Department of Environmental Chemistry (IDAEA-CSIC), Jordi Girona, 18-26, 08034, Barcelona, Spain
| | - Amadeu M V M Soares
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal
| | - João L T Pestana
- Departamento de Biologia & CESAM, Universidade de Aveiro, Campus Universitário de Santiago, 3810-193, Aveiro, Portugal.
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Beckers V, Dersch LM, Lotz K, Melzer G, Bläsing OE, Fuchs R, Ehrhardt T, Wittmann C. In silico metabolic network analysis of Arabidopsis leaves. BMC SYSTEMS BIOLOGY 2016; 10:102. [PMID: 27793154 PMCID: PMC5086045 DOI: 10.1186/s12918-016-0347-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Accepted: 10/21/2016] [Indexed: 12/23/2022]
Abstract
Background During the last decades, we face an increasing interest in superior plants to supply growing demands for human and animal nutrition and for the developing bio-based economy. Presently, our limited understanding of their metabolism and its regulation hampers the targeted development of desired plant phenotypes. In this regard, systems biology, in particular the integration of metabolic and regulatory networks, is promising to broaden our knowledge and to further explore the biotechnological potential of plants. Results The thale cress Arabidopsis thaliana provides an ideal model to understand plant primary metabolism. To obtain insight into its functional properties, we constructed a large-scale metabolic network of the leaf of A. thaliana. It represented 511 reactions with spatial separation into compartments. Systematic analysis of this network, utilizing elementary flux modes, investigates metabolic capabilities of the plant and predicts relevant properties on the systems level: optimum pathway use for maximum growth and flux re-arrangement in response to environmental perturbation. Our computational model indicates that the A. thaliana leaf operates near its theoretical optimum flux state in the light, however, only in a narrow range of photon usage. The simulations further demonstrate that the natural day-night shift requires substantial re-arrangement of pathway flux between compartments: 89 reactions, involving redox and energy metabolism, substantially change the extent of flux, whereas 19 reactions even invert flux direction. The optimum set of anabolic pathways differs between day and night and is partly shifted between compartments. The integration with experimental transcriptome data pinpoints selected transcriptional changes that mediate the diurnal adaptation of the plant and superimpose the flux response. Conclusions The successful application of predictive modelling in Arabidopsis thaliana can bring systems-biological interpretation of plant systems forward. Using the gained knowledge, metabolic engineering strategies to engage plants as biotechnological factories can be developed. Electronic supplementary material The online version of this article (doi:10.1186/s12918-016-0347-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Veronique Beckers
- Institute for Systems Biotechnology, Saarland University, Campus A1.5, 66123, Saarbrücken, Germany
| | - Lisa Maria Dersch
- Institute for Systems Biotechnology, Saarland University, Campus A1.5, 66123, Saarbrücken, Germany
| | | | - Guido Melzer
- Institute of Biochemical Engineering, Technical University Braunschweig, Braunschweig, Germany
| | | | | | | | - Christoph Wittmann
- Institute for Systems Biotechnology, Saarland University, Campus A1.5, 66123, Saarbrücken, Germany.
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Enders LS, Nunney L. Reduction in the cumulative effect of stress-induced inbreeding depression due to intragenerational purging in Drosophila melanogaster. Heredity (Edinb) 2015; 116:304-13. [PMID: 26604190 DOI: 10.1038/hdy.2015.103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 10/05/2015] [Accepted: 10/06/2015] [Indexed: 11/09/2022] Open
Abstract
Environmental stress generally exacerbates the harmful effects of inbreeding and it has been proposed that this could be exploited in purging deleterious alleles from threatened inbred populations. However, understanding what factors contribute to variability in the strength of inbreeding depression (ID) observed across adverse environmental conditions remains a challenge. Here, we examined how the nature and timing of stress affects ID and the potential for purging using inbred and outbred Drosophila melanogaster larvae exposed to biotic (larval competition, bacteria infection) and abiotic (ethanol, heat) stressors compared with unstressed controls. ID was measured during (larval survival) and after (male mating success) stress exposure. The level of stress imposed by each stressor was approximately equal, averaging a 42% reduction in outbred larval survival relative to controls. All stressors induced on average the same ID, causing a threefold increase in lethal equivalents for larval survival relative to controls. However, stress-induced ID in larval success was followed by a 30% reduction in ID in mating success of surviving males. We propose that this fitness recovery is due to 'intragenerational purging' whereby fitness correlations facilitate stress-induced purging that increases the average fitness of survivors in later life history stages. For biotic stressors, post-stress reductions in ID are consistent with intragenerational purging, whereas for abiotic stressors, there appeared to be an interaction between purging and stress-induced physiological damage. For all stressors, there was no net effect of stress on lifetime ID compared with unstressed controls, undermining the prediction that stress enhances the effectiveness of population-level purging across generations.
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Affiliation(s)
- L S Enders
- Department of Biology, University of California, Riverside, Riverside, CA, USA.,Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, USA
| | - L Nunney
- Department of Biology, University of California, Riverside, Riverside, CA, USA
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Bonhoure N, Byrnes A, Moir RD, Hodroj W, Preitner F, Praz V, Marcelin G, Chua SC, Martinez-Lopez N, Singh R, Moullan N, Auwerx J, Willemin G, Shah H, Hartil K, Vaitheesvaran B, Kurland I, Hernandez N, Willis IM. Loss of the RNA polymerase III repressor MAF1 confers obesity resistance. Genes Dev 2015; 29:934-47. [PMID: 25934505 PMCID: PMC4421982 DOI: 10.1101/gad.258350.115] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
MAF1 is a global repressor of RNA polymerase III transcription that regulates the expression of highly abundant noncoding RNAs in response to nutrient availability and cellular stress. Thus, MAF1 function is thought to be important for metabolic economy. Here we show that a whole-body knockout of Maf1 in mice confers resistance to diet-induced obesity and nonalcoholic fatty liver disease by reducing food intake and increasing metabolic inefficiency. Energy expenditure in Maf1(-/-) mice is increased by several mechanisms. Precursor tRNA synthesis was increased in multiple tissues without significant effects on mature tRNA levels, implying increased turnover in a futile tRNA cycle. Elevated futile cycling of hepatic lipids was also observed. Metabolite profiling of the liver and skeletal muscle revealed elevated levels of many amino acids and spermidine, which links the induction of autophagy in Maf1(-/-) mice with their extended life span. The increase in spermidine was accompanied by reduced levels of nicotinamide N-methyltransferase, which promotes polyamine synthesis, enables nicotinamide salvage to regenerate NAD(+), and is associated with obesity resistance. Consistent with this, NAD(+) levels were increased in muscle. The importance of MAF1 for metabolic economy reveals the potential for MAF1 modulators to protect against obesity and its harmful consequences.
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Affiliation(s)
- Nicolas Bonhoure
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Ashlee Byrnes
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Robyn D Moir
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Wassim Hodroj
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland
| | - Frédéric Preitner
- Mouse Metabolic Evaluation Facility, Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Viviane Praz
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland; Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Genevieve Marcelin
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Streamson C Chua
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Nuria Martinez-Lopez
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Rajat Singh
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Norman Moullan
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Johan Auwerx
- Laboratory for Integrative and Systems Physiology, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Gilles Willemin
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland; Mouse Metabolic Evaluation Facility, Center for Integrative Genomics, University of Lausanne, 1015 Lausanne, Switzerland
| | - Hardik Shah
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Kirsten Hartil
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Bhavapriya Vaitheesvaran
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Irwin Kurland
- Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Nouria Hernandez
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, 1015 Lausanne, Switzerland;
| | - Ian M Willis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA; Diabetes Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA;
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Sokolova IM. Energy-Limited Tolerance to Stress as a Conceptual Framework to Integrate the Effects of Multiple Stressors. Integr Comp Biol 2013; 53:597-608. [DOI: 10.1093/icb/ict028] [Citation(s) in RCA: 333] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Govindaraju DR, Larson MG, Yin X, Benjamin EJ, Rao MB, Vasan RS. Association between SNP heterozygosity and quantitative traits in the Framingham Heart Study. Ann Hum Genet 2009; 73:465-73. [PMID: 19523151 PMCID: PMC3760672 DOI: 10.1111/j.1469-1809.2009.00514.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Associations between multilocus heterozygosity and fitness traits, also termed heterozygosity and fitness correlations (HFCs), have been reported in numerous organisms. These studies, in general, indicate a positive relationship between heterozygosity and fitness traits. We studied the association between genome-wide heterozygosity at 706 non-synonymous and synonymous SNPs and 19 quantitative traits, including morphological, biochemical and fitness traits in the Framingham Heart Study. Statistically significant association was found between heterozygosity and systolic and diastolic blood pressures as well as left ventricular diameter and wall thickness. These results suggest that heterozygosity may be associated with traits, such as blood pressure that closely track environmental variations. Balancing selection may be operating in the maintenance of heterozygosity and the major components of blood pressure and hypertension. Genome wide SNP heterozygosity may be used to understand the phenomenon of dominance as well as the evolutionary basis of many quantitative traits in humans.
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Parsons PA. Antagonistic pleiotropy and the stress theory of aging. Biogerontology 2007; 8:613-7. [PMID: 17610139 DOI: 10.1007/s10522-007-9101-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 05/15/2007] [Indexed: 11/30/2022]
Abstract
The ecological stress theory of aging incorporates the normally harsh environments of natural populations and hence restricted resources. Especially towards lethal extremes, positive associations are expected among fitness traits underlain by selection for energetic efficiency favoring genotypes for stress resistance. Positive pleiotropy is therefore expected for fitness traits across varying ages under these conditions. Furthermore, hormetic zones are regions of maximum energetic efficiency, also implying positive pleiotropy. Negative pleiotropy may therefore be mainly a phenomenon of benign environments.
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Parsons PA. The ecological stress theory of aging and hormesis: an energetic evolutionary model. Biogerontology 2007; 8:233-42. [PMID: 17473992 DOI: 10.1007/s10522-007-9080-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Accepted: 12/30/2006] [Indexed: 10/23/2022]
Abstract
Free-living organisms normally struggle to exist in harsh environments that are nutritionally and energetically inadequate, where evolutionary adaptation is challenged by internal stresses within organisms and external stresses from the environment. The incorporation of environmental variables into aging theories such as the free-radical and metabolic rate/oxidative stress theories, is the basis of the ecological stress theory of aging and hormesis. Environmental variation from optimum to lethal extremes gives a fitness-stress continuum, where energetic efficiency, or fitness, is inversely related to stress level; in the evolutionary context survival is a more direct measure of fitness for assessing aging than is lifespan. On this continuum, the hormetic zone is in the optimum region, while aging emphasizes survival towards lethal extremes. At the limits of survival, a convergence of physiological and genetical processes is expected under accumulating stress from Reactive Oxygen Species, ROS. Limited ecologically-oriented studies imply that major genes are important towards limits of survival compared with the hormetic zone. Future investigations could usefully explore outlier populations physiologically and genetically, since there is the likelihood that genetic variability may be lower in those cohorts managing to survive to extremely advanced ages as found in highly stressed ecological outlier populations. If so, an evolutionary explanation of the mortality-rate decline typical of cohorts of the extremely old emerges. In summary, an energetic evolutionary approach produces a general aging theory which automatically incorporates hormesis, since the theory is based on a fitness-stress continuum covering the whole range of possible abiotic environments of natural populations.
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Parsons PA. Survival and longevity improvements at extreme ages: an interpretation assuming an ecological stress theory of aging. Biogerontology 2006; 8:225-31. [PMID: 17082910 DOI: 10.1007/s10522-006-9064-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Accepted: 08/15/2006] [Indexed: 11/25/2022]
Abstract
The primary determinant of survival during aging is the energetic efficiency and metabolic stability required to counter the accumulated internal and external stresses of a lifetime. Hence, genetically stress-resistant individuals should accumulate with age; frailer, less robust, less energetically efficient and less metabolically stable individuals should succumb in parallel. This selection process implies the accumulation of energetically efficient stress-resistant individuals with age to the exclusion of all others. High additive genetic variability for survival is expected under extreme circumstances, however there is limited evidence close to the absolute extremes of life that diversity may fall. At this stage, only a few highly adaptive, oxidative-stress-resistant and presumably somewhat homozygous genotypes should remain. Therefore a fall in variability may occur in these outliers, when frailer individuals are unable to cope and are eliminated at extreme ages. This process could provide an explanation of mortality-rate declines in domesticated (laboratory) and free-living populations of the extremely old. That is, mortality-rate declines may be an expectation from a process of genetic sorting resulting from the accumulated responses to environmental stress over time. Application of an ecological stress theory of aging, which combines the external stresses to which organisms are exposed with internal stresses, appears to be the prerequisite for this conclusion.
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Parsons PA. Do Energetic Costs Underlie Variability and Evolutionary Potential Across Variably Stressful Environments? Isr J Ecol Evol 2006. [DOI: 10.1560/ijee_52_3-4_423] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Stress can be viewed as an environmental probe that targets energy carriers, and hence can determine the energetic efficiency or fitness to survive. Thus, variability and evolutionary potential are interpreted in terms of the ecological scenario of predominantly stressful environments in the wild that restrict energy availability. This can explain how the observed variability of direct fitness traits is high at extremes of abiotic stresses, giving U-shaped curves for variability that incorporate more benign regions between the extremes. Some consistency with interpretations based upon conventional quantitative genetic techniques occurs, incorporating this ecological/energetic approach. However, investigations into the quantification of stress levels are required for more comprehensive assessments. Even so, evolutionary potential can in principle be investigated in terms of energetic consequences of the functional biology of organisms in their challenging habitats. This approach appears predictive for variability patterns of direct fitness traits as well as for developmentally more complex morphometric traits and for relationships among fitness traits in natural populations. That is, energetic costs are basic in determining evolutionary potential across variably stressful environments.
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