To give an idea of how quickly the 13C composition of the main energy vector, mouse-liver glycogen, changes (for the evaluation of certain pharmaceuticals) between a C3 and C4 diet, we developed a Stable-Isotopic Indirect Calorimeter (SIIC).  The SIIC  permitted us to evaluate the change of rate CO2 production under the influence of a variety of pharmaceuticals for a good medical cause. 
 
        For an abstract, see http://www.naturesfingerprint.com/abstracts/abstract_i10272000.shtml  Briefly, the 13C value of glycogen (as parameterized via CO2) varied at 3.3o/oo per hour as the diet was immediately changed from C3 (mouse chow, -25o/oo) to C4 (corn syrup, -12o/oo) values.
 
        Best Regards,
            John

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----- Original Message -----
From: [log in to unmask] href="mailto:[log in to unmask]">William Patterson
To: [log in to unmask] href="mailto:[log in to unmask]">[log in to unmask]
Sent: Thursday, January 22, 2009 5:57 PM
Subject: Re: [ISOGEOCHEM] Corn Influenced Diet Shifts?

Hello Marilyn and others
If the discussion will go beyond the influence of corn on humans then you may be interested in the following papers by Antoine Zazzo and the references therein. The cows were fed a C3 diet and then switched to a corn diet. A record of this transition is then recovered from tooth dentine and enamel using micromilling techniques.
Cheers,
Bill

Zazzo, A., Balasse, M., and Patterson, W.P. 2006. The reconstruction of mammal individual history: refining high-resolution isotope record in bovine tooth dentine. Journal of Archaeological Science, v. 33, p. 1177-1187.

Zazzo, A., Balasse, M., and Patterson, W.P. 2005. High-resolution d13C intra-tooth profiles in bovine enamel: Implications for mineralization pattern and isotopic attenuation. Geochimica et Cosmochimica Acta, v. 69, no. 14, p. 3631-3642.

Dear Folks,

I received this message from a colleague who is teaching students about the influence of corn. Do any of you alert readers have a reference at your fingertips that you could recommend for Charlie?

"Next Tuesday Washington College is hosting a viewing of the movie "King
Corn," which is a critique of the use of corn products in our country (see
description below).

One of the most fascinating things I heard about this issue was in one of
your talks: The stable isotope evidence that Europeans coming to the US
experience a shift in their carbon isotope ratios in response to the
corn-heavy diet.  Does that data appear in publication anywhere? I would
love to bring that up at the viewing of this movie during the discussion
period."

Marilyn Fogel


Dr. Marilyn L. Fogel
Geophysical Laboratory
Carnegie Institution of Washington
5251 Broad Branch Rd., NW
Washington, DC 20015
Phone (202) 478-8981
Main office (202) 478-8900
FAX (202) 478-8901
Website: http://fogel.gl.ciw.edu/


--
Dr. William P. Patterson
Professor and Director of the Saskatchewan Isotope Laboratory
Department of Geological Sciences
University of Saskatchewan
114 Science Place
Saskatoon SK S7N 5E2
Canada
Phone: 306-966-5691(office); 306-966-5712(lab)
Email: [log in to unmask]
Web: http://geochemistry.usask.ca/bill.html