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Guinea DNA nitrogen and carbon isotope ratios are depleted relative to tissue and mildly responsive to physiological state
Author(s) -
Strable Maggie S,
Varamini Behzad,
Tschanz Carolyn L,
Brenna J Thomas
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a1122-b
Subject(s) - cerebellum , in utero , stable isotope ratio , isotope , δ13c , chemistry , δ15n , dna , endogeny , isotopes of carbon , endocrinology , medicine , biology , biochemistry , fetus , pregnancy , environmental chemistry , genetics , total organic carbon , physics , quantum mechanics
Background. Natural, endogenous, δ 13 C and δ 15 N isotope ratios are routinely used to probe environmental systems but have not been much exploited for nutritional studies. Cerebellar neuronal DNA maintains a long‐lived record of isotope ratio because it does not turnover. We investigated the endogenous δ 13 C and δ 15 N of DNA and bulk tissue of cerebellum to determine baseline isotope ratios and whether in utero physiology influences isotope ratios at this level. Methods. Pregnant guinea pigs were randomized to five different groups: Control (C), low protein (LP), high protein (HP), feed restricted (FR), and diabetic (D). Pups were fed the C diet from birth. Pup cerebellum δ 13 C and δ 15 N was analyzed for DNA and bulk by elemental analysis‐isotope ratio mass spectrometry at 2 da and 120 da of age. All isotope ratios are expressed relative to that of the feed. Results. Cerebellar DNA averaged about δ 15 N = −5‰ at both 2 and 120 da of age. Bulk cerebellum was δ 15 N = +4‰. Cerebellar DNA δ 13 C was +3.4‰ at 2 da and about +5.4% at 120 da. Bulk cerebellar δ 13 C at 120 days followed the in utero protein level: −0.85, +1.3, +4.9‰ for LP, C and HP, respectively. Conclusions. We show for the first time that δ 15 N of DNA is depleted relative to feed and that it is largely unresponsive to physiological state. δ 13 C of whole tissue increased with in utero dietary protein level. Funding: NIH GM071534.