Stable isotopes of H, C and N in mice bone collagen as a reflection of isotopically controlled food and water intake^*

* Originally presented at the Stable Isotope Summer School 2018 ‘Stable isotopes in ancient and contemporary environments’, 15–19 April 2018, University of Konstanz, Germany

ABSTRACT

²H/¹H ratios in animal biomass reflect isotopic input from food and water. A 10-week controlled laboratory study raised 48 mice divided in two generations (8 mothers Mus musculus and their offspring). The mice were divided into four groups based on the combination of ²H, ¹³C, ¹⁵N-enriched and non-enriched food and water. Glycine, the most common amino acid in bone collagen, carried the ²H, ¹³C, ¹⁵N-isotopic spike in food. ANOVA data analysis indicated that hydrogen in food accounted for ∼81 % of the hydrogen isotope inventory in collagen whereas drinking water hydrogen contributed ∼17 %. Air humidity contributed an unspecified amount. Additionally, we monitored ¹³C and ¹⁵N-enrichment in bone collagen and found strong linear correlations with the ²H-enrichment. The experiments with food and water indicate two biosynthetic pathways, namely (i) de novo creation of non-essential amino acids using hydrogen from water, and (ii) the integration of essential and non-essential amino acids from food. The lower rate of isotope uptake in mothers’ collagen relative to their offspring indicates incomplete bone collagen turnover after ten weeks. The variance of hydrogen stable isotope ratios within the same cohort may limit its usefulness as a single sample proxy for archaeological or palaeoenvironmental research.

KEYWORDS:

• Carbon-13
• diet
• food
• hydrogen-2
• isotope ecology
• mice
• nitrogen-15
• tracer technique

Acknowledgments

We thank the lab staff at the School of Optometry animal facilities at Indiana University for their patience and passing down their knowledge on lab animal care. David Finkelstein kindly performed water analyses. This manuscript was improved by helpful suggestions from four reviewers.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Arndt Schimmelmann http://orcid.org/0000-0003-4648-5253

Notes

* Originally presented at the Stable Isotope Summer School 2018 ‘Stable isotopes in ancient and contemporary environments’, 15–19 April 2018, University of Konstanz, Germany

Additional information

Funding

The Department of Earth and Atmospheric Sciences’ Stable Isotope Research Facility (SIRF) is supported by Indiana University’s Prepared for Environmental Change Grand Challenge initiative. This research did not receive funding from agencies in the public, commercial, or not-for-profit sectors.