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Brzęk P. What do molecular laws of life mean for species: absolute restrictions or mere suggestions? J Exp Biol 2023; 226:jeb245849. [PMID: 37756603 DOI: 10.1242/jeb.245849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
Evolutionary biologists are interested in finding universal patterns of covariation between macroscopic and molecular traits. Knowledge of such laws of life can be essential for understanding the course of evolutionary processes. Molecular parameters are presumably close to fundamental limits set to all organisms by laws of physics and chemistry. Thus, laws of life that include such parameters are hypothesized to be similar at both wide interspecific levels of variation and narrower levels of intraspecific and intraindividual variation in different species. In this Commentary, I discuss examples where the significance or direction of such molecular laws of life can be compared at different levels of biological variation: (1) the membrane pacemaker theory of metabolism, (2) the correlation between variation in metabolic rate and mitochondrial efficiency and (3) the allometric scaling of metabolism. All three examples reveal that covariations within species or individuals that include molecular parameters do not always follow patterns observed between species. I conclude that limits set by molecular laws of life can be circumvented (at least to some degree) by changes in other traits, and thus, they usually do not impose strict limitations on minor within-species evolutionary changes (i.e. microevolution). I also briefly discuss some of the most promising perspectives for future studies on the universality of molecular laws of life.
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Affiliation(s)
- Paweł Brzęk
- Faculty of Biology, University of Białystok, Ciołkowskiego 1J, 15-245 Białystok, Poland
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2
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Fiedler A, Careau V. Individual (Co)variation in Resting and Maximal Metabolic Rates in Wild Mice. Physiol Biochem Zool 2021; 94:338-352. [PMID: 34343458 DOI: 10.1086/716042] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractBasal metabolic rate (BMR) represents the lowest level of aerobic metabolism in a resting, postabsorptive endotherm as measured within the thermoneutral zone. By contrast, maximal metabolic rate ([Formula: see text]max) reflects the upper limit of aerobic metabolism achieved during intensive exercise. As BMR and [Formula: see text]max define the boundaries of the possible levels of aerobic metabolism expressed by a normothermic individual, a key question is whether BMR and [Formula: see text]max are correlated. In the present study, we took repeated paired measurements of thermoneutral resting metabolic rate (RMRt) and [Formula: see text]max on 165 white-footed mice (Peromyscus leucopus). Over a single summer (May-October), repeatability (R ± SE) was low but statistically significant ([Formula: see text]) for both RMRt and [Formula: see text]max ([Formula: see text] for RMRt; [Formula: see text] for [Formula: see text]max). Willingness to run during the forced-exercise trials was also significantly repeatable ([Formula: see text]). At the residual level (within individual), RMRt and [Formula: see text]max tended to be positively correlated ([Formula: see text], [Formula: see text]), suggesting the presence of correlated phenotypic plasticity. By contrast, RMRt and [Formula: see text]max were significantly negatively correlated at the among-individual level ([Formula: see text]). To the extent that variation in RMRt reflects variation in BMR, the negative among-individual correlation does not corroborate the idea that a costly metabolic machinery is needed to support a high [Formula: see text]max. Future research should investigate the (genetic) relationship between RMRt (and BMR) and other energetically expensive behaviors and activities to better understand how energy is allocated within individuals.
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3
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Young KG, Vanderboor CM, Regnault TRH, Guglielmo CG. Species-specific metabolic responses of songbird, shorebird, and murine cultured myotubes to n-3 polyunsaturated fatty acids. Am J Physiol Regul Integr Comp Physiol 2020; 320:R362-R376. [PMID: 33356878 DOI: 10.1152/ajpregu.00249.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Migratory birds may benefit from diets rich in polyunsaturated fatty acids (PUFAs) that could improve exercise performance. Previous investigations suggest that different types of birds may respond differently to PUFA. We established muscle myocyte cell culture models from muscle satellite cells of a migratory passerine songbird (yellow-rumped warbler, Setophaga coronata coronata) and a nonpasserine shorebird (sanderling, Calidris alba). We differentiated and treated avian myotubes and immortalized murine C2C12 myotubes with n-3 PUFA docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), and with monounsaturated oleic acid (OA) to compare effects on aerobic performance, metabolic enzyme activities, key fatty acid (FA) transporters, and expression of peroxisome proliferator-activated receptors (PPARs). Sanderling and C2C12 myotubes increased expression of PPARs with n-3 PUFA treatments, whereas expression was unchanged in yellow-rumped warblers. Both sanderlings and yellow-rumped warblers increased expression of fatty acid transporters, whereas C2C12 cells decreased expression following n-3 PUFA treatments. Only yellow-rumped warbler myotubes increased expression of some metabolic enzymes, whereas the sanderling and C2C12 cells were unchanged. PUFA supplementation in C2C12 myotubes increased mitochondrial respiratory chain efficiency, whereas sanderlings increased proton leak-associated respiration and maximal respiration (measurements were not made in warblers). This research indicates that songbirds and shorebirds respond differently to n-3 PUFA and provides support for the hypothesis that n-3 PUFA increase the aerobic capacity of migrant shorebird muscle, which may improve overall endurance flight performance.
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Affiliation(s)
- Kevin G Young
- Department of Biology, Advanced Facility for Avian Research, Western University, London, Ontario, Canada
| | - Christina M Vanderboor
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada
| | - Timothy R H Regnault
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Department of Obstetrics and Gynaecology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada.,Children's Health Research Institute, Lawson Health Research Institute, London, Ontario, Canada
| | - Christopher G Guglielmo
- Department of Biology, Advanced Facility for Avian Research, Western University, London, Ontario, Canada
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4
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Khanal P, Patil BM, Unger BS. Zebrafish shares common metabolic pathways with mammalian olanzapine-induced obesity. FUTURE JOURNAL OF PHARMACEUTICAL SCIENCES 2020. [DOI: 10.1186/s43094-020-00049-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Abstract
Background
Olanzapine is one of the most prescribed antipsychotic agents in the pharmacotherapy of psychiatric illness; however, it is associated with multiple side effects primarily obesity. Multiple investigations have been made to model the olanzapine-induced obesity in rodent models which was found to be dose-dependent, gender-dependent, and species-dependent. Danio rerio is a choice of an animal model to understand the pathogenesis of multiple diseases. The present study dealt to understand the olanzapine-associated obesity in zebrafish using in silico and wet-lab experimental protocols by performing gene set enrichment analysis, phylogeny comparison of receptors, and assessing the effect of olanzapine on metabolic rate, lipid metabolism, body weight, and food intake in zebrafish.
Results
The metabolic pathway was predicted to be majorly modulated by olanzapine in human, rat, mouse, and zebrafish. A clade of receptors of rat, mouse, and human receptor for feeding and satiety center was found similar to zebrafish. The decrease in lipid metabolism was observed in zebrafish larvae if exposed to olanzapine solution. Similarly, there was a significant decrease in metabolic rate in 200 μM and 400 μM concentration of olanzapine.
Conclusion
Enrichment analysis predicted the probable modulation of metabolic pathways in zebrafish if exposed to olanzapine. Further, olanzapine was identified to play a prime role in decreasing lipid metabolism and metabolic rate and increasing food intake and weight gain in zebrafish which suggests the validation of this model for olanzapine-induced obesity.
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5
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Downs CJ, Brown JL, Wone BWM, Donovan ER, Hayes JP. Effects of Selection for Mass-Independent Maximal Metabolic Rate on Food Consumption. Physiol Biochem Zool 2019; 93:23-36. [PMID: 31671012 DOI: 10.1086/706206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Metabolic rates potentially regulate the pace of important physiological and life-history traits. Natural selection has shaped the evolution of metabolic rates and the physiology that supports them, including digestibility and the rate of food consumption. Understanding the relationship between metabolic rates and energy internalization is central to understanding how resources are allocated among competing physiological functions. We investigated how artificial selection on mass-independent basal metabolic rate (BMR) and mass-independent aerobic maximal metabolic rate (MMR) affected food consumption and apparent digestibility in mice. Evolved changes in mass-corrected BMR-but not mass-corrected MMR-corresponded with changes in food consumption. This result is consistent with previous work showing that BMR constitutes a large portion of an animal's daily energy budget and thus that BMR might provide a better indicator of daily food requirements than MMR. In contrast, digestive efficiencies did not differ among selection treatments and did not evolve in these mice. This study provides insights into how evolution of metabolic rates may affect food consumption and overall energy use.
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6
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Chung DJ, Healy TM, McKenzie JL, Chicco AJ, Sparagna GC, Schulte PM. Mitochondria, Temperature, and the Pace of Life. Integr Comp Biol 2018; 58:578-590. [DOI: 10.1093/icb/icy013] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Affiliation(s)
- Dillon J Chung
- Department of Zoology and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Timothy M Healy
- Department of Zoology and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
- Marine Biology Research Division, Scripps Institution of Oceanography, University of California, San Diego, CA 92037, USA
| | - Jessica L McKenzie
- Department of Zoology and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Adam J Chicco
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523-1680, USA
| | - Genevieve C Sparagna
- Anschutz Medical Campus, Division of Cardiology, University of Colorado Denver, Aurora, CO 80045, USA
| | - Patricia M Schulte
- Department of Zoology and Biodiversity Research Centre, The University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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Price ER, Sirsat TS, Sirsat SKG, Curran T, Venables BJ, Dzialowski EM. The membrane pacemaker hypothesis: novel tests during the ontogeny of endothermy. J Exp Biol 2018; 221:jeb.174466. [DOI: 10.1242/jeb.174466] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/14/2018] [Indexed: 01/09/2023]
Abstract
The ‘membrane pacemaker’ hypothesis proposes a biochemical explanation for among-species variation in resting metabolism, based on the positive correlation between membrane docosahexaenoic acid (DHA) and metabolic rate. We tested this hypothesis using a novel model, altricial red-winged blackbird nestlings, predicting that the proportion of DHA in muscle and liver membranes should increase with the increasing metabolic rate of the nestling as it develops endothermy. We also used a dietary manipulation, supplementing the natural diet with fish oil (high DHA) or sunflower oil (high linoleic acid) to alter membrane composition and then assessed metabolic rate. In support of the membrane pacemaker hypothesis, DHA proportions increased in membranes from pectoralis muscle, muscle mitochondria, and liver during post-hatch development. By contrast, elevated dietary DHA had no effect on resting metabolic rate, despite causing significant changes to membrane lipid composition. During cold challenges, higher metabolic rates were achieved by birds that had lower DHA and higher linoleic acid in membrane phospholipids. Given the mixed support for this hypothesis, we conclude that correlations between membrane DHA and metabolic rate are likely spurious, and should be attributed to a still-unidentified confounding variable.
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Affiliation(s)
- Edwin R. Price
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| | - Tushar S. Sirsat
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
- Current address: Department of Biology, State University of New York Potsdam, Potsdam NY 13676, USA
| | - Sarah K. G. Sirsat
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
- Current address: Department of Biology, State University of New York Potsdam, Potsdam NY 13676, USA
| | - Thomas Curran
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| | - Barney J. Venables
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
| | - Edward M. Dzialowski
- Department of Biological Sciences, University of North Texas, Denton TX, 76201, USA
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8
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Price ER, Dzialowski EM. Development of endothermy in birds: patterns and mechanisms. J Comp Physiol B 2017; 188:373-391. [DOI: 10.1007/s00360-017-1135-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 10/25/2017] [Accepted: 10/29/2017] [Indexed: 02/08/2023]
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9
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Swanson DL, McKechnie AE, Vézina F. How low can you go? An adaptive energetic framework for interpreting basal metabolic rate variation in endotherms. J Comp Physiol B 2017; 187:1039-1056. [PMID: 28401293 DOI: 10.1007/s00360-017-1096-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/13/2017] [Accepted: 04/06/2017] [Indexed: 11/24/2022]
Abstract
Adaptive explanations for both high and low body mass-independent basal metabolic rate (BMR) in endotherms are pervasive in evolutionary physiology, but arguments implying a direct adaptive benefit of high BMR are troublesome from an energetic standpoint. Here, we argue that conclusions about the adaptive benefit of BMR need to be interpreted, first and foremost, in terms of energetics, with particular attention to physiological traits on which natural selection is directly acting. We further argue from an energetic perspective that selection should always act to reduce BMR (i.e., maintenance costs) to the lowest level possible under prevailing environmental or ecological demands, so that high BMR per se is not directly adaptive. We emphasize the argument that high BMR arises as a correlated response to direct selection on other physiological traits associated with high ecological or environmental costs, such as daily energy expenditure (DEE) or capacities for activity or thermogenesis. High BMR thus represents elevated maintenance costs required to support energetically demanding lifestyles, including living in harsh environments. BMR is generally low under conditions of relaxed selection on energy demands for high metabolic capacities (e.g., thermoregulation, activity) or conditions promoting energy conservation. Under these conditions, we argue that selection can act directly to reduce BMR. We contend that, as a general rule, BMR should always be as low as environmental or ecological conditions permit, allowing energy to be allocated for other functions. Studies addressing relative reaction norms and response times to fluctuating environmental or ecological demands for BMR, DEE, and metabolic capacities and the fitness consequences of variation in BMR and other metabolic traits are needed to better delineate organismal metabolic responses to environmental or ecological selective forces.
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Affiliation(s)
- David L Swanson
- Department of Biology, University of South Dakota, 414 East Clark Street, Vermillion, SD, 57069, USA.
| | - Andrew E McKechnie
- Department of Zoology and Entomology, DST-NRF Centre of Excellence at the Percy FitzPatrick Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - François Vézina
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, QC, Canada.,Groupe de recherche sur les environnements nordiques BORÉAS, Centre d'Études Nordiques, Centre de la Science de la Biodiversité du Québec, Rimouski, QC, Canada
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10
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Downs CJ, Brown JL, Wone BWM, Donovan ER, Hayes JP. Speeding up Growth: Selection for Mass-Independent Maximal Metabolic Rate Alters Growth Rates. Am Nat 2016; 187:295-307. [PMID: 26913943 DOI: 10.1086/684837] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Investigations into relationships between life-history traits, such as growth rate and energy metabolism, typically focus on basal metabolic rate (BMR). In contrast, investigators rarely examine maximal metabolic rate (MMR) as a relevant metric of energy metabolism, even though it indicates the maximal capacity to metabolize energy aerobically, and hence it might also be important in trade-offs. We studied the relationship between energy metabolism and growth in mice (Mus musculus domesticus Linnaeus) selected for high mass-independent metabolic rates. Selection for high mass-independent MMR increased maximal growth rate, increased body mass at 20 weeks of age, and generally altered growth patterns in both male and female mice. In contrast, there was little evidence that the correlated response in mass-adjusted BMR altered growth patterns. The relationship between mass-adjusted MMR and growth rate indicates that MMR is an important mediator of life histories. Studies investigating associations between energy metabolism and life histories should consider MMR because it is potentially as important in understanding life history as BMR.
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11
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Rodríguez E, Weber JM, Pagé B, Roubik DW, Suarez RK, Darveau CA. Setting the pace of life: membrane composition of flight muscle varies with metabolic rate of hovering orchid bees. Proc Biol Sci 2016; 282:rspb.2014.2232. [PMID: 25652831 DOI: 10.1098/rspb.2014.2232] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Patterns of metabolic rate variation have been documented extensively in animals, but their functional basis remains elusive. The membrane pacemaker hypothesis proposes that the relative abundance of polyunsaturated fatty acids in membrane phospholipids sets the metabolic rate of organisms. Using species of tropical orchid bees spanning a 16-fold range in body size, we show that the flight muscles of smaller bees have more linoleate (%18 : 3) and stearate (%18 : 0), but less oleate (%18 : 1). More importantly, flight metabolic rate (FlightMR) varies with the relative abundance of 18 : 3 according to the predictions of the membrane pacemaker hypothesis. Although this relationship was found across large differences in metabolic rate, a direct association could not be detected when taking phylogeny and body mass into account. Higher FlightMR, however, was related to lower %16 : 0, independent of phylogeny and body mass. Therefore, this study shows that flight muscle membrane composition plays a significant role in explaining diversity in FlightMR, but that body mass and phylogeny are other factors contributing to their variation. Multiple factors are at play to modulate metabolic capacity, and changing membrane composition can have gradual and stepwise effects to achieve a new range of metabolic rates. Orchid bees illustrate the correlated evolution between membrane composition and metabolic rate, supporting the functional link proposed in the membrane pacemaker hypothesis.
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Affiliation(s)
- Enrique Rodríguez
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Jean-Michel Weber
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Benoît Pagé
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - David W Roubik
- Smithsonian Tropical Research Institute, Balboa, Republic of Panama
| | - Raul K Suarez
- Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara, CA 93106-9610, USA
| | - Charles-A Darveau
- Department of Biology, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
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12
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Stawski C, Valencak TG, Ruf T, Sadowska ET, Dheyongera G, Rudolf A, Maiti U, Koteja P. Effect of Selection for High Activity-Related Metabolism on Membrane Phospholipid Fatty Acid Composition in Bank Voles. Physiol Biochem Zool 2015; 88:668-79. [PMID: 26658414 DOI: 10.1086/683039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Endothermy, high basal metabolic rates (BMRs), and high locomotor-related metabolism were important steps in the evolution of mammals. It has been proposed that the composition of membrane phospholipid fatty acids plays an important role in energy metabolism and exercise muscle physiology. In particular, the membrane pacemaker theory of metabolism suggests that an increase in cell membrane fatty acid unsaturation would result in an increase in BMR. We aimed to determine whether membrane phospholipid fatty acid composition of heart, liver, and gastrocnemius muscles differed between lines of bank voles selected for high swim-induced aerobic metabolism-which also evolved an increased BMR-and unselected control lines. Proportions of fatty acids significantly differed among the organs: liver was the least unsaturated, whereas the gastrocnemius muscles were most unsaturated. However, fatty acid proportions of the heart and liver did not differ significantly between selected and control lines. In gastrocnemius muscles, significant differences between selection directions were found: compared to control lines, membranes of selected voles were richer in saturated C18:0 and unsaturated C18:2n-6 and C18:3n-3, whereas the pattern was reversed for saturated C16:0 and unsaturated C20:4n-6. Neither unsaturation index nor other combined indexes of fatty acid proportions differed between lines. Thus, our results do not support the membrane pacemaker hypothesis. However, the differences between selected and control lines in gastrocnemius muscles reflect chain lengths rather than number of double bonds and are probably related to differences in locomotor activity per se rather than to differences in the basal or routine metabolic rate.
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Affiliation(s)
- Clare Stawski
- Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland; 2Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Savoyenstrasse 1, 1160 Vienna, Austria
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13
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Perspectives on the membrane fatty acid unsaturation/pacemaker hypotheses of metabolism and aging. Chem Phys Lipids 2015; 191:48-60. [PMID: 26291495 DOI: 10.1016/j.chemphyslip.2015.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 08/10/2015] [Accepted: 08/12/2015] [Indexed: 12/27/2022]
Abstract
The membrane pacemaker hypotheses of metabolism and aging are distinct, but interrelated hypotheses positing that increases in unsaturation of lipids within membranes are correlated with increasing basal metabolic rate and decreasing longevity, respectively. The two hypotheses each have evidence that either supports or contradicts them, but consensus has failed to emerge. In this review, we identify sources of weakness of previous studies supporting and contradicting these hypotheses and suggest different methods and lines of inquiry. The link between fatty acyl composition of membranes and membrane-bound protein activity is a central tenet of the membrane pacemaker hypothesis of metabolism, but the mechanism by which unsaturation would change protein activity is not well defined and, whereas fatty acid desaturases have been put forward by some as the mechanism behind evolutionary differences in fatty acyl composition of phospholipids among organisms, there have been no studies to differentiate whether desaturases have been more affected by natural selection on aging and metabolic rate than have elongases or acyltransferases. Past analyses have been hampered by potentially incorrect estimates of the peroxidizability of lipids and longevity of study animals, and by the confounding effect of phylogeny. According to some authors, body mass may also be a confounding effect that should be taken into account, though this is not universally accepted. Further research on this subject should focus more on mechanisms and take weaknesses of past studies into account.
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14
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Gonzalez A, Pagé B, Weber JM. Membranes as a possible pacemaker of metabolism in cypriniform fish: does phylogeny matter? ACTA ACUST UNITED AC 2015; 218:2563-72. [PMID: 26089526 DOI: 10.1242/jeb.117630] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 05/28/2015] [Indexed: 01/29/2023]
Abstract
The 'membrane pacemaker theory of metabolism' proposes that membranes set metabolic rate by modulating protein activity, and thus purports to explain membrane fatty acid allometry. This relationship has never been tested across species in ectotherms. After accounting for phylogeny, recent analyses have failed to support this theory based on correlations between muscle membrane composition and body mass across mammals. Therefore, the goal of this study was to seek phylogenetically corrected correlations between membrane composition, body mass and calcium-ATPase activity, using 12 species of closely related cypriniform fish (4-5500 g) covering a much narrower genetic scale than in previous tests. The results show that fish membrane unsaturation decreases with mass, but through different mechanisms from those in endotherms: 16:0 replacing 22:6 in muscle and 18:0 replacing 16:1, 18:1 and 18:2 in liver. This shows that allometric patterns differ between endotherms and ectotherms as well as between tissues. After accounting for phylogeny, however, almost all these relationships lose significance except for overall unsaturation. No relationship between calcium-ATPase activity and mass or phospholipid composition was detected. This study shows that membrane unsaturation of cypriniforms decreases with mass, but that genetic cues unrelated to size account for differences in the relative abundance of individual fatty acids. The membrane pacemaker concept accurately predicts general membrane properties such as unsaturation, but fails to explain finer scale allometric patterns. Future examinations of the membrane pacemaker hypothesis will have to take into account that allometric patterns vary between endotherms and ectotherms and between tissues of the same animal class.
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Affiliation(s)
- Alex Gonzalez
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Benoît Pagé
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
| | - Jean-Michel Weber
- Biology Department, University of Ottawa, Ottawa, Ontario, Canada K1N 6N5
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15
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16
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Calhoon EA, Jimenez AG, Harper JM, Jurkowitz MS, Williams JB. Linkages between mitochondrial lipids and life history in temperate and tropical birds. Physiol Biochem Zool 2014; 87:265-75. [PMID: 24642544 DOI: 10.1086/674696] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Temperate birds tend to have a fast pace of life and short life spans with high reproductive output, whereas tropical birds tend to have a slower pace of life, invest fewer resources in reproduction, and have higher adult survival rates. How these differences in life history at the organismal level are rooted in differences at the cellular level is a major focus of current research. Here, we cultured fibroblasts from phylogenetically paired tropical and temperate species, isolated mitochondria from each, and compared their mitochondrial membrane lipids. We also correlated the amounts of these lipids with an important life history parameter, clutch size. We found that tropical birds tended to have less mitochondrial lipid per cell, especially less cardiolipin per cell, suggesting that cells from tropical birds have fewer mitochondria or less inner mitochondrial membrane per cell. We also found that the mitochondria of tropical birds and the species with the smallest clutch sizes had higher amounts of plasmalogens, a lipid that could serve as an antioxidant. Overall, our findings are consistent with the idea that there are underlying molecular and cellular physiological traits that could account for the differences in whole-animal physiology between animals with different life histories.
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Affiliation(s)
- Elisabeth A Calhoon
- Department of Evolution, Ecology, and Organismal Biology, Ohio State University, 318 West 12th Avenue, Columbus, Ohio 43210; 2Department of Pathology, University of Michigan, 1301 Catherine Road, Ann Arbor, Michigan 48109; 3Department of Molecular and Cellular Biochemistry, Ohio State University, 1645 Neil Avenue, Columbus, Ohio 43210
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Ben-Hamo M, McCue MD, Khozin-Goldberg I, McWilliams SR, Pinshow B. Ambient temperature and nutritional stress influence fatty acid composition of structural and fuel lipids in Japanese quail (Coturnix japonica) tissues. Comp Biochem Physiol A Mol Integr Physiol 2013; 166:244-50. [DOI: 10.1016/j.cbpa.2013.06.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 06/11/2013] [Accepted: 06/17/2013] [Indexed: 01/15/2023]
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