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Robinson AL, Elliott Smith EA, Besser AC, Newsome SD. Tissue-specific carbon isotope patterns of amino acids in southern sea otters. Oecologia 2024; 204:13-24. [PMID: 38227253 DOI: 10.1007/s00442-023-05505-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 12/13/2023] [Indexed: 01/17/2024]
Abstract
The measurement of stable isotope values of individual compounds, such as amino acids (AAs), has become a powerful tool in animal ecology and ecophysiology. As with any emerging technique, questions remain regarding the capabilities and limitations of this approach, including how metabolism and tissue synthesis impact the isotopic values of individual AAs and subsequent multivariate patterns. We measured carbon isotope (δ13C) values of essential (AAESS) and nonessential (AANESS) AAs in bone collagen, whisker, muscle, and liver from ten southern sea otters (Enhydra lutris nereis) that stranded in Monterey Bay, California. Sea otters in this population exhibit high degrees of individual dietary specialization, making this an excellent dataset to explore differences in AA δ13C values among tissues in a wild population. We found the δ13C values of the AANESS glutamic acid, proline, serine, and glycine and the AAESS threonine differed significantly among tissues, indicating possible isotopic discrimination during tissue synthesis. Threonine δ13C values were higher in liver relative to bone collagen and muscle, which may indicate catabolism of threonine for gluconeogenesis, an interpretation further supported by correlations between the δ13C values of threonine and its gluconeogenic products glycine and serine in liver. This intraindividual isotopic variation yielded different ecological interpretations among tissues; for 6/10 of the sea otter individuals analyzed, at least one tissue indicated reliance on a different primary producer source than the other tissues. Our results highlight the importance of gluconeogenesis in a carnivorous marine mammal and indicate that metabolic processes influence AAESS and AANESS δ13C values and multivariate AA δ13C patterns.
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Affiliation(s)
- Alana L Robinson
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA.
| | - Emma A Elliott Smith
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
- Department of Anthropology, National Museum of Natural History, Smithsonian Institution, Washington, DC, 20560, USA
| | - Alexi C Besser
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA
| | - Seth D Newsome
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA
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Hesse T, Nachev M, Khaliq S, Jochmann MA, Franke F, Scharsack JP, Kurtz J, Sures B, Schmidt TC. A new technique to study nutrient flow in host-parasite systems by carbon stable isotope analysis of amino acids and glucose. Sci Rep 2023; 13:1054. [PMID: 36658208 PMCID: PMC9852285 DOI: 10.1038/s41598-022-24933-9] [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: 09/13/2022] [Accepted: 11/22/2022] [Indexed: 01/20/2023] Open
Abstract
Stable isotope analysis of individual compounds is emerging as a powerful tool to study nutrient origin and conversion in host-parasite systems. We measured the carbon isotope composition of amino acids and glucose in the cestode Schistocephalus solidus and in liver and muscle tissues of its second intermediate host, the three-spined stickleback (Gasterosteus aculeatus), over the course of 90 days in a controlled infection experiment. Similar linear regressions of δ13C values over time and low trophic fractionation of essential amino acids indicate that the parasite assimilates nutrients from sources closely connected to the liver metabolism of its host. Biosynthesis of glucose in the parasite might occur from the glucogenic precursors alanine, asparagine and glutamine and with an isotope fractionation of - 2 to - 3 ‰ from enzymatic reactions, while trophic fractionation of glycine, serine and threonine could be interpreted as extensive nutrient conversion to fuel parasitic growth through one-carbon metabolism. Trophic fractionation of amino acids between sticklebacks and their diets was slightly increased in infected compared to uninfected individuals, which could be caused by increased (immune-) metabolic activities due to parasitic infection. Our results show that compound-specific stable isotope analysis has unique opportunities to study host and parasite physiology.
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Affiliation(s)
- Tobias Hesse
- Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
| | - Milen Nachev
- Aquatic Ecology, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.,Centre for Water and Environmental Research, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
| | - Shaista Khaliq
- Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
| | - Maik A Jochmann
- Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany. .,Centre for Water and Environmental Research, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.
| | - Frederik Franke
- Institute for Evolution & Biodiversity, University of Münster, Hüfferstr. 1, 48149, Münster, Germany.,Bavarian State Institute of Forestry, Hans-Carl-Von-Carlowitz-Platz 1, 85354, Freising, Germany
| | - Jörn P Scharsack
- Institute for Evolution & Biodiversity, University of Münster, Hüfferstr. 1, 48149, Münster, Germany.,Thünen Institute of Fisheries Ecology, Herwigstr. 31, 27572, Bremerhaven, Germany
| | - Joachim Kurtz
- Institute for Evolution & Biodiversity, University of Münster, Hüfferstr. 1, 48149, Münster, Germany
| | - Bernd Sures
- Aquatic Ecology, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.,Centre for Water and Environmental Research, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
| | - Torsten C Schmidt
- Instrumental Analytical Chemistry, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany.,Centre for Water and Environmental Research, University of Duisburg-Essen, Universitätsstr. 5, 45141, Essen, Germany
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