Insect flight metabolic rate revealed by bolus injection of the stable isotope 13C.
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ABSTRACT:
SUBMITTER: Urca T
PROVIDER: S-EPMC8242924 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:The high growth rate of Ulva seaweeds makes it a potential algal biomass resource. In particular, Ulva meridionalis grows up to fourfold a day. Here, we demonstrated strong carbon fixation by U. meridionalis using 13C stable isotope labelling and traced the 13C flux through sugar metabolites with isotope-ratio mass spectrometry (IR-MS), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), 13C-nuclear magnetic resonance spectrometry (13C-NMR), and gas chromatography-mass spectrometry (GC-MS). U. meridionalis was first cultured in 13C-labelled enriched artificial seawater for 0-12 h, and the algae were collected every 4 h. U. meridionalis grew 1.8-fold (dry weight), and the 13C ratio reached 40% in 12 h, whereas 13C incorporation hardly occurred under darkness. At the beginning of the light period, 13C was incorporated into nucleic diphosphate (NDP) sugars in 4 h, and 13C labelled peaks were identified using FT-ICR-MS spectra. Using semiquantitative 13C-NMR measurements and GC-MS, 13C was detected in starch and matrix polysaccharides after the formation of NDP sugars. Moreover, the 14:10 light:dark regime resulted into 85% of 13C labelling was achieved after 72 h of cultivation. The rapid 13C uptake by U. meridionalis shows its strong carbon fixation capacity as a promising seaweed biomass feedstock.
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Project description:Stable isotope probing (SIP) has emerged as a powerful tool to address key questions about microbiota structure and function. To date, diverse isotopically labeled substrates have been used to characterize in situ growth activity of specific bacterial taxa and have revealed the flux of bioavailable substrates through microbial communities associated with health and disease. A major limitation to the growth of the field is the dearth of biologically relevant "heavy" labeled substrates. Mucin glycoproteins, for example, comprise an abundant source of carbon in the gut, oral cavity, respiratory tract, and other mucosal surfaces but are not commercially available. Here, we describe a method to incorporate a 13C-labeled monosaccharide into MUC5AC, a predominant mucin in both gastrointestinal and airway environments. Using the lung adenocarcinoma cell line, Calu-3, polarized cell cultures grown in 13C-labeled d-glucose resulted in liberal mucin production on the apical surface. Mucins were isolated by size-exclusion chromatography, and O-linked glycans were released by β-elimination, permethylated, and analyzed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) techniques. We demonstrate a 98.7% incorporation of 13C in the heterogeneous O-linked oligosaccharides that make up >80% of mucin dry weight. These "heavy" labeled glycoproteins represent a valuable tool for probing in vivo activity of host-associated bacterial communities and their interactions with the mucosal barrier. The continued expansion of labeled substrates for use in SIP will eventually allow bacterial taxa that degrade host compounds to be identified, with long-term potential for improved health and disease management.
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Project description:A novel metabolomics approach for NMR-based stable isotope tracer studies called PEPA is presented, and its performance validated using human cancer cells. PEPA detects the position of carbon label in isotopically enriched metabolites and quantifies fractional enrichment by indirect determination of 13 C-satellite peaks using 1D-1 H-NMR spectra. In comparison with 13 C-NMR, TOCSY and HSQC, PEPA improves sensitivity, accelerates the elucidation of 13 C positions in labeled metabolites and the quantification of the percentage of stable isotope enrichment. Altogether, PEPA provides a novel framework for extending the high-throughput of 1 H-NMR metabolic profiling to stable isotope tracing in metabolomics, facilitating and complementing the information derived from 2D-NMR experiments and expanding the range of isotopically enriched metabolites detected in cellular extracts.
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Project description:BackgroundPlasma lactate concentrations and their trends over time are used for clinical prognosis, and to guide treatment, in critically ill patients. Although heavily relied upon for clinical decision-making, lactate kinetics of these patients is sparsely studied.AimTo establish and validate a feasible method to study lactate kinetics in critically ill patients.MethodsHealthy volunteers (n =?6) received a bolus dose of 13C-labeled lactate (20??mol/kg body weight), and 43 blood samples were drawn over 2 h to determine the decay in labeled lactate. Data was analyzed using non-compartmental modeling calculating rates of appearance (Ra) and clearance of lactate. The area under the curve (AUC) was calculated using a linear-up log-down trapezoidal approach with extrapolation beyond 120?min using the terminal slope to obtain the whole AUC. After evaluation, the same protocol was used in an unselected group of critically ill patients (n =?10).ResultsRa for healthy volunteers and ICU patients were 12.8?±?3.9 vs 22.7?±?11.1??mol/kg/min and metabolic clearance 1.56?±?0.39 vs 1.12?±?0.43?L/min, respectively. ICU patients with normal lactate concentrations showed kinetics very similar to healthy volunteers. Simulations showed that reducing the number of samples from 43 to 14 gave the same results. Our protocol yielded results on lactate kinetics very similar to previously published data using other techniques.ConclusionThis simple and user-friendly protocol using an isotopically labeled bolus dose of lactate was accurate and feasible for studying lactate kinetics in critically ill ICU patients.Trial registrationANZCTR, ACTRN12617000626369, registered 8 March 2017. https://anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372507&isReview=true.
| S-EPMC7011254 | biostudies-literature
Project description:The earliest Native Americans have often been portrayed as either megafaunal specialists or generalist foragers, but this debate cannot be resolved by studying the faunal record alone. Stable isotope analysis directly reveals the foods consumed by individuals. We present multi-tissue isotope analyses of two Ancient Beringian infants from the Upward Sun River site (USR), Alaska (~11,500 years ago). Models of fetal bone turnover combined with seasonally-sensitive taxa show that the carbon and nitrogen isotope composition of USR infant bone collagen reflects maternal diets over the summer. Using comparative faunal isotope data, we demonstrate that although terrestrial sources dominated maternal diets, salmon was also important, supported by carbon isotope analysis of essential amino acids and bone bioapatite. Tooth enamel samples indicate increased salmon use between spring and summer. Our results do not support either strictly megafaunal specialists or generalized foragers but indicate that Ancient Beringian diets were complex and seasonally structured.
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Project description:Annual antler growth begins in the spring and is completed by late summer for male caribou (Rangifer tarandus groenlandicus) from the Qamanirjuaq herd (Nunavut, Canada), aligned with both the spring migration and a seasonal dietary shift. Antlers may provide a non-lethal means of studying short- and long-term changes in caribou ecology through incorporated isotopes of carbon (δ13C) and nitrogen (δ15N). We sampled the antlers of 12 male caribou from the Qamanirjuaq herd culled in September 1967. We predicted that serial sampling of antlers would reflect the known seasonal dietary change from lichen to grass-like and shrub diet based on rumen contents from individuals culled during the same period. The δ13C and δ15N were analyzed in food sources and every 3 cm along each antler's length. The carbon isotope compositions of collagen (δ13Ccol) varied by ~0.5‰ among individuals and within antlers, while the carbon isotope compositions of antler bioapatite (δ13CCO3) increased by 1-1.5‰ from pedicle to tip. Values of δ15Ncol increased within antlers by 1-3‰ from pedicle to tip and varied by 3‰ among the individuals sampled. Antler collagen was lower in δ15Ncol by ~1‰ relative to bone collagen. Bayesian mixing models were conducted to test for changes in dietary proportions from antler isotope compositions. Mixing models did not indicate significant dietary shifts for any individual during antler formation, showing consistently mixed diets of fungi, horsetail, lichen, and woody plants. Increases in δ15Ncol in antler tissue could, therefore, correspond to subtle seasonal dietary changes and/or the physiological stress of antler tissue development.
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Project description:Salt marshes exist along the gradient of the marine mudflat to the terrestrial dunes, with a gradient of shore height and associated plant zonation. The lower salt marsh (LSM) extends from the mean high tidal level to 35 cm above that level and is followed by the upper salt marsh (USM). Despite changes in the amount of allochthonous marine input and in abiotic conditions, little is known about changes in the trophic structure and used of basal resources by the soil macrofauna along marine-terrestrial boundaries. Natural variations in carbon stable isotope ratios (δ13C signatures) allow insight into basal resources of consumers such as marine algae, terrestrial C3 and C4 photosynthesising plants. Furthermore, variations in nitrogen stable isotope ratios (δ15N signatures) allow insight into the trophic position of consumers. We investigated spatial and temporal changes in stable isotope signatures in salt marsh soil macrofauna of the island of Spiekeroog, German Wadden Sea. The range of δ15N signatures indicated no changes in food chain length across salt marsh zones with consumers in both zones comprising primary decomposers, secondary decomposers and first order predators. However, the trophic position of individual species changed between zones, but in particular with season. Contrasting δ15N signatures, the range in δ13C signatures in the LSM was twice that in the USM indicating a wider range of resources consumed. Bayesian mixing models indicated predominant autochthonous resource use in both the LSM and USM, with the use of marine allochthonous resources never exceeding 29.6%. However, the models also indicate an increase in the use of marine resources in certain species in the LSM with no use in the USM. Overall, the results indicate that the resource use of salt marsh macrofauna varies more in space than in time, with the food web being generally based on autochthonous rather than allochthonous resources. However, there also is trophic plasticity in certain species across both temporal and spatial scales including variations in the use of allochthonous resources. Generally, however, marine input contributes little to the nutrition of salt marsh soil macroinvertebrates.
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Project description:A temporal change in the stable isotope (SI) composition of jellyfish in the Kiel Fjord, Western Baltic Sea, was documented by analyzing δ13C, δ15N and δ34S of bell tissue of Aurelia aurita and Cyanea capillata in the period between June and October 2011. A strong and significant temporal change in all SI values of A. aurita was found, including an increase of ~3 ‰ in δ13C, a decrease of ~4 ‰ in δ15N and sharp decline of ~7 ‰ in δ34S. While knowledge gaps in jellyfish isotope ecology, in particular the lack of reliable trophic enrichment factors, call for a conservative interpretation of our data, observed changes in particular in δ34S, as indicated by means of a MixSIR mixing model, would be consistent with a temporal dietary shift in A. aurita from mesozooplankton (>150 µm) to microplankton and small re-suspended particles (0.8-20 µm) from the benthos. Presence of a hitherto unidentified food source not included in the model could also contribute to the shift. During the 2-month occurrence of C. capillata, its isotope composition remained stable and was consistent with a mainly mesozooplanktonic diet. Mixing model output, mainly driven by δ34S values, indicated a lower proportion of A. aurita in the diet of C. capillata than previously reported, and thus to a potentially lesser importance of intraguild predation among jellyfish in the Kiel Fjord. Overall, our results clearly highlighted the potential for substantial intraspecific isotopic seasonal variation in jellyfish, which should be taken into account in future feeding ecology studies on this group.
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Project description:Stable isotope tracers are applied for in vivo and in vitro studies to reveal the activity of enzymes and intracellular metabolic pathways. Most often, such tracers are used with gas chromatography coupled to mass spectrometry (GC-MS) owing to its ease of operation and reproducible mass spectral databases. Differences in isotope tracer performance of the classic GC-quadrupole MS instrument and newer time-of-flight instruments are not well studied. Here, we used three commercially available instruments for the analysis of identical samples from a stable isotope labeling study that used [U-13C6] d-glucose to investigate the metabolism of the bacterium Rothia mucilaginosa with respect to 29 amino acids and hydroxyl acids involved in primary metabolism. The prokaryote R. mucilaginosa belongs to the family of Micrococcaceae and is present and metabolically active in the airways and sputum of cystic fibrosis patients. Overall, all three GC-MS instruments (low-resolution GC-SQ MS, low-resolution GC-TOF MS, and high-resolution GC-QTOF MS) can be used to perform stable isotope tracing studies for glycolytic intermediates, tricarboxylic acid (TCA) metabolites, and amino acids, yielding similar biological results, with high-resolution GC-QTOF MS offering additional capabilities to identify the chemical structures of unknown compounds that might show significant isotope enrichments in biological studies.
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Project description:Understanding the geodynamic and Earth surface processes at the origin of post-collisional surface uplift in mountain ranges requires reconstruction of paleo-elevation. Here, we focus on the topographic evolution of the Cerdanya Basin in the eastern Pyrenees formed by post-orogenic extension during the Late Miocene. Stable isotope (?18O) analyses of small rodent teeth and biogenic carbonates show the basin uplifted by 500?m since 6.5?Ma. These new paleoaltitudes constraints when combined with the regional geology and geophysical data reveal the anomalously high topography of the region is the result of density changes in the sublithospheric mantle associated with crustal thinning and then opening of Gulf of Lion during the Chattian-early Burdigalian.
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