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Kjeld T, Krag TO, Brenøe A, Møller AM, Arendrup HC, Højberg J, Fuglø D, Hancke S, Tolbod LP, Gormsen LC, Vissing J, Hansen EG. Hemoglobin concentration and blood shift during dry static apnea in elite breath hold divers. Front Physiol 2024; 15:1305171. [PMID: 38745836 PMCID: PMC11092981 DOI: 10.3389/fphys.2024.1305171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 01/23/2024] [Indexed: 05/16/2024] Open
Abstract
Introduction Elite breath-hold divers (BHD) enduring apneas of more than 5 min are characterized by tolerance to arterial blood oxygen levels of 4.3 kPa and low oxygen-consumption in their hearts and skeletal muscles, similar to adult seals. Adult seals possess an adaptive higher hemoglobin-concentration and Bohr effect than pups, and when sedated, adult seals demonstrate a blood shift from the spleen towards the brain, lungs, and heart during apnea. We hypothesized these observations to be similar in human BHD. Therefore, we measured hemoglobin- and 2,3-biphosphoglycerate-concentrations in BHD (n = 11) and matched controls (n = 11) at rest, while myocardial mass, spleen and lower extremity volumes were assessed at rest and during apnea in BHD. Methods and results After 4 min of apnea, left ventricular myocardial mass (LVMM) determined by 15O-H2O-PET/CT (n = 6) and cardiac MRI (n = 6), was unaltered compared to rest. During maximum apnea (∼6 min), lower extremity volume assessed by DXA-scan revealed a ∼268 mL decrease, and spleen volume, assessed by ultrasonography, decreased ∼102 mL. Compared to age, BMI and VO2max matched controls (n = 11), BHD had similar spleen sizes and 2,3- biphosphoglycerate-concentrations, but higher total hemoglobin-concentrations. Conclusion Our results indicate: 1) Apnea training in BHD may increase hemoglobin concentration as an oxygen conserving adaptation similar to adult diving mammals. 2) The blood shift during dry apnea in BHD is 162% more from the lower extremities than from the spleen. 3) In contrast to the previous theory of the blood shift demonstrated in sedated adult seals, blood shift is not towards the heart during dry apnea in humans.
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Affiliation(s)
- Thomas Kjeld
- Copenhagen Neuromuscular Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Thomas O. Krag
- Copenhagen Neuromuscular Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Anders Brenøe
- Department of Clinical Medicine, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Ann Merete Møller
- Department of Anesthesiology, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
| | | | - Jens Højberg
- Department of Cardiothoracic Anesthesiology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Dan Fuglø
- Department of Nuclear Medicine, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Søren Hancke
- Department of Clinical Medicine, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Lars Poulsen Tolbod
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - Lars Christian Gormsen
- Department of Nuclear Medicine and PET Centre, Aarhus University Hospital, Aarhus, Denmark
| | - John Vissing
- Copenhagen Neuromuscular Center, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Egon Godthaab Hansen
- Department of Anesthesiology, Herlev Hospital, University of Copenhagen, Copenhagen, Denmark
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2
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Northey AD, Holser RR, Shipway GT, Costa DP, Crocker DE. Adrenal response to ACTH challenge alters thyroid and immune function and varies with body reserves in molting adult female northern elephant seals. Am J Physiol Regul Integr Comp Physiol 2023; 325:R1-R12. [PMID: 37125769 PMCID: PMC10259847 DOI: 10.1152/ajpregu.00277.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/24/2023] [Accepted: 04/23/2023] [Indexed: 05/02/2023]
Abstract
Intrinsic stressors associated with life-history stages may alter the responsiveness of the hypothalamic-pituitary-adrenal axis and responses to extrinsic stressors. We administered adrenocorticotropic hormone (ACTH) to 24 free-ranging adult female northern elephant seals (NESs) at two life-history stages: early and late in their molting period and measured a suite of endocrine, immune, and metabolite responses. Our objective was to evaluate the impact of extended, high-energy fasting on adrenal responsiveness. Animals were blood sampled every 30 min for 120 min post-ACTH injection, then blood was sampled 24 h later. In response to ACTH injection, cortisol levels increased 8- to 10-fold and remained highly elevated compared with baseline at 24 h. Aldosterone levels increased 6- to 9-fold before returning to baseline at 24 h. The magnitude of cortisol and aldosterone release were strongly associated, and both were greater after extended fasting. We observed an inverse relationship between fat mass and the magnitude of cortisol and aldosterone responses, suggesting that body reserves influenced adrenal responsiveness. Sustained elevation in cortisol was associated with alterations in thyroid hormones; both tT3 and tT4 concentrations were suppressed at 24 h, while rT3 increased. Immune cytokine IL-1β was also suppressed after 24 h of cortisol elevation, and numerous acute and sustained impacts on substrate metabolism were evident. Our data suggest that female NESs are more sensitive to stress after the molt fast and that acute stress events can have important impacts on metabolism and immune function. These findings highlight the importance of considering life-history context when assessing the impacts of anthropogenic stressors on wildlife.
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Affiliation(s)
- Allison D Northey
- Department of Biology, Sonoma State University, Rohnert Park, California, United States
| | - Rachel R Holser
- Department of Ecology and Evolutionary Biology, Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, United States
| | - Garrett T Shipway
- Department of Biology, Sonoma State University, Rohnert Park, California, United States
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, United States
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California, United States
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3
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Holser RR, Crocker DE, Favilla AR, Adachi T, Keates TR, Naito Y, Costa DP. Effects of disease on foraging behaviour and success in an individual free-ranging northern elephant seal. CONSERVATION PHYSIOLOGY 2023; 11:coad034. [PMID: 37250476 PMCID: PMC10214463 DOI: 10.1093/conphys/coad034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 04/14/2023] [Accepted: 05/17/2023] [Indexed: 05/31/2023]
Abstract
Evaluating consequences of stressors on vital rates in marine mammals is of considerable interest to scientific and regulatory bodies. Many of these species face numerous anthropogenic and environmental disturbances. Despite its importance as a critical form of mortality, little is known about disease progression in air-breathing marine megafauna at sea. We examined the movement, diving, foraging behaviour and physiological state of an adult female northern elephant seal (Mirounga angustirostris) who suffered from an infection while at sea. Comparing her to healthy individuals, we identified abnormal behavioural patterns from high-resolution biologging instruments that are likely indicators of diseased and deteriorating condition. We observed continuous extended (3-30 minutes) surface intervals coinciding with almost no foraging attempts (jaw motion) during 2 weeks of acute illness early in her post-breeding foraging trip. Elephant seals typically spend ~ 2 minutes at the surface. There were less frequent but highly extended (30-200 minutes) surface periods across the remainder of the trip. Dive duration declined throughout the trip rather than increasing. This seal returned in the poorest body condition recorded for an adult female elephant seal (18.3% adipose tissue; post-breeding trip average is 30.4%). She was immunocompromised at the end of her foraging trip and has not been seen since that moulting season. The timing and severity of the illness, which began during the end of the energy-intensive lactation fast, forced this animal over a tipping point from which she could not recover. Additional physiological constraints to foraging, including thermoregulation and oxygen consumption, likely exacerbated her already poor condition. These findings improve our understanding of illness in free-ranging air-breathing marine megafauna, demonstrate the vulnerability of individuals at critical points in their life history, highlight the importance of considering individual health when interpreting biologging data and could help differentiate between malnutrition and other causes of at-sea mortality from transmitted data.
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Affiliation(s)
- Rachel R Holser
- Corresponding author: Institute of Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA. Tel.: +1 253-514-0110.
| | - Daniel E Crocker
- Department of Biology, Sonoma State University, Rohnert Park, California, 94928, USA
| | - Arina R Favilla
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, 95064 USA
| | - Taiki Adachi
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, 95064 USA
- National Institute of Polar Research, Tachikawa, Tokyo, Japan
| | - Theresa R Keates
- Department of Ocean Sciences, University of California Santa Cruz, Santa Cruz, California, 95064, USA
| | - Yasuhiko Naito
- National Institute of Polar Research, Tachikawa, Tokyo, Japan
| | - Daniel P Costa
- Institute of Marine Sciences, University of California Santa Cruz, 115 McAllister Way, Santa Cruz, CA, 95060, USA
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, California, 95064 USA
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4
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Miller ML, Glandon HL, Tift MS, Pabst DA, Koopman HN. Remarkable consistency of spinal cord microvasculature in highly adapted diving odontocetes. Front Physiol 2022; 13:1011869. [PMID: 36505066 PMCID: PMC9728530 DOI: 10.3389/fphys.2022.1011869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 11/02/2022] [Indexed: 11/24/2022] Open
Abstract
Odontocetes are breath-hold divers with a suite of physiological, anatomical, and behavioral adaptations that are highly derived and vastly different from those of their terrestrial counterparts. Because of these adaptations for diving, odontocetes were originally thought to be exempt from the harms of nitrogen gas embolism while diving. However, recent studies have shown that these mammals may alter their dive behavior in response to anthropogenic sound, leading to the potential for nitrogen supersaturation and bubble formation which may cause decompression sickness in the central nervous system (CNS). We examined the degree of interface between blood, gases, and neural tissues in the spinal cord by quantifying its microvascular characteristics in five species of odontocetes (Tursiops truncatus, Delphinus delphis, Grampus griseus, Kogia breviceps, and Mesoplodon europaeus) and a model terrestrial species (the pig-Sus scrofa domesticus) for comparison. This approach allowed us to compare microvascular characteristics (microvascular density, branching, and diameter) at several positions (cervical, thoracic, and lumbar) along the spinal cord from odontocetes that are known to be either deep or shallow divers. We found no significant differences (p < 0.05 for all comparisons) in microvessel density (9.30-11.18%), microvessel branching (1.60-2.12 branches/vessel), or microvessel diameter (11.83-16.079 µm) between odontocetes and the pig, or between deep and shallow diving odontocete species. This similarity of spinal cord microvasculature anatomy in several species of odontocetes as compared to the terrestrial mammal is in contrast to the wide array of remarkable physio-anatomical adaptations marine mammals have evolved within their circulatory system to cope with the physiological demands of diving. These results, and other studies on CNS lipids, indicate that the spinal cords of odontocetes do not have specialized features that might serve to protect them from Type II DCS.
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Affiliation(s)
- Megan L. Miller
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, United States
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Madelaire CB, Klink AC, Israelsen WJ, Hindle AG. Fibroblasts as an experimental model system for the study of comparative physiology. Comp Biochem Physiol B Biochem Mol Biol 2022; 260:110735. [PMID: 35321853 DOI: 10.1016/j.cbpb.2022.110735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 10/18/2022]
Abstract
Mechanistic evaluations of processes that underlie organism-level physiology often require reductionist approaches. Dermal fibroblasts offer one such approach. These cells are easily obtained from minimally invasive skin biopsy, making them appropriate for the study of protected and/or logistically challenging species. Cell culture approaches permit extensive and fine-scale sampling regimes as well as gene manipulation techniques that are not feasible in vivo. Fibroblast isolation and culture protocols are outlined here for primary cells, and the benefits and drawbacks of immortalization are discussed. We show examples of physiological metrics that can be used to characterize primary cells (oxygen consumption, translation, proliferation) and readouts that can be informative in understanding cell-level responses to environmental stress (lactate production, heat shock protein induction). Importantly, fibroblasts may display fidelity to whole animal physiological phenotypes, facilitating their study. Fibroblasts from Antarctic Weddell seals show greater resilience to low temperatures and hypoxia exposure than fibroblasts from humans or rats. Fibroblast oxygen consumption rates are not affected by temperature stress in the heat-tolerant camel, whereas similar temperature exposures depress mitochondrial metabolism in fibroblasts from rhinoceros. Finally, dermal fibroblasts from a hibernator, the meadow jumping mouse, better resist experimental cooling than a fibroblast line from the laboratory mouse, with the hibernator demonstrating a greater maintenance of homeostatic processes such as protein translation. These results exemplify the parallels that can be drawn between fibroblast physiology and expectations in vivo, and provide evidence for the power of fibroblasts as a model system to understand comparative physiology and biomedicine.
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Affiliation(s)
- Carla B Madelaire
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - Amy C Klink
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA
| | - William J Israelsen
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA; Skroot Laboratory, Inc., Ames, IA, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, USA.
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Geßner C, Krüger A, Folkow LP, Fehrle W, Mikkelsen B, Burmester T. Transcriptomes Suggest That Pinniped and Cetacean Brains Have a High Capacity for Aerobic Metabolism While Reducing Energy-Intensive Processes Such as Synaptic Transmission. Front Mol Neurosci 2022; 15:877349. [PMID: 35615068 PMCID: PMC9126210 DOI: 10.3389/fnmol.2022.877349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/19/2022] [Indexed: 11/24/2022] Open
Abstract
The mammalian brain is characterized by high energy expenditure and small energy reserves, making it dependent on continuous vascular oxygen and nutritional supply. The brain is therefore extremely vulnerable to hypoxia. While neurons of most terrestrial mammals suffer from irreversible damage after only short periods of hypoxia, neurons of the deep-diving hooded seal (Cystophora cristata) show a remarkable hypoxia-tolerance. To identify the molecular mechanisms underlying the intrinsic hypoxia-tolerance, we excised neurons from the visual cortices of hooded seals and mice (Mus musculus) by laser capture microdissection. A comparison of the neuronal transcriptomes suggests that, compared to mice, hooded seal neurons are endowed with an enhanced aerobic metabolic capacity, a reduced synaptic transmission and an elevated antioxidant defense. Publicly available whole-tissue brain transcriptomes of the bowhead whale (Balaena mysticetus), long-finned pilot whale (Globicephala melas), minke whale (Balaenoptera acutorostrata) and killer whale (Orcinus orca), supplemented with 2 newly sequenced long-finned pilot whales, suggest that, compared to cattle (Bos taurus), the cetacean brain also displays elevated aerobic capacity and reduced synaptic transmission. We conclude that the brain energy balance of diving mammals is preserved during diving, due to reduced synaptic transmission that limits energy expenditure, while the elevated aerobic capacity allows efficient use of oxygen to restore energy balance during surfacing between dives.
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Affiliation(s)
- Cornelia Geßner
- Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Alena Krüger
- Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Lars P. Folkow
- Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
| | - Wilfrid Fehrle
- Institute of Pathology With the Sections Molecular Pathology and Cytopathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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Noh HJ, Turner-Maier J, Schulberg SA, Fitzgerald ML, Johnson J, Allen KN, Hückstädt LA, Batten AJ, Alfoldi J, Costa DP, Karlsson EK, Zapol WM, Buys ES, Lindblad-Toh K, Hindle AG. The Antarctic Weddell seal genome reveals evidence of selection on cardiovascular phenotype and lipid handling. Commun Biol 2022; 5:140. [PMID: 35177770 PMCID: PMC8854659 DOI: 10.1038/s42003-022-03089-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 01/31/2022] [Indexed: 12/24/2022] Open
Abstract
AbstractThe Weddell seal (Leptonychotes weddellii) thrives in its extreme Antarctic environment. We generated the Weddell seal genome assembly and a high-quality annotation to investigate genome-wide evolutionary pressures that underlie its phenotype and to study genes implicated in hypoxia tolerance and a lipid-based metabolism. Genome-wide analyses included gene family expansion/contraction, positive selection, and diverged sequence (acceleration) compared to other placental mammals, identifying selection in coding and non-coding sequence in five pathways that may shape cardiovascular phenotype. Lipid metabolism as well as hypoxia genes contained more accelerated regions in the Weddell seal compared to genomic background. Top-significant genes were SUMO2 and EP300; both regulate hypoxia inducible factor signaling. Liver expression of four genes with the strongest acceleration signals differ between Weddell seals and a terrestrial mammal, sheep. We also report a high-density lipoprotein-like particle in Weddell seal serum not present in other mammals, including the shallow-diving harbor seal.
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Physiology, pathophysiology and (mal)adaptations to chronic apnoeic training: a state-of-the-art review. Eur J Appl Physiol 2021; 121:1543-1566. [PMID: 33791844 PMCID: PMC8144079 DOI: 10.1007/s00421-021-04664-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 03/04/2021] [Indexed: 02/08/2023]
Abstract
Breath-hold diving is an activity that humans have engaged in since antiquity to forage for resources, provide sustenance and to support military campaigns. In modern times, breath-hold diving continues to gain popularity and recognition as both a competitive and recreational sport. The continued progression of world records is somewhat remarkable, particularly given the extreme hypoxaemic and hypercapnic conditions, and hydrostatic pressures these athletes endure. However, there is abundant literature to suggest a large inter-individual variation in the apnoeic capabilities that is thus far not fully understood. In this review, we explore developments in apnoea physiology and delineate the traits and mechanisms that potentially underpin this variation. In addition, we sought to highlight the physiological (mal)adaptations associated with consistent breath-hold training. Breath-hold divers (BHDs) are evidenced to exhibit a more pronounced diving-response than non-divers, while elite BHDs (EBHDs) also display beneficial adaptations in both blood and skeletal muscle. Importantly, these physiological characteristics are documented to be primarily influenced by training-induced stimuli. BHDs are exposed to unique physiological and environmental stressors, and as such possess an ability to withstand acute cerebrovascular and neuronal strains. Whether these characteristics are also a result of training-induced adaptations or genetic predisposition is less certain. Although the long-term effects of regular breath-hold diving activity are yet to be holistically established, preliminary evidence has posed considerations for cognitive, neurological, renal and bone health in BHDs. These areas should be explored further in longitudinal studies to more confidently ascertain the long-term health implications of extreme breath-holding activity.
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Allen KN, Vázquez-Medina JP. Natural Tolerance to Ischemia and Hypoxemia in Diving Mammals: A Review. Front Physiol 2019; 10:1199. [PMID: 31620019 PMCID: PMC6763568 DOI: 10.3389/fphys.2019.01199] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 09/03/2019] [Indexed: 12/15/2022] Open
Abstract
Reperfusion injury follows ischemia/reperfusion events occurring during myocardial infarction, stroke, embolism, and other peripheral vascular diseases. Decreased blood flow and reduced oxygen tension during ischemic episodes activate cellular pathways that upregulate pro-inflammatory signaling and promote oxidant generation. Reperfusion after ischemia recruits inflammatory cells to the vascular wall, further exacerbating oxidant production and ultimately resulting in cell death, tissue injury, and organ dysfunction. Diving mammals tolerate repetitive episodes of peripheral ischemia/reperfusion as part of the cardiovascular adjustments supporting long duration dives. These adjustments allow marine mammals to optimize the use of their body oxygen stores while diving but can result in selectively reduced perfusion to peripheral tissues. Remarkably, diving mammals show no apparent detrimental effects associated with these ischemia/reperfusion events. Here, we review the current knowledge regarding the strategies marine mammals use to suppress inflammation and cope with oxidant generation potentially derived from diving-induced ischemia/reperfusion.
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Allen KN, Vázquez-Medina JP, Lawler JM, Mellish JAE, Horning M, Hindle AG. Muscular apoptosis but not oxidative stress increases with old age in a long-lived diver, the Weddell seal. ACTA ACUST UNITED AC 2019; 222:jeb.200246. [PMID: 31171605 DOI: 10.1242/jeb.200246] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 05/30/2019] [Indexed: 01/07/2023]
Abstract
Seals experience repeated bouts of ischemia-reperfusion while diving, potentially exposing their tissues to increased oxidant generation and thus oxidative damage and accelerated aging. We contrasted markers of oxidative damage with antioxidant profiles across age and sex for propulsive (longissismus dorsi) and maneuvering (pectoralis) muscles of Weddell seals to determine whether previously observed morphological senescence is associated with oxidative stress. In longissismus dorsi, old (age 17-26 years) seals exhibited a nearly 2-fold increase in apoptosis over young (age 9-16 years) seals. There was no evidence of age-associated changes in lipid peroxidation or enzymatic antioxidant profiles. In pectoralis, 4-hydroxynonenal-Lys (4-HNE-Lys) levels increased 1.5-fold in old versus young seals, but lipid hydroperoxide levels and apoptotic index did not vary with age. Glutathione peroxidase activity was 1.5-fold higher in pectoralis of old versus young animals, but no other antioxidants changed with age in this muscle. With respect to sex, no differences in lipid hydroperoxides or apoptosis were observed in either muscle. Males had higher HSP70 expression (1.4-fold) and glutathione peroxidase activity (1.3-fold) than females in longissismus dorsi, although glutathione reductase activity was 1.4-fold higher in females. No antioxidants varied with sex in pectoralis. These results show that apoptosis is not associated with oxidative stress in aged Weddell seal muscles. Additionally, the data suggest that adult seals utilize sex-specific antioxidant strategies in longissismus dorsi but not pectoralis to protect skeletal muscles from oxidative damage.
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Affiliation(s)
- Kaitlin N Allen
- Department of Integrative Biology, University of California Berkeley, 3040 Valley Life Sciences Building #3140, Berkeley, CA 94720, USA
| | - José Pablo Vázquez-Medina
- Department of Integrative Biology, University of California Berkeley, 3040 Valley Life Sciences Building #3140, Berkeley, CA 94720, USA
| | - John M Lawler
- Department of Health and Kinesiology, Texas A&M University, College Station, TX 77840, USA
| | - Jo-Ann E Mellish
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, USA
| | - Markus Horning
- Alaska SeaLife Center, 301 Railway Avenue, Seward, AK 99664, USA.,Department of Fisheries & Wildlife, Marine Mammal Institute, Oregon State University, 2030 Marine Science Drive, Newport, OR 97365, USA
| | - Allyson G Hindle
- School of Life Sciences, University of Nevada Las Vegas, 4505 S. Maryland Pkwy, Las Vegas, NV 89154, USA
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Ghosh A, Dai Y, Biswas P, Stuehr DJ. Myoglobin maturation is driven by the hsp90 chaperone machinery and by soluble guanylyl cyclase. FASEB J 2019; 33:9885-9896. [PMID: 31170354 DOI: 10.1096/fj.201802793rr] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Myoglobin (Mb) maturation involves heme incorporation as a final step. We investigated a role for heat shock protein (hsp) 90 in Mb maturation in C2C12 skeletal muscle myoblasts and cell lines. We found the following: 1) Hsp90 directly interacts preferentially with heme-free Mb both in purified form and in cells. 2) Hsp90 drives heme insertion into apoprotein-Mb in an ATP-dependent process. 3) During differentiation of C2C12 myoblasts into myotubes, the apo-Mb-hsp90 complex associates with 5 cell cochaperons, Hsp70, activator of hsp90 ATPase protein 1 (Aha1), alanyl-tRNA synthetase domain containing 1 (Aarsd1), cell division cycle 37 (Cdc37), and stress induced phosphoprotein 1 (STIP1) in a pattern that is consistent with their enabling Mb maturation. 4) Mb heme insertion was significantly increased in cells that had a functional soluble guanylyl cyclase (sGC)-cGMP signaling pathway and was diminished upon small interfering RNA knockdown of sGCβ1 or upon overexpression of a phosphodiesterase to prevent cGMP buildup. Together, our findings suggest that hsp90 works in concert with cochaperons (Hsp70, Aha1, Aarsd1, STIP1, and Cdc37) and an active sGC-cGMP signaling pathway to promote heme insertion into immature apo-Mb, and thus generate functional Mb during muscle myotube formation. This fills gaps in our understanding and suggests new ways to potentially control these processes.-Ghosh, A., Dai, Y., Biswas, P., Stuehr, D. J. Myoglobin maturation is driven by the hsp90 chaperone machinery and by soluble guanylyl cyclase.
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Affiliation(s)
- Arnab Ghosh
- Department of Inflammation and Immunity, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio, USA
| | - Yue Dai
- Department of Inflammation and Immunity, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio, USA
| | - Pranjal Biswas
- Department of Inflammation and Immunity, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio, USA
| | - Dennis J Stuehr
- Department of Inflammation and Immunity, Lerner Research Institute, The Cleveland Clinic, Cleveland, Ohio, USA
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Kjeld T, Stride N, Gudiksen A, Hansen EG, Arendrup HC, Horstmann PF, Zerahn B, Jensen LT, Nordsborg N, Bejder J, Halling JF. Oxygen conserving mitochondrial adaptations in the skeletal muscles of breath hold divers. PLoS One 2018; 13:e0201401. [PMID: 30231055 PMCID: PMC6145504 DOI: 10.1371/journal.pone.0201401] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 07/14/2018] [Indexed: 12/22/2022] Open
Abstract
Background The performance of elite breath hold divers (BHD) includes static breath hold for more than 11 minutes, swimming as far as 300 m, or going below 250 m in depth, all on a single breath of air. Diving mammals are adapted to sustain oxidative metabolism in hypoxic conditions through several metabolic adaptations, including improved capacity for oxygen transport and mitochondrial oxidative phosphorylation in skeletal muscle. It was hypothesized that similar adaptations characterized human BHD. Hence, the purpose of this study was to examine the capacity for oxidative metabolism in skeletal muscle of BHD compared to matched controls. Methods Biopsies were obtained from the lateral vastus of the femoral muscle from 8 Danish BHD and 8 non-diving controls (Judo athletes) matched for morphometry and whole body VO2max. High resolution respirometry was used to determine mitochondrial respiratory capacity and leak respiration with simultaneous measurement of mitochondrial H2O2 emission. Maximal citrate synthase (CS) and 3-hydroxyacyl CoA dehydrogenase (HAD) activity were measured in muscle tissue homogenates. Western Blotting was used to determine protein contents of respiratory complex I-V subunits and myoglobin in muscle tissue lysates. Results Muscle biopsies of BHD revealed lower mitochondrial leak respiration and electron transfer system (ETS) capacity and higher H2O2 emission during leak respiration than controls, with no differences in enzyme activities (CS and HAD) or protein content of mitochondrial complex subunits myoglobin, myosin heavy chain isoforms, markers of glucose metabolism and antioxidant enzymes. Conclusion We demonstrated for the first time in humans, that the skeletal muscles of BHD are characterized by lower mitochondrial oxygen consumption both during low leak and high (ETS) respiration than matched controls. This supports previous observations of diving mammals demonstrating a lower aerobic mitochondrial capacity of the skeletal muscles as an oxygen conserving adaptation during prolonged dives.
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Affiliation(s)
- Thomas Kjeld
- Department of Anesthesiology, Herlev Hospital, Herlev, University of Copenhagen, Denmark
- * E-mail:
| | - Nis Stride
- Department of Cardiology, Rigshospitalet, Copenhagen, University of Copenhagen, Denmark
| | - Anders Gudiksen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Egon Godthaab Hansen
- Department of Anesthesiology, Herlev Hospital, Herlev, University of Copenhagen, Denmark
| | | | | | - Bo Zerahn
- Department of Clinical Physiology and Nuclear Medicine, Herlev Hospital, Herlev, University of Copenhagen, Denmark
| | - Lars Thorbjørn Jensen
- Department of Clinical Physiology and Nuclear Medicine, Herlev Hospital, Herlev, University of Copenhagen, Denmark
| | - Nikolai Nordsborg
- Department of Nutrition, Exercise and Sport (NEXS), Copenhagen, University of Copenhagen, Denmark
| | - Jacob Bejder
- Department of Nutrition, Exercise and Sport (NEXS), Copenhagen, University of Copenhagen, Denmark
| | - Jens Frey Halling
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
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13
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Abstract
This Review focuses on the original papers that have made a difference to our thinking and were first in describing an adaptation to diving, and less on those that later repeated the findings with better equipment. It describes some important anatomical peculiarities of phocid seals, as well as their many physiological responses to diving. In so doing, it is argued that the persistent discussions on the relevance and differences between responses seen in forced dives in the laboratory and those during free diving in the wild are futile. In fact, both are two sides of the same coin, aimed at protecting the body against asphyxic insult and extending diving performance.
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Affiliation(s)
- Arnoldus Schytte Blix
- Department of Arctic and Marine Biology, UiT - The Arctic University of Norway, 9037 Tromsø, Norway .,St Catharine's College, Cambridge CB2 1RL, UK
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14
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Rivero JLL. Locomotor muscle fibre heterogeneity and metabolism in the fastest large-bodied rorqual: the fin whale ( Balaenoptera physalus). ACTA ACUST UNITED AC 2018; 221:jeb.177758. [PMID: 29691309 DOI: 10.1242/jeb.177758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 04/18/2018] [Indexed: 11/20/2022]
Abstract
From a terrestrial ancestry, the fin whale (Balaenoptera physalus) is one of the largest animals on Earth with a sprinter anti-predator strategy, and a characteristic feeding mode, lunge feeding, which involves bouts of high-intensity muscle activity demanding high metabolic output. We investigated the locomotor muscle morphology and metabolism of this cetacean to determine whether its muscle profile (1) explains this unique swimming performance and feeding behaviour, (2) is or is not homogeneous within the muscle, and (3) predicts allometric variations inherent to an extreme body size. A predominantly fast-glycolytic phenotype characterized the fin whale locomotor muscle, composed of abundant fast-twitch (type IIA) fibres with high glycolytic potential, low oxidative capacity, relatively small size, and reduced number of capillaries. Compared with superficial areas, deep regions of this muscle exhibited a slower and more oxidative profile, suggesting a division of labour between muscle strata. As expected, the fin whale locomotor muscle only expressed the two slowest myosin heavy chain isoforms (I and IIA). However, it displayed anaerobic (glycolytic) and aerobic (lipid-based metabolism) capabilities higher than would be predicted from the allometric perspective of its extreme body size. Relationships between muscle metabolism and body mass were fibre-type specific. The 'sprinter' profile of the fin whale swimming muscle, particularly of its superficial compartment, supports physiological demands during both high-speed swimming and the lunge, when energy expenditure reaches maximal or supramaximal levels. Comparatively, the slower and more oxidative profile of the deep compartment of this muscle seems to be well designed for sustained, low-intensity muscle activity during routine swimming.
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Affiliation(s)
- José-Luis L Rivero
- Laboratory of Muscular Biopathology, Department of Comparative Anatomy and Pathological Anatomy, Faculty of Veterinary Sciences, University of Cordoba, Campus Universitario de Rabanales, 14014 Cordoba, Spain
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15
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Jue T, Simond G, Wright TJ, Shih L, Chung Y, Sriram R, Kreutzer U, Davis RW. Effect of fatty acid interaction on myoglobin oxygen affinity and triglyceride metabolism. J Physiol Biochem 2017; 73:359-370. [PMID: 28357578 DOI: 10.1007/s13105-017-0559-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/08/2017] [Indexed: 01/04/2023]
Abstract
Recent studies have suggested myoglobin (Mb) may have other cellular functions in addition to storing and transporting O2. Indeed, NMR experiments have shown that the saturated fatty acid (FA) palmitate (PA) can interact with myoglobin (Mb) in its ligated state (MbCO and MbCN) but does not interact with Mb in its deoxygenated state. The observation has led to the hypothesis that Mb can also serve as a fatty acid transporter. The present study further investigates fatty acid interaction with the physiological states of Mb using the more soluble but unsaturated fatty acid, oleic acid (OA). OA binds to MbCO but does not bind to deoxy Mb. OA binding to Mb, however, does not alter its O2 affinity. Without any Mb, muscle has a significantly lower level of triglyceride (TG). In Mb knock-out (MbKO) mice, both heart and skeletal muscles have lower level of TG relative to the control mice. Training further decreases the relative TG in the MbKO skeletal muscle. Nevertheless, the absence of Mb and lower TG level in muscle does not impair the MbKO mouse performance as evidenced by voluntary wheel running measurements. The results support the hypothesis of a complex physiological role for Mb, especially with respect to fatty acid metabolism.
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Affiliation(s)
- Thomas Jue
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, 95616-8635, USA.
| | - Gregory Simond
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, 95616-8635, USA
| | - Traver J Wright
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Lifan Shih
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, 95616-8635, USA
| | - Youngran Chung
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, 95616-8635, USA
| | - Renuka Sriram
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, 95616-8635, USA
| | - Ulrike Kreutzer
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, 95616-8635, USA
| | - Randall W Davis
- Department of Wildlife and Fisheries Sciences, Texas A&M University, College Station, TX, 77843, USA
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16
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Pabst DA, McLellan WA, Rommel SA. How to Build a Deep Diver: The Extreme Morphology of Mesoplodonts. Integr Comp Biol 2016; 56:1337-1348. [DOI: 10.1093/icb/icw126] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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17
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López-Cruz RI, Crocker DE, Gaxiola-Robles R, Bernal JA, Real-Valle RA, Lugo-Lugo O, Zenteno-Savín T. Plasma Hypoxanthine-Guanine Phosphoribosyl Transferase Activity in Bottlenose Dolphins Contributes to Avoiding Accumulation of Non-recyclable Purines. Front Physiol 2016; 7:213. [PMID: 27375492 PMCID: PMC4898134 DOI: 10.3389/fphys.2016.00213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/23/2016] [Indexed: 02/04/2023] Open
Abstract
Marine mammals are exposed to ischemia/reperfusion and hypoxia/reoxygenation during diving. During oxygen deprivation, adenosine triphosphate (ATP) breakdown implies purine metabolite accumulation, which in humans is associated with pathological conditions. Purine recycling in seals increases in response to prolonged fasting and ischemia. Concentrations of metabolites and activities of key enzymes in purine metabolism were examined in plasma and red blood cells from bottlenose dolphins (Tursiops truncatus) and humans. Hypoxanthine and inosine monophosphate concentrations were higher in plasma from dolphins than humans. Plasma hypoxanthine-guanine phosphoribosyl transferase (HGPRT) activity in dolphins suggests an elevated purine recycling rate, and a mechanism for avoiding accumulation of non-recyclable purines (xanthine and uric acid). Red blood cell concentrations of hypoxanthine, adenosine diphosphate, ATP and guanosine triphosphate were lower in dolphins than in humans; adenosine monophosphate and nicotinamide adenine dinucleotide concentrations were higher in dolphins. HGPRT activity in red blood cells was higher in humans than in dolphins. The lower concentrations of purine catabolism and recycling by-products in plasma from dolphins could be beneficial in providing substrates for recovery of ATP depleted during diving or vigorous swimming. These results suggest that purine salvage in dolphins could be a mechanism for delivering nucleotide precursors to tissues with high ATP and guanosine triphosphate requirements.
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Affiliation(s)
- Roberto I. López-Cruz
- Programa de Planeación Ambiental y Conservación, Laboratorio de Estrés Oxidativo, Centro de Investigaciones Biológicas del Noroeste, S.C.La Paz, México
| | | | - Ramón Gaxiola-Robles
- Programa de Planeación Ambiental y Conservación, Laboratorio de Estrés Oxidativo, Centro de Investigaciones Biológicas del Noroeste, S.C.La Paz, México
- Instituto Mexicano del Seguro Social, Hospital General de Zona No. 1La Paz, México
| | | | | | - Orlando Lugo-Lugo
- Programa de Planeación Ambiental y Conservación, Laboratorio de Estrés Oxidativo, Centro de Investigaciones Biológicas del Noroeste, S.C.La Paz, México
| | - Tania Zenteno-Savín
- Programa de Planeación Ambiental y Conservación, Laboratorio de Estrés Oxidativo, Centro de Investigaciones Biológicas del Noroeste, S.C.La Paz, México
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18
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Cartwright R, Newton C, West KM, Rice J, Niemeyer M, Burek K, Wilson A, Wall AN, Remonida-Bennett J, Tejeda A, Messi S, Marcial-Hernandez L. Tracking the Development of Muscular Myoglobin Stores in Mysticete Calves. PLoS One 2016; 11:e0145893. [PMID: 26788728 PMCID: PMC4720374 DOI: 10.1371/journal.pone.0145893] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/09/2015] [Indexed: 11/30/2022] Open
Abstract
For marine mammals, the ability to tolerate apnea and make extended dives is a defining adaptive trait, facilitating the exploitation of marine food resources. Elevated levels of myoglobin within the muscles are a consistent hallmark of this trait, allowing oxygen collected at the surface to be stored in the muscles and subsequently used to support extended dives. In mysticetes, the largest of marine predators, details on muscular myoglobin levels are limited. The developmental trajectory of muscular myoglobin stores has yet to be documented and any physiological links between early behavior and the development of muscular myoglobin stores remain unknown. In this study, we used muscle tissue samples from stranded mysticetes to investigate these issues. Samples from three different age cohorts and three species of mysticetes were included (total sample size = 18). Results indicate that in mysticete calves, muscle myoglobin stores comprise only a small percentage (17–23%) of conspecific adult myoglobin complements. Development of elevated myoglobin levels is protracted over the course of extended maturation in mysticetes. Additionally, comparisons of myoglobin levels between and within muscles, along with details of interspecific differences in rates of accumulation of myoglobin in very young mysticetes, suggest that levels of exercise may influence the rate of development of myoglobin stores in young mysticetes. This new information infers a close interplay between the physiology, ontogeny and early life history of young mysticetes and provides new insight into the pressures that may shape adaptive strategies in migratory mysticetes. Furthermore, the study highlights the vulnerability of specific age cohorts to impending changes in the availability of foraging habitat and marine resources.
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Affiliation(s)
- Rachel Cartwright
- California State University Channel Islands, Camarillo, California, United States of America
- The Keiki Kohola Project, Lahaina, Hawaii, United States of America
- * E-mail:
| | - Cori Newton
- California State University Channel Islands, Camarillo, California, United States of America
| | - Kristi M. West
- Hawaii Pacific University Stranding Program, College of Natural and Computational Sciences, Hawaii Pacific University, Kaneohe, Hawaii, United States of America
| | - Jim Rice
- Oregon Marine Mammal Stranding Network, Marine Mammal Institute, Oregon State University, Newport, Oregon, United States of America
| | - Misty Niemeyer
- International Fund for Animal Welfare, Yarmouth Port, Massachusetts, United States of America
| | - Kathryn Burek
- Alaska Veterinary Pathology Services, Eagle River, Alaska, United States of America
| | - Andrew Wilson
- California State University Channel Islands, Camarillo, California, United States of America
| | - Alison N. Wall
- California State University Channel Islands, Camarillo, California, United States of America
| | - Jean Remonida-Bennett
- California State University Channel Islands, Camarillo, California, United States of America
| | - Areli Tejeda
- California State University Channel Islands, Camarillo, California, United States of America
| | - Sarah Messi
- California State University Channel Islands, Camarillo, California, United States of America
| | - Lila Marcial-Hernandez
- California State University Channel Islands, Camarillo, California, United States of America
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19
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Sierra E, Fernández A, Espinosa de los Monteros A, Díaz-Delgado J, Bernaldo de Quirós Y, García-Álvarez N, Arbelo M, Herráez P. Comparative histology of muscle in free ranging cetaceans: shallow versus deep diving species. Sci Rep 2015; 5:15909. [PMID: 26514564 PMCID: PMC4626863 DOI: 10.1038/srep15909] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 10/05/2015] [Indexed: 12/19/2022] Open
Abstract
Different marine mammal species exhibit a wide range of diving behaviour based on their breath-hold diving capabilities. They are classically categorized as long duration, deep-diving and short duration, shallow-diving species. These abilities are likely to be related to the muscle characteristics of each species. Despite the increasing number of publications on muscle profile in different cetacean species, very little information is currently available concerning the characteristics of other muscle components in these species. In this study, we examined skeletal muscle fiber type, fiber size (cross sectional area and lesser diameter), intramuscular substrates, and perimysium-related structures, by retrospective study in 146 stranded cetaceans involving 15 different species. Additionally, we investigated diving profile-specific histological features. Our results suggest that deep diving species have higher amount of intramyocyte lipid droplets, and evidence higher percentage of intramuscular adipose tissue, and larger fibre sizes in this group of animals.
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Affiliation(s)
- E Sierra
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - A Fernández
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - A Espinosa de los Monteros
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - J Díaz-Delgado
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - Y Bernaldo de Quirós
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - N García-Álvarez
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - M Arbelo
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
| | - P Herráez
- Department of Veterinary Pathology, Institute for Animal Health, Veterinary School, University of Las Palmas de Gran Canaria, Spain
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20
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Shero MR, Costa DP, Burns JM. Scaling matters: incorporating body composition into Weddell seal seasonal oxygen store comparisons reveals maintenance of aerobic capacities. J Comp Physiol B 2015; 185:811-24. [PMID: 26164426 DOI: 10.1007/s00360-015-0922-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 06/24/2015] [Accepted: 07/02/2015] [Indexed: 12/24/2022]
Abstract
Adult Weddell seals (Leptonychotes weddellii) haul-out on the ice in October/November (austral spring) for the breeding season and reduce foraging activities for ~4 months until their molt in the austral fall (January/February). After these periods, animals are at their leanest and resume actively foraging for the austral winter. In mammals, decreased exercise and hypoxia exposure typically lead to decreased production of O2-carrying proteins and muscle wasting, while endurance training increases aerobic potential. To test whether similar effects were present in marine mammals, this study compared the physiology of 53 post-molt female Weddell seals in the austral fall to 47 pre-breeding females during the spring in McMurdo Sound, Antarctica. Once body mass and condition (lipid) were controlled for, there were no seasonal changes in total body oxygen (TBO2) stores. Within each season, hematocrit and hemoglobin values were negatively correlated with animal size, and larger animals had lower mass-specific TBO2 stores. But because larger seals had lower mass-specific metabolic rates, their calculated aerobic dive limit was similar to smaller seals. Indicators of muscular efficiency, myosin heavy chain composition, myoglobin concentrations, and aerobic enzyme activities (citrate synthase and β-hydroxyacyl CoA dehydrogenase) were likewise maintained across the year. The preservation of aerobic capacity is likely critical to foraging capabilities, so that following the molt Weddell seals can rapidly regain body mass at the start of winter foraging. In contrast, muscle lactate dehydrogenase activity, a marker of anaerobic metabolism, exhibited seasonal plasticity in this diving top predator and was lowest after the summer period of reduced activity.
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Affiliation(s)
- Michelle R Shero
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, 99508, USA. .,School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA.
| | - Daniel P Costa
- Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, 95060, USA
| | - Jennifer M Burns
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK, 99508, USA
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21
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Somo DA, Ensminger DC, Sharick JT, Kanatous SB, Crocker DE. Development of Dive Capacity in Northern Elephant Seals (Mirounga angustirostris): Reduced Body Reserves at Weaning Are Associated with Elevated Body Oxygen Stores during the Postweaning Fast. Physiol Biochem Zool 2015; 88:471-82. [PMID: 26658245 DOI: 10.1086/682386] [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
Developmental increases in dive capacity have been reported in numerous species of air-breathing marine vertebrates. Previous studies in juvenile phocid seals suggest that increases in physiological dive capacity during the postweaning fast (PWF) are critical to support independent aquatic foraging. Although there is a strong relationship between size at weaning and PWF duration and body reserves at weaning vary considerably, few studies have considered whether such variation in body reserve magnitude promotes phenotypic modulation of dive capacity development during the PWF. Phenotypic modulation, a form of developmental plasticity in which rates and degrees of expression of the developmental program are modulated by environmental factors, may enhance diving capacity in weanlings with reduced PWF durations due to smaller body reserves at weaning if reduced body reserves promote accelerated development of dive capacity. We longitudinally measured changes in blood and muscle oxygen stores and muscle metabolic enzymes over the first 8 wk of the PWF in northern elephant seals and determined whether rates of change in these parameters varied with body reserves at weaning. We assessed whether erythropoietin (EPO), thyroid hormones, serum nonesterified fatty acid levels, and iron status influenced blood and muscle oxygen store development or were influenced by body reserves at weaning. Although mass-specific plasma volume and blood volume were relatively stable across the fast, both were elevated in animals with reduced body reserves. Surprisingly, hemoglobin and mean corpuscular hemoglobin concentrations declined over the PWF while hematocrit remained stable, and these variables were not associated with body reserves or EPO. Swimming muscle myoglobin and serum iron levels increased rapidly early in the PWF and were not related to body reserves. Patterns in maximal activities of muscle enzymes suggested a decline in total aerobic and anaerobic metabolic capacity over the PWF, despite maintenance of fat oxidation capacity. These results suggest that only development of blood volume is increased in smaller weanlings and that extended fasting durations in larger weanlings do not improve physiological dive capacity.
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Affiliation(s)
- Derek A Somo
- Department of Biology, Sonoma State University, Rohnert Park, California 94928; 2Extreme Physiology Laboratory, Department of Biology, Colorado State University, Fort Collins, Colorado 80523
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22
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Moore CD, Fahlman A, Crocker DE, Robbins KA, Trumble SJ. The degradation of proteins in pinniped skeletal muscle: viability of post-mortem tissue in physiological research. CONSERVATION PHYSIOLOGY 2015; 3:cov019. [PMID: 27293704 PMCID: PMC4778441 DOI: 10.1093/conphys/cov019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/21/2015] [Accepted: 04/11/2015] [Indexed: 06/06/2023]
Abstract
As marine divers, pinnipeds have a high capacity for exercise at depth while holding their breath. With finite access to oxygen, these species need to be capable of extended aerobic exercise and conservation of energy. Pinnipeds must deal with common physiological hurdles, such as hypoxia, exhaustion and acidosis, that are common to all exercising mammals. The physiological mechanisms in marine mammals used for managing oxygen and carbon dioxide have sparked much research, but access to animals and tissues is difficult and requires permits. Deceased animals that are either bycaught or stranded provide one potential source for tissues, but the validity of biochemical data from post-mortem samples has not been rigorously assessed. Tissues collected from stranded diving mammals may be a crucial source to add to our limited knowledge on the physiology of some of these animals and important to the conservation and management of these species. We aim to determine the reliability of biochemical assays derived from post-mortem tissue and to promote the immediate sampling of stranded animals for the purpose of physiological research. In this study, we mapped the temporal degradation of muscle enzymes from biopsied Northern elephant seals (Mirounga angustirostris) and highlight recommendations for storage protocols for the best preservation of tissue. We also compared the enzymatic activity of different muscle groups (pectoral and latissimus dorsi) in relation to locomotion and measured the effects of four freeze-thaw cycles on muscle tissue enzyme function. Results indicate that enzymatic activity fluctuates greatly, especially with varying storage temperature, storage time, species and muscle group being assayed. In contrast, proteins, such as myoglobin, remain relatively continuous in their increase at 4°C for 48 h. Stranded animals can be a valuable source of biochemical data, but enzyme assays should be used only with great caution in post-mortem tissues.
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Affiliation(s)
- Colby D. Moore
- Department of Biology, Baylor University, One Bear Place, Waco, TX 76706, USA
| | - Andreas Fahlman
- Department of Life Sciences, Texas A&M University Corpus Christi, 6300 Ocean Drive, Corpus Christi, TX 78412, USA
| | - Daniel E. Crocker
- Department of Biology, Sonoma State University, 1801 East Cotati Avenue, Rohnert Park, CA 94928, USA
| | - Kathleen A. Robbins
- Department of Biology, Baylor University, One Bear Place, Waco, TX 76706, USA
| | - Stephen J. Trumble
- Department of Biology, Baylor University, One Bear Place, Waco, TX 76706, USA
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23
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Martín López LM, Miller PJO, Aguilar de Soto N, Johnson M. Gait switches in deep-diving beaked whales: biomechanical strategies for long-duration dives. J Exp Biol 2015; 218:1325-38. [DOI: 10.1242/jeb.106013] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
ABSTRACT
Diving animals modulate their swimming gaits to promote locomotor efficiency and so enable longer, more productive dives. Beaked whales perform extremely long and deep foraging dives that probably exceed aerobic capacities for some species. Here, we use biomechanical data from suction-cup tags attached to three species of beaked whales (Mesoplodon densirostris, N=10; Ziphius cavirostris, N=9; and Hyperoodon ampullatus, N=2) to characterize their swimming gaits. In addition to continuous stroking and stroke-and-glide gaits described for other diving mammals, all whales produced occasional fluke-strokes with distinctly larger dorso-ventral acceleration, which we termed ‘type-B’ strokes. These high-power strokes occurred almost exclusively during deep dive ascents as part of a novel mixed gait. To quantify body rotations and specific acceleration generated during strokes we adapted a kinematic method combining data from two sensors in the tag. Body rotations estimated with high-rate magnetometer data were subtracted from accelerometer data to estimate the resulting surge and heave accelerations. Using this method, we show that stroke duration, rotation angle and acceleration were bi-modal for these species, with B-strokes having 76% of the duration, 52% larger body rotation and four times more surge than normal strokes. The additional acceleration of B-strokes did not lead to faster ascents, but rather enabled brief glides, which may improve the overall efficiency of this gait. Their occurrence towards the end of long dives leads us to propose that B-strokes may recruit fast-twitch fibres that comprise ∼80% of swimming muscles in Blainville's beaked whales, thus prolonging foraging time at depth.
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Affiliation(s)
| | - Patrick J. O. Miller
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
| | - Natacha Aguilar de Soto
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
- BIOECOMAC (Biodiversidad, Ecología Marina y Conservación), University of La Laguna, La Laguna, 38206, Spain
| | - Mark Johnson
- SMRU (Sea Mammal Research Unit), University of St Andrews, St Andrews, Fife KY16 8LB, UK
- Department of Bioscience, Aarhus University, 8000 Aarhus C, Denmark
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24
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Atkinson S, Crocker D, Houser D, Mashburn K. Stress physiology in marine mammals: how well do they fit the terrestrial model? J Comp Physiol B 2015; 185:463-86. [PMID: 25913694 DOI: 10.1007/s00360-015-0901-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/23/2015] [Accepted: 04/09/2015] [Indexed: 12/28/2022]
Abstract
Stressors are commonly accepted as the causal factors, either internal or external, that evoke physiological responses to mediate the impact of the stressor. The majority of research on the physiological stress response, and costs incurred to an animal, has focused on terrestrial species. This review presents current knowledge on the physiology of the stress response in a lesser studied group of mammals, the marine mammals. Marine mammals are an artificial or pseudo grouping from a taxonomical perspective, as this group represents several distinct and diverse orders of mammals. However, they all are fully or semi-aquatic animals and have experienced selective pressures that have shaped their physiology in a manner that differs from terrestrial relatives. What these differences are and how they relate to the stress response is an efflorescent topic of study. The identification of the many facets of the stress response is critical to marine mammal management and conservation efforts. Anthropogenic stressors in marine ecosystems, including ocean noise, pollution, and fisheries interactions, are increasing and the dramatic responses of some marine mammals to these stressors have elevated concerns over the impact of human-related activities on a diverse group of animals that are difficult to monitor. This review covers the physiology of the stress response in marine mammals and places it in context of what is known from research on terrestrial mammals, particularly with respect to mediator activity that diverges from generalized terrestrial models. Challenges in conducting research on stress physiology in marine mammals are discussed and ways to overcome these challenges in the future are suggested.
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Affiliation(s)
- Shannon Atkinson
- School of Fisheries and Ocean Sciences, Juneau Center, University of Alaska Fairbanks, 17101 Pt. Lena Loop Road, Juneau, AK, 99801, USA,
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25
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Schlater AE, De Miranda MA, Frye MA, Trumble SJ, Kanatous SB. Changing the paradigm for myoglobin: a novel link between lipids and myoglobin. J Appl Physiol (1985) 2014; 117:307-15. [DOI: 10.1152/japplphysiol.00973.2013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Myoglobin (Mb) is an oxygen-binding muscular hemeprotein regulated via Ca2+-signaling pathways involving calcineurin (CN), with Mb increases attributed to hypoxia, exercise, and nitric oxide. Here, we show a link between lipid supplementation and increased Mb in skeletal muscle. C2C12 cells were cultured in normoxia or hypoxia with glucose or 5% lipid. Mb assays revealed that lipid cohorts had higher Mb than control cohorts in both normoxia and hypoxia, whereas Mb Western blots showed lipid cohorts having higher Mb than control cohorts exclusively under hypoxia. Normoxic cells were compared with soleus tissue from normoxic rats fed high-fat diets; whereas tissue sample cohorts showed no difference in CO-binding Mb, fat-fed rats showed increases in total Mb protein (similar to hypoxic cells), suggesting increases in modified Mb. Moreover, Mb increases did not parallel CN increases but did, however, parallel oxidative stress marker augmentation. Addition of antioxidant prevented Mb increases in lipid-supplemented normoxic cells and mitigated Mb increases in lipid-supplemented hypoxic cells, suggesting a pathway for Mb regulation through redox signaling independent of CN.
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Affiliation(s)
| | | | - Melinda A. Frye
- Biomedical Sciences, Colorado State University, Fort Collins, Colorado
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Moore CD, Crocker DE, Fahlman A, Moore MJ, Willoughby DS, Robbins KA, Kanatous SB, Trumble SJ. Ontogenetic changes in skeletal muscle fiber type, fiber diameter and myoglobin concentration in the Northern elephant seal (Mirounga angustirostris). Front Physiol 2014; 5:217. [PMID: 24959151 PMCID: PMC4050301 DOI: 10.3389/fphys.2014.00217] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2014] [Accepted: 05/20/2014] [Indexed: 11/13/2022] Open
Abstract
Northern elephant seals (Mirounga angustirostris) (NES) are known to be deep, long-duration divers and to sustain long-repeated patterns of breath-hold, or apnea. Some phocid dives remain within the bounds of aerobic metabolism, accompanied by physiological responses inducing lung compression, bradycardia, and peripheral vasoconstriction. Current data suggest an absence of type IIb fibers in pinniped locomotory musculature. To date, no fiber type data exist for NES, a consummate deep diver. In this study, NES were biopsied in the wild. Ontogenetic changes in skeletal muscle were revealed through succinate dehydrogenase (SDH) based fiber typing. Results indicated a predominance of uniformly shaped, large type I fibers and elevated myoglobin (Mb) concentrations in the longissimus dorsi (LD) muscle of adults. No type II muscle fibers were detected in any adult sampled. This was in contrast to the juvenile animals that demonstrated type II myosin in Western Blot analysis, indicative of an ontogenetic change in skeletal muscle with maturation. These data support previous hypotheses that the absence of type II fibers indicates reliance on aerobic metabolism during dives, as well as a depressed metabolic rate and low energy locomotion. We also suggest that the lack of type IIb fibers (adults) may provide a protection against ischemia reperfusion (IR) injury in vasoconstricted peripheral skeletal muscle.
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Affiliation(s)
- Colby D Moore
- Department of Biology, Baylor University Waco, TX, USA
| | - Daniel E Crocker
- Department of Biology, Sonoma State University Rohnert Park, CA, USA
| | - Andreas Fahlman
- Department of Life Sciences, Texas A&M University Corpus Christi, TX, USA
| | - Michael J Moore
- Department of Biology, Woods Hole Oceanographic Institution Woods Hole, MA, USA
| | - Darryn S Willoughby
- Department of Health, Human Performance and Recreation, Baylor University Waco, TX, USA
| | | | - Shane B Kanatous
- Department of Biology, College of Natural Sciences, Colorado State University Fort Collins, CO, USA
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Lawler JM, Kunst M, Hord JM, Lee Y, Joshi K, Botchlett RE, Ramirez A, Martinez DA. EUK-134 ameliorates nNOSμ translocation and skeletal muscle fiber atrophy during short-term mechanical unloading. Am J Physiol Regul Integr Comp Physiol 2014; 306:R470-82. [PMID: 24477538 DOI: 10.1152/ajpregu.00371.2013] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Reduced mechanical loading during bedrest, spaceflight, and casting, causes rapid morphological changes in skeletal muscle: fiber atrophy and reduction of slow-twitch fibers. An emerging signaling event in response to unloading is the translocation of neuronal nitric oxide synthase (nNOSμ) from the sarcolemma to the cytosol. We used EUK-134, a cell-permeable mimetic of superoxide dismutase and catalase, to test the role of redox signaling in nNOSμ translocation and muscle fiber atrophy as a result of short-term (54 h) hindlimb unloading. Fischer-344 rats were divided into ambulatory control, hindlimb-unloaded (HU), and hindlimb-unloaded + EUK-134 (HU-EUK) groups. EUK-134 mitigated the unloading-induced phenotype, including muscle fiber atrophy and muscle fiber-type shift from slow to fast. nNOSμ immunolocalization at the sarcolemma of the soleus was reduced with HU, while nNOSμ protein content in the cytosol increased with unloading. Translocation of nNOS from the sarcolemma to cytosol was virtually abolished by EUK-134. EUK-134 also mitigated dephosphorylation at Thr-32 of FoxO3a during HU. Hindlimb unloading elevated oxidative stress (4-hydroxynonenal) and increased sarcolemmal localization of Nox2 subunits gp91phox (Nox2) and p47phox, effects normalized by EUK-134. Thus, our findings are consistent with the hypothesis that oxidative stress triggers nNOSμ translocation from the sarcolemma and FoxO3a dephosphorylation as an early event during mechanical unloading. Thus, redox signaling may serve as a biological switch for nNOS to initiate morphological changes in skeletal muscle fibers.
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Affiliation(s)
- John M Lawler
- Redox Biology and Cell Signaling Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas
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28
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Panneton WM. The mammalian diving response: an enigmatic reflex to preserve life? Physiology (Bethesda) 2014; 28:284-97. [PMID: 23997188 DOI: 10.1152/physiol.00020.2013] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mammalian diving response is a remarkable behavior that overrides basic homeostatic reflexes. It is most studied in large aquatic mammals but is seen in all vertebrates. Pelagic mammals have developed several physiological adaptations to conserve intrinsic oxygen stores, but the apnea, bradycardia, and vasoconstriction is shared with those terrestrial and is neurally mediated. The adaptations of aquatic mammals are reviewed here as well as the neural control of cardiorespiratory physiology during diving in rodents.
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Affiliation(s)
- W Michael Panneton
- Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, MO, USA.
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Molecular cloning, characterization and expression of myoglobin in Tibetan antelope (Pantholops hodgsonii), a species with hypoxic tolerance. Gene 2014; 533:532-7. [DOI: 10.1016/j.gene.2013.09.030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2013] [Revised: 08/17/2013] [Accepted: 09/08/2013] [Indexed: 11/17/2022]
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30
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Chicco AJ, Le CH, Schlater AE, Nguyen AD, Kaye SD, Beals JW, Scalzo RL, Bell C, Gnaiger E, Costa DP, Crocker DE, Kanatous SB. High fatty acid oxidation capacity and phosphorylation control despite elevated leak and reduced respiratory capacity in northern elephant seal muscle mitochondria. J Exp Biol 2014; 217:2947-55. [DOI: 10.1242/jeb.105916] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Abstract
Northern elephant seals (Mirounga angustirostris) are extreme, hypoxia-adapted endotherms that rely largely on aerobic metabolism during extended breath-hold dives in near freezing water temperatures. While many aspects of their physiology have been characterized to account for these remarkable feats, the contribution of adaptations in the aerobic powerhouses of muscle cells, the mitochondria, are unknown. In the present study, the ontogeny and comparative physiology of elephant seal muscle mitochondrial respiratory function was investigated under a variety of substrate conditions and respiratory states. Intact mitochondrial networks were studied by high-resolution respirometry in saponin-permeabilized fiber bundles obtained from primary swimming muscles of pup, juvenile, and adult seals, and compared to fibers from adult human vastus laterais. Results indicate that seal muscle maintains a high capacity for fatty acid oxidation despite a progressive decrease in total respiratory capacity as animals mature from pups to adults. This is explained by a progressive increase in phosphorylation control and fatty acid utilization over pyruvate in adult seals compared to humans and seal pups. Interestingly, despite higher indices of oxidative phosphorylation efficiency, juvenile and adult seals also exhibit a ~50% greater capacity for respiratory leak compared to humans and pups. The ontogeny of this phenotype suggests it is an adaptation of muscle to the prolonged breath-hold exercise and highly variable ambient temperatures experienced by mature elephant seals. These studies highlight the remarkable plasticity of mammalian mitochondria to meet the demands for both efficient ATP production and endothermy in a cold, oxygen-limited environment.
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A review of the multi-level adaptations for maximizing aerobic dive duration in marine mammals: from biochemistry to behavior. J Comp Physiol B 2013; 184:23-53. [DOI: 10.1007/s00360-013-0782-z] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 08/27/2013] [Accepted: 08/30/2013] [Indexed: 11/26/2022]
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Prolonged fasting activates hypoxia inducible factors-1α, -2α and -3α in a tissue-specific manner in northern elephant seal pups. Gene 2013; 526:155-63. [PMID: 23707926 DOI: 10.1016/j.gene.2013.05.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 04/09/2013] [Accepted: 05/01/2013] [Indexed: 01/10/2023]
Abstract
Hypoxia inducible factors (HIFs) are important regulators of energy homeostasis and cellular adaptation to low oxygen conditions. Northern elephant seals are naturally adapted to prolonged periods (1-2 months) of food deprivation (fasting) which result in metabolic changes that may activate HIF-1. However, the effects of prolonged fasting on HIFs are not well defined. We obtained the full-length cDNAs of HIF-1α and HIF-2α, and partial cDNA of HIF-3α in northern elephant seal pups. We also measured mRNA and nuclear protein content of HIF-1α, -2α, -3α in muscle and adipose during prolonged fasting (1, 3, 5 & 7 weeks), along with mRNA expression of HIF-mediated genes, LDH and VEGF. HIF-1α, -2α and -3α are 2595, 2852 and 1842 bp and encode proteins of 823, 864 and 586 amino acid residues with conserved domains needed for their function (bHLH and PAS) and regulation (ODD and TAD). HIF-1α and -2α mRNA expression increased 3- to 5-fold after 7 weeks of fasting in adipose and muscle, whereas HIF-3α increased 5-fold after 7 weeks of fasting in adipose. HIF-2α protein expression was detected in nuclear fractions from adipose and muscle, increasing approximately 2-fold, respectively with fasting. Expression of VEGF increased 3-fold after 7 weeks in adipose and muscle, whereas LDH mRNA expression increased 12-fold after 7 weeks in adipose. While the 3 HIFα genes are expressed in muscle and adipose, only HIF-2α protein was detectable in the nucleus suggesting that HIF-2α may contribute more significantly in the up-regulation of genes involved in the metabolic adaptation during fasting in the elephant seal.
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33
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Kielhorn CE, Dillaman RM, Kinsey ST, McLellan WA, Mark Gay D, Dearolf JL, Ann Pabst D. Locomotor muscle profile of a deep (Kogia breviceps) versus shallow (Tursiops truncatus) diving cetacean. J Morphol 2013; 274:663-75. [DOI: 10.1002/jmor.20124] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 10/31/2012] [Accepted: 12/16/2012] [Indexed: 01/08/2023]
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Velten BP, Dillaman RM, Kinsey ST, McLellan WA, Pabst DA. Novel locomotor muscle design in extreme deep-diving whales. J Exp Biol 2013; 216:1862-71. [DOI: 10.1242/jeb.081323] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Summary
Most marine mammals are hypothesized to routinely dive within their aerobic dive limit (ADL). Mammals that regularly perform deep, long-duration dives have locomotor muscles with elevated myoglobin concentrations and are composed of predominantly large, slow-twitch (Type I) fibers with low mitochondrial volume densities (Vmt). These features contribute to extending ADL by increasing oxygen stores and decreasing metabolic rate. Recent tagging studies, however, have challenged the view that two groups of extreme deep-diving cetaceans dive within their ADLs. Beaked whales (Ziphius cavirostris, Cuvier and Mesoplodon densirostris, Blainville) routinely perform the deepest and longest average dives of any air-breathing vertebrate, and short-finned pilot whales (Globicephala macrorhynchus, Gray) perform high-speed sprints at depth. We investigated the locomotor muscle morphology and estimated total body oxygen stores of these cetaceans to determine whether they (a) shared muscle design features with other deep-divers and (b) performed dives within their calculated ADLs. Muscle of both cetaceans displayed high myoglobin concentrations and large fibers, as predicted, but novel fiber profiles for diving mammals. Beaked whales possessed a sprinter's fiber-type profile, composed of approximately 80% fast-twitch (Type II) fibers with low Vmt. Approximately one-third of the muscle fibers of short-finned pilot whales were slow-twitch, oxidative, glycolytic fibers, a rare fiber-type for any mammal. The muscle morphology of beaked whales likely decreases the energetic cost of diving, while that of short-finned pilot whales supports high activity events. Calculated ADLs indicate that, at low metabolic rates, both cetaceans carry sufficient onboard oxygen to aerobically support their dives.
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35
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De Miranda MA, Schlater AE, Green TL, Kanatous SB. In the face of hypoxia: myoglobin increases in response to hypoxic conditions and lipid supplementation in cultured Weddell seal skeletal muscle cells. ACTA ACUST UNITED AC 2012; 215:806-13. [PMID: 22323203 DOI: 10.1242/jeb.060681] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A key cellular adaptation to diving in Weddell seals is enhanced myoglobin concentrations in their skeletal muscles, which serve to store oxygen to sustain a lipid-based aerobic metabolism. The aim of this study was to determine whether seal muscle cells are inherently adapted to possess the unique skeletal muscle adaptations to diving seen in the whole animal. We hypothesized that the seal skeletal muscle cells would have enhanced concentrations of myoglobin de novo that would be greater than those from a C(2)C(12) skeletal muscle cell line and reflect the concentrations of myoglobin observed in previous studies. In addition we hypothesized that the seal cells would respond to environmental hypoxia similarly to the C(2)C(12) cells in that citrate synthase activity and myoglobin would remain the same or decrease under hypoxia and lactate dehydrogenase activity would increase under hypoxia as previously reported. We further hypothesized that β-hydroxyacyl CoA dehydrogenase activity would increase in response to the increasing amounts of lipid supplemented to the culture medium. Our results show that myoglobin significantly increases in response to environmental hypoxia and lipids in the Weddell seal cells, while appearing similar metabolically to the C(2)C(12) cells. The results of this study suggest the regulation of myoglobin expression is fundamentally different in Weddell seal skeletal muscle cells when compared with a terrestrial mammalian cell line in that hypoxia and lipids initially prime the skeletal muscles for enhanced myoglobin expression. However, the cells need a secondary stimulus to further increase myoglobin to levels seen in the whole animal.
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36
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Kim JH, Lawler JM. Amplification of proinflammatory phenotype, damage, and weakness by oxidative stress in the diaphragm muscle of mdx mice. Free Radic Biol Med 2012; 52:1597-606. [PMID: 22330042 DOI: 10.1016/j.freeradbiomed.2012.01.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2011] [Revised: 01/10/2012] [Accepted: 01/20/2012] [Indexed: 12/27/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a common and devastating type of childhood-onset muscular dystrophy, attributed to an X-linked defect in the gene that encodes dystrophin. Myopathy with DMD is most pronounced in the diaphragm muscle and fast-twitch limb muscles and is dependent upon susceptibility to damage, inflammatory cell infiltration, and proinflammatory signaling (nuclear factor-κB; NF-κB). Although recent papers have reawakened the notion that oxidative stress links inflammatory signaling with pathology in DMD in limb muscle, the importance of redox mechanisms had been clouded by inconsistent results from indirect scavenger approaches, including in the diaphragm muscle. Therefore, we used a novel catalytic mimetic of superoxide dismutase and catalase (EUK-134) as a direct scavenger of oxidative stress in myopathy in the diaphragm of the mdx mouse model. EUK-134 reduced 4-hydroxynonenal and total hydroperoxides, markers of oxidative stress in the mdx diaphragm. EUK-134 also attenuated positive staining of macrophages and T-cells as well as activation of NF-κB and p65 protein abundance. Moreover, EUK-134 ameliorated markers of muscle damage including internalized nuclei, variability of cross-sectional area, and type IIc fibers. Finally, impairment of contractile force was partially rescued by EUK-134 in the diaphragm of mdx mice. We conclude that oxidative stress amplifies DMD pathology in the diaphragm muscle.
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Affiliation(s)
- Jong-Hee Kim
- Redox Biology and Cell Signaling Laboratory, Department of Health & Kinesiology, Texas A&M University, College Station, TX 77843-4243, USA
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37
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Alvarez GI, Díaz AO, Longo MV, Becerra F, Vassallo AI. Histochemical and Morphometric Analyses of the Musculature of the Forelimb of the Subterranean Rodent Ctenomys talarum (Octodontoidea). Anat Histol Embryol 2012; 41:317-25. [DOI: 10.1111/j.1439-0264.2012.01137.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Accepted: 01/01/2012] [Indexed: 11/26/2022]
Affiliation(s)
- G. I. Alvarez
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - A. O. Díaz
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - M. V. Longo
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - F. Becerra
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
| | - A. I. Vassallo
- Departamento de Biología; Instituto de Investigaciones Marinas y Costeras, FCEyN, CONICET; Universidad Nacional de Mar del Plata; Provincia de Buenos Aires; Argentina
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38
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LaRosa DA, Cannata DJ, Arnould JPY, O'Sullivan LA, Snow RJ, West JM. Changes in muscle composition during the development of diving ability in the Australian fur seal. AUST J ZOOL 2012. [DOI: 10.1071/zo11072] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
During development the Australian fur seal transitions from a terrestrial, maternally dependent pup to an adult marine predator. Adult seals have adaptations that allow them to voluntarily dive at depth for long periods, including increased bradycardic control, increased myoglobin levels and haematocrit. To establish whether the profile of skeletal muscle also changes in line with the development of diving ability, biopsy samples were collected from the trapezius muscle of pups, juveniles and adults. The proportions of different fibre types and their oxidative capacity were determined. Only oxidative fibre types (Type I and IIa) were identified, with a significant change in proportions from pup to adult. There was no change in oxidative capacity of Type I and IIa fibres between pups and juveniles but there was a two-fold increase between juveniles and adults. Myoglobin expression increased between pups and juveniles, suggesting improved oxygen delivery, but with no increase in oxidative capacity, oxygen utilisation within the muscle may still be limited. Adult muscle had the highest oxidative capacity, suggesting that fibres are able to effectively utilise available oxygen during prolonged dives. Elevated levels of total creatine in the muscles of juveniles may act as an energy buffer when fibres are transitioning from a fast to slow fibre type.
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39
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Casey DP, Imray CHE, Wilson MH, Flouris AD, Carrillo AE, Tedjasaputra V, Hopkins SR, Birchard GF, Billat V, West JB, Vagula MC, Nelatury C, Bennet L, Gasier HG, Gunga HC, Egginton S, Kumar P. Comments on point: counterpoint: high altitude is/is not for the birds! J Appl Physiol (1985) 2011; 111:1520-4. [PMID: 22096211 DOI: 10.1152/japplphysiol.01117.2011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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40
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Shero MR, Andrews RD, Lestyk KC, Burns JM. Development of the aerobic dive limit and muscular efficiency in northern fur seals (Callorhinus ursinus). J Comp Physiol B 2011; 182:425-36. [PMID: 22001970 DOI: 10.1007/s00360-011-0619-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 09/16/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
Northern fur seal (Callorhinus ursinus; NFS) populations have been declining, perhaps due to limited foraging ability of pups. Because a marine mammal's proficiency at exploiting underwater prey resources is based on the ability to store large amounts of oxygen (O(2)) and to utilize these reserves efficiently, this study was designed to determine if NFS pups had lower blood, muscle, and total body O(2) stores than adults. Pups (<1-month old) had a calculated aerobic dive limit only ~40% of adult females due to lower blood and, to a much greater extent, muscle O(2) stores. Development of the Pectoralis (Pec) and Longissimus dorsi (LD) skeletal muscles was further examined by determining their myosin heavy chain (MHC) composition and enzyme activities. In all animals, the slow MHC I and fast-twitch IIA proteins typical of oxidative fiber types were dominant, but adult muscles contained more (Pec ~50%; LD ~250% higher) fast-twitch MHC IID/X protein characteristic of glycolytic muscle fibers, than pup muscles. This suggests that adults have greater ability to generate muscle power rapidly and/or under anaerobic conditions. Pup muscles also had lower aerobic and anaerobic ATP production potential, as indicated by lower metabolically scaled citrate synthase, β-hydroxyacyl CoA dehydrogenase, and lactate dehydrogenase activities (all P values ≤0.001). In combination, these findings indicate that pups are biochemically and physiologically limited in their diving capabilities relative to adults. This may contribute to lower NFS first year survival.
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Affiliation(s)
- Michelle R Shero
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA.
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41
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Ponganis PJ, Meir JU, Williams CL. In pursuit of Irving and Scholander: a review of oxygen store management in seals and penguins. J Exp Biol 2011; 214:3325-39. [DOI: 10.1242/jeb.031252] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Summary
Since the introduction of the aerobic dive limit (ADL) 30 years ago, the concept that most dives of marine mammals and sea birds are aerobic in nature has dominated the interpretation of their diving behavior and foraging ecology. Although there have been many measurements of body oxygen stores, there have been few investigations of the actual depletion of those stores during dives. Yet, it is the pattern, rate and magnitude of depletion of O2 stores that underlie the ADL. Therefore, in order to assess strategies of O2 store management, we review (a) the magnitude of O2 stores, (b) past studies of O2 store depletion and (c) our recent investigations of O2 store utilization during sleep apnea and dives of elephant seals (Mirounga angustirostris) and during dives of emperor penguins (Aptenodytes forsteri). We conclude with the implications of these findings for (a) the physiological responses underlying O2 store utilization, (b) the physiological basis of the ADL and (c) the value of extreme hypoxemic tolerance and the significance of the avoidance of re-perfusion injury in these animals.
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Affiliation(s)
- Paul J. Ponganis
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
| | - Jessica U. Meir
- Department of Zoology, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Cassondra L. Williams
- Center for Marine Biotechnology and Biomedicine, Scripps Institution of Oceanography, University of California San Diego, La Jolla, CA 92093-0204, USA
- Department of Ecology and Evolutionary Biology, University of California Irvine, Irvine, CA, 92697, USA
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42
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Abstract
Mammalian skeletal muscle comprises different fiber types, whose identity is first established during embryonic development by intrinsic myogenic control mechanisms and is later modulated by neural and hormonal factors. The relative proportion of the different fiber types varies strikingly between species, and in humans shows significant variability between individuals. Myosin heavy chain isoforms, whose complete inventory and expression pattern are now available, provide a useful marker for fiber types, both for the four major forms present in trunk and limb muscles and the minor forms present in head and neck muscles. However, muscle fiber diversity involves all functional muscle cell compartments, including membrane excitation, excitation-contraction coupling, contractile machinery, cytoskeleton scaffold, and energy supply systems. Variations within each compartment are limited by the need of matching fiber type properties between different compartments. Nerve activity is a major control mechanism of the fiber type profile, and multiple signaling pathways are implicated in activity-dependent changes of muscle fibers. The characterization of these pathways is raising increasing interest in clinical medicine, given the potentially beneficial effects of muscle fiber type switching in the prevention and treatment of metabolic diseases.
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Affiliation(s)
- Stefano Schiaffino
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Venetian Institute of Molecular Medicine, Department of Biomedical Sciences, University of Padova, Consiglio Nazionale delle Ricerche Institute of Neurosciences, and Department of Human Anatomy and Physiology, University of Padova, Padova, Italy
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44
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Abstract
Myoglobin is a well-characterized, cytoplasmic hemoprotein that is expressed primarily in cardiomyocytes and oxidative skeletal muscle fibers. However, recent studies also suggest low-level myoglobin expression in various non-muscle tissues. Prior studies incorporating molecular, pharmacological, physiological and transgenic technologies have demonstrated that myoglobin is an essential oxygen-storage hemoprotein capable of facilitating oxygen transport and modulating nitric oxide homeostasis within cardiac and skeletal myocytes. Concomitant with these studies, scientific investigations into the transcriptional regulation of myoglobin expression have been undertaken. These studies have indicated that activation of key transcription factors (MEF2, NFAT and Sp1) and co-activators (PGC-1alpha) by locomotor activity, differential intracellular calcium fluxes and low intracellular oxygen tension collectively regulate myoglobin expression. Future studies focused on tissue-specific transcriptional regulatory pathways and post-translational modifications governing myoglobin expression will need to be undertaken. Finally, further studies investigating the modulation of myoglobin expression under various myopathic processes may identify myoglobin as a novel therapeutic target for the treatment of various cardiac and skeletal myopathies.
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Affiliation(s)
- Shane B Kanatous
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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45
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Gros G, Wittenberg BA, Jue T. Myoglobin's old and new clothes: from molecular structure to function in living cells. J Exp Biol 2010; 213:2713-25. [PMID: 20675540 PMCID: PMC2912754 DOI: 10.1242/jeb.043075] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2010] [Indexed: 11/20/2022]
Abstract
Myoglobin, a mobile carrier of oxygen, is without a doubt an important player central to the physiological function of heart and skeletal muscle. Recently, researchers have surmounted technical challenges to measure Mb diffusion in the living cell. Their observations have stimulated a discussion about the relative contribution made by Mb-facilitated diffusion to the total oxygen flux. The calculation of the relative contribution, however, depends upon assumptions, the cell model and cell architecture, cell bioenergetics, oxygen supply and demand. The analysis suggests that important differences can be observed whether steady-state or transient conditions are considered. This article reviews the current evidence underlying the evaluation of the biophysical parameters of myoglobin-facilitated oxygen diffusion in cells, specifically the intracellular concentration of myoglobin, the intracellular diffusion coefficient of myoglobin and the intracellular myoglobin oxygen saturation. The review considers the role of myoglobin in oxygen transport in vertebrate heart and skeletal muscle, in the diving seal during apnea as well as the role of the analogous leghemoglobin of plants. The possible role of myoglobin in intracellular fatty acid transport is addressed. Finally, the recent measurements of myoglobin diffusion inside muscle cells are discussed in terms of their implications for cytoarchitecture and microviscosity in these cells and the identification of intracellular impediments to the diffusion of proteins inside cells. The recent experimental data then help to refine our understanding of Mb function and establish a basis for future investigation.
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Affiliation(s)
- Gerolf Gros
- Zentrum Physiologie, Medizinische Hochschule Hannover, 30625 Hannover, Germany
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Hindle AG, Horning M. Energetics of breath-hold hunting: modeling the effects of aging on foraging success in the Weddell seal. J Theor Biol 2010; 264:673-82. [PMID: 20363231 DOI: 10.1016/j.jtbi.2010.03.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2009] [Revised: 01/27/2010] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
Abstract
A simulation model was developed to predict age-related changes in foraging energetics of individual Weddell seals, Leptonychotes weddellii. Aging in diving animals is interesting because their characteristic cyclic sequence of apneustic hunting and eupnea should elevate oxidative stress, possibly accelerating aging. Such a hypothesis can be evaluated by modeling energetics of constrained, time-partitioned activities with well-defined costs. Three possible consequences of physiological aging in divers were specified and appraised. The model examined the potential impacts of age-related decline in muscle contractile ability, increased buoyancy, and reduced aerobic dive limit, alone and in combination, on a daily energy budget. A uniform age effect evident in model outputs is reduced foraging efficiency. The components of this net effect are exacerbated for sub-optimal behavioral-response settings or environmental conditions. The model predicts that with advancing age, efficiency declines increase for aging scenarios in the following order: simulated 'young' adults; 'old' seals with increased buoyancy; 'old' seals with reduced aerobic dive limit; 'old' seals having reduced muscle contractile efficiency; and, 'old' seals with all three conditions. The model indicates narrowed behavioral options to maintain positive energy balance in older animals, suggesting that behavioral plasticity may not allow older animals to compensate for age-related performance constraints.
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Prewitt JS, Freistroffer DV, Schreer JF, Hammill MO, Burns JM. Postnatal development of muscle biochemistry in nursing harbor seal (Phoca vitulina) pups: limitations to diving behavior? J Comp Physiol B 2010; 180:757-66. [PMID: 20140678 DOI: 10.1007/s00360-010-0448-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 01/12/2010] [Accepted: 01/15/2010] [Indexed: 10/19/2022]
Abstract
Adult marine mammal muscles rely upon a suite of adaptations for sustained aerobic metabolism in the absence of freely available oxygen (O(2)). Although the importance of these adaptations for supporting aerobic diving patterns of adults is well understood, little is known about postnatal muscle development in young marine mammals. However, the typical pattern of vertebrate muscle development, and reduced tissue O(2) stores and diving ability of young marine mammals suggest that the physiological properties of harbor seal (Phoca vitulina) pup muscle will differ from those of adults. We examined myoglobin (Mb) concentration, and the activities of citrate synthase (CS), beta-hydroxyacyl coA dehydrogenase (HOAD), and lactate dehydrogenase (LDH) in muscle biopsies from harbor seal pups throughout the nursing period, and compared these biochemical parameters to those of adults. Pups had reduced O(2) carrying capacity ([Mb] 28-41% lower than adults) and reduced metabolically scaled catabolic enzyme activities (LDH/RMR 20-58% and CS/RMR 29-89% lower than adults), indicating that harbor seal pup muscles are biochemically immature at birth and weaning. This suggests that pup muscles do not have the ability to support either the aerobic or anaerobic performance of adult seals. This immaturity may contribute to the lower diving capacity and behavior in younger pups. In addition, the trends in myoglobin concentration and enzyme activity seen in this study appear to be developmental and/or exercise-driven responses that together work to produce the hypoxic endurance phenotype seen in adults, rather than allometric effects due to body size.
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Affiliation(s)
- J S Prewitt
- Department of Biological Sciences, University of Alaska Anchorage, 3211 Providence Dr, Anchorage, AK 99508, USA.
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Hindle AG, Lawler JM, Campbell KL, Horning M. Muscle senescence in short-lived wild mammals, the soricine shrews Blarina brevicauda and Sorex palustris. ACTA ACUST UNITED AC 2009; 311:358-67. [PMID: 19296507 DOI: 10.1002/jez.534] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Red-toothed (soricine) shrews are consummate predators exhibiting the highest energy turnovers and shortest life spans (ca. 18 months) of any mammal, yet virtually nothing is known regarding their physiological aging. We assessed the emerging pattern of skeletal muscle senescence (contractile/connective tissue components) in sympatric species, the semi-aquatic water shrew (WS), Sorex palustris, and the terrestrial short-tailed shrew (STS), Blarina brevicauda, to determine if muscle aging occurs in wild, short-lived mammals (H(0): shrews do not survive to an age where senescence occurs), and if so, whether these alterations are species-specific. Gracilis muscles were collected from first-year (n=17) and second-year (n=17) field-caught shrews. Consistent with typical mammalian aging, collagen content (% area) increased with age in both species (S. palustris: approximately 50%; B. brevicauda: approximately 60%). Muscle was dominated by stiffer Type I collagen, and the ratio of collagen Type I:Type III more than doubled with age. The area ratio of muscle:collagen decreased with age in both species, but was considerably lower in adult STS, suggesting species-specificity of senescence. Extracellular space was age-elevated in B. brevicauda, but was preserved in S. palustris ( approximately 50 vs. 10% elevation). Though juvenile interspecific comparisons revealed no significance, adult WS myocytes had 68% larger cross-sectional area and occurred at 28% lower fibers/area than those of adult STS. We demonstrate that age-related muscle senescence does occur in wild-caught, short-lived mammals, and we therefore reject this classic aging theory tenet. Our findings moreover illustrate that differential age adjustments in contractile/connective tissue components of muscle occur in the two species of wild-caught shrews.
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Affiliation(s)
- Allyson G Hindle
- Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas, USA.
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Lestyk KC, Folkow LP, Blix AS, Hammill MO, Burns JM. Development of myoglobin concentration and acid buffering capacity in harp (Pagophilus groenlandicus) and hooded (Cystophora cristata) seals from birth to maturity. J Comp Physiol B 2009; 179:985-96. [PMID: 19565249 DOI: 10.1007/s00360-009-0378-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 06/08/2009] [Accepted: 06/12/2009] [Indexed: 12/01/2022]
Abstract
Pinnipeds rely on muscle oxygen stores to help support aerobic diving, therefore muscle maturation may influence the behavioral ecology of young pinnipeds. To investigate the pattern of muscle development, myoglobin concentration ([Mb]) and acid buffering ability (beta) was measured in ten muscles from 23 harp and 40 hooded seals of various ages. Adult [Mb] ranged from 28-97 to 35-104 mg g tissue(-1) in harp and hooded seals, respectively, with values increasing from the cervical, non-swimming muscles to the main swimming muscles of the lumbar region. Neonatal and weaned pup muscles exhibited lower (approximately 30% adult values) and less variable [Mb] across the body than adults. In contrast, adult beta showed little regional variation (60-90 slykes), while high pup values (approximately 75% adult values) indicate significant in utero development. These findings suggest that intra-uterine conditions are sufficiently hypoxic to stimulate prenatal beta development, but that [Mb] development requires additional postnatal signal such as exercise, and/or growth factors. However, because of limited development in both beta and [Mb] during the nursing period, pups are weaned with muscles with lower aerobic and anaerobic capacities than those of adults.
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Affiliation(s)
- Keri C Lestyk
- Department of Biological Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA.
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Kanatous SB, Mammen PPA, Rosenberg PB, Martin CM, White MD, Dimaio JM, Huang G, Muallem S, Garry DJ. Hypoxia reprograms calcium signaling and regulates myoglobin expression. Am J Physiol Cell Physiol 2008; 296:C393-402. [PMID: 19005161 DOI: 10.1152/ajpcell.00428.2008] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Myoglobin is an oxygen storage molecule that is selectively expressed in cardiac and slow-twitch skeletal muscles that have a high oxygen demand. Numerous studies have implicated hypoxia in the regulation of myoglobin expression as an adaptive response to hypoxic stress. However, the details of this relationship remain undefined. In the present study, adult mice exposed to 10% oxygen for periods up to 3 wk exhibited increased myoglobin expression only in the working heart, whereas myoglobin was either diminished or unchanged in skeletal muscle groups. In vitro and in vivo studies revealed that hypoxia in the presence or absence of exercise-induced stimuli reprograms calcium signaling and modulates myoglobin gene expression. Hypoxia alone significantly altered calcium influx in response to cell depolarization or depletion of endoplasmic reticulum calcium stores, which inhibited the expression of myoglobin. In contrast, our whole animal and transcriptional studies indicate that hypoxia in combination with exercise enhanced the release of calcium from the sarcoplasmic reticulum via the ryanodine receptors triggered by caffeine, which increased the translocation of nuclear factor of activated T-cells into the nucleus to transcriptionally activate myoglobin expression. The present study unveils a previously unrecognized mechanism where the hypoxia-mediated regulation of calcium transients from different intracellular pools modulates myoglobin gene expression. In addition, we observed that changes in myoglobin expression, in response to hypoxia, are not dependent on hypoxia-inducible factor-1 or changes in skeletal muscle fiber type. These studies enhance our understanding of hypoxia-mediated gene regulation and will have broad applications for the treatment of myopathic diseases.
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Affiliation(s)
- Shane B Kanatous
- Department of Biology, Colorado State University, Fort Collins, CO, USA
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