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Ciccone C, Kante F, Folkow LP, Hazlerigg DG, West AC, Wood SH. Circadian coupling of mitochondria in a deep-diving mammal. J Exp Biol 2024; 227:jeb246990. [PMID: 38495024 PMCID: PMC11058691 DOI: 10.1242/jeb.246990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 03/11/2024] [Indexed: 03/19/2024]
Abstract
Regulation of mitochondrial oxidative phosphorylation is essential to match energy supply to changing cellular energy demands, and to cope with periods of hypoxia. Recent work implicates the circadian molecular clock in control of mitochondrial function and hypoxia sensing. Because diving mammals experience intermittent episodes of severe hypoxia, with diel patterning in dive depth and duration, it is interesting to consider circadian-mitochondrial interaction in this group. Here, we demonstrate that the hooded seal (Cystophora cristata), a deep-diving Arctic pinniped, shows strong daily patterning of diving behaviour in the wild. Cultures of hooded seal skin fibroblasts exhibit robust circadian oscillation of the core clock genes per2 and arntl. In liver tissue collected from captive hooded seals, expression of arntl was some 4-fold higher in the middle of the night than in the middle of the day. To explore the clock-mitochondria relationship, we measured the mitochondrial oxygen consumption in synchronized hooded seal skin fibroblasts and found a circadian variation in mitochondrial activity, with higher coupling efficiency of complex I coinciding with the trough of arntl expression. These results open the way for further studies of circadian-hypoxia interactions in pinnipeds during diving.
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Affiliation(s)
- Chiara Ciccone
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Fayiri Kante
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Lars P. Folkow
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø NO-9037, Norway
| | - David G. Hazlerigg
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Alexander C. West
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø NO-9037, Norway
| | - Shona H. Wood
- Arctic Seasonal Timekeeping Initiative (ASTI), Arctic Chronobiology and Physiology Research Group, Department of Arctic and Marine Biology, UiT – The Arctic University of Norway, Tromsø NO-9037, Norway
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Martens GA, Geßner C, Osterhof C, Hankeln T, Burmester T. Transcriptomes of Clusterin- and S100B-transfected neuronal cells elucidate protective mechanisms against hypoxia and oxidative stress in the hooded seal (Cystophora cristata) brain. BMC Neurosci 2022; 23:59. [PMID: 36243678 PMCID: PMC9571494 DOI: 10.1186/s12868-022-00744-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 10/10/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The hooded seal (Cystophora cristata) exhibits impressive diving skills and can tolerate extended durations of asphyxia, hypoxia and oxidative stress, without suffering from irreversible neuronal damage. Thus, when exposed to hypoxia in vitro, neurons of fresh cortical and hippocampal tissue from hooded seals maintained their membrane potential 4-5 times longer than neurons of mice. We aimed to identify the molecular mechanisms underlying the intrinsic neuronal hypoxia tolerance. Previous comparative transcriptomics of the visual cortex have revealed that S100B and clusterin (apolipoprotein J), two stress proteins that are involved in neurological disorders characterized by hypoxic conditions, have a remarkably high expression in hooded seals compared to ferrets. When overexpressed in murine neuronal cells (HN33), S100B and clusterin had neuroprotective effects when cells were exposed to hypoxia. However, their specific roles in hypoxia have remained largely unknown. METHODS In order to shed light on potential molecular pathways or interaction partners, we exposed HN33 cells transfected with either S100B, soluble clusterin (sCLU) or nuclear clusterin (nCLU) to normoxia, hypoxia and oxidative stress for 24 h. We then determined cell viability and compared the transcriptomes of transfected cells to control cells. Potential pathways and upstream regulators were identified via Gene Ontology (GO) and Ingenuity Pathway Analysis (IPA). RESULTS HN33 cells transfected with sCLU and S100B demonstrated improved glycolytic capacity and reduced aerobic respiration at normoxic conditions. Additionally, sCLU appeared to enhance pathways for cellular homeostasis to counteract stress-induced aggregation of proteins. S100B-transfected cells sustained lowered energy-intensive synaptic signaling. In response to hypoxia, hypoxia-inducible factor (HIF) pathways were considerably elevated in nCLU- and sCLU-transfected cells. In a previous study, S100B and sCLU decreased the amount of reactive oxygen species and lipid peroxidation in HN33 cells in response to oxidative stress, but in the present study, these functional effects were not mirrored in gene expression changes. CONCLUSIONS sCLU and S100B overexpression increased neuronal survival by decreasing aerobic metabolism and synaptic signaling in advance to hypoxia and oxidative stress conditions, possibly to reduce energy expenditure and the build-up of deleterious reactive oxygen species (ROS). Thus, a high expression of CLU isoforms and S100B is likely beneficial during hypoxic conditions.
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Affiliation(s)
- Gerrit A Martens
- Institute of Animal Cell and Systems Biology, Biocenter Grindel, University of Hamburg, 20146, Hamburg, Germany.
| | - Cornelia Geßner
- Institute of Animal Cell and Systems Biology, Biocenter Grindel, University of Hamburg, 20146, Hamburg, Germany
| | - Carina Osterhof
- Institute of Organismic and Molecular Evolution, Molecular Genetics & Genome Analysis, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Thomas Hankeln
- Institute of Organismic and Molecular Evolution, Molecular Genetics & Genome Analysis, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Thorsten Burmester
- Institute of Animal Cell and Systems Biology, Biocenter Grindel, University of Hamburg, 20146, Hamburg, Germany
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Schots PC, Bue ME, Nordøy ES. Hooded seal (Cystophora cristata) pups ingest snow and seawater during their post-weaning fast. J Comp Physiol B 2016; 187:493-502. [PMID: 27830333 PMCID: PMC5364953 DOI: 10.1007/s00360-016-1048-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Revised: 10/21/2016] [Accepted: 10/26/2016] [Indexed: 11/24/2022]
Abstract
The purpose of this study was to evaluate the importance of exogenous water intake (snow/seawater) in hooded seal (Cystophora cristata) pups during their post-weaning fast. In this study, five hooded seal pups had ad lib access to snow and seawater for the first 12 and last 21 days of their post-weaning fast, respectively. Total body water and water flux were determined during both exposure periods by use of the tritiated water method. Blood samples were collected to monitor changes in hematocrit, plasma urea and plasma osmolality. Body mass loss was on average 0.36 kg day−1. Average total body water changed from 15.7 to 11.4 L, while total water influx changed from 15 to 18 mL day−1 kg−1 during snow and seawater exposure, respectively. Of this influx an average of 35% can be attributed to metabolic water, while approximately 8% was due to respiratory water influx. Interestingly, 56 and 58% of the total water influx was due to snow and seawater ingestion, respectively, amounting to 8 mL day−1 kg−1 snow (counted as liquid water) and 10 mL day−1 kg−1 seawater. Based on the results of the plasma parameters it is concluded that fasting hooded seal pups maintain water balance and homeostasis when access to snow or seawater is permitted. It is further concluded that snow and seawater intake, in addition to metabolic and respiratory water, is important for maintenance of water balance and excretion of urea during the post-weaning fast of hooded seal pups.
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Affiliation(s)
- Pauke C Schots
- Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Breivika, 9037, Tromsø, Norway.
| | - Marie E Bue
- Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Breivika, 9037, Tromsø, Norway
| | - Erling S Nordøy
- Department of Arctic and Marine Biology, UiT-The Arctic University of Norway, Breivika, 9037, Tromsø, Norway
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Fabrizius A, Hoff MLM, Engler G, Folkow LP, Burmester T. When the brain goes diving: transcriptome analysis reveals a reduced aerobic energy metabolism and increased stress proteins in the seal brain. BMC Genomics 2016; 17:583. [PMID: 27507242 PMCID: PMC4979143 DOI: 10.1186/s12864-016-2892-y] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Accepted: 07/06/2016] [Indexed: 12/19/2022] Open
Abstract
Background During long dives, the brain of whales and seals experiences a reduced supply of oxygen (hypoxia). The brain neurons of the hooded seal (Cystophora cristata) are more tolerant towards low-oxygen conditions than those of mice, and also better survive other hypoxia-related stress conditions like a reduction in glucose supply and high concentrations of lactate. Little is known about the molecular mechanisms that support the hypoxia tolerance of the diving brain. Results Here we employed RNA-seq to approach the molecular basis of the unusual stress tolerance of the seal brain. An Illumina-generated transcriptome of the visual cortex of the hooded seal was compared with that of the ferret (Mustela putorius furo), which served as a terrestrial relative. Gene ontology analyses showed a significant enrichment of transcripts related to translation and aerobic energy production in the ferret but not in the seal brain. Clusterin, an extracellular chaperone, is the most highly expressed gene in the seal brain and fourfold higher than in the ferret or any other mammalian brain transcriptome. The largest difference was found for S100B, a calcium-binding stress protein with pleiotropic function, which was 38-fold enriched in the seal brain. Notably, significant enrichment of S100B mRNA was also found in the transcriptomes of whale brains, but not in the brains of terrestrial mammals. Conclusion Comparative transcriptomics indicates a lower aerobic capacity of the seal brain, which may be interpreted as a general energy saving strategy. Elevated expression of stress-related genes, such as clusterin and S100B, possibly contributes to the remarkable hypoxia tolerance of the brain of the hooded seal. Moreover, high levels of S100B that possibly protect the brain appear to be the result of the convergent adaptation of diving mammals. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2892-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrej Fabrizius
- Institute of Zoology, Biocenter Grindel, University of Hamburg, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
| | - Mariana Leivas Müller Hoff
- Institute of Zoology, Biocenter Grindel, University of Hamburg, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany
| | - Gerhard Engler
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, 20246, Hamburg, Germany
| | - Lars P Folkow
- Department of Arctic and Marine Biology, University of Tromsø - The Arctic University of Norway, NO-9037, Tromsø, Norway
| | - Thorsten Burmester
- Institute of Zoology, Biocenter Grindel, University of Hamburg, Martin-Luther-King-Platz 3, D-20146, Hamburg, Germany.
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Pearson LE, Liwanag HEM, Hammill MO, Burns JM. To each its own: Thermoregulatory strategy varies among neonatal polar phocids. Comp Biochem Physiol A Mol Integr Physiol 2014; 178:59-67. [PMID: 25151642 DOI: 10.1016/j.cbpa.2014.08.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 08/09/2014] [Accepted: 08/13/2014] [Indexed: 11/18/2022]
Abstract
Cold environmental conditions and small body size promote heat loss and may create thermoregulatory challenges for marine mammals born in polar regions. However, among polar-born phocid seal species there are variations in physical attributes and environmental conditions at birth, allowing for an interesting contrast in thermoregulatory strategy. We compared thermoregulatory strategies through morphometrics, sculp attributes (conductivity and resistance), nonshivering thermogenesis (NST via uncoupling protein 1; UCP1), and muscle thermogenesis (via enzyme activity) in neonatal harp (Pagophilus groenlandicus), hooded (Cystophora cristata), and Weddell seals (Leptonychotes weddellii). Harp seals are the smallest at birth (9.8±0.7 kg), rely on lanugo (82.49±3.70% of thermal resistance), and are capable of NST through expression of UCP1 in brown adipose tissue (BAT). In contrast, hooded seal neonates (26.8±1.3 kg) have 2.06±0.23 cm of blubber, accounting for 38.19±6.07% of their thermal resistance. They are not capable of NST, as UCP1 is not expressed. The large Weddell seal neonates (31.5±4.9 kg) rely on lanugo (89.85±1.25% of thermal resistance) like harp seals, but no evidence of BAT was found. Muscle enzyme activity was highest in Weddell seal neonates, suggesting that they rely primarily on muscle thermogenesis. Similar total thermal resistance, combined with marked differences in thermogenic capacity of NST and ST among species, strongly supports that thermoregulatory strategy in neonatal phocids is more closely tied to pups' surface area to volume ratio (SA:V) and potential for early water immersion rather than mass and ambient environmental conditions.
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MESH Headings
- Adipose Tissue, Brown/growth & development
- Adipose Tissue, Brown/physiology
- Adiposity
- Animals
- Animals, Newborn/growth & development
- Animals, Newborn/physiology
- Antarctic Regions
- Arctic Regions
- Birth Weight
- Body Temperature Regulation
- Canada
- Female
- Greenland
- Hair/growth & development
- Hair/physiology
- Ion Channels/metabolism
- Male
- Mitochondrial Proteins/metabolism
- Models, Biological
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/growth & development
- Muscle, Skeletal/physiology
- Seals, Earless/growth & development
- Seals, Earless/physiology
- Skin/growth & development
- Skin Physiological Phenomena
- Species Specificity
- Subcutaneous Fat/growth & development
- Subcutaneous Fat/physiology
- Thermal Conductivity
- Uncoupling Protein 1
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Affiliation(s)
- Linnea E Pearson
- School of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 905N. Koyukuk Dr., Fairbanks, AK 99775-7220, USA; Department of Biology, University of Alaska Anchorage, 3101 Science Cir., Anchorage, AK 99508, USA.
| | - Heather E M Liwanag
- Department of Biology, Adelphi University, 1 South Ave., Garden City, NY 11530, USA
| | - Mike O Hammill
- Department of Fisheries and Oceans, Maurice Lamontagne Institute, 850 route de la Mer, Mont-Joli, Quebec H5H 3Z4, Canada
| | - Jennifer M Burns
- Department of Biology, University of Alaska Anchorage, 3101 Science Cir., Anchorage, AK 99508, USA
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