Oxygen and hydrogen isotopes in rodent tissues: Impact of diet, water and ontogeny

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Date: Sept. 15, 2011
Publisher: Elsevier B.V.
Document Type: Article
Length: 356 words

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Abstract :

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.palaeo.2011.03.022 Byline: Karola Kirsanow, Noreen Tuross Keywords: Oxygen isotopes; Hydrogen isotopes; Bone collagen; Hair keratin; Ontogeny Abstract: Stable oxygen ([delta].sup.18O) and hydrogen ([delta]D) isotope compositions in heterotroph tissues are known to reflect the seasonal variation of meteoric water intake and dietary inputs. However, the magnitude of the seasonal signal recorded in different tissues of ecological and geological significance has not been fully established. In addition, the effects of organism age and body size on tissue [delta].sup.18O and [delta]D values remain unexplored. This paper examines carbonate and phosphate oxygen ([delta].sup.18O) from tooth enamel, and the oxygen ([delta].sup.18O) and hydrogen ([delta]D) values from the bone collagen, subcutaneous fat, and hair of rats raised on a monotonous diet approaching constant hydrogen and oxygen isotopic composition and local drinking water. The rats were of two age classes, post-weaning (40g) and mature (375g), and from two different hydrological regions (Houston, Texas, USA and Germantown, New York, USA) having dissimilar tap water isotopic values but a single food source with nearly identical hydrogen and oxygen values. Significant differences in the tissue [delta]D and [delta].sup.18O of post-weaning and mature rats were found; however these ontogenetic differences did not completely obscure the contribution of drinking water [delta].sup.18O and [delta]D. Animals raised under different hydrological regimes had distinct tissue [delta]D and [delta].sup.18O values. Apatite.sub.(carbonate), apatite.sub.(phosphate), hair, collagen and subcutaneous fat [delta].sup.18O reflect varying proportions of the difference in drinking water [delta].sup.18O values. Phosphate oxygen in enamel apatite appears most sensitive to drinking water [delta].sup.18O differences, while subcutaneous fat of adult rats appears to best reflect the differences in the [delta]D of the drinking water sources. An examination of the statistical significance associated with the isotopic differences in [delta]D and [delta].sup.18O between the Texas and New York rat tissues suggests that differences in the isotopic composition of local water of less than 2.5a[degrees] in [delta].sup.18O and 10-20a[degrees] in [delta]D may be invisible in tissue values of archeological, palaeontological, or ecological interest unless isotopically distinct food resources contribute to regional isotopic separations. Article History: Received 8 April 2010; Revised 28 February 2011; Accepted 18 March 2011

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Gale Document Number: GALE|A267292690