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Derežanin L, Blažytė A, Dobrynin P, Duchêne DA, Grau JH, Jeon S, Kliver S, Koepfli KP, Meneghini D, Preick M, Tomarovsky A, Totikov A, Fickel J, Förster DW. Multiple types of genomic variation contribute to adaptive traits in the mustelid subfamily Guloninae. Mol Ecol 2022; 31:2898-2919. [PMID: 35334142 DOI: 10.1111/mec.16443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 03/06/2022] [Accepted: 03/14/2022] [Indexed: 11/28/2022]
Abstract
Species of the mustelid subfamily Guloninae inhabit diverse habitats on multiple continents, and occupy a variety of ecological niches. They differ in feeding ecologies, reproductive strategies and morphological adaptations. To identify candidate loci associated with adaptations to their respective environments, we generated a de novo assembly of the tayra (Eira barbara), the earliest diverging species in the subfamily, and compared this with the genomes available for the wolverine (Gulo gulo) and the sable (Martes zibellina). Our comparative genomic analyses included searching for signs of positive selection, examining changes in gene family sizes, as well as searching for species-specific structural variants (SVs). Among candidate loci associated with phenotypic traits, we observed many related to diet, body condition and reproduction. For example, for the tayra, which has an atypical gulonine reproductive strategy of aseasonal breeding, we observe species-specific changes in many pregnancy-related genes. For the wolverine, a circumpolar hypercarnivore that must cope with seasonal food scarcity, we observed many changes in genes associated with diet and body condition. All types of genomic variation examined (single nucleotide polymorphisms, gene family expansions, structural variants) contributed substantially to the identification of candidate loci. This strongly argues for consideration of variation other than single nucleotide polymorphisms in comparative genomics studies aiming to identify loci of adaptive significance.
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Affiliation(s)
- Lorena Derežanin
- Leibniz Institute for Zoo and Wildlife Research (IZW, Alfred Kowalke Straße 17, 10315, Berlin, Germany
| | - Asta Blažytė
- Department of Biomedical Engineering, College of Information and Biotechnology, Ulsan National Institute of Science and Technology (UNIST, Ulsan, 44919, Republic of Korea
| | - Pavel Dobrynin
- Computer Technologies Laboratory, ITMO University, 49 Kronverkskiy Pr, 197101, Saint Petersburg, Russia
| | - David A Duchêne
- Center for Evolutionary Hologenomics, The GLOBE Institute, Faculty of Health and Medical Sciences, University of Copenhagen, Øster Farimagsgade 5, 1353, Copenhagen, Denmark
| | - José Horacio Grau
- amedes Genetics, amedes Medizinische Dienstleistungen GmbH, Jägerstr. 61, 10117, Berlin, Germany
| | - Sungwon Jeon
- Department of Biomedical Engineering, College of Information and Biotechnology, Ulsan National Institute of Science and Technology (UNIST, Ulsan, 44919, Republic of Korea.,Clinomics Inc, Ulsan, 44919, Republic of Korea
| | - Sergei Kliver
- Institute of Molecular and Cellular Biology, SB RAS, 8/2 Acad. Lavrentiev Ave, Novosibirsk, 630090, Russia
| | - Klaus-Peter Koepfli
- Computer Technologies Laboratory, ITMO University, 49 Kronverkskiy Pr, 197101, Saint Petersburg, Russia.,Smithsonian-Mason School of Conservation, 1500 Remount Road, Front Royal, VA, 22630, USA.,Smithsonian Conservation Biology Institute, Center for Species Survival, National Zoological Park, 1500 Remount Road, Front Royal, VA, 22630, USA
| | - Dorina Meneghini
- Leibniz Institute for Zoo and Wildlife Research (IZW, Alfred Kowalke Straße 17, 10315, Berlin, Germany
| | - Michaela Preick
- Institute for Biochemistry and Biology, Faculty of Mathematics and Natural Sciences, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, OT, Germany
| | - Andrey Tomarovsky
- Computer Technologies Laboratory, ITMO University, 49 Kronverkskiy Pr, 197101, Saint Petersburg, Russia.,Institute of Molecular and Cellular Biology, SB RAS, 8/2 Acad. Lavrentiev Ave, Novosibirsk, 630090, Russia.,Novosibirsk State University, 1 Pirogova str, Novosibirsk, 630090, Russia
| | - Azamat Totikov
- Computer Technologies Laboratory, ITMO University, 49 Kronverkskiy Pr, 197101, Saint Petersburg, Russia.,Institute of Molecular and Cellular Biology, SB RAS, 8/2 Acad. Lavrentiev Ave, Novosibirsk, 630090, Russia.,Novosibirsk State University, 1 Pirogova str, Novosibirsk, 630090, Russia
| | - Jörns Fickel
- Leibniz Institute for Zoo and Wildlife Research (IZW, Alfred Kowalke Straße 17, 10315, Berlin, Germany.,Institute for Biochemistry and Biology, Faculty of Mathematics and Natural Sciences, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, OT, Germany
| | - Daniel W Förster
- Leibniz Institute for Zoo and Wildlife Research (IZW, Alfred Kowalke Straße 17, 10315, Berlin, Germany
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2
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Wright DN, Katundu KGH, Viscarra JA, Crocker DE, Newman JW, La Frano MR, Ortiz RM. Oxylipin Responses to Fasting and Insulin Infusion in a Large Mammalian Model of Fasting-Induced Insulin Resistance, the Northern Elephant Seal. Am J Physiol Regul Integr Comp Physiol 2021; 321:R537-R546. [PMID: 34346724 DOI: 10.1152/ajpregu.00016.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The prolonged, post-weaning fast of northern elephant seal (Mirounga angustirostris) pups is characterized by a reliance on lipid metabolism and reversible, fasting-induced insulin resistance providing a unique model to examine the effects of insulin on lipid metabolism. We have previously shown that acute insulin infusion induced a shift in fatty acid metabolism dependent on fasting duration. This study complements the previous study by examining the effects of fasting duration and insulin infusion on circulating levels of oxylipins, bioactive metabolites derived from the oxygenation of polyunsaturated fatty acids. Northern elephant seal pups were studied at two post-weaning periods (n = 5/period): early fasting (1-2 weeks post-weaning; 127 ± 1 kg) and late fasting (6-7 weeks post-weaning; 93 ± 4 kg). Different cohorts of pups were weighed, sedated, and infused with 65 mU/kg of insulin. Plasma was collected prior to infusion (T0), and at 10, 30, 60, and 120 min post-infusion. A profile of ~80 oxylipins were analyzed by UPLC-ESI-MS/MS. Nine oxylipins changed between early and late fasting and eight were altered in response to insulin infusion. Fasting decreased PGF2a and increased 14,15-DiHETrE, 20-HETE, and 4-HDoHE (p<0.03) in T0 samples, while insulin infusion resulted in an inverse change in area under the curve (AUC) levels in these same metabolites (p<0.05). In addition, 12-HpETE and 12-HETE decreased with fasting and insulin infusion, respectively (p<0.04). The oxylipins altered during fasting and in response to insulin infusion may contribute to the manifestation of insulin resistance and participate in the metabolic regulation of associated cellular processes.
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Affiliation(s)
- Dana N Wright
- Department of Food Science and Nutrition, California Polytechnic State University, San Luis Obispo, CA, United States
| | - Kondwani G H Katundu
- Division of Physiology, Biomedical Sciences Department, College of Medicine, University of Malawi, Blantyre, Southern Region, Malawi
| | - Jose A Viscarra
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, United States
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA, United States
| | - John W Newman
- Obesity and Metabolism Research Unit, USDA-Agricultural Research Service Western Human Nutrition Research Center, University of California, Davis, Davis, CA, United States.,NIH West Coast Metabolomics Center, University of California, Davis, Davis, CA, United States.,Department of Nutrition, University of California, Davis, CA, United States
| | - Michael R La Frano
- Department of Food Science and Nutrition, California Polytechnic State University, San Luis Obispo, CA, United States.,Center for Health Research, California Polytechnic State University, San Luis Obispo, CA, United States.,Cal Poly Metabolomics Service Center, California Polytechnic State University, San Luis Obispo, CA, United States
| | - Rudy M Ortiz
- Department of Molecular and Cell Biology, School of Natural Sciences, University of California, Merced, United States
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3
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Rzucidlo CL, Sperou ES, Holser RR, Khudyakov JI, Costa DP, Crocker DE. Changes in serum adipokines during natural extended fasts in female northern elephant seals. Gen Comp Endocrinol 2021; 308:113760. [PMID: 33781740 DOI: 10.1016/j.ygcen.2021.113760] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 12/30/2020] [Accepted: 03/10/2021] [Indexed: 12/31/2022]
Abstract
Adipose tissue is essential to endotherms for thermoregulation and energy storage as well as functioning as an endocrine organ. Adipose derived hormones, or adipokines, regulate metabolism, energy expenditure, reproduction, and immune function in model systems but are less well studied in wildlife. Female northern elephant seals (NES) achieve high adiposity during foraging and then undergo natural fasts up to five weeks long during haul-outs associated with reproduction and molting, resulting in large changes in adipose reserves. We measured circulating levels of four adipokines: leptin, resistin, adiponectin, and kisspeptin-54, in 196 serum samples from female NES at the beginning and end of their breeding and molting fasts. We examined the relationships between these adipokines and life-history stage, adiposity, mass, cortisol, and an immune cytokine involved in the innate immune response interleukin 6 (IL-6). All four adipokines varied with life-history stage. Leptin concentrations were highest at the beginning of the breeding haul-out. Resistin concentrations were higher throughout the breeding haul-out compared to the molt haul-out. Adiponectin concentrations were highest at the beginning of both haul-outs. Kisspeptin-54 concentrations were highest at the end of the breeding haul-out. Leptin, resistin, and adiponectin were associated with measures of body condition, either adiposity, mass, or both. Resistin, adiponectin, and kisspeptin-54 were associated with circulating cortisol concentrations. Resistin was strongly associated with circulating IL-6, a multifunctional cytokine. Adiponectin was associated with glucose concentrations, suggesting a potential role in tissue-specific insulin sensitivity during life-history stages categorized by high adiposity. Increased cortisol concentrations late in lactation were associated with increased kisspeptin-54, suggesting a link to ovulation initiation in NES. This study suggests dramatic changes in circulating adipokines with life-history and body condition that may exert important regulatory roles in NES. The positive relationship between adiponectin and adiposity as well as the lack of a relationship between leptin and kisspeptin-54 differed from model systems. These differences from biomedical model systems suggest the potential for modifications of expression and function of adipose-derived hormones in species that undergo natural changes in adiposity as part of their life-history.
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Affiliation(s)
- Caroline L Rzucidlo
- Department of Biology, Sonoma State University, Rohnert Park, CA 94928, United States.
| | - Emily S Sperou
- Department of Biology, Sonoma State University, Rohnert Park, CA 94928, United States
| | - Rachel R Holser
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, United States
| | - Jane I Khudyakov
- Department of Biological Sciences, University of the Pacific, Stockton, CA 95211, United States
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, United States
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA 94928, United States
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4
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Houser DS, Derous D, Douglas A, Lusseau D. Metabolic response of dolphins to short-term fasting reveals physiological changes that differ from the traditional fasting model. J Exp Biol 2021; 224:jeb238915. [PMID: 33766933 PMCID: PMC8126448 DOI: 10.1242/jeb.238915] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 03/18/2021] [Indexed: 12/11/2022]
Abstract
Bottlenose dolphins (Tursiops truncatus) typically feed on prey that are high in lipid and protein content and nearly devoid of carbohydrate, a dietary feature shared with other marine mammals. However, unlike fasted-adapted marine mammals that predictably incorporate fasting into their life history, dolphins feed intermittently throughout the day and are not believed to be fasting-adapted. To assess whether the physiological response to fasting in the dolphin shares features with or distinguishes them from those of fasting-adapted marine mammals, the plasma metabolomes of eight bottlenose dolphins were compared between post-absorptive and 24-h fasted states. Increases in most identified free fatty acids and lipid metabolites and reductions in most amino acids and their metabolites were consistent with the upregulation of lipolysis and lipid oxidation and the downregulation of protein catabolism and synthesis. Consistent with a previously hypothesized diabetic-like fasting state, fasting was associated with elevated glucose and patterns of certain metabolites (e.g. citrate, cis-aconitate, myristoleic acid) indicative of lipid synthesis and glucose cycling to protect endogenous glucose from oxidative disposal. Pathway analysis predicted an upregulation of cytokines, decreased cell growth and increased apoptosis including apoptosis of insulin-secreting β-cells. Metabolomic conditional mutual information networks were estimated for the post-absorptive and fasted states and 'topological modules' were estimated for each using the eigenvector approach to modularity network division. A dynamic network marker indicative of a physiological shift toward a negative energy state was subsequently identified that has the potential conservation application of assessing energy state balance in at-risk wild dolphins.
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Affiliation(s)
| | - Davina Derous
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - Alex Douglas
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
| | - David Lusseau
- School of Biological Sciences, University of Aberdeen, Aberdeen AB24 2TZ, UK
- National Institute of Aquatic Resources, DTU Aqua, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
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5
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Dhillon J, Viscarra JA, Newman JW, Fiehn O, Crocker DE, Ortiz RM. Exogenous GLP-1 stimulates TCA cycle and suppresses gluconeogenesis and ketogenesis in late-fasted northern elephant seals pups. Am J Physiol Regul Integr Comp Physiol 2021; 320:R393-R403. [PMID: 33407018 DOI: 10.1152/ajpregu.00211.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The postweaning fast of northern elephant seal pups is characterized by a lipid-dependent metabolism and associated with a decrease in plasma glucagon-like peptide-1 (GLP-1), insulin, and glucose and increased gluconeogenesis (GNG) and ketogenesis. We have also demonstrated that exogenous GLP-1 infusion increased plasma insulin despite simultaneous increases in cortisol and glucagon, which collectively present contradictory regulatory stimuli of GNG, ketogenesis, and glycolysis. To assess the effects of GLP-1 on metabolism using primary carbon metabolite profiles in late-fasted seal pups, we dose-dependently infused late-fasted seals with low (LDG; 10 pM/kg; n = 3) or high (HDG; 100 pM/kg; n = 4) GLP-1 immediately following a glucose bolus (0.5 g/kg), using glucose without GLP-1 as control (n = 5). Infusions were performed in similarly aged animals 6-8 wk into their postweaning fast. The plasma metabolome was measured from samples collected at five time points just prior to and during the infusions, and network maps constructed to robustly evaluate the effects of GLP-1 on primary carbon metabolism. HDG increased key tricarboxylic acid (TCA) cycle metabolites, and decreased phosphoenolpyruvate and acetoacetate (P < 0.05) suggesting that elevated levels of GLP-1 promote glycolysis and suppress GNG and ketogenesis, which collectively increase glucose clearance. These GLP-1-mediated effects on cellular metabolism help to explain why plasma GLP-1 concentrations decrease naturally in fasting pups as an evolved mechanism to help conserve glucose during the late-fasting period.
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Affiliation(s)
- Jaapna Dhillon
- Department of Molecular & Cell Biology, School of Natural Sciences, University of California, Merced, California.,Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, Missouri
| | - Jose A Viscarra
- Department of Molecular & Cell Biology, School of Natural Sciences, University of California, Merced, California.,Department of Nutritional Sciences and Toxicology, University of California, Berkeley, California
| | - John W Newman
- Obesity and Metabolism Research Unit, USDA Agricultural Research Service Western Human Nutrition Research Center, University of California, Davis, California.,NIH West Coast Metabolomics Center, University of California, Davis, California
| | - Oliver Fiehn
- NIH West Coast Metabolomics Center, University of California, Davis, California
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California
| | - Rudy M Ortiz
- Department of Molecular & Cell Biology, School of Natural Sciences, University of California, Merced, California
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6
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Debier C, Pirard L, Verhaegen M, Rzucidlo C, Tinant G, Dewulf C, Larondelle Y, Smith DR, Rees JF, Crocker DE. In vitro Lipolysis and Leptin Production of Elephant Seal Blubber Using Precision-Cut Adipose Tissue Slices. Front Physiol 2020; 11:615784. [PMID: 33362587 PMCID: PMC7758477 DOI: 10.3389/fphys.2020.615784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 11/20/2020] [Indexed: 11/13/2022] Open
Abstract
Adipose tissue plays key roles in energy homeostasis. Understanding its metabolism and regulation is essential to predict the impact of environmental changes on wildlife health, especially in fasting-adapted species. However, in vivo experimental work in wild vertebrates can be challenging. We have developed a novel in vitro approach of precision-cut adipose tissue slices from northern elephant seal (Mirounga angustirostris) as a complementary approach to whole animal models. Blubber biopsies were collected from 14 pups during early and late post-weaning fast (Año Nuevo, CA, United States), precision-cut into 1 mm thick slices and maintained in culture at 37°C for at least 63 h. The slices exhibited an efficient response to ß-adrenergic stimulation, even after 2 days of culture, revealing good in vitro tissue function. The response to lipolytic stimulus did not vary between regions of outer and inner blubber, but was higher at early than at late fast for inner blubber slices. At early fast, lipolysis significantly reduced leptin production. At this stage, inner blubber slices were also more efficient at producing leptin than outer blubber slices, especially in the non-lipolytic condition. This model will aid the study of adipose tissue metabolism and its response to environmental stressors in marine mammals.
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Affiliation(s)
- Cathy Debier
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Laura Pirard
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Marie Verhaegen
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Caroline Rzucidlo
- Department of Biology, Sonoma State University, Rohnert Park, CA, United States
| | - Gilles Tinant
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Clément Dewulf
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Yvan Larondelle
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Donald R Smith
- Department of Microbiology and Environmental Toxicology, University of California, Santa Cruz, Santa Cruz, CA, United States
| | - Jean-François Rees
- Louvain Institute of Biomolecular Science and Technology, UCLouvain, Louvain-la-Neuve, Belgium
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, CA, United States
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7
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Lam EK, Allen KN, Torres-Velarde JM, Vázquez-Medina JP. Functional Studies with Primary Cells Provide a System for Genome-to-Phenome Investigations in Marine Mammals. Integr Comp Biol 2020; 60:348-360. [PMID: 32516367 DOI: 10.1093/icb/icaa065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Marine mammals exhibit some of the most dramatic physiological adaptations in their clade and offer unparalleled insights into the mechanisms driving convergent evolution on relatively short time scales. Some of these adaptations, such as extreme tolerance to hypoxia and prolonged food deprivation, are uncommon among most terrestrial mammals and challenge established metabolic principles of supply and demand balance. Non-targeted omics studies are starting to uncover the genetic foundations of such adaptations, but tools for testing functional significance in these animals are currently lacking. Cellular modeling with primary cells represents a powerful approach for elucidating the molecular etiology of physiological adaptation, a critical step in accelerating genome-to-phenome studies in organisms in which transgenesis is impossible (e.g., large-bodied, long-lived, fully aquatic, federally protected species). Gene perturbation studies in primary cells can directly evaluate whether specific mutations, gene loss, or duplication confer functional advantages such as hypoxia or stress tolerance in marine mammals. Here, we summarize how genetic and pharmacological manipulation approaches in primary cells have advanced mechanistic investigations in other non-traditional mammalian species, and highlight the need for such investigations in marine mammals. We also provide key considerations for isolating, culturing, and conducting experiments with marine mammal cells under conditions that mimic in vivo states. We propose that primary cell culture is a critical tool for conducting functional mechanistic studies (e.g., gene knockdown, over-expression, or editing) that can provide the missing link between genome- and organismal-level understanding of physiological adaptations in marine mammals.
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Affiliation(s)
- Emily K Lam
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kaitlin N Allen
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720, USA
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8
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Cornejo MA, Nguyen J, Cazares J, Escobedo B, Nishiyama A, Nakano D, Ortiz RM. Partial Body Mass Recovery After Caloric Restriction Abolishes Improved Glucose Tolerance in Obese, Insulin Resistant Rats. Front Endocrinol (Lausanne) 2020; 11:363. [PMID: 32587574 PMCID: PMC7298117 DOI: 10.3389/fendo.2020.00363] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/11/2020] [Indexed: 11/13/2022] Open
Abstract
Caloric restriction, among other behavioral interventions, has demonstrated benefits on improving glycemic control in obesity-associated diabetic subjects. However, an acute and severe intervention without proper maintenance could reverse the initial benefits, with additional metabolic derangements. To assess the effects of an acute caloric restriction in a metabolic syndrome model, a cohort of 15-week old Long Evans Tokushima Otsuka (LETO) and Otsuka Long Evans Tokushima Fatty (OLETF) rats were calorie restricted (CR: 50% × 10 days) with or without a 10-day body mass (BM) recovery period, along with their respective ad libitum controls. An oral glucose tolerance test (oGTT) was performed after CR and BM recovery. Both strains had higher rates of mass gain during recovery vs. ad lib controls; however, the regain was partial (ca. 50% of ad lib controls) over the measurement period. Retroperitoneal and epididymal adipose masses decreased 30% (8.8 g, P < 0.001) in OLETF; however, this loss only accounted for 11.5% of the total BM loss. CR decreased blood glucose AUC 16% in LETO and 19% in OLETF, without significant decreases in insulin. Following CR, hepatic expression of the gluconeogenic enzyme, PEPCK, was reduced 55% in OLETF compared to LETO, and plasma triglycerides (TG) decreased 86%. Acute CR induced improvements in glucose tolerance and TG suggestive of improvements in metabolism; however, partial recovery of BM following CR abolished the improvement in glucose tolerance. The present study highlights the importance of proper maintenance of BM after CR as only partial recovery of the lost BM reversed benefits of the initial mass loss.
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Affiliation(s)
- Manuel A. Cornejo
- School of Natural Sciences, University of California, Merced, Merced, CA, United States
- *Correspondence: Manuel A. Cornejo
| | - Julie Nguyen
- School of Natural Sciences, University of California, Merced, Merced, CA, United States
| | - Joshua Cazares
- School of Natural Sciences, University of California, Merced, Merced, CA, United States
| | - Benny Escobedo
- School of Natural Sciences, University of California, Merced, Merced, CA, United States
| | - Akira Nishiyama
- Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Daisuke Nakano
- Department of Pharmacology, Faculty of Medicine, Kagawa University, Kagawa, Japan
| | - Rudy M. Ortiz
- School of Natural Sciences, University of California, Merced, Merced, CA, United States
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9
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Martinez B, Khudyakov J, Rutherford K, Crocker DE, Gemmell N, Ortiz RM. Adipose transcriptome analysis provides novel insights into molecular regulation of prolonged fasting in northern elephant seal pups. Physiol Genomics 2018; 50:495-503. [PMID: 29625017 DOI: 10.1152/physiolgenomics.00002.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The physiological and cellular adaptations to extreme fasting in northern elephant seals ( Mirounga angustirostris, NES) are remarkable and may help to elucidate endocrine mechanisms that regulate lipid metabolism and energy homeostasis in mammals. Recent studies have highlighted the importance of thyroid hormones in the maintenance of a lipid-based metabolism during prolonged fasting in weaned NES pups. To identify additional molecular regulators of fasting, we used a transcriptomics approach to examine changes in global gene expression profiles before and after 6-8 wk of fasting in weaned NES pups. We produced a de novo assembly and identified 98 unique protein-coding genes that were differentially expressed between early and late fasting. Most of the downregulated genes were associated with lipid, carbohydrate, and protein metabolism. A number of downregulated genes were also associated with maintenance of the extracellular matrix, consistent with tissue remodeling during weight loss and the multifunctional nature of blubber tissue, which plays both metabolic and structural roles in marine mammals. Using this data set, we predict potential mechanisms by which NES pups sustain metabolism and regulate adipose stores throughout the fast, and provide a valuable resource for additional studies of extreme metabolic adaptations in mammals.
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Affiliation(s)
- Bridget Martinez
- Department of Molecular & Cellular Biology, University of California, Merced, California.,Department of Medicine, St. George's University School of Medicine, St. George, Grenada.,Department of Anatomy, University of Otago , Dunedin , New Zealand.,Department of Physics and Engineering, Los Alamos National Laboratory , Los Alamos, New Mexico
| | - Jane Khudyakov
- Department of Biological Sciences, University of the Pacific , Stockton, California
| | - Kim Rutherford
- Department of Anatomy, University of Otago , Dunedin , New Zealand
| | - Daniel E Crocker
- Department of Biology, Sonoma State University , Rohnert Park, California
| | - Neil Gemmell
- Department of Anatomy, University of Otago , Dunedin , New Zealand
| | - Rudy M Ortiz
- Department of Molecular & Cellular Biology, University of California, Merced, California
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10
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Fowler M, Champagne C, Crocker D. Adiposity and fat metabolism during combined fasting and lactation in elephant seals. J Exp Biol 2018. [DOI: 10.1242/jeb.161554] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
ABSTRACT
Animals that fast depend on mobilizing lipid stores to power metabolism. Northern elephant seals (Mirounga angustirostris) incorporate extended fasting into several life-history stages: development, molting, breeding and lactation. The physiological processes enabling fasting and lactation are important in the context of the ecology and life history of elephant seals. The rare combination of fasting and lactation depends on the efficient mobilization of lipid from adipose stores and its direction into milk production. The mother elephant seal must ration her finite body stores to power maintenance metabolism, as well as to produce large quantities of lipid and protein-rich milk. Lipid from body stores must first be mobilized; the action of lipolytic enzymes and hormones stimulate the release of fatty acids into the bloodstream. Biochemical processes affect the release of specific fatty acids in a predictable manner, and the pattern of release from lipid stores is closely reflected in the fatty acid content of the milk lipid. The content of the milk may have substantial developmental, thermoregulatory and metabolic consequences for the pup. The lactation and developmental patterns found in elephant seals are similar in some respects to those of other mammals; however, even within the limited number of mammals that simultaneously fast and lactate, there are important differences in the mechanisms that regulate lipid mobilization and milk lipid content. Although ungulates and humans do not fast during lactation, there are interesting comparisons to these groups regarding lipid mobilization and milk lipid content patterns.
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Jelincic JA, Tift MS, Houser DS, Crocker DE. Variation in adrenal and thyroid hormones with life-history stage in juvenile northern elephant seals (Mirounga angustirostris). Gen Comp Endocrinol 2017; 252:111-118. [PMID: 28782534 DOI: 10.1016/j.ygcen.2017.08.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/26/2017] [Accepted: 08/02/2017] [Indexed: 02/06/2023]
Abstract
The classical approach to quantifying the impact of stressors on wildlife is through characterization of hormones associated with the generalized stress response. However, interpretation of hormone data can be difficult due to the range of natural variation within a species and potential confounds of individual and life-history variables. Blood adrenal and thyroid hormones were measured in 144 chemically immobilized yearling northern elephant seals (Mirounga angustirostris) to characterize variation between sexes and across semiannual haul-outs. There was no relationship between hormone concentrations and time needed for collecting blood nor evidence of diel patterns, suggesting that collection of samples for baseline values can be accomplished without bias due to handling artifacts or time of day. Serum cortisol concentrations did not vary with gender or across haul-out fasts but increased dramatically during molting. Cortisol was correlated with aldosterone across all measured life-history stages. Thyroid hormone levels were lower in females and decreased with fasting in both sexes during the fall haul-out. Cortisol concentrations were inversely associated with total triiodothyronine (T3) and positively associated with reverse T3 concentrations across all measured life-history stages suggesting an important impact of cortisol on deiodinase enzymes and thyroid function. Epinephrine concentrations increased across fasts and norepinephrine concentrations were higher in males than in females. Significant variation in stress hormone concentrations with gender and life-history stage emphasizes the importance of contextual variables when interpreting serum hormone concentrations.
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Affiliation(s)
- J A Jelincic
- Department of Biological Sciences, San Jose State University, 1 Washington Square, San Jose, CA 95112, United States
| | - M S Tift
- Ocean Biosciences, Scripps Institution of Oceanography, 9500 Gilman Drive, La Jolla, CA 92093, United States
| | - D S Houser
- National Marine Mammal Foundation, 2240 Shelter Island Dr, San Diego, CA 92106, United States
| | - D E Crocker
- Department of Biology, Sonoma State University, 1801 E. Cotati Ave., Rohnert Park, CA 94928, United States.
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Martinez B, Scheibner M, Soñanez-Organis JG, Jaques JT, Crocker DE, Ortiz RM. Increased sensitivity of thyroid hormone-mediated signaling despite prolonged fasting. Gen Comp Endocrinol 2017; 252:36-47. [PMID: 28743556 PMCID: PMC5580341 DOI: 10.1016/j.ygcen.2017.07.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 11/24/2022]
Abstract
Thyroid hormones (TH) can increase cellular metabolism. Food deprivation in mammals is typically associated with reduced thyroid gland responsiveness, in an effort to suppress cellular metabolism and abate starvation. However, in prolonged-fasted, elephant seal pups, cellular TH-mediated proteins are up-regulated and TH levels are maintained with fasting duration. The function and contribution of the thyroid gland to this apparent paradox is unknown and physiologically perplexing. Here we show that the thyroid gland remains responsive during prolonged food deprivation, and that its function and production of TH increase with fasting duration in elephant seals. We discovered that our modeled plasma TH data in response to exogenous thyroid stimulating hormone predicted cellular signaling, which was corroborated independently by the enzyme expression data. The data suggest that the regulation and function of the thyroid gland in the northern elephant seal is atypical for a fasted animal, and can be better described as, "adaptive fasting". Furthermore, the modeling data help substantiate the in vivo responses measured, providing unique insight on hormone clearance, production rates, and thyroid gland responsiveness. Because these unique endocrine responses occur simultaneously with a nearly strict reliance on the oxidation of lipid, these findings provide an intriguing model to better understand the TH-mediated reliance on lipid metabolism that is not otherwise present in morbidly obese humans. When coupled with cellular, tissue-specific responses, these data provide a more integrated assessment of thyroidal status that can be extrapolated for many fasting/food deprived mammals.
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Affiliation(s)
- Bridget Martinez
- Department of Molecular and Cellular Biology, University of California Merced, 5200 North Lake Road, Merced, CA 95343, USA.
| | - Michael Scheibner
- Department of Physics, University of California Merced, 5200 North Lake Road, Merced, CA 95343, USA
| | - José G Soñanez-Organis
- Departamento de Ciencias Químico Biológicas y Agropecuarias, Universidad de Sonora, Lázaro Cárdenas del Río No. 100, Francisco Villa, Navojoa, Sonora 85880, Mexico
| | - John T Jaques
- Texas A&M Veterinary Diagnostic Laboratory, 1 Sippel Road, College Station, TX 77843, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, 1801 E. Cotati Avenue, Rohnert Park, CA 94928, USA
| | - Rudy M Ortiz
- Department of Molecular and Cellular Biology, University of California Merced, 5200 North Lake Road, Merced, CA 95343, USA
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Martinez B, Ortiz RM. Thyroid Hormone Regulation and Insulin Resistance: Insights From Animals Naturally Adapted to Fasting. Physiology (Bethesda) 2017; 32:141-151. [PMID: 28202624 DOI: 10.1152/physiol.00018.2016] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The contribution of thyroidal status in insulin signaling and glucose homeostasis has been implicated as a potential pathophysiological factor in humans, but the specific mechanisms remain largely elusive. Fasting induces changes in both thyroid hormone secretion and insulin signaling. Here, we explore how mammals that undergo natural, prolonged bouts of fasting provide unique insight into evolved physiological adaptations that allow them to tolerate such conditions despite intermittent states of reversible insulin resistance. Such insights from nature may provide clues to better understand the basis of thyroidal involvement in insulin dysregulation in humans.
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Affiliation(s)
- Bridget Martinez
- Department of Molecular & Cellular Biology, University of California, Merced, California
| | - Rudy M Ortiz
- Department of Molecular & Cellular Biology, University of California, Merced, California
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14
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Olmstead KI, La Frano MR, Fahrmann J, Grapov D, Viscarra JA, Newman JW, Fiehn O, Crocker DE, Filipp FV, Ortiz RM. Insulin induces a shift in lipid and primary carbon metabolites in a model of fasting-induced insulin resistance. Metabolomics 2017; 13:60. [PMID: 28757815 PMCID: PMC5526460 DOI: 10.1007/s11306-017-1186-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 02/20/2017] [Indexed: 02/07/2023]
Abstract
INTRODUCTION Prolonged fasting in northern elephant seals (NES) is characterized by a reliance on lipid metabolism, conservation of protein, and reduced plasma insulin. During early fasting, glucose infusion previously reduced plasma free fatty acids (FFA); however, during late-fasting, it induced an atypical elevation in FFA despite comparable increases in insulin during both periods suggestive of a dynamic shift in tissue responsiveness to glucose-stimulated insulin secretion. OBJECTIVE To better assess the contribution of insulin to this fasting-associated shift in substrate metabolism. METHODS We compared the responses of plasma metabolites (amino acids (AA), FFA, endocannabinoids (EC), and primary carbon metabolites (PCM)) to an insulin infusion (65 mU/kg) in early- and late-fasted NES pups (n = 5/group). Plasma samples were collected prior to infusion (T0) and at 10, 30, 60, and 120 min post-infusion, and underwent untargeted and targeted metabolomics analyses utilizing a variety of GC-MS and LC-MS technologies. RESULTS In early fasting, the majority (72%) of metabolite trajectories return to baseline levels within 2 h, but not in late fasting indicative of an increase in tissue sensitivity to insulin. In late-fasting, increases in FFA and ketone pools, coupled with decreases in AA and PCM, indicate a shift toward lipolysis, beta-oxidation, ketone metabolism, and decreased protein catabolism. Conversely, insulin increased PCM AUC in late fasting suggesting that gluconeogenic pathways are activated. Insulin also decreased FFA AUC between early and late fasting suggesting that insulin suppresses triglyceride hydrolysis. CONCLUSION Naturally adapted tolerance to prolonged fasting in these mammals is likely accomplished by suppressing insulin levels and activity, providing novel insight on the evolution of insulin during a condition of temporary, reversible insulin resistance.
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Affiliation(s)
- Keedrian I. Olmstead
- Systems Biology and Cancer Metabolism, Program for Quantitative Systems Biology, University of California, Merced
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, USA
| | - Michael R. La Frano
- NIH West Coast Metabolomics Center, University of California, Davis
- Obesity and Metabolism Research Unit, USDA-Agricultural Research Service Western Human Nutrition Research Center, University of California, Davis, USA
- Department of Food Science and Nutrition, California Polytechnic State University, San Luis Obispo, USA
| | - Johannes Fahrmann
- NIH West Coast Metabolomics Center, University of California, Davis
- Cancer Treatment Center, UT MD Anderson, Houston, USA
| | - Dmitry Grapov
- NIH West Coast Metabolomics Center, University of California, Davis
| | - Jose A. Viscarra
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, USA
| | - John W. Newman
- NIH West Coast Metabolomics Center, University of California, Davis
- Obesity and Metabolism Research Unit, USDA-Agricultural Research Service Western Human Nutrition Research Center, University of California, Davis, USA
| | - Oliver Fiehn
- NIH West Coast Metabolomics Center, University of California, Davis
- Biochemistry Department, King Abdulaziz University, Jeddah, Saudi Arabia
| | | | - Fabian V. Filipp
- Systems Biology and Cancer Metabolism, Program for Quantitative Systems Biology, University of California, Merced
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, USA
- NIH West Coast Metabolomics Center, University of California, Davis
| | - Rudy M. Ortiz
- Molecular Cell Biology, School of Natural Sciences, University of California, Merced, USA
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Crocker DE, Wenzel BK, Champagne CD, Houser DS. Adult male northern elephant seals maintain high rates of glucose production during extended breeding fasts. J Comp Physiol B 2017; 187:1183-1192. [DOI: 10.1007/s00360-017-1098-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 03/15/2017] [Accepted: 04/06/2017] [Indexed: 10/19/2022]
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Martinez B, Soñanez-Organis JG, Godoy-Lugo JA, Horin LJ, Crocker DE, Ortiz RM. Thyroid hormone-stimulated increases in PGC-1α and UCP2 promote life history-specific endocrine changes and maintain a lipid-based metabolism. Am J Physiol Regul Integr Comp Physiol 2016; 312:R189-R196. [PMID: 27903512 DOI: 10.1152/ajpregu.00395.2016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 10/31/2016] [Accepted: 11/18/2016] [Indexed: 12/12/2022]
Abstract
Thyroid hormones (THs) regulate metabolism, but are typically suppressed during times of stressful physiological conditions, including fasting. Interestingly, prolonged fasting in northern elephant seal pups is associated with reliance on a lipid-based metabolism and increased levels of circulating THs that are partially attributed to active secretion as opposed to reduced clearance. This apparent paradox is coupled with complementary increases in cellular TH-mediated activity, suggesting that in mammals naturally adapted to prolonged fasting, THs are necessary to support metabolism. However, the functional relevance of this physiological paradox has remained largely unexplored, especially as it relates to the regulation of lipids. To address the hypothesis that TSH-mediated increase in THs contributes to lipid metabolism, we infused early and late-fasted pups with TSH and measured several key genes in adipose and muscle, and plasma hormones associated with regulation of lipid metabolism. TSH infusion increased the mRNA expressions of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) more than 6.5-fold at 60 min in muscle, and expression of uncoupling protein 2 (UCP2) more than 27-fold during the early fast at 60 min, in adipose. Additionally, during the late fast period, the protein content of adipose CD36 increased 1.1-fold, and plasma nonesterified fatty acid (NEFA) concentrations increased 25% at 120 min, with NEFA levels returning to baseline after 24 h. We show that the TSH-induced increases in THs in fasting pups are functional and likely contribute to the maintenance of a lipid-based metabolism.
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Affiliation(s)
- Bridget Martinez
- Molecular and Cellular Biology, University of California Merced, Merced, California;
| | - José G Soñanez-Organis
- Departamento de Ciencias Químico Biológicas y Agropecuarias, Universidad de Sonora, Francisco Villa, Navojoa Sonora, México
| | - José Arquimides Godoy-Lugo
- Departamento de Ciencias Químico Biológicas y Agropecuarias, Universidad de Sonora, Francisco Villa, Navojoa Sonora, México
| | - Lillian J Horin
- W. M. Keck Science Department, Pitzer College, Claremont, California; and
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California
| | - Rudy M Ortiz
- Molecular and Cellular Biology, University of California Merced, Merced, California
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17
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Abstract
Extended bouts of fasting are ingrained in the ecology of many organisms, characterizing aspects of reproduction, development, hibernation, estivation, migration, and infrequent feeding habits. The challenge of long fasting episodes is the need to maintain physiological homeostasis while relying solely on endogenous resources. To meet that challenge, animals utilize an integrated repertoire of behavioral, physiological, and biochemical responses that reduce metabolic rates, maintain tissue structure and function, and thus enhance survival. We have synthesized in this review the integrative physiological, morphological, and biochemical responses, and their stages, that characterize natural fasting bouts. Underlying the capacity to survive extended fasts are behaviors and mechanisms that reduce metabolic expenditure and shift the dependency to lipid utilization. Hormonal regulation and immune capacity are altered by fasting; hormones that trigger digestion, elevate metabolism, and support immune performance become depressed, whereas hormones that enhance the utilization of endogenous substrates are elevated. The negative energy budget that accompanies fasting leads to the loss of body mass as fat stores are depleted and tissues undergo atrophy (i.e., loss of mass). Absolute rates of body mass loss scale allometrically among vertebrates. Tissues and organs vary in the degree of atrophy and downregulation of function, depending on the degree to which they are used during the fast. Fasting affects the population dynamics and activities of the gut microbiota, an interplay that impacts the host's fasting biology. Fasting-induced gene expression programs underlie the broad spectrum of integrated physiological mechanisms responsible for an animal's ability to survive long episodes of natural fasting.
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Affiliation(s)
- Stephen M Secor
- Department of Biological Sciences, University of Alabama, Tuscaloosa, Alabama, USA
| | - Hannah V Carey
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison, Wisconsin, USA
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18
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Martinez B, Soñanez-Organis JG, Viscarra JA, Jaques JT, MacKenzie DS, Crocker DE, Ortiz RM. Glucose delays the insulin-induced increase in thyroid hormone-mediated signaling in adipose of prolong-fasted elephant seal pups. Am J Physiol Regul Integr Comp Physiol 2016; 310:R502-12. [PMID: 26739649 DOI: 10.1152/ajpregu.00054.2015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Accepted: 01/04/2016] [Indexed: 12/14/2022]
Abstract
Prolonged food deprivation in mammals typically reduces glucose, insulin, and thyroid hormone (TH) concentrations, as well as tissue deiodinase (DI) content and activity, which, collectively, suppress metabolism. However, in elephant seal pups, prolonged fasting does not suppress TH levels; it is associated with upregulation of adipose TH-mediated cellular mechanisms and adipose-specific insulin resistance. The functional relevance of this apparent paradox and the effects of glucose and insulin on TH-mediated signaling in an insulin-resistant tissue are not well defined. To address our hypothesis that insulin increases adipose TH signaling in pups during extended fasting, we assessed the changes in TH-associated genes in response to an insulin infusion in early- and late-fasted pups. In late fasting, insulin increased DI1, DI2, and THrβ-1 mRNA expression by 566%, 44%, and 267% at 60 min postinfusion, respectively, with levels decreasing by 120 min. Additionally, we performed a glucose challenge in late-fasted pups to differentiate between insulin- and glucose-mediated effects on TH signaling. In contrast to the insulin-induced effects, glucose infusion did not increase the expressions of DI1, DI2, and THrβ-1 until 120 min, suggesting that glucose delays the onset of the insulin-induced effects. The data also suggest that fasting duration increases the sensitivity of adipose TH-mediated mechanisms to insulin, some of which may be mediated by increased glucose. These responses appear to be unique among mammals and to have evolved in elephant seals to facilitate their adaptation to tolerate an extreme physiological condition.
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Affiliation(s)
- Bridget Martinez
- Department of Molecular & Cellular Biology, University of California, Merced, California;
| | - José G Soñanez-Organis
- Departamento de Ciencias Químico Biológicas y Agropecuarias, Universidad de Sonora, Navojoa, Sonora, México
| | - Jose A Viscarra
- Department of Molecular & Cellular Biology, University of California, Merced, California
| | - John T Jaques
- Veterinary Medical Diagnostic Laboratory, Texas A&M University, College Station, Texas
| | - Duncan S MacKenzie
- Department of Biology, Texas A&M University, College Station, Texas; and
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California
| | - Rudy M Ortiz
- Department of Molecular & Cellular Biology, University of California, Merced, California
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Louis C, Perdaens L, Suciu S, Tavoni SK, Crocker DE, Debier C. Mobilisation of blubber fatty acids of northern elephant seal pups (Mirounga angustirostris) during the post-weaning fast. Comp Biochem Physiol A Mol Integr Physiol 2015; 183:78-86. [DOI: 10.1016/j.cbpa.2015.01.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Revised: 12/23/2014] [Accepted: 01/15/2015] [Indexed: 11/26/2022]
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Fowler MA, Costa DP, Crocker DE, Shen WJ, Kraemer FB. Adipose Triglyceride Lipase, Not Hormone-Sensitive Lipase, Is the Primary Lipolytic Enzyme in Fasting Elephant Seals (Mirounga angustirostris). Physiol Biochem Zool 2015; 88:284-94. [PMID: 25860827 DOI: 10.1086/680079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Little is known about the mechanisms that allow capital breeders to rapidly mobilize large amounts of body reserves. Northern elephant seals (Mirounga angustirostris) utilize fat reserves for maternal metabolism and to create high fat milk for the pup. Hormone-sensitive lipase (HSL) has been hypothesized to be an important lipolytic enzyme in fasting seals, but the activity of HSL and adipose triglyceride lipase (ATGL) has not been quantified in fasting adult seals, nor has their relationship to milk lipid content been assessed. Blubber and milk samples were obtained from 18 early lactation and 19 late lactation females, as well as blubber from five early and five late molting female seals. Blubber lipolytic activity was assessed with radiometric assays. HSL activity was negligible in seal blubber at all fasting stages. Total triglyceride lipase activity was stable among early and late lactation and early molt but increased in late molting seals. Relative abundance of ATGL protein increased across fasting, but neither activity nor relative protein levels were related to circulating nonesterified fatty acids or milk lipid content, suggesting the possibility of other regulatory pathways between lipolytic activity and milk lipid content. These results demonstrate that HSL is not the primary lipolytic enzyme in fasting adult female seals and that ATGL contributes more to lipolysis than HSL.
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Affiliation(s)
- Melinda A Fowler
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California; 2Department of Biology, Sonoma State University, Rohnert Park, California; 3Division of Endocrinology, Gerontology, and Metabolism, Stanford University and Veterans Affairs Palo Alto Health Care System, Palo Alto, California
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Bennett KA, Hughes J, Stamatas S, Brand S, Foster NL, Moss SEW, Pomeroy PP. Adiponectin and Insulin in Gray Seals during Suckling and Fasting: Relationship with Nutritional State and Body Mass during Nursing in Mothers and Pups. Physiol Biochem Zool 2015; 88:295-310. [PMID: 25860828 DOI: 10.1086/680862] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Animals that fast during breeding and/or development, such as phocids, must regulate energy balance carefully to maximize reproductive fitness and survival probability. Adiponectin, produced by adipose tissue, contributes to metabolic regulation by modulating sensitivity to insulin, increasing fatty acid oxidation by liver and muscle, and promoting adipogenesis and lipid storage in fat tissue. We tested the hypotheses that (1) circulating adiponectin, insulin, or relative adiponectin gene expression is related to nutritional state, body mass, and mass gain in wild gray seal pups; (2) plasma adiponectin or insulin is related to maternal lactation duration, body mass, percentage milk fat, or free fatty acid (FFA) concentration; and (3) plasma adiponectin and insulin are correlated with circulating FFA in females and pups. In pups, plasma adiponectin decreased during suckling (linear mixed-effects model [LME]: T = 4.49; P < 0.001) and the early postweaning fast (LME: T = 3.39; P = 0.004). In contrast, their blubber adiponectin gene expression was higher during the early postweaning fast than early in suckling (LME: T = 2.11; P = 0.046). Insulin levels were significantly higher in early (LME: T = 3.52; P = 0.004) and late (LME: T = 6.99; P < 0.001) suckling than in fasting and, given the effect of nutritional state, were also positively related to body mass (LME: T = 3.58; P = 0.004). Adiponectin and insulin levels did not change during lactation and were unrelated to milk FFA or percentage milk fat in adult females. Our data suggest that adiponectin, in conjunction with insulin, may facilitate fat storage in seals and is likely to be particularly important in the development of blubber reserves in pups.
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Affiliation(s)
- K A Bennett
- Marine Biology and Ecology Research Centre, School of Marine Science and Engineering, Plymouth University, Portland Square, Drake Circus, Plymouth, Devon PL4 8AA, United Kingdom; 2Natural Environment Research Council Sea Mammal Research Unit, Gatty Marine Laboratories, Scottish Oceans Institute, University of St. Andrews, St. Andrews, Fife KY16 8LB, United Kingdom
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Ensminger DC, Somo DA, Houser DS, Crocker DE. Metabolic responses to adrenocorticotropic hormone (ACTH) vary with life-history stage in adult male northern elephant seals. Gen Comp Endocrinol 2014; 204:150-7. [PMID: 24798580 DOI: 10.1016/j.ygcen.2014.04.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 04/26/2014] [Indexed: 01/24/2023]
Abstract
Strong individual and life-history variation in serum glucocorticoids has been documented in many wildlife species. Less is known about variation in hypothalamic-pituitary-adrenal (HPA) axis responsiveness and its impact on metabolism. We challenged 18 free-ranging adult male northern elephant seals (NES) with an intramuscular injection of slow-release adrenocorticotropic hormone (ACTH) over 3 sample periods: early in the breeding season, after 70+ days of the breeding fast, and during peak molt. Subjects were blood sampled every 30 min for 2h post-injection. Breeding animals were recaptured and sampled at 48 h. In response to the ACTH injection, cortisol increased 4-6-fold in all groups, and remained elevated at 48 h in early breeding subjects. ACTH was a strong secretagogue for aldosterone, causing a 3-8-fold increase in concentration. Cortisol and aldosterone responses did not vary between groups but were correlated within individuals. The ACTH challenge produced elevations in plasma glucose during late breeding and molting, suppressed testosterone and thyroid hormone at 48 h in early breeding, and increased plasma non-esterified fatty acids and ketoacids during molting. These data suggest that sensitivity of the HPA axis is maintained but the metabolic impacts of cortisol and feedback inhibition of the axis vary with life history stage. Strong impacts on testosterone and thyroid hormone suggest the importance of maintaining low cortisol levels during the breeding fast. These data suggest that metabolic adaptations to extended fasting in NES include alterations in tissue responses to hormones that mitigate deleterious impacts of acute or moderately sustained stress responses.
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Affiliation(s)
- David C Ensminger
- Dept. of Biology, Sonoma State University, 1801 E. Cotati Ave., Rohnert Park, CA 94928, USA
| | - Derek A Somo
- Dept. of Biology, Sonoma State University, 1801 E. Cotati Ave., Rohnert Park, CA 94928, USA
| | - Dorian S Houser
- Dept. of Biology, Sonoma State University, 1801 E. Cotati Ave., Rohnert Park, CA 94928, USA
| | - Daniel E Crocker
- Dept. of Biology, Sonoma State University, 1801 E. Cotati Ave., Rohnert Park, CA 94928, USA.
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Crocker DE, Champagne CD, Fowler MA, Houser DS. Adiposity and fat metabolism in lactating and fasting northern elephant seals. Adv Nutr 2014; 5:57-64. [PMID: 24425723 PMCID: PMC3884100 DOI: 10.3945/an.113.004663] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Several taxa of animals fast completely from food and water during energy-intensive periods such as lactation, breeding, and development. In elephant seals, these behaviors are sustained by high adiposity, high rates of fat mobilization, and reduced oxidation of carbohydrates and proteins. Adiposity and the regulation of lipolysis directly affect lactation energetics, milk composition, and mating success. Long-term fasting induces changes in regulation of lipolysis and lipid metabolism that influence fatty acid (FA) availability and the onset of insulin resistance. Hypoinsulinemia and elevated circulating FAs are also associated with several unique features of carbohydrate metabolism, including elevated plasma glucose, gluconeogenesis, and Cori cycle activity as well as high rates of pyruvate and tricarboxylic acid cycling. Glucose-lactate pools and triacylglycerol-FA cycles may be linked via glyceroneogenesis and this may be an important pathway influencing both fat and carbohydrate metabolism. Together, these features allow a sustained, high intensity, fat-based metabolism without substantial accumulation of ketoacids.
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Affiliation(s)
- Daniel E. Crocker
- Sonoma State University, Rohnert Park, CA;,To whom correspondence should be addressed. E-mail:
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