Can the carbon and nitrogen isotope values of offspring be used as a proxy for their mother’s diet? Using foetal physiology to interpret bulk tissue and amino acid δ15N values

Details

• Journal Title:
  Conservation Physiology
• Personal Author:
  Lübcker, Nico ; Whiteman, John P ; Newsome, Seth D ; Millar, Robert P ; de Bruyn, P J Nico
• NOAA Program & Office:
  NMFS (National Marine Fisheries Service)
• Description:
  The measurement of bulk tissue nitrogen (delta N-15) and carbon isotope values (delta C-13) chronologically along biologically inert tissues sampled from offspring can provide a longitudinal record of their mothers'foraging habits.This study tested the important assumption that mother-offspring stable isotope values are positively and linearly correlated. In addition, any change in the mother-offspring bulk tissues and individual amino acids that occurred during gestation was investigated. Whiskers sampled from southern elephant seal pups (Mirounga leonina) and temporally overlapping whiskers from their mothers were analyzed. This included n = 1895 chronologically subsampled whisker segments for bulk tissue delta N-15 and delta C-13 in total and n = 20 whisker segments for amino acid delta N-15 values, sampled from recently weaned pups (n = 1 7), juvenile southern elephant seals (SES) < 2 years old (n = 23) and adult female SES (n = 1 7), which included nine mother-offspring pairs. In contrast to previous studies, the mother-offspring pairs were not in isotopic equilibrium or linearly correlated during gestation: the Delta N-15 and Delta C-13 mother-offspring offsets increased by 0.8 and 1.2 parts per thousand, respectively, during gestation. The foetal bulk delta N-15 values were 1.7 +/- 0.5 parts per thousand (0.9-2.7 parts per thousand) higher than mothers delta N-15 values before birth, while the foetal delta C-13 increased by similar to 1.7 parts per thousand during gestation and were 1.0 +/- 0.5 parts per thousand (0.0-1.9 parts per thousand) higher than their mothers delta C-13 at the end of pregnancy.The mother-offspring serine and glycine Delta N-15 differed by similar to 4.3 parts per thousand, while the foetal alanine delta N-15 values were 1.4 parts per thousand lower than that of their mothers during the third trimester of pregnancy. The observed mother-offspring delta N-15 differences are likely explained by shuttling of glutamate- glutamine and glycine-serine amongst skeletal muscle, liver, placenta and foetal tissue. Foetal development relies primarily on remobilized endogenous maternal proteinaceous sources. Researchers should consider foetal physiology when using offspring bulk tissue isotope values as biomarkers for the mother's isotopic composition as part of monitoring programmes.
• Keywords:
  Amino Acid-specific Stable Isotopes Biodiversity Conservation Ecology Environmental Sciences Fractionation Glucose-production Growth Intrauterine Lions Eumetopias-jubatus Marine Mammals Marine Predator Metabolism Mirounga-leonina Mother-offspring Pairs Nutrition Physiology Southern Elephant Seals Stable-isotopes Trophic Ecology Whiskers Amino Acid-specific Stable Isotopes Lions Eumetopias-jubatus Marine Mammals Marine Predator Mother-offspring Pairs Southern Elephant Seals Trophic Ecology

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• Source:
  Conservation Physiology, Volume 8, Issue 1, 2020, coaa060, https://doi.org/10.1093/conphys/coaa060
• DOI:
  https://doi.org/10.1093/conphys/coaa060
• Pubmed ID:
  32765882
• Pubmed Central ID:
  PMC7397484
• Document Type:
  Journal Article
• Funding:
  Permit no. 1943
• Rights Information:
  CC BY
• Compliance:
  PMC
• Main Document Checksum:
  urn:sha256:defc64854a721cdf9bc0ef2afe095cf066729217a170d775235173c734e8a134
• Download URL:
  https://repository.library.noaa.gov/view/noaa/29257/noaa_29257_DS1.pdf
• File Type:
  [PDF - 1.25 MB ]