Browsing by Author "Walls, Dorothy Mae"

Now showing 1 - 1 of 1
  • Thumbnail Image
    ItemOpen Access
    Investigation of the effect gut microbiota have on the calcium isotopic composition in different calcium reservoirs of mice
    (2023-07) Walls, Dorothy Mae; Wieser, Michael E.; Gomes da Rocha, Claudia; Brown, Jo-Anne; Mayer, Bernhard
    The determination of the isotopic composition of calcium (Ca) in the body has gained increasing recognition as a powerful tool to monitor Ca metabolism, and bone metabolism in biological systems. Calcium is an essential mineral in the body and is critical for building and maintaining strong teeth and bones. Mishandling of this metal is associated with several diseases and disorders within the body. Therefore, understanding calcium metabolism is necessary to address the significance of this mineral, and the role it plays in the health of an individual. This thesis describes the development of an analytical technique to measure calcium isotope amount ratios in biological samples from as little as 670 ng, which is a two-fold decrease in the amount of Ca required compared to recent studies using MC TIMS. The technique was used to determine how the distribution of calcium isotopes changes in mice where calcium metabolism has been impacted by an altered composition of gut microbiota in the gastrointestinal tract of the mice. This technique developed in this thesis was applied to biological standard reference materials, and the δ(44/40Ca) isotope amount ratio of the reference materials NIST SRM 1400, NIST SRM 1486, and IAPSO were in good agreement and within uncertainty of literature data. Others were measured for Ca isotopic composition for the first time. The technique was then applied to the analysis of the calcium isotopic fractionation for three mouse groups with different gut bacterial compositions in four different tissue pools (diet, kidney, bone, and feces). Two cohorts of mice differentiated by age were investigated, where the first cohort was 91 days old, and the second was approximately 85 days old. There were no observed trends in the Ca isotopic compositions in the Ca reservoirs of the mice for given gut bacteria groups across the two cohorts. Therefore, we conclude that changes in gut microbiota do not produce a significant change in the redistribution of the isotopes of Ca in the different Ca pools in mice.