Changes in Northern Elephant Seal Skeletal Muscle Following Thirty Days of Fasting and Reduced Activity
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ABSTRACT:
PROVIDER: PRJNA636169 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11884684_1.fastq.gz | Fastqsanger.gz | |||
| SRR11884684_2.fastq.gz | Fastqsanger.gz | |||
| SRR11884685_1.fastq.gz | Fastqsanger.gz | |||
| SRR11884685_2.fastq.gz | Fastqsanger.gz | |||
| SRR11884686_1.fastq.gz | Fastqsanger.gz |
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Project description:Northern elephant seals (NES, Mirounga angustirostris) undergo an annual molt during which they spend ~40 days fasting on land with reduced activity and lose approximately one-quarter of their body mass. Reduced activity and muscle load in stereotypic terrestrial mammalian models results in decreased muscle mass and capacity for force production and aerobic metabolism. However, the majority of lost mass in fasting female NES is from fat while muscle mass is largely preserved. Although muscle mass is preserved, potential changes to the metabolic and contractile capacity are unknown. To assess potential changes in NES skeletal muscle during molt, we collected muscle biopsies from 6 adult female NES at the beginning of the molt and after ~30 days at the end of the molt. Skeletal muscle was assessed for respiratory capacity using high resolution respirometry, and RNA was extracted to assess changes in gene expression. Despite a month of reduced activity, fasting, and weight loss, skeletal muscle respiratory capacity was preserved with no change in OXPHOS respiratory capacity. Molt was associated with 162 upregulated genes including genes favoring lipid metabolism and regulating cell cycles. We identified 172 downregulated genes including those coding for ribosomal proteins and genes associated with skeletal muscle force transduction and glucose metabolism. Following ~30 days of molt, NES skeletal muscle metabolic capacity appears largely preserved although mechanotransduction may be compromised. In the absence of exercise stimulus, fasting-induced shifts in skeletal muscle lipid metabolism may stimulate lipid signaling pathways associated with preserving the mass and metabolic capacity of slow oxidative muscle.
2020-09-15 | GSE151509 | GEO
Project description:Northern elephant seals (NES, Mirounga angustirostris) undergo an annual molt during which they spend ∼40 days fasting on land with reduced activity and lose approximately one-quarter of their body mass. Reduced activity and muscle load in stereotypic terrestrial mammalian models results in decreased muscle mass and capacity for force production and aerobic metabolism. However, the majority of lost mass in fasting female NES is from fat while muscle mass is largely preserved. Although muscle mass is preserved, potential changes to the metabolic and contractile capacity are unknown. To assess potential changes in NES skeletal muscle during molt, we collected muscle biopsies from 6 adult female NES before the molt and after ∼30 days at the end of the molt. Skeletal muscle was assessed for respiratory capacity using high resolution respirometry, and RNA was extracted to assess changes in gene expression. Despite a month of reduced activity, fasting, and weight loss, skeletal muscle respiratory capacity was preserved with no change in OXPHOS respiratory capacity. Molt was associated with 162 upregulated genes including those favoring lipid metabolism. We identified 172 downregulated genes including those coding for ribosomal proteins and genes associated with skeletal muscle force transduction and glucose metabolism. Following ∼30 days of molt, NES skeletal muscle metabolic capacity is preserved although mechanotransduction may be compromised. In the absence of exercise stimulus, fasting-induced shifts in muscle metabolism may stimulate pathways associated with preserving the mass and metabolic capacity of slow oxidative muscle.
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Project description:Mirounga angustirostris strain:northern elephant seal Transcriptome or Gene expression
| PRJNA258305 | ENA
Project description:Northern elephant seal skeletal muscle, blubber, and plasma were collected from 5 adult females early and late in a 5-week molting fast (mean 33 days apart; see Sample Key in supplementary files). Proteins were isolated from muscle using the Trizol method and blubber using Qiazol with the Qiagen RNeasy Lipid Mini kit (see Khudyakov et al., 2018, doi: 10.1242/bio.036731). Plasma samples were used raw (without depletion of highly abundant proteins). Muscle, blubber, and plasma proteins were denatured using 1% sodium deoxycholate, 8 M urea, and 5 mM DTT in 50 mM ammonium bicarbonate and digested in-solution using trypsin (1:50 trypsin to protein ratio).
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Project description:Early sexual dimorphism in the developing gut microbiome of northern elephant seals
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Project description:Proteins were extracted from the outer (closer to skin) blubber layer of 4 northern elephant seals (Mirounga angustirostris) using either 1) A standard detergent lysis buffer containing 1% sodium deoxycholate, 8 M urea, 5 mM DTT in 50 mM ammonium bicarbonate (SDC method) or 2) the phenol and guanidine thiocyanate reagent Qiazol (QIA method). Mass spectrometry analysis was performed using an Orbitrap Fusion Tribrid mass spectrometer in DDA mode. Briefly, full MS1 scans were resolved by the orbitrap, and ions were selected for MS2 using DDA. These precursor ions were quadrupole filtered and subsequently fragmented using stepped collision HCD. MS2 product ions were resolved by the orbitrap. MS/MS data was analyzed using Proteome Discoverer v2.2.
2018-06-12 | MSV000082455 | MassIVE
Project description:The physiological and cellular adaptations to extreme fasting in northern elephant seals ( Mirounga angustirostris, NES) are remarkable and may help to elucidate endocrine mechanisms that regulate lipid metabolism and energy homeostasis in mammals. Recent studies have highlighted the importance of thyroid hormones in the maintenance of a lipid-based metabolism during prolonged fasting in weaned NES pups. To identify additional molecular regulators of fasting, we used a transcriptomics approach to examine changes in global gene expression profiles before and after 6-8 wk of fasting in weaned NES pups. We produced a de novo assembly and identified 98 unique protein-coding genes that were differentially expressed between early and late fasting. Most of the downregulated genes were associated with lipid, carbohydrate, and protein metabolism. A number of downregulated genes were also associated with maintenance of the extracellular matrix, consistent with tissue remodeling during weight loss and the multifunctional nature of blubber tissue, which plays both metabolic and structural roles in marine mammals. Using this data set, we predict potential mechanisms by which NES pups sustain metabolism and regulate adipose stores throughout the fast, and provide a valuable resource for additional studies of extreme metabolic adaptations in mammals.
| S-EPMC6087879 | biostudies-literature
Project description:The prolonged, postweaning fast of northern elephant seal (Mirounga angustirostris) pups is characterized by a reliance on lipid metabolism and reversible, fasting-induced insulin resistance, providing a unique model to examine the effects of insulin on lipid metabolism. We have previously shown that acute insulin infusion induced a shift in fatty acid metabolism dependent on fasting duration. This study complements the previous study by examining the effects of fasting duration and insulin infusion on circulating levels of oxylipins, bioactive metabolites derived from the oxygenation of polyunsaturated fatty acids. Northern elephant seal pups were studied at two postweaning periods (n = 5/period): early fasting (1-2 wk postweaning; 127 ± 1 kg) and late fasting (6-7 wk postweaning; 93 ± 4 kg). Different cohorts of pups were weighed, sedated, and infused with 65 mU/kg of insulin. Plasma was collected prior to infusion (T0) and at 10, 30, 60, and 120 min postinfusion. A profile of ∼80 oxylipins was analyzed by UPLC-ESI-MS/MS. Nine oxylipins changed between early and late fasting and eight were altered in response to insulin infusion. Fasting decreased prostaglandin F2α (PGF2α) and increased 14,15-dihydroxyicosatrienoic acid (14,15-DiHETrE), 20-hydroxyeicosatetraenoic acid (20-HETE), and 4-hydroxy-docosahexaenoic acid (4-HDoHE) (P < 0.03) in T0 samples, whereas insulin infusion resulted in an inverse change in area-under-the-curve (AUC) levels in these same metabolites (P < 0.05). In addition, 12-12-hydroperoxyeicosatetraenoic acid (HpETE) and 12-HETE decreased with fasting and insulin infusion, respectively (P < 0.04). The oxylipins altered during fasting and in response to insulin infusion may contribute to the manifestation of insulin resistance and participate in the metabolic regulation of associated cellular processes.
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Project description:The identity of most functional elements in the mammalian genome and the phenotypes they impact are unclear. Here, we perform a genome-wide comparative analysis of patterns of accelerated evolution in species with highly distinctive traits to discover candidate functional elements for clinically important phenotypes. We identify accelerated regions (ARs) in the elephant, hibernating bat, orca, dolphin, naked mole rat and thirteen-lined ground squirrel lineages in mammalian conserved regions, uncovering ~33,000 elements that bind hundreds of different regulatory proteins in humans and mice. ARs in the elephant, the largest land mammal, are uniquely enriched at elephant DNA damage response genes and changed conserved regulatory sites. The genomic hotspot for elephant ARs is the E3 ligase subunit of the Fanconi Anemia Complex, a master regulator of DNA repair. Additionally, ARs in the six species are associated with specific human clinical phenotypes that have apparent concordance with overt traits in each species.
2018-01-01 | GSE107117 | GEO
Project description:The northern elephant seal, Mirounga angustirostris, was heavily hunted and declared extinct in the 19th century. However, a colony remained on remote Guadalupe Island, Mexico and the species has since repopulated most of its historical distribution. Here, we present a comprehensive evaluation of genetic variation in the species. First, we assess the effect of the demographic bottleneck on microsatellite variability and compare it with that found in other pinnipeds, demonstrating levels of variation similar to that in species that continue to be threatened with extinction. Next, we use sequence data from these markers to demonstrate that some of the limited polymorphism predates the bottleneck. However, most contemporary variation appears to have arisen recently and persisted due to exponential growth. We also describe how we use the range in allele size of microsatellites to estimate ancestral effective population size before the bottleneck, demonstrating a large reduction in effective size. We then employ a classical method for bacteria to estimate the microsatellite mutation rate in the species, deriving an estimate that is extremely similar to that estimated for a similar set of loci in humans, indicating consistency of microsatellite mutation rates in mammals. Finally, we find slight significant structure between some geographically separated colonies, although its biological significance is unclear. This work demonstrates that genetic analysis can be useful for evaluating the population biology of the northern elephant seal, in spite of the bottleneck that removed most genetic variation from the species.
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