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Sadowska J, Carlson KM, Buck CL, Lee TN, Duddleston KN. Microbial urea-nitrogen recycling in arctic ground squirrels: the effect of ambient temperature of hibernation. J Comp Physiol B 2024; 194:909-924. [PMID: 39237834 DOI: 10.1007/s00360-024-01579-9] [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: 10/18/2023] [Revised: 07/14/2024] [Accepted: 08/13/2024] [Indexed: 09/07/2024]
Abstract
Energy conservation associated with hibernation is maximized at the intersection of low body temperature (Tb), long torpor bouts, and few interbout arousals. In the arctic ground squirrel (Urocitellus parryii), energy conservation during hibernation is best achieved at ambient temperatures (Ta) around 0 °C; however, they spend the majority of hibernation at considerably lower Ta. Because arctic ground squirrels switch to mixed fuel metabolism, including protein catabolism, at extreme low Ta of hibernation, we sought to investigate how microbial urea-nitrogen recycling is used under different thermal conditions. Injecting squirrels with isotopically labeled urea (13C/15N) during hibernation at Ta's of - 16 °C and 2 °C and while active and euthermic allowed us to assess the ureolytic activity of gut microbes and the amount of liberated nitrogen incorporated into tissues. We found greater incorporation of microbially-liberated nitrogen into tissues of hibernating squirrels. Although ureolytic activity appears higher in euthermic squirrels, liberated nitrogen likely makes up a smaller percentage of the available nitrogen pool in active, fed animals. Because non-lipid fuel is a limiting factor for torpor at lower Ta in this species, we hypothesized there would be greater incorporation of liberated nitrogen in animals hibernating at - 16 °C. However, we found higher microbial-ureolytic activity and incorporation of microbially-liberated nitrogen, particularly in the liver, in squirrels hibernating at 2 °C. Likely this is because squirrels hibernating at 2 °C had higher Tb and longer interbout arousals, a combination of factors creating more favorable conditions for gut microbes to thrive and maintain greater activity while giving the host more time to absorb microbial metabolites.
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Affiliation(s)
- Julita Sadowska
- Department of Evolutionary and Physiological Ecology, Faculty of Biology, University of Białystok, Białystok, Poland
| | - Karen M Carlson
- Department of Biological Sciences, College of Arts and Sciences, University of Alaska Anchorage, Anchorage, USA
| | - C Loren Buck
- Department of Biological Sciences, Northern Arizona University, Flagstaff, USA
| | - Trixie N Lee
- Department of Biology, Harding University, Searcy, AR, USA
| | - Khrystyne N Duddleston
- Department of Biological Sciences, College of Arts and Sciences, University of Alaska Anchorage, Anchorage, USA.
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Wasserfurth P, Huelsemann F, Koehler K. Changes in urinary stable nitrogen isotope ratios during controlled short-term energy deficit: a proof-of-principle analysis. Eur J Nutr 2024; 63:919-926. [PMID: 38243136 PMCID: PMC10948555 DOI: 10.1007/s00394-023-03320-8] [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: 04/20/2023] [Accepted: 12/29/2023] [Indexed: 01/21/2024]
Abstract
PURPOSE Stable isotope ratios of nitrogen (δ15N) have previously been shown to increase in human hair during periods of catabolism. The goal of this study was to assess changes in δ15N in urinary urea (δ15Nurea) and Δ15N during a short-term controlled energy deficit. METHODS We analyzed samples from 6 recreationally active men (25 ± 1 years, BMI: 23.5 ± 0.6 kg/m2) who participated in a repeated measures cross-over study involving 4 days of energy deficit (ED, ~ 15 kcal/kg FFM) without and with exercise (ED-EX, ED + EX) and control conditions in energy balance (CON-EX, CON + EX). δ15Nurea was analyzed from urine samples, and Δ15N was calculated as δ15Nurea-δ15Ndiet, with δ15Ndiet obtained from diet prescriptions. RESULTS δ15Nurea was significantly elevated in ED-EX (4.4 ± 0.2‰) when compared to CON-EX (3.7 ± 0.1‰; p = 0.026) and CON + EX (3.34 ± 0.13‰, p = 0.001). As a consequence, Δ15N was positive in ED-EX (0.2 ± 0.2‰) and remained negative in ED + EX (- 0.6 ± 0.5‰), CON-EX (- 1.0 ± 0.2) and CON + EX (- 1.1 ± 0.2). Differences in Δ15N were significant between ED-EX and CON-EX (p = 0.005) and ED-EX and CON + EX (p = 0.006). CONCLUSION Our results suggest that δ15Nurea and subsequently Δ15N are responsive to a short-term energy deficit, likely due to increased amino acid oxidation to meet energy demands and preferable elimination of 14N.
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Affiliation(s)
- Paulina Wasserfurth
- Department of Health and Sport Sciences, TUM School of Medicine and Health, Technical University of Munich, Munich, Germany
| | - Frank Huelsemann
- Institute of Biochemistry, German Sport University, Cologne, Germany
| | - Karsten Koehler
- Department of Health and Sport Sciences, TUM School of Medicine and Health, Technical University of Munich, Munich, Germany.
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Grond K, Buck CL, Duddleston KN. Microbial gene expression during hibernation in arctic ground squirrels: greater differences across gut sections than in response to pre-hibernation dietary protein content. Front Genet 2023; 14:1210143. [PMID: 37636260 PMCID: PMC10450147 DOI: 10.3389/fgene.2023.1210143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/27/2023] [Indexed: 08/29/2023] Open
Abstract
Obligate seasonal hibernators fast for 5-9 months depending on species yet resist muscle atrophy and emerge with little lean mass loss. The role of the gut microbiome in host nitrogen metabolism during hibernation is therefore of considerable interest, and recent studies support a role for urea nitrogen salvage (UNS) in host-protein conservation. We were interested in the effect of pre-hibernation diet on UNS and the microbial provision of essential amino acids (EAAs) during hibernation; therefore, we conducted a study whereby we fed arctic ground squirrels (Urocitellus parryii) pre-hibernation diets containing 9% vs. 18% protein and compared the expression of gut bacterial urease and amino acid (AA) metabolism genes in 4 gut sections (cecum mucosa, cecum lumen, small intestine [SI] mucosa, and SI lumen) during hibernation. We found that pre-hibernation dietary protein content did not affect expression of complete bacterial AA pathway genes during hibernation; however, several individual genes within EAA pathways were differentially expressed in squirrels fed 18% pre-hibernation dietary protein. Expression of genes associated with AA pathways was highest in the SI and lowest in the cecum mucosa. Additionally, the SI was the dominant expression site of AA and urease genes and was distinct from other sections in its overall microbial functional and taxonomic composition. Urease expression in the gut microbiome of hibernating squirrels significantly differed by gut section, but not by pre-hibernation dietary protein content. We identified two individual genes that are part of the urea cycle and involved in arginine biosynthesis, which were significantly more highly expressed in the cecum lumen and SI mucosa of squirrels fed a pre-hibernation diet containing 18% protein. Six bacterial genera were responsible for 99% of urease gene expression: Cupriavidus, Burkholderia, Laribacter, Bradhyrizobium, Helicobacter, and Yersinia. Although we did not find a strong effect of pre-hibernation dietary protein content on urease or AA metabolism gene expression during hibernation, our data do suggest the potential for pre-hibernation diet to modulate gut microbiota function during hibernation, and further investigations are warranted.
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Affiliation(s)
- Kirsten Grond
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, United States
| | - C. Loren Buck
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, United States
| | - Khrystyne N. Duddleston
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, United States
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Khanaki H, Dewhurst RJ, Leury BJ, Cantalapiedra-Hijar G, Cheng L. Relationship Between Nitrogen Isotopic Discrimination and the Proportion of Dietary Nitrogen Excreted in Urine by Sheep Offered Different Levels of Dietary Non-Protein Nitrogen. FRONTIERS IN ANIMAL SCIENCE 2022. [DOI: 10.3389/fanim.2022.911673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Urinary nitrogen (N) excretion (UN) as a proportion of N intake (NI; UN/NI) is a major determinant of N excretion from ruminants and could be predicted from the N isotopic discrimination occurring between dietary and animal proteins (Δ15N). This study investigated the usefulness of Δ15N and other plasma biomarkers to reflect changes in UN/NI from sheep offered different levels of dietary urea. Eighteen Merino rams (age, 1–2 years; live weight, 41 ± 3 kg) were allocated to three dietary N treatments for a N balance study. Treatments were control (C), control + 0.5% urea (C+0.5%), and control + 1.2% urea (C+1.2%) and designed to provide maintenance, maintenance plus an additional 15%, and maintenance plus an additional 33% NI, respectively. The urea effect term was used for one-way ANOVA and regression analysis. As NI increased, the UN and retained N (RN) increased linearly (p < 0.001), but UN/NI only increased in treatment C+1.2% compared with C (p < 0.05). Plasma Δ15N was positively and significantly correlated with UN and UN/NI (r = 0.52, p = 0.028; and r = 0.68, p = 0.002, respectively) and increased linearly (p < 0.001) with the highest values observed in C+1.2%. Urine δ15N changed linearly between C and C+1.2%, but plasma δ15N increased quadratically (p < 0.05). Plasma urea N increased in a linear way across dietary urea levels (p < 0.001). The N isotopic difference between plasma and urine (plasma δ15N–urine δ15N) of C did not vary from either of the other treatments; however, it differed between C+0.5% and C+1.2% (p < 0.05). The study confirmed the potential usefulness of plasma Δ15N to estimate UN/NI from sheep. Moreover, plasma δ15N–urine δ15N can be proposed as a new biomarker of N excretion from small ruminants. These approaches, however, need to be tested in various study conditions.
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Shipley ON, Olin JA, Whiteman JP, Bethea DM, Newsome SD. Bulk and amino acid nitrogen isotopes suggest shifting nitrogen balance of pregnant sharks across gestation. Oecologia 2022; 199:313-328. [PMID: 35718810 DOI: 10.1007/s00442-022-05197-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 05/21/2022] [Indexed: 10/18/2022]
Abstract
Nitrogen isotope (δ15N) analysis of bulk tissues and individual amino acids (AA) can be used to assess how consumers maintain nitrogen balance with broad implications for predicting individual fitness. For elasmobranchs, a ureotelic taxa thought to be constantly nitrogen limited, the isotopic effects associated with nitrogen-demanding events such as prolonged gestation remain unknown. Given the linkages between nitrogen isotope variation and consumer nitrogen balance, we used AA δ15N analysis of muscle and liver tissue collected from female bonnethead sharks (Sphyrna tiburo, n = 16) and their embryos (n = 14) to explore how nitrogen balance may vary across gestation. Gestational stage was a strong predictor of bulk tissue and AA δ15N values in pregnant shark tissues, decreasing as individuals neared parturition. This trend was observed in trophic (e.g., Glx, Ala, Val), source (e.g., Lys), and physiological (e.g., Gly) AAs. Several potential mechanisms may explain these results including nitrogen conservation, scavenging, and bacterially mediated breakdown of urea to free ammonia that is used to synthesize AAs. We observed contrasting patterns of isotopic discrimination in embryo tissues, which generally became enriched in 15N throughout development. This was attributed to greater excretion of nitrogenous waste in more developed embryos, and the role of physiologically sensitive AAs (i.e., Gly and Ser) to molecular processes such as nucleotide synthesis. These findings underscore how AA isotopes can quantify shifts in nitrogen balance, providing unequivocal evidence for the role of physiological condition in driving δ15N variation in both bulk tissues and individual AAs.
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Affiliation(s)
- Oliver N Shipley
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA. .,Beneath the Waves, PO Box 126, Herndon, VA, 20172, USA.
| | - Jill A Olin
- Biological Sciences, Great Lakes Research Center, Michigan Technological University, Houghton, MI, 49931, USA
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA
| | - Dana M Bethea
- NOAA Fisheries Southeast Regional Office, Saint Petersburg, FL, 33701, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Summer/fall diet and macronutrient assimilation in an Arctic predator. Oecologia 2022; 198:917-931. [PMID: 35412091 DOI: 10.1007/s00442-022-05155-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 03/28/2022] [Indexed: 10/18/2022]
Abstract
Free-ranging predator diet estimation is commonly achieved by applying molecular-based tracers because direct observation is not logistically feasible or robust. However, tracers typically do not represent all dietary macronutrients, which likely obscures resource use as prey proximate composition varies and tissue consumption can be specific. For example, polar bears (Ursus maritimus) preferentially consume blubber, yet diets have been estimated using fatty acids based on prey blubber or stable isotopes of lipid-extracted prey muscle, neither of which represent both protein and lipid macronutrient contributions. Further, additional bias can be introduced because dietary fat is known to be flexibly routed beyond short-term energy production and storage. We address this problem by simultaneously accounting for protein and lipid assimilation using carbon and nitrogen isotope compositions of lipid-containing prey muscle and blubber to infer summer/fall diet composition and macronutrient proportions from Chukchi Sea polar bear guard hair (n = 229) sampled each spring between 2008 and 2017. Inclusion of blubber (85-95% lipid by dry mass) expanded the isotope mixing space and improved separation among prey species. Ice-associated seals, including nutritionally dependent pups, were the primary prey in summer/fall diets with lower contributions by Pacific walruses (Odobenus rosmarus) and whales. Percent blubber estimates confirmed preferential selection of this tissue and represented the highest documented lipid assimilation for any animal species. Our results offer an improved understanding of summer/fall prey macronutrient usage by Chukchi Sea polar bears which likely coincides with a nutritional bottleneck as the sea ice minimum is approached.
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Rice SA, Ten Have GAM, Reisz JA, Gehrke S, Stefanoni D, Frare C, Barati Z, Coker RH, D'Alessandro A, Deutz NEP, Drew KL. Nitrogen recycling buffers against ammonia toxicity from skeletal muscle breakdown in hibernating arctic ground squirrels. Nat Metab 2020; 2:1459-1471. [PMID: 33288952 PMCID: PMC7744440 DOI: 10.1038/s42255-020-00312-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 10/15/2020] [Indexed: 02/06/2023]
Abstract
Hibernation is a state of extraordinary metabolic plasticity. The pathways of amino acid metabolism as they relate to nitrogen homeostasis in hibernating mammals in vivo are unknown. Here we show, using pulse isotopic tracing, evidence of increased myofibrillar (skeletal muscle) protein breakdown and suppressed whole-body production of metabolites in vivo throughout deep torpor. As whole-body production of metabolites is suppressed, amino acids with nitrogenous side chains accumulate during torpor, while urea cycle intermediates do not. Using 15N stable isotope methodology in arctic ground squirrels (Urocitellus parryii), we provide evidence that free nitrogen is buffered and recycled into essential amino acids, non-essential amino acids and the gamma-glutamyl system during the inter-bout arousal period of hibernation. In the absence of nutrient intake or physical activity, our data illustrate the orchestration of metabolic pathways that sustain the provision of essential and non-essential amino acids and prevent ammonia toxicity during hibernation.
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Affiliation(s)
- Sarah A Rice
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Gabriella A M Ten Have
- Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX, USA
| | - Julie A Reisz
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Sarah Gehrke
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Davide Stefanoni
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Carla Frare
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Zeinab Barati
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Robert H Coker
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Angelo D'Alessandro
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Nicolaas E P Deutz
- Center for Translational Research in Aging and Longevity, Department of Health and Kinesiology, Texas A&M University, College Station, TX, USA
| | - Kelly L Drew
- Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA.
- Institute of Arctic Biology, Center for Transformative Research in Metabolism, University of Alaska Fairbanks, Fairbanks, AK, USA.
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Chen Y, McNamara J, Ma G, Harrison J, Block E. Milk 13C and 15N discriminations as biomarkers of feed efficiency and energy status in early lactation cows. Anim Feed Sci Technol 2020. [DOI: 10.1016/j.anifeedsci.2020.114638] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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9
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Funck J, Kellam C, Seaton CT, Wooller MJ. Stable isotopic signatures in modern wood bison (Bison bison athabascae) hairs as telltale biomarkers of nutritional stress. CAN J ZOOL 2020. [DOI: 10.1139/cjz-2019-0185] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Assessing the challenges faced by wildlife populations is key to providing effective management but is problematic when dealing with populations in remote locations. Analyses of the stable carbon and nitrogen isotope composition (expressed as δ13C and δ15N values) of sequentially grown tissues, such as hairs, can be used to track changes in the eco-physiology of organisms. We generated δ13C and δ15N values from sequentially sampled (n = 465) hairs taken from wood bison (Bison bison athabascae Rhoads, 1898) (n = 27). Samples were taken from individuals prior to and after their release from captivity into the lower Innoko–Yukon river area of Alaska in 2015. Twenty months after release, individuals had a distinct seasonal pattern in δ13C values. Hairs from individuals that experienced food scarcity or long-distance movement were sampled as case studies. Nutritional stress in these cases lead to a rise in δ15N values and a decrease in δ13C values. Applications of δ13C and δ15N analyses of bison tail hairs could provide wildlife managers a valuable and minimally invasive tool to better understand bison seasonal metabolic status and determine the historical health and behavior of living and dead individuals.
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Affiliation(s)
- Juliette Funck
- Department of Geology and Geoscience, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
- Alaska Stable Isotope Facility, Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Cade Kellam
- Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - C. Tom Seaton
- Wood Bison Restoration Project, Alaska Department of Fish and Game, Fairbanks, AK 99701, USA
| | - Matthew J. Wooller
- Alaska Stable Isotope Facility, Water and Environmental Research Center, Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
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Lübcker N, Whiteman JP, Millar RP, de Bruyn PJN, Newsome SD. Fasting affects amino acid nitrogen isotope values: a new tool for identifying nitrogen balance of free-ranging mammals. Oecologia 2020; 193:53-65. [PMID: 32300864 DOI: 10.1007/s00442-020-04645-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 04/07/2020] [Indexed: 11/25/2022]
Abstract
Changes in the nutritional status of free-ranging animals have a strong influence on individual fitness, yet it remains challenging to monitor longitudinally. Nitrogen (δ15N) and carbon (δ13C) isotope values measured chronologically along the length of metabolically inert keratinous tissues can be used as a nutritional biomarker to retrospectively reconstruct the foraging ecology and eco-physiology of consumers. We quantitatively describe the physiological effects of fasting on amino acid metabolism using sequentially measured bulk tissue and amino acid δ15N values along the length of whiskers sampled from free-ranging juvenile, subadults, adult female, and male southern elephant seals (SES; Mirounga leonina) on Marion Island in the Southern Ocean. For both juveniles and adult females, whisker segments representing fasting had significantly higher bulk tissue δ15N values of 0.6 ± 0.5‰ and 1.3-1.8‰, respectively, in comparison to segments unaffected by fasting. We also found a large increase (2-6‰) in δ15N values for most glucogenic amino acids and a simultaneous depletion (2-3‰) of alanine in segments reflecting fasting, which enabled us to accurately predict (74%) the nutritional status of our model species. We hypothesize that the glucose-alanine cycle is the mechanism driving the observed depletion of alanine δ15N values during fasting. We demonstrated that keratinaceous tissues can be used as a longitudinal nutritional biomarker to detect changes in the nitrogen balance of an individual. Moreover, it is evident that physiological factors have an important influence on tissue δ15N values and can lead to erroneous bulk tissue or amino acid isotope-based reconstructions of foraging habits.
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Affiliation(s)
- Nico Lübcker
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.
| | - John P Whiteman
- Department of Biological Sciences, Old Dominion University, Norfolk, VA, 23529, USA.,Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Robert P Millar
- Centre for Neuroendocrinology and Department of Immunology, Faculty of Health Sciences, University of Pretoria, Pretoria, 0001, South Africa
| | - P J Nico de Bruyn
- Department of Zoology and Entomology, Mammal Research Institute, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Curto A, Mahoney P, Maurer AF, Barrocas-Dias C, Fernandes T, Fahy GE. Effect of different healing stages on stable isotope ratios in skeletal lesions. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2019; 171:285-297. [PMID: 31702830 DOI: 10.1002/ajpa.23958] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 10/11/2019] [Accepted: 10/17/2019] [Indexed: 11/06/2022]
Abstract
INTRODUCTION Physiological stress is one of the various factors that can have an impact on stable isotope ratios. However, its effect on bone collagen stable isotope ratios is still not fully understood. This study aims to build on previous research on how different disease stages may affect bone collagen stable isotope ratios. MATERIALS AND METHODS Carbon (δ13 C) and nitrogen (δ15 N) isotope ratios were assessed in 33 skeletons that retained evidence of infectious disease and healed fractures. Samples were taken from active lesions (long bones n = 14; ribs n = 4), healed lesions (long bones n = 10; ribs n = 9), or a fracture callus (long bones n = 9; ribs n = 3). Results were compared to stable isotope ratios calculated for regions on these bones that did not retain evidence of disease or fracture. RESULTS Long bones with active lesions had a significantly higher average δ15 N (δ15 N = 11.1 ± 0.9‰) compared to those without lesions (δ15 N = 10.7 ± 0.7‰; p = .02), while fracture calluses showed the largest range for both δ15 N and δ13 C. There were no significant differences in stable isotope ratios when compared between nonlesion and lesion sites in the ribs. DISCUSSION The increase in δ15 N seen in active lesions, when compared with δ15 N from nonlesion regions on the same long bone, may be a consequence of altered protein metabolism. The high variability of δ15 N and δ13 C in fractures may be related to different healing stages of the calluses. This study suggests that stable isotope data can contribute information about diseases in the past, as well as an individual's response to diseases in the absence of modern medicine and antibiotics.
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Affiliation(s)
- Ana Curto
- Human Osteology Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK.,Research Centre for Anthropology and Health, Department of Life Sciences, University of Coimbra, Coimbra, Portugal
| | - Patrick Mahoney
- Human Osteology Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | | | - Cristina Barrocas-Dias
- HERCULES Laboratory, Évora University, Évora, Portugal.,School of Sciences and Technology, Chemistry Department, University of Évora, Évora, Portugal
| | - Teresa Fernandes
- Research Centre for Anthropology and Health, Department of Life Sciences, University of Coimbra, Coimbra, Portugal.,School of Sciences and Technology, Biology Department, University of Évora, Pólo da Mitra, Évora, Portugal
| | - Geraldine E Fahy
- Human Osteology Lab, Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
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Natural Isotope Abundances of Carbon and Nitrogen in Tissue Proteins and Amino Acids as Biomarkers of the Decreased Carbohydrate Oxidation and Increased Amino Acid Oxidation Induced by Caloric Restriction under a Maintained Protein Intake in Obese Rats. Nutrients 2019; 11:nu11051087. [PMID: 31100870 PMCID: PMC6567081 DOI: 10.3390/nu11051087] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 05/10/2019] [Accepted: 05/14/2019] [Indexed: 12/14/2022] Open
Abstract
A growing body of evidence supports a role for tissue-to-diet 15N and 13C discrimination factors (Δ15N and Δ13C), as biomarkers of metabolic adaptations to nutritional stress, but the underlying mechanisms remain poorly understood. In obese rats fed ad libitum or subjected to gradual caloric restriction (CR), under a maintained protein intake, we measured Δ15N and Δ13C levels in tissue proteins and their constitutive amino acids (AA) and the expression of enzymes involved in the AA metabolism. CR was found to lower protein mass in the intestine, liver, heart and, to a lesser extent, some skeletal muscles. This was accompanied by Δ15N increases in urine and the protein of the liver and plasma, but Δ15N decreases in the proteins of the heart and the skeletal muscles, alongside Δ13C decreases in all tissue proteins. In Lys, Δ15N levels rose in the plasma, intestine, and some muscles, but fell in the heart, while in Ala, and to a lesser extent Glx and Asx, Δ13C levels fell in all these tissues. In the liver, CR was associated with an increase in the expression of genes involved in AA oxidation. During CR, the parallel rises of Δ15N in urine, liver, and plasma proteins reflected an increased AA catabolism occurring at the level of the liver metabolic branch point, while Δ15N decreases in cardiac and skeletal muscle proteins indicated increased protein and AA catabolism in these tissues. Thus, an increased protein and AA catabolism results in opposite Δ15N effects in splanchnic and muscular tissues. In addition, the Δ13C decrease in all tissue proteins, reflects a reduction in carbohydrate (CHO) oxidation and routing towards non-indispensable AA, to achieve fuel economy.
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13
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A Guide to Using Compound-Specific Stable Isotope Analysis to Study the Fates of Molecules in Organisms and Ecosystems. DIVERSITY-BASEL 2019. [DOI: 10.3390/d11010008] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The measurement of stable isotopes in ‘bulk’ animal and plant tissues (e.g., muscle or leaf) has become an important tool for studies of functional diversity from organismal to continental scales. In consumers, isotope values reflect their diet, trophic position, physiological state, and geographic location. However, interpretation of bulk tissue isotope values can be confounded by variation in primary producer baseline values and by overlapping values among potential food items. To resolve these issues, biologists increasingly use compound-specific isotope analysis (CSIA), in which the isotope values of monomers that constitute a macromolecule (e.g., amino acids in protein) are measured. In this review, we provide the theoretical underpinnings for CSIA, summarize its methodology and recent applications, and identify future research directions. The key principle is that some monomers are reliably routed directly from the diet into animal tissue, whereas others are biochemically transformed during assimilation. As a result, CSIA of consumer tissue simultaneously provides information about an animal’s nutrient sources (e.g., food items or contributions from gut microbes) and its physiology (e.g., nitrogen excretion mode). In combination, these data clarify many of the confounding issues in bulk analysis and enable novel precision for tracing nutrient and energy flow within and among organisms and ecosystems.
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Amino acid isotope discrimination factors for a carnivore: physiological insights from leopard sharks and their diet. Oecologia 2018; 188:977-989. [DOI: 10.1007/s00442-018-4276-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 10/14/2018] [Indexed: 11/26/2022]
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15
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Pomerleau C, Matthews CJD, Gobeil C, Stern GA, Ferguson SH, Macdonald RW. Mercury and stable isotope cycles in baleen plates are consistent with year-round feeding in two bowhead whale (Balaena mysticetus) populations. Polar Biol 2018. [DOI: 10.1007/s00300-018-2329-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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16
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Mahlert B, Gerritsmann H, Stalder G, Ruf T, Zahariev A, Blanc S, Giroud S. Implications of being born late in the active season for growth, fattening, torpor use, winter survival and fecundity. eLife 2018; 7:31225. [PMID: 29458712 PMCID: PMC5819945 DOI: 10.7554/elife.31225] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 01/10/2018] [Indexed: 12/05/2022] Open
Abstract
For hibernators, being born late in the active season may have important effects on growth and fattening, hence on winter survival and reproduction. This study investigated differences in growth, fattening, energetic responses, winter survival and fecundity between early-born (‘EB’) and late-born (‘LB’) juvenile garden dormice (Eliomys quercinus). LB juveniles grew and gained mass twice as fast as EB individuals. Torpor use was low during intensive growth, that are, first weeks of body mass gain, but increased during pre-hibernation fattening. LB juveniles showed higher torpor use, reached similar body sizes but lower fat content than EB individuals before hibernation. Finally, LB individuals showed similar patterns of hibernation, but higher proportion of breeders during the following year than EB dormice. These results suggest that torpor is incompatible with growth but promotes fattening and consolidates pre-hibernation fat depots. In garden dormice, being born late in the reproductive season is associated with a fast life history. Garden dormice are small rodents which are common in European woodlands. They were historically widespread from Portugal in the west to the Urals (Russia) in the east. However they are now largely confined to western Europe with north-eastern and eastern populations having become scattered and fragmented. During the course of a year in northern and central Europe, they make the most of the warm season to fatten up and to produce up to two litters of youngsters. When winter comes, dormice enter hibernation, sometimes for more than six months. During this time, they must rely on their fat reserves to survive. Every year, the young from the second litter have less time to prepare for the winter compared to their siblings born earlier in the season. So, how do they still manage to get ready on time for hibernation? Here, Mahlert et al. studied captive pups from first and second litters for their first year, following them as they grew up, entered and then emerged from their first hibernation. The late-born individuals developed nearly twice as fast as the ones born early in the season. In fact, both reached a similar body size, but the second-litter dormice had less fat reserves. Just before their first winter, both early- and late-born animals increasingly started to enter torpor – short and daily resting-like periods when the body slows down. Torpor rarely happens when animals are growing (because growth requires a warm body), but it is useful to help storing and consolidating fat before the cold months. Late-born dormice experienced more torpor on average than their first-litter peers. Both groups survived their first hibernation; but when they emerged, late-born individuals were more likely to reproduce that year. In other words, the dormice which grew quickly might also have sexually matured earlier. This could suggest that animals born later in the season have a faster life history: they grow rapidly, reproduce quickly but may die younger than their early-born peers. Mahlert et al. highlighted how early-life events can shape the course of animals’ existences and influence how their bodies operate. It remains to be examined how these circumstances may affect the individuals in the longer term, and perhaps even their descendants.
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Affiliation(s)
- Britta Mahlert
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria
| | - Hanno Gerritsmann
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria
| | - Gabrielle Stalder
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria
| | - Thomas Ruf
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria
| | - Alexandre Zahariev
- Université de Strasbourg, IPHC, Strasbourg, France.,CNRS, UMR7178, Strasbourg, France
| | - Stéphane Blanc
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria.,Université de Strasbourg, IPHC, Strasbourg, France.,CNRS, UMR7178, Strasbourg, France
| | - Sylvain Giroud
- Department of Integrative Biology and Evolution, Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna, Austria
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Hughes KL, Whiteman JP, Newsome SD. The relationship between dietary protein content, body condition, and Δ15N in a mammalian omnivore. Oecologia 2017; 186:357-367. [DOI: 10.1007/s00442-017-4010-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 11/09/2017] [Indexed: 11/29/2022]
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18
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Tessier SN, Zhang Y, Wijenayake S, Storey KB. MAP kinase signaling and Elk1 transcriptional activity in hibernating thirteen-lined ground squirrels. Biochim Biophys Acta Gen Subj 2017; 1861:2811-2821. [DOI: 10.1016/j.bbagen.2017.07.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Revised: 07/07/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022]
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19
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Doi H, Akamatsu F, González AL. Starvation effects on nitrogen and carbon stable isotopes of animals: an insight from meta-analysis of fasting experiments. ROYAL SOCIETY OPEN SCIENCE 2017; 4:170633. [PMID: 28879005 PMCID: PMC5579121 DOI: 10.1098/rsos.170633] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Accepted: 07/26/2017] [Indexed: 05/25/2023]
Abstract
Nitrogen and carbon stable isotopic compositions (δ15N and δ13C) of consumers have been used for physiological and food web studies. Previous studies have shown δ15N and δ13C values are affected by several biological and environmental factors during starvation, but the generality of the effect of starvation on δ15N and δ13C values has not yet been tested. Here, we performed a meta-analysis to evaluate the effects of starvation on δ15N and δ13C values of consumers, and the underlying factors that may explain the observed variation. The δ15N and δ13C values were calculated as the differences between the final δ15N and δ13C values of consumers (post-starvation) and the pre-starvation values on each experiment. Our meta-analysis showed a large variation in the δ15N and δ13C values of consumers (δ15N range: -0.82 to 4.30‰; mean: 0.47‰ and δ13C range: -1.92 to 2.62‰; mean: 0.01‰). The δ15N values of most consumers increased along the length of the starvation period and were influenced by nitrogen excretion and thermoregulation types, probably because differences in nitrogen metabolism and thermoregulation affect nitrogen processing and excretion rates. None of our predictor variables accounted for the variation in δ13C values, which showed both increases and decreases due to fasting. Our findings suggest that starvation results in changes in consumer δ15N values which are mainly explained by the length of the fasting period and by nitrogen and energy metabolism, but the underlying mechanisms of the starvation effects on δ13C values seem to be more complex than previously thought.
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Affiliation(s)
- Hideyuki Doi
- Graduate School of Simulation Studies, University of Hyogo, 7-1-28 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Fumikazu Akamatsu
- National Research Institute of Brewing, 3-7-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - Angélica L. González
- Biology Department and Center for Computational and Integrative Biology, Rutgers University, Camden, NJ, USA
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20
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Lee TN, Richter MM, Williams CT, Tøien Ø, Barnes BM, O'Brien DM, Buck CL. Stable isotope analysis of CO 2 in breath indicates metabolic fuel shifts in torpid arctic ground squirrels. Comp Biochem Physiol A Mol Integr Physiol 2017; 209:10-15. [PMID: 28396263 DOI: 10.1016/j.cbpa.2017.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/04/2017] [Accepted: 04/05/2017] [Indexed: 11/19/2022]
Abstract
Stable carbon isotope ratios (δ13C) in breath show promise as an indicator of immediate metabolic fuel utilization in animals because tissue lipids have a lower δ13C value than carbohydrates and proteins. Metabolic fuel consumption is often estimated using the respiratory exchange ratio (RER), which has lipid and carbohydrate boundaries, but does not differentiate between protein and mixed fuel catabolism at intermediate values. Because lipids have relatively low δ13C values, measurements of stable carbon isotopes in breath may help distinguish between catabolism of protein and mixed fuel that includes lipid. We measured breath δ13C and RER concurrently in arctic ground squirrels (Urocitellus parryii) during steady-state torpor at ambient temperatures from -2 to -26°C. As predicted, we found a correlation between RER and breath δ13C values; however, the range of RER in this study did not reach intermediate levels to allow further resolution of metabolic substrate use with the addition of breath δ13C measurements. These data suggest that breath δ13C values are 1.1‰ lower than lipid tissue during pure lipid metabolism. From RER, we determined that arctic ground squirrels rely on nonlipid fuel sources for a significant portion of energy during torpor (up to 37%). The shift toward nonlipid fuel sources may be influenced by adiposity of the animals in addition to thermal challenge.
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Affiliation(s)
- Trixie N Lee
- Institute of Arctic Biology, 311 Irving I, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
| | - Melanie M Richter
- Department of Biological Sciences, University of Alaska Anchorage, 3101 Science Circle, Anchorage, AK 99508, USA
| | - Cory T Williams
- Institute of Arctic Biology, 311 Irving I, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Øivind Tøien
- Institute of Arctic Biology, 311 Irving I, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Brian M Barnes
- Institute of Arctic Biology, 311 Irving I, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - Diane M O'Brien
- Institute of Arctic Biology, 311 Irving I, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
| | - C Loren Buck
- Department of Biological Sciences, University of Alaska Anchorage, 3101 Science Circle, Anchorage, AK 99508, USA
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Barreto-Curiel F, Focken U, D’Abramo LR, Viana MT. Metabolism of Seriola lalandi during Starvation as Revealed by Fatty Acid Analysis and Compound-Specific Analysis of Stable Isotopes within Amino Acids. PLoS One 2017; 12:e0170124. [PMID: 28095488 PMCID: PMC5240982 DOI: 10.1371/journal.pone.0170124] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 12/29/2016] [Indexed: 11/19/2022] Open
Abstract
Fish starvation is defined as food deprivation for a long period of time, such that physiological processes become confined to basal metabolism. Starvation provides insights in physiological processes without interference from unknown factors in digestion and nutrient absorption occurring in fed state. Juveniles of amberjack Seriola lalandi were isotopically equilibrated to a formulated diet for 60 days. One treatment consisted of fish that continued to be fed and fish in the other treatment were not fed for 35 days. The isotopic signatures prior to the beginning of and after the starvation period, for fish in the starvation and control treatments, were analysed for lipid content, fatty acid composition and isotopic analysis of bulk (EA-IRMS) and of amino acids (compound specific isotope analysis, CSIA). There were three replicates for the starvation group. Fatty acid content in muscle and liver tissue before and after starvation was determined to calculate percent change. Results showed that crude lipid was the most used source of energy in most cases; the PUFAs and LC-PUFAs were highly conserved. According to the protein signature in bulk (δ15N) and per amino acid (δ13C and δ15N), in muscle tissue, protein synthesis did not appear to occur substantially during starvation, whereas in liver, increases in δ13C and δ15N indicate that protein turnover occurred, probably for metabolic routing to energy-yielding processes. As a result, isotopic values of δ15N in muscle tissue do not change, whereas CSIA net change occurred in the liver tissue. During the study period of 35 days, muscle protein was largely conserved, being neither replenished from amino acid pools in the plasma and liver nor catabolized.
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Affiliation(s)
- Fernando Barreto-Curiel
- Facultad de Ciencias Marinas, Universidad Autónoma de Baja California (UABC), Ensenada, México
| | - Ulfert Focken
- Thuenen Institute of Fisheries Ecology, Ahrensburg, Germany
| | - Louis R. D’Abramo
- Department of Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - María Teresa Viana
- Instituto de Investigaciones Oceanologicas, UABC, Ensenada, Baja California, México
- * E-mail:
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Zhang Y, Storey KB. Regulation of gene expression by NFAT transcription factors in hibernating ground squirrels is dependent on the cellular environment. Cell Stress Chaperones 2016; 21:883-94. [PMID: 27344571 PMCID: PMC5003805 DOI: 10.1007/s12192-016-0713-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/30/2016] [Accepted: 06/13/2016] [Indexed: 12/22/2022] Open
Abstract
Calcineurin is a calmodulin-stimulated phosphatase that regulates the nuclear translocation of nuclear factor of activated T cell (NFAT) c1-4 through dephosphorylation. We believe that this mechanism plays various roles in the remodeling and maintenance of Ictidomys tridecemlineatus skeletal muscle. During hibernation, bouts of torpor and arousal take place, and squirrels do not lose muscle mass despite being inactive. Protein expression of Ca(2+) signaling proteins were studied using immunoblotting. A DNA-protein interaction ELISA technique was created to test the binding of NFATs in the nucleus to DNA probes containing the NFAT response element under environmental conditions reflective of those during hibernation. Calcineurin protein levels increased by 3.08-fold during torpor (compared to euthermic control), whereas calpain1 levels also rose by 3.66-fold during torpor. Calmodulin levels were elevated upon entering torpor. NFATc4 binding to DNA showed a 1.4-fold increase during torpor, and we found that this binding was further enhanced when 600 nM of Ca(2+) was supplemented. We also found that decreasing the temperature of ELISAs resulted in progressive decreases in the binding of NFATs c1, c3, and c4 to DNA. In summary, calmodulin and calpain1 appear to activate calcineurin and NFATc4 during torpor. NFAT binding to target promoters is affected by intranuclear [Ca(2+)] and environmental temperatures. Therefore, Ca(2+) signaling and temperature changes play key roles in regulation of the NFAT-calcineurin pathway in skeletal muscle of hibernating 13-lined ground squirrels over the torpor-arousal cycle, and they may contribute to the avoidance of disuse-induced muscle atrophy that occurs naturally in these animals.
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Affiliation(s)
- Yichi Zhang
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada
| | - Kenneth B Storey
- Institute of Biochemistry and Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada.
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Rode KD, Stricker CA, Erlenbach J, Robbins CT, Cherry SG, Newsome SD, Cutting A, Jensen S, Stenhouse G, Brooks M, Hash A, Nicassio N. Isotopic Incorporation and the Effects of Fasting and Dietary Lipid Content on Isotopic Discrimination in Large Carnivorous Mammals. Physiol Biochem Zool 2016; 89:182-97. [DOI: 10.1086/686490] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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24
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Hertz E, Trudel M, Cox MK, Mazumder A. Effects of fasting and nutritional restriction on the isotopic ratios of nitrogen and carbon: a meta-analysis. Ecol Evol 2015; 5:4829-39. [PMID: 26640663 PMCID: PMC4662305 DOI: 10.1002/ece3.1738] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 07/27/2015] [Accepted: 08/22/2015] [Indexed: 12/03/2022] Open
Abstract
Many organisms experience fasting in their life time, and this physiological process has the potential to alter stable isotope values of organisms, and confound interpretation of food web studies. However, previous studies on the effects of fasting and starvation on stable isotopes show disparate results, and have never been quantitatively synthesized. We performed a laboratory experiment and meta‐analysis to determine how stable isotopes of δ15N and δ13C change with fasting, and we tested whether moderators such as taxa and tissue explain residual variation. We collected literature data from a wide variety of taxa and tissues. We surveyed over 2000 papers, and of these, 26 met our selection criteria, resulting in 51 data points for δ15N, and 43 data points for δ13C. We determine that fasting causes an average increase in the isotopic value of organisms of 0.5‰ for δ15N and that the only significant moderator is tissue type. We find that the overall effect size for δ13C is not significant, but when the significant moderator of tissue is considered, significant increases in blood and whole organisms are seen with fasting. Our results show that across tissues and taxa, the nutritional status of an organism must be considered when interpreting stable isotope data, as fasting can cause large differences in stable isotope values that would be otherwise attributed to other factors.
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Affiliation(s)
- Eric Hertz
- Department of Biology University of Victoria PO BOX 3020 Station CSC Victoria BC Canada V8W 3N5
| | - Marc Trudel
- Department of Biology University of Victoria PO BOX 3020 Station CSC Victoria BC Canada V8W 3N5 ; Pacific Biological Station Department of Fisheries and Oceans Canada 3190 Hammond Bay Road Nanaimo BC Canada V9T 6N7
| | - Marlin K Cox
- University of Alaska Southeast 11120 Glacier Hwy Juneau Alaska 99801
| | - Asit Mazumder
- Department of Biology University of Victoria PO BOX 3020 Station CSC Victoria BC Canada V8W 3N5
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25
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van Gils JA, Ahmedou Salem MV. Validating the Incorporation of 13C and 15N in a Shorebird That Consumes an Isotopically Distinct Chemosymbiotic Bivalve. PLoS One 2015; 10:e0140221. [PMID: 26458005 PMCID: PMC4601768 DOI: 10.1371/journal.pone.0140221] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2015] [Accepted: 09/23/2015] [Indexed: 11/18/2022] Open
Abstract
The wealth of field studies using stable isotopes to make inferences about animal diets require controlled validation experiments to make proper interpretations. Despite several pleas in the literature for such experiments, validation studies are still lagging behind, notably in consumers dwelling in chemosynthesis-based ecosystems. In this paper we present such a validation experiment for the incorporation of 13C and 15N in the blood plasma of a medium-sized shorebird, the red knot (Calidris canutus canutus), consuming a chemosymbiotic lucinid bivalve (Loripes lucinalis). Because this bivalve forms a symbiosis with chemoautotrophic sulphide-oxidizing bacteria living inside its gill, the bivalve is isotopically distinct from 'normal' bivalves whose food has a photosynthetic basis. Here we experimentally tested the hypothesis that isotope discrimination and incorporation dynamics are different when consuming such chemosynthesis-based prey. The experiment showed that neither the isotopic discrimination factor, nor isotopic turnover time, differed between birds consuming the chemosymbiotic lucinid and a control group consuming a photosynthesis-based bivalve. This was true for 13C as well as for 15N. However, in both groups the 15N discrimination factor was much higher than expected, which probably had to do with the birds losing body mass over the course of the experiment.
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Affiliation(s)
- Jan A. van Gils
- NIOZ Royal Netherlands Institute for Sea Research, 1790 AB Den Burg, The Netherlands
- * E-mail:
| | - Mohamed Vall Ahmedou Salem
- EBIOME Ecobiologie Marine et Environnement, Département de Biologie, Université des Sciences, de Technologie et de Médecine, B.P. 880, Nouakchott, Mauritania
- Laboratoire de Biologie Appliquée et Pathologie, Département de Biologie, Faculté des Science, B.P. 2121, Tetouan, Morocco
- Parc National du Banc d’Arguin, B.P. 5355, Nouakchott, Mauritania
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26
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Calandra I, Labonne G, Mathieu O, Henttonen H, Lévêque J, Milloux MJ, Renvoisé É, Montuire S, Navarro N. Isotopic partitioning by small mammals in the subnivium. Ecol Evol 2015; 5:4132-40. [PMID: 26445663 PMCID: PMC4588660 DOI: 10.1002/ece3.1653] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 07/13/2015] [Accepted: 07/25/2015] [Indexed: 01/24/2023] Open
Abstract
In the Arctic, food limitation is one of the driving factors behind small mammal population fluctuations. Active throughout the year, voles and lemmings (arvicoline rodents) are central prey in arctic food webs. Snow cover, however, makes the estimation of their winter diet challenging. We analyzed the isotopic composition of ever‐growing incisors from species of voles and lemmings in northern Finland trapped in the spring and autumn. We found that resources appear to be reasonably partitioned and largely congruent with phylogeny. Our results reveal that winter resource use can be inferred from the tooth isotopic composition of rodents sampled in the spring, when trapping can be conducted, and that resources appear to be partitioned via competition under the snow.
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Affiliation(s)
- Ivan Calandra
- GEGENAA - EA 3795 Université de Reims Champagne-Ardenne Reims France
| | - Gaëlle Labonne
- Laboratoire PALEVO École Pratique des Hautes Études Dijon France ; Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Olivier Mathieu
- Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | | | - Jean Lévêque
- Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Marie-Jeanne Milloux
- Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Élodie Renvoisé
- Evo-Devo Lab Institute of Biotechnology University of Helsinki Helsinki Finland
| | - Sophie Montuire
- Laboratoire PALEVO École Pratique des Hautes Études Dijon France ; Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
| | - Nicolas Navarro
- Laboratoire PALEVO École Pratique des Hautes Études Dijon France ; Biogéosciences - UMR uB/CNRS 6282 Université Bourgogne Franche-Comté Dijon France
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Abstract
Diet is a leading modifiable risk factor for chronic disease, but it remains difficult to measure accurately due to the error and bias inherent in self-reported methods of diet assessment. Consequently, there is a pressing need for more objective biomarkers of diet for use in health research. The stable isotope ratios of light elements are a promising set of candidate biomarkers because they vary naturally and reproducibly among foods, and those variations are captured in molecules and tissues with high fidelity. Recent studies have identified valid isotopic measures of short- and long-term sugar intake, meat intake, and fish intake in specific populations. These studies provide a strong foundation for validating stable isotopic biomarkers in the general US population. Approaches to improve specificity for specific foods are needed; for example, by modeling intake using multiple stable isotope ratios or by isolating and measuring specific molecules linked to foods of interest.
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Affiliation(s)
- Diane M O'Brien
- Center for Alaska Native Health Research, Institute of Arctic Biology and Department of Biology and Wildlife, University of Alaska, Fairbanks, Alaska 99775-7000;
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28
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Robb G, Woodborne S, de Bruin P, Medger K, Bennett N. The influence of food quantity on carbon and nitrogen stable isotope values in southern African spiny mice (Acomys spinosissimus). CAN J ZOOL 2015. [DOI: 10.1139/cjz-2014-0134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stable isotope analysis is frequently applied as a tool to examine dietary patterns in animals. However, some of the underlying assumptions associated with using this approach are increasingly being questioned. We carried out a controlled diet experiment on the southern African spiny mouse (Acomys spinosissimus Peters, 1852) to test a number of aspects relating to these assumptions and also examine the hypothesis that stable isotopes, especially δ15N, can be used to provide evidence of nutritional stress. We compared the δ13C and δ15N values of livers and blood from animals that were fed ad libitum with animals undergoing a 10% reduction in food supply. Food-restricted animals showed no significant difference in δ15N; however, δ13C values of both liver and blood were depleted. Restricted animals also had a significantly lower C:N ratio. We examined the role of lipids and found following lipid extraction that both livers and lipids still showed the same separation in carbon values. Tissue–diet discrimination values were also calculated and found to be higher for both Δ13C and Δ15N compared with other mice species. Empirical values for discrimination rates were then compared with values calculated using an alternative method based on employing generic values and were found to be dissimilar, suggesting the use of generic values are not always appropriate. Our results highlight the need for greater understanding of the assumptions associated with using stable isotope analysis to examine diet and we suggest that studying a single species under captive conditions presents an ideal method to begin to test these hypotheses.
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Affiliation(s)
- G.N. Robb
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - S. Woodborne
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
- iThemba LABS, Private Bag 11, WITS 2050, Gauteng, South Africa
| | - P.R. de Bruin
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - K. Medger
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
| | - N.C. Bennett
- Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa
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29
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Reitsema LJ, Muir AB. Growth velocity and weaning δ15N “Dips” during ontogeny inMacaca mulatta. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2015; 157:347-57. [DOI: 10.1002/ajpa.22713] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 01/24/2015] [Accepted: 01/26/2015] [Indexed: 11/05/2022]
Affiliation(s)
| | - Andrew B. Muir
- Department of Pediatrics; Emory University; Atlanta Georgia 30322
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30
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Popa-Lisseanu AG, Kramer-Schadt S, Quetglas J, Delgado-Huertas A, Kelm DH, Ibáñez C. Seasonal variation in stable carbon and nitrogen isotope values of bats reflect environmental baselines. PLoS One 2015; 10:e0117052. [PMID: 25700080 PMCID: PMC4336313 DOI: 10.1371/journal.pone.0117052] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Accepted: 12/17/2014] [Indexed: 11/18/2022] Open
Abstract
The stable carbon and nitrogen isotope composition of animal tissues is commonly used to trace wildlife diets and analyze food chains. Changes in an animal's isotopic values over time are generally assumed to indicate diet shifts or, less frequently, physiological changes. Although plant isotopic values are known to correlate with climatic seasonality, only a few studies restricted to aquatic environments have investigated whether temporal isotopic variation in consumers may also reflect environmental baselines through trophic propagation. We modeled the monthly variation in carbon and nitrogen isotope values in whole blood of four insectivorous bat species occupying different foraging niches in southern Spain. We found a common pattern of isotopic variation independent of feeding habits, with an overall change as large as or larger than one trophic step. Physiological changes related to reproduction or to fat deposition prior to hibernation had no effect on isotopic variation, but juvenile bats had higher δ13C and δ15N values than adults. Aridity was the factor that best explained isotopic variation: bat blood became enriched in both 13C and 15N after hotter and/or drier periods. Our study is the first to show that consumers in terrestrial ecosystems reflect seasonal environmental dynamics in their isotope values. We highlight the danger of misinterpreting stable isotope data when not accounting for seasonal isotopic baselines in food web studies. Understanding how environmental seasonality is integrated in animals' isotope values will be crucial for developing reliable methods to use stable isotopes as dietary tracers.
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Affiliation(s)
- Ana G. Popa-Lisseanu
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | | | - Juan Quetglas
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
| | - Antonio Delgado-Huertas
- Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas (CSIC), Granada, Spain
| | - Detlev H. Kelm
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
| | - Carlos Ibáñez
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas (CSIC), Sevilla, Spain
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31
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Poupin N, Mariotti F, Huneau JF, Hermier D, Fouillet H. Natural isotopic signatures of variations in body nitrogen fluxes: a compartmental model analysis. PLoS Comput Biol 2014; 10:e1003865. [PMID: 25275306 PMCID: PMC4183419 DOI: 10.1371/journal.pcbi.1003865] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Accepted: 08/19/2014] [Indexed: 11/18/2022] Open
Abstract
Body tissues are generally 15N-enriched over the diet, with a discrimination factor (Δ15N) that varies among tissues and individuals as a function of their nutritional and physiopathological condition. However, both 15N bioaccumulation and intra- and inter-individual Δ15N variations are still poorly understood, so that theoretical models are required to understand their underlying mechanisms. Using experimental Δ15N measurements in rats, we developed a multi-compartmental model that provides the first detailed representation of the complex functioning of the body's Δ15N system, by explicitly linking the sizes and Δ15N values of 21 nitrogen pools to the rates and isotope effects of 49 nitrogen metabolic fluxes. We have shown that (i) besides urea production, several metabolic pathways (e.g., protein synthesis, amino acid intracellular metabolism, urea recycling and intestinal absorption or secretion) are most probably associated with isotope fractionation and together contribute to 15N accumulation in tissues, (ii) the Δ15N of a tissue at steady-state is not affected by variations of its P turnover rate, but can vary according to the relative orientation of tissue free amino acids towards oxidation vs. protein synthesis, (iii) at the whole-body level, Δ15N variations result from variations in the body partitioning of nitrogen fluxes (e.g., urea production, urea recycling and amino acid exchanges), with or without changes in nitrogen balance, (iv) any deviation from the optimal amino acid intake, in terms of both quality and quantity, causes a global rise in tissue Δ15N, and (v) Δ15N variations differ between tissues depending on the metabolic changes involved, which can therefore be identified using simultaneous multi-tissue Δ15N measurements. This work provides proof of concept that Δ15N measurements constitute a new promising tool to investigate how metabolic fluxes are nutritionally or physiopathologically reorganized or altered. The existence of such natural and interpretable isotopic biomarkers promises interesting applications in nutrition and health. Body proteins ensure vital functions, and their constancy is maintained through the tight coordination of many nitrogen metabolic fluxes, but our understanding of how this flux system is regulated, and sometimes dysregulated, remains fragmentary and incomplete. Besides, body tissues are generally naturally enriched in the heavier stable nitrogen isotope (15N) over the diet: this 15N bioaccumulation (Δ15N) varies depending on tissues and metabolic orientations, likely as the result of isotope effects associated to some metabolic pathways. We used a novel approach, combining multi-tissue Δ15N measurements and their analysis using modeling, to understand how body Δ15N values relate to nitrogen fluxes. The multi-tissue model we have developed provides a clearer understanding of the metabolic processes that generate isotopic fractionation, and of how tissue Δ15N values are modulated in response to changes in the body distribution of specific nitrogen fluxes. We show that Δ15N values tend to rise when the amino acids intake does not optimally fit the metabolic demand, and that Δ15N values constitute natural and interpretable signatures of nutritionally-induced variations in nitrogen fluxes. This approach constitutes a new promising tool to investigate how nitrogen metabolism is nutritionally or physiopathologically reorganized or altered, and promises interesting applications in many areas (nutrition, pathology, ecology, paleontology, etc).
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Affiliation(s)
- Nathalie Poupin
- INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France; AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - François Mariotti
- INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France; AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Jean-François Huneau
- INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France; AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Dominique Hermier
- INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France; AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
| | - Hélène Fouillet
- INRA, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France; AgroParisTech, CRNH-IdF, UMR914 Nutrition Physiology and Ingestive Behavior, Paris, France
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32
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Higginson AD, McNamara JM, Houston AI. The starvation-predation trade-off shapes the strategic use of protein for energy during fasting. J Theor Biol 2014; 359:208-19. [PMID: 24973597 DOI: 10.1016/j.jtbi.2014.06.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 06/04/2014] [Accepted: 06/10/2014] [Indexed: 10/25/2022]
Abstract
The primary function of lipid storage by animals is as an energy source for surviving periods without food. However, muscle and organ protein can be metabolised for energy, and empirical studies have shown that the onset of protein metabolism begins before the exhaustion of lipid reserves. Since protein tissues are important for reasons other than resisting starvation, the adaptive basis for this early onset is unclear. Here, we report the results of a model of the optimal proportion of energy to obtain from protein catabolism during a period without food of unpredictable duration. We assume either that the animal aims only to maximise the duration of survival or that it also has to take account of its future reproductive success given its state when the food supply recommences. In the latter case we find impressive quantitative agreement with observations on lean and obese penguins and rats. Analysis shows that this agreement breaks down if predation risk is insignificant, protein in the form of muscle is ineffective against predation, or there is no benefit to conserving lipid (e.g. for reproduction). This result implies that animals have not evolved to maximise their starvation resistance because doing so would leave them vulnerable when an interruption ends. Our model allows us to make several specific predictions concerning the relationship between the ecological pressures on animals and their starvation survival strategies.
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Affiliation(s)
- Andrew D Higginson
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK.
| | - John M McNamara
- School of Mathematics, University of Bristol, University Walk, Bristol BS8 1TW, UK
| | - Alasdair I Houston
- School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK
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33
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Boggs CL, Niitepõld K. Insights from stable isotopic tracers on reproductive allocation under stress. Integr Comp Biol 2014; 54:880-9. [PMID: 24920750 DOI: 10.1093/icb/icu074] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fecundity is affected by changes in the nutritional and energetic environment, as a result of changes in acquisition, assimilation, or allocation of macro-nutrients and micro-nutrients. Stable isotopes of carbon and nitrogen offer a window into the processes underlying these changes. In insects that feed on nectar as adults, carbon isotopes can be used to trace allocation of carbon to eggs from larval (capital) and adult (income) sources. If adults are fed sugar-water, there is no source of nitrogen from the adult diet. Thus, nitrogen isotopes in eggs reflect fractionation of larval nitrogen due to protein catabolism and anabolism. We subjected adult females of two butterfly species, Speyeria mormonia and Colias eurytheme, to dietary restriction (DR), larval female S. mormonia to DR, and adult female S. mormonia to extra flight. Females subjected to extra flight were previously found to eat more as adults and to have a higher resting metabolic rate. As predicted, significantly less carbon obtained by feeding as adults was incorporated into eggs in both species under DR when adult. Speyeria mormonia eggs contained significantly more carbon derived from adult feeding under DR as larvae and when subjected to extra flight as adult females. Again as predicted, eggs from females of both species subjected to DR when adults were enriched for (15)N, suggesting that increased protein catabolism or anabolism generated additional carbon compounds. Speyeria mormonia eggs from females subjected to DR when larvae or to additional flight as adults were depleted for (15)N. The result for DR of larvae suggests minimization of protein catabolism when protein reserves are relatively scarce. The results for flight were not as predicted, and deserve further exploration. In most cases, isotopic signature in eggs changed with females' age. Eggs were progressively more enriched for the carbon signature of adults, consistent with a two-compartment mixing model for the carbon sources of larvae and adults. Eggs laid across the life of a female were progressively depleted for (15)N, followed by stabilization. This could be due to high total investment in eggs early in life, as the results are consistent with those for other growing animals. Overall, these results indicate shifts in allocation of incoming and stored (capital) carbon in response to various environmental stresses. The results for nitrogen suggest hypotheses to be tested concerning nitrogen metabolism under environmental stress.
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Affiliation(s)
- C L Boggs
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA; Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
| | - K Niitepõld
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA; Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
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34
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Crowley BE, Rasoazanabary E, Godfrey LR. Stable isotopes complement focal individual observations and confirm dietary variability in reddish-gray mouse lemurs (Microcebusgriseorufus) from southwestern Madagascar. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2014; 155:77-90. [DOI: 10.1002/ajpa.22555] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 05/08/2014] [Accepted: 05/24/2014] [Indexed: 11/11/2022]
Affiliation(s)
- Brooke E. Crowley
- Department of Geology; University of Cincinnati; Cincinnati OH 45221
- Department of Anthropology; University of Cincinnati; Cincinnati OH 45221
| | | | - Laurie R. Godfrey
- Department of Anthropology; University of Massachusetts; Amherst MA 01003
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35
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Macharia AN, Cerling TE, Jorgensen MJ, Kaplan JR. The Hair-Diet13C and15N Fractionation inChlorocebus aethiops sabaeusBased on a Control Diet Study. ANN ZOOL FENN 2014. [DOI: 10.5735/086.051.0208] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Crowley BE, Blanco MB, Arrigo-Nelson SJ, Irwin MT. Stable isotopes document resource partitioning and effects of forest disturbance on sympatric cheirogaleid lemurs. Naturwissenschaften 2013; 100:943-56. [DOI: 10.1007/s00114-013-1094-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 08/19/2013] [Accepted: 08/21/2013] [Indexed: 12/25/2022]
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37
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Seger R, Servello F, Cross R, Keisler D. Body mass and mast abundance influence foraging ecology of the American black bear (Ursus americanus) in Maine. CAN J ZOOL 2013. [DOI: 10.1139/cjz-2012-0326] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We studied nutritional ecology of American black bears (Ursus americanus Pallas, 1780) in Maine, including active and hibernating bears during 5 years, across three study areas, using nitrogen stable isotope analyses of blood samples (n = 152). Our central finding, in two study areas, is positive correlation between body mass and δ15N. This suggests use of large body size to acquire or guard food resources that have relatively high δ15N, consistent with importance of ungulates as food for the largest bears in Maine. In these two study areas, hibernating bears across the spectrum of body mass showed greater δ15N during 2 years of beechnut (Fagus grandifolia Ehrh.) scarcity compared with 2 years of beechnut abundance. Adiposity, measured by serum leptin, was greater in hibernating bears following a season of beechnut abundance compared with one of beechnut scarcity. Total litter mass correlated positively with maternal serum leptin and negatively with maternal δ15N, supporting the importance of mast, including beechnuts, to reproductive success of bears in Maine. In the third study area, bears across the spectrum of body mass had greater δ15N in all years, consistent with food resources relatively high in 15N that were available to bears of all sizes.
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Affiliation(s)
- R.L. Seger
- University of Maine, Department of Animal and Veterinary Sciences, 130 Hitchner Hall, Orono, ME 04469, USA
| | - F.A. Servello
- University of Maine, Department of Wildlife Ecology, 210 Nutting Hall, Orono, ME 04469, USA
| | - R.A. Cross
- Maine Department of Inland Fisheries and Wildlife; 650 State Street, Bangor, ME 04401, USA
| | - D.H. Keisler
- University of Missouri, Division of Animal Sciences, 160 Animal Sciences Research Center, 920 East Campus Drive, Columbia, MO 65211, USA
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38
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da Silveira LC, do Nascimento LFR, Colquhoun A, Abe AS, de Souza SCR. Cardiac hypertrophy and structural and metabolic remodeling related to seasonal dormancy in the first annual cycle in tegu lizards. Comp Biochem Physiol A Mol Integr Physiol 2013; 165:371-80. [PMID: 23603066 DOI: 10.1016/j.cbpa.2013.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 04/09/2013] [Accepted: 04/11/2013] [Indexed: 11/16/2022]
Abstract
Morpho-functional adjustments in the heart of juvenile tegu lizards (Tupinambis merianae) were analyzed at distinct seasonal periods to investigate how the demands of growth and of energy saving are reconciled during the first annual cycle. The relative ventricular mass (Mv) was 31% and 69% larger in late autumn and winter dormancy, respectively, compared to early autumn. This effect did not persist during unfed arousal, suggesting that protein accumulates in the heart during hypometabolism and is degraded on arousal. Both the hypertrophy and the atrophy were disproportionate in the largest individuals. In contrast, Mv was smaller in lizards that were starved during spring activity compared to fed lizards, this effect being larger in smaller individuals. In late autumn and winter dormancy the spongy myocardium had 8% of the section area covered by lacunary spaces, which expanded after food intake during arousal and reached 29% in spring activity together with higher density of cardiomyocytes. Total and soluble proteins per mass unity were unchanged, and maximum activities of selected enzymes suggest sustained glycolytic and aerobic capacities during hypometabolism. Results indicate that important structural adjustments occur in the heart in anticipation of dormancy, and that the protein balance in the tissue is maintained at winter temperatures ~17°C.
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