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Crawford SG, Coker RH, O’Hara TM, Breed GA, Gelatt T, Fadely B, Burkanov V, Rivera PM, Rea LD. Fasting durations of Steller sea lion pups vary among subpopulations-evidence from two plasma metabolites. CONSERVATION PHYSIOLOGY 2023; 11:coad084. [PMID: 38026798 PMCID: PMC10673819 DOI: 10.1093/conphys/coad084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 08/28/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023]
Abstract
Geographic differences in population growth trends are well-documented in Steller sea lions (Eumetopias jubatus), a species of North Pacific pinniped listed under the U.S. Endangered Species Act in 1990 following a marked decline in population abundance that began during the 1970s. As population growth is intrinsically linked to pup production and survival, examining factors related to pup physiological condition provides useful information to management authorities regarding potential drivers of regional differences. During dam foraging trips, pups predictably transition among three fasting phases, distinguished by the changes in the predominant metabolic byproduct. We used standardized ranges of two plasma metabolites (blood urea nitrogen and β-hydroxybutyrate) to assign pups to fasting categories (n = 1528, 1990-2016, 12 subpopulations): Recently Fed-Phase I (digestion/assimilation-expected hepatic/muscle glycogen usage), Phase II (expected lipid utilization), transitioning between Phases II-III (expected lipid utilization with increased protein reliance), or Phase III (expected protein catabolism). As anticipated, the majority of pups were classified as Recently Fed-Phase I (overall mean proportion = 0.72) and few pups as Phase III (overall mean proportion = 0.04). By further comparing pups in Short (Recently Fed-Phase II) and Long (all other pups) duration fasts, we identified three subpopulations with significantly (P < 0.03) greater proportions of pups dependent upon endogenous sources of energy for extended periods, during a life stage of somatic growth and development: the 1) central (0.27 ± 0.09) and 2) western (0.36 ± 0.13) Aleutian Island (declining population trend) and 3) southern Southeast Alaska (0.32 ± 0.06; increasing population trend) subpopulations had greater Long fast proportions than the eastern Aleutian Islands (0.10 ± 0.05; stabilized population). Due to contrasting population growth trends among these highlighted subpopulations over the past 50+ years, both density-independent and density-dependent factors likely influence the dam foraging trip duration, contributing to longer fasting durations for pups at some rookeries.
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Affiliation(s)
- Stephanie G Crawford
- Department of Biology and Wildlife and Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775, USA
| | - Robert H Coker
- Montana Center for Work Physiology and Exercise Metabolism, University of Montana, 32 Campus Drive, Missoula, Montana 59812, USA
| | - Todd M O’Hara
- Veterinary Integrative Biosciences, School of Veterinary Medicine & Biomedical Sciences, Texas A&M University, 402 Raymond Stotzer Parkway, Bldg 2, College Station, Texas 77843, USA
| | - Greg A Breed
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, USA
| | - Tom Gelatt
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way N.E., Bldg. 4, Seattle, Washington 98115, USA
| | - Brian Fadely
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way N.E., Bldg. 4, Seattle, Washington 98115, USA
| | - Vladimir Burkanov
- Marine Mammal Laboratory, Alaska Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, 7600 Sand Point Way N.E., Bldg. 4, Seattle, Washington 98115, USA
| | - Patricia M Rivera
- Center for Alaska Native Health Research, Institute of Arctic Biology, University of Alaska Fairbanks, 2141 Koyukuk Drive, Fairbanks, Alaska 99775, USA
| | - Lorrie D Rea
- Institute of Northern Engineering, University of Alaska Fairbanks, 1764 Tanana Loop, Fairbanks, Alaska 99775, USA
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Hastings KK, Johnson DS, Pendleton GW, Fadely BS, Gelatt TS. Investigating life-history traits of Steller sea lions with multistate hidden Markov mark-recapture models: Age at weaning and body size effects. Ecol Evol 2021; 11:714-734. [PMID: 33520160 PMCID: PMC7820167 DOI: 10.1002/ece3.6878] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 09/03/2020] [Accepted: 09/10/2020] [Indexed: 11/07/2022] Open
Abstract
The duration of offspring care is critical to female fitness and population resilience by allowing flexibility in life-history strategies in a variable environment. Yet, for many mammals capable of extended periods of maternal care, estimates of the duration of offspring dependency are not available and the relative importance of flexibility of this trait on fitness and population viability has rarely been examined. We used data from 4,447 Steller sea lions Eumetopias jubatus from the Gulf of Alaska and multistate hidden Markov mark-recapture models to estimate age-specific weaning probabilities. Maternal care beyond age 1 was common: Weaning was later for animals from Southeast Alaska (SEAK) and Prince William Sound (PWS, weaning probabilities: 0.536-0.648/0.784-0.873 by age 1/2) compared with animals born to the west (0.714-0.855/0.798-0.938). SEAK/PWS animals were also smaller than those born farther west, suggesting a possible link. Females weaned slightly earlier (+0.080 at age 1 and 2) compared with males in SEAK only. Poor survival for weaned versus unweaned yearlings occurred in southern SEAK (female survival probabilities: 0.609 vs. 0.792) and the central Gulf (0.667 vs. 0.901), suggesting poor conditions for juveniles in these areas. First-year survival increased with neonatal body mass (NBM) linearly in the Gulf and nonlinearly in SEAK. The probability of weaning at age 1 increased linearly with NBM for SEAK animals only. Rookeries where juveniles weaned at earlier ages had lower adult female survival, but age at weaning was unrelated to population trends. Our results suggest the time to weaning may be optimized for different habitats based on long-term average conditions (e.g., prey dynamics), that may also shape body size, with limited short-term plasticity. An apparent trade-off of adult survival in favor of juvenile survival and large offspring size in the endangered Gulf of Alaska population requires further study.
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Affiliation(s)
- Kelly K. Hastings
- Division of Wildlife ConservationAlaska Department of Fish and GameJuneauAlaskaUSA
| | - Devin S. Johnson
- NOAA FisheriesAlaska Fisheries Science CenterSeattleWashingtonUSA
| | - Grey W. Pendleton
- Division of Wildlife ConservationAlaska Department of Fish and GameJuneauAlaskaUSA
| | - Brian S. Fadely
- NOAA FisheriesAlaska Fisheries Science CenterSeattleWashingtonUSA
| | - Thomas S. Gelatt
- NOAA FisheriesAlaska Fisheries Science CenterSeattleWashingtonUSA
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Fragoso R, Santos-Reis M, Rosalino LM. Drivers of wood mouse body condition in Mediterranean agroforestry landscapes. EUR J WILDLIFE RES 2020. [DOI: 10.1007/s10344-019-1356-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Gallego-Carmona CA, Castro-Arango JA, Bernal-Bautista MH. Effect of Habitat Disturbance on the Body Condition Index of the Colombian Endemic LizardAnolis antonii(Squamata: Dactyloidae). SOUTH AMERICAN JOURNAL OF HERPETOLOGY 2016. [DOI: 10.2994/sajh-d-16-00020.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Pharo EA, Cane KN, McCoey J, Buckle AM, Oosthuizen WH, Guinet C, Arnould JPY. A colostrum trypsin inhibitor gene expressed in the Cape fur seal mammary gland during lactation. Gene 2016; 578:7-16. [PMID: 26639991 DOI: 10.1016/j.gene.2015.11.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 10/13/2015] [Accepted: 11/25/2015] [Indexed: 10/22/2022]
Abstract
The colostrum trypsin inhibitor (CTI) gene and transcript were cloned from the Cape fur seal mammary gland and CTI identified by in silico analysis of the Pacific walrus and polar bear genomes (Order Carnivora), and in marine and terrestrial mammals of the Orders Cetartiodactyla (yak, whales, camel) and Perissodactyla (white rhinoceros). Unexpectedly, Weddell seal CTI was predicted to be a pseudogene. Cape fur seal CTI was expressed in the mammary gland of a pregnant multiparous seal, but not in a seal in its first pregnancy. While bovine CTI is expressed for 24-48 h postpartum (pp) and secreted in colostrum only, Cape fur seal CTI was detected for at least 2-3 months pp while the mother was suckling its young on-shore. Furthermore, CTI was expressed in the mammary gland of only one of the lactating seals that was foraging at-sea. The expression of β-casein (CSN2) and β-lactoglobulin II (LGB2), but not CTI in the second lactating seal foraging at-sea suggested that CTI may be intermittently expressed during lactation. Cape fur seal and walrus CTI encode putative small, secreted, N-glycosylated proteins with a single Kunitz/bovine pancreatic trypsin inhibitor (BPTI) domain indicative of serine protease inhibition. Mature Cape fur seal CTI shares 92% sequence identity with Pacific walrus CTI, but only 35% identity with BPTI. Structural homology modelling of Cape fur seal CTI and Pacific walrus trypsin based on the model of the second Kunitz domain of human tissue factor pathway inhibitor (TFPI) and porcine trypsin (Protein Data Bank: 1TFX) confirmed that CTI inhibits trypsin in a canonical fashion. Therefore, pinniped CTI may be critical for preventing the proteolytic degradation of immunoglobulins that are passively transferred from mother to young via colostrum and milk.
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Affiliation(s)
- Elizabeth A Pharo
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia; Cooperative Research Centre for Innovative Dairy Products, Australia.
| | - Kylie N Cane
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia; Cooperative Research Centre for Innovative Dairy Products, Australia.
| | - Julia McCoey
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - Ashley M Buckle
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC 3800, Australia.
| | - W H Oosthuizen
- Oceans and Coasts, Department of Environmental Affairs, Private Bag X2, Roggebaai 8012, South Africa.
| | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé, CNRS, 79360 Villiers en Bois, France.
| | - John P Y Arnould
- School of BioSciences, The University of Melbourne, Melbourne, VIC 3010, Australia; Cooperative Research Centre for Innovative Dairy Products, Australia; School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia.
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Oosthuizen WC, de Bruyn PJN, Wege M, Bester MN. Geographic variation in subantarctic fur seal pup growth: linkages with environmental variability and population density. J Mammal 2015. [DOI: 10.1093/jmammal/gyv181] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Marine predator populations are sensitive to temporal variation in prey availability, but prey dynamics are often difficult to quantify. Long-term measures of offspring growth is a useful performance attribute to gauge the potential demographic direction for such predator populations, especially where other metrics (e.g., population size estimates) are lacking. Subantarctic fur seal ( Arctocephalus tropicalis ) females are central place foragers during a protracted lactation period, and their foraging success determines the growth and vitality of their offspring. Using data spanning over 2 decades, we assessed geographic and temporal variation in growth rates and weaning mass of subantarctic fur seal pups at 2 of the species’ principal populations (Gough and Marion islands) and identified environmental conditions that may, through assumed bottom-up mechanisms, affect body mass at weaning. While Marion Island pups grew at an average rate of between 0.040 and 0.067kg/day early in lactation (comparable to conspecific growth at Amsterdam Island), the mean growth rate at Gough Island (approximately 0.030kg/day) was lower than the growth rate represented by the bottom 5% of the body mass distribution at Marion Island. Notwithstanding substantial interannual variability, we found support for a negative trend in weaning mass at both populations, suggesting a rise in limiting factors that is hypothesized to relate to concurrent local population size increases. Weaning mass tended to be higher when sea surface temperatures were warmer (with a stronger positive effect at Gough Island) and during positive phases of the Southern Oscillation Index (La Niña events), with a stronger positive effect in males. Given the low weaning mass of Gough Island fur seal pups, continued population growth here seems unlikely. While density-dependent regulation appears to have increased in strength at Marion Island, terminating rapid population growth, current weaning weights remain above the physiological limits of growth in subantarctic fur seals.
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Affiliation(s)
- W. Chris Oosthuizen
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria , Private Bag X20, Hatfield 0028 , South Africa (WCO, PJNdB, MW, MNB)
| | - P. J. Nico de Bruyn
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria , Private Bag X20, Hatfield 0028 , South Africa (WCO, PJNdB, MW, MNB)
| | - Mia Wege
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria , Private Bag X20, Hatfield 0028 , South Africa (WCO, PJNdB, MW, MNB)
| | - Marthán N. Bester
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria , Private Bag X20, Hatfield 0028 , South Africa (WCO, PJNdB, MW, MNB)
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Gmuca NV, Pearson LE, Burns JM, Liwanag HEM. The Fat and the Furriest: Morphological Changes in Harp Seal Fur with Ontogeny. Physiol Biochem Zool 2015; 88:158-66. [DOI: 10.1086/680080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Bourbonnais ML, Nelson TA, Cattet MRL, Darimont CT, Stenhouse GB, Janz DM. Environmental factors and habitat use influence body condition of individuals in a species at risk, the grizzly bear. CONSERVATION PHYSIOLOGY 2014; 2:cou043. [PMID: 27293664 PMCID: PMC4732474 DOI: 10.1093/conphys/cou043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 08/20/2014] [Accepted: 08/21/2014] [Indexed: 05/30/2023]
Abstract
Metrics used to quantify the condition or physiological states of individuals provide proactive mechanisms for understanding population dynamics in the context of environmental factors. Our study examined how anthropogenic disturbance, habitat characteristics and hair cortisol concentrations interpreted as a sex-specific indicator of potential habitat net-energy demand affect the body condition of grizzly bears (n = 163) in a threatened population in Alberta, Canada. We quantified environmental variables by modelling spatial patterns of individual habitat use based on global positioning system telemetry data. After controlling for gender, age and capture effects, we assessed the influence of biological and environmental variables on body condition using linear mixed-effects models in an information theoretical approach. Our strongest model suggested that body condition was improved when patterns of habitat use included greater vegetation productivity, increased influence of forest harvest blocks and oil and gas well sites, and a higher percentage of regenerating and coniferous forest. However, body condition was negatively affected by habitat use in close proximity to roads and in areas where potential energetic demands were high. Poor body condition was also associated with increased selection of parks and protected areas and greater seasonal vegetation productivity. Adult females, females with cubs-of-year, juvenile females and juvenile males were in poorer body condition compared with adult males, suggesting that intra-specific competition and differences in habitat use based on gender and age may influence body condition dynamics. Habitat net-energy demand also tended to be higher in areas used by females which, combined with observed trends in body condition, could affect reproductive success in this threatened population. Our results highlight the importance of considering spatiotemporal variability in environmental factors and habitat use when assessing the body condition of individuals. Long-term and large-scale monitoring of the physiological state of individuals provides a more comprehensive approach to support management and conservation of species at risk.
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Affiliation(s)
- Mathieu L. Bourbonnais
- Spatial Pattern Analysis and Research Laboratory, Department of Geography, University of Victoria, Victoria, British Columbia, Canada V8W 3R4
| | - Trisalyn A. Nelson
- Spatial Pattern Analysis and Research Laboratory, Department of Geography, University of Victoria, Victoria, British Columbia, Canada V8W 3R4
| | - Marc R. L. Cattet
- Canadian Wildlife Health Cooperative, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4
| | - Chris T. Darimont
- Applied Conservation Science Laboratory, Department of Geography, University of Victoria, Victoria, British Columbia, Canada V8W 3R4
| | | | - David M. Janz
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4
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Thometz NM, Tinker MT, Staedler MM, Mayer KA, Williams TM. Energetic demands of immature sea otters from birth to weaning: implications for maternal costs, reproductive behavior and population-level trends. J Exp Biol 2014; 217:2053-61. [DOI: 10.1242/jeb.099739] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Sea otters (Enhydra lutris) have the highest mass-specific metabolic rate of any marine mammal, which is superimposed on the inherently high costs of reproduction and lactation in adult females. These combined energetic demands have been implicated in the poor body condition and increased mortality of female sea otters nearing the end of lactation along the central California coast. However, the cost of lactation is unknown and currently cannot be directly measured for this marine species in the wild. Here, we quantified the energetic demands of immature sea otters across five developmental stages as a means of assessing the underlying energetic challenges associated with pup rearing that may contribute to poor maternal condition. Activity-specific metabolic rates, daily activity budgets and field metabolic rates (FMR) were determined for each developmental stage. Mean FMR of pre-molt pups was 2.29±0.81 MJ day−1 and increased to 6.16±2.46 and 7.41±3.17 MJ day−1 in post-molt pups and dependent immature animals, respectively. Consequently, daily energy demands of adult females increase 17% by 3 weeks postpartum and continue increasing to 96% above pre-pregnancy levels by the average age of weaning. Our results suggest that the energetics of pup rearing superimposed on small body size, marine living and limited on-board energetic reserves conspire to make female sea otters exceptionally vulnerable to energetic shortfalls. By controlling individual fitness, maternal behavior and pup provisioning strategies, this underlying metabolic challenge appears to be a major factor influencing current population trends in southern sea otters (Enhydra lutris nereis).
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Affiliation(s)
- N. M. Thometz
- Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California at Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, USA
| | - M. T. Tinker
- U.S. Geological Survey, Center for Ocean Health, Long Marine Laboratory, University of California at Santa Cruz, Santa Cruz, CA 95060, USA
| | - M. M. Staedler
- Monterey Bay Aquarium, 886 Cannery Row, Monterey, CA 93950, USA
| | - K. A. Mayer
- Monterey Bay Aquarium, 886 Cannery Row, Monterey, CA 93950, USA
| | - T. M. Williams
- Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California at Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, USA
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Champagne CD, Houser DS, Fowler MA, Costa DP, Crocker DE. Gluconeogenesis is associated with high rates of tricarboxylic acid and pyruvate cycling in fasting northern elephant seals. Am J Physiol Regul Integr Comp Physiol 2012; 303:R340-52. [PMID: 22673783 DOI: 10.1152/ajpregu.00042.2012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Animals that endure prolonged periods of food deprivation preserve vital organ function by sparing protein from catabolism. Much of this protein sparing is achieved by reducing metabolic rate and suppressing gluconeogenesis while fasting. Northern elephant seals (Mirounga angustirostris) endure prolonged fasts of up to 3 mo at multiple life stages. During these fasts, elephant seals maintain high levels of activity and energy expenditure associated with breeding, reproduction, lactation, and development while maintaining rates of glucose production typical of a postabsorptive mammal. Therefore, we investigated how fasting elephant seals meet the requirements of glucose-dependent tissues while suppressing protein catabolism by measuring the contribution of glycogenolysis, glycerol, and phosphoenolpyruvate (PEP) to endogenous glucose production (EGP) during their natural 2-mo postweaning fast. Additionally, pathway flux rates associated with the tricarboxylic acid (TCA) cycle were measured specifically, flux through phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate cycling. The rate of glucose production decreased during the fast (F(1,13) = 5.7, P = 0.04) but remained similar to that of postabsorptive mammals. The fractional contributions of glycogen, glycerol, and PEP did not change with fasting; PEP was the primary gluconeogenic precursor and accounted for ∼95% of EGP. This large contribution of PEP to glucose production occurred without substantial protein loss. Fluxes through the TCA cycle, PEPCK, and pyruvate cycling were higher than reported in other species and were the most energetically costly component of hepatic carbohydrate metabolism. The active pyruvate recycling fluxes detected in elephant seals may serve to rectify gluconeogeneic PEP production during restricted anaplerotic inflow in these fasting-adapted animals.
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Affiliation(s)
- Cory D Champagne
- Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, USA.
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Verrier D, Atkinson S, Guinet C, Groscolas R, Arnould JPY. Hormonal responses to extreme fasting in subantarctic fur seal (Arctocephalus tropicalis) pups. Am J Physiol Regul Integr Comp Physiol 2012; 302:R929-40. [DOI: 10.1152/ajpregu.00370.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Surviving prolonged fasting implies closely regulated alterations in fuel provisioning to meet metabolic requirements, while preserving homeostasis. Little is known, however, of the endocrine regulations governing such metabolic adaptations in naturally fasting free-ranging animals. The hormonal responses to natural prolonged fasting and how they correlate to the metabolic adaptations observed, were investigated in subantarctic fur seal ( Arctocephalus tropicalis ) pups, which, because of the intermittent pattern of maternal attendance, repeatedly endure exceptionally long fasting episodes throughout their development (1–3 mo). Phase I fasting was characterized by a dramatic decrease in plasma insulin, glucagon, leptin, and total l-thyroxine (T4) associated with reductions in mass-specific resting metabolic rate (RMR), plasma triglycerides, glycerol, and urea-to-creatine ratio, while nonesterified fatty acids (NEFA) and β-OHB increased. In contrast, the metabolic steady-state of phase II fasting reached within 6 days was associated with minimal concentrations of insulin, glucagon, and leptin; unchanged cortisol and triiodothyronine (T3); and moderately increased T4. The early fall in insulin and leptin may mediate the shift to the strategy of energy conservation, protein sparing, and primary reliance on body lipids observed in response to the cessation of feeding. In contrast to the typical mammalian starvation response, nonelevated cortisol and minimal glucagon levels may contribute to body protein preservation and downregulation of catabolic pathways, in general. Furthermore, thyroid hormones may be involved in a process of energy conservation, independent of pups' nutritional state. These original hormonal settings might reflect an adaptation to the otariid repeated fasting pattern and emphasize the crucial importance of a tight physiological control over metabolism to survive extreme energetic constraints.
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Affiliation(s)
- Delphine Verrier
- Department of Zoology, University of Melbourne, Parkville, Victoria, Australia
- Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, UMR 7178 Centre National de la Recherche Scientifique (CNRS)-Université des Sciences, Strasbourg, France
| | - Shannon Atkinson
- School of Fisheries and Ocean Sciences, Juneau Center, University of Alaska Fairbanks, Juneau, Alaska
| | - Christophe Guinet
- Centre d'Etudes Biologiques de Chizé, UPR 1934 CNRS, Villiers-en-Bois, France; and
| | - René Groscolas
- Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, UMR 7178 Centre National de la Recherche Scientifique (CNRS)-Université des Sciences, Strasbourg, France
| | - John P. Y. Arnould
- School of Life and Environmental Sciences, Deakin University, Burwood, Victoria, Australia
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Verrier D, Guinet C, Authier M, Tremblay Y, Shaffer S, Costa DP, Groscolas R, Arnould JP. The ontogeny of diving abilities in subantarctic fur seal pups: developmental trade-off in response to extreme fasting? Funct Ecol 2011. [DOI: 10.1111/j.1365-2435.2011.01846.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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