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Metabolites 2014, 4(1), 53-70; doi:10.3390/metabo4010053

Fluxomics of the Eastern Oyster for Environmental Stress Studies

1,2,* , 1,2,3
 and 1,2
Received: 21 August 2013 / Revised: 27 November 2013 / Accepted: 19 December 2013 / Published: 7 January 2014
(This article belongs to the Special Issue Response to Environment and Stress Metabolism)
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Abstract: The metabolism of 2-13C/15N-glycine and U-13C-glucose was determined in four tissue blocks (adductor muscle, stomach and digestive gland, mantle, and gills) of the Eastern oyster (Crassostrea virginica) using proton (1H) and carbon-13 (13C) nuclear magnetic resonance (NMR) spectroscopy. The oysters were treated in aerated seawater with three treatments (5.5 mM U-13C-glucose, 2.7 mM 2-13C/15N-glycine, and 5.5 mM U-13C-glucose plus 2.7 mM 2-13C/15N-glycine) and the relative mass balance and 13C fractional enrichments were determined in the four tissue blocks. In all tissues, glycine was metabolized by the glycine cycle forming serine exclusively in the mitochondria by the glycine cleavage system forming 2,3-13C-serine. In muscle, a minor amount of serine-derived pyruvate entered the Krebs cycle as substantiated by detection of a trace of 2,3-13C-aspartate. In all tissues, U-13C-glucose formed glycogen by glycogen synthesis, alanine by glycolysis, and glutamate and aspartate through the Krebs cycle. Alanine was formed exclusively from glucose via alanine transaminase and not glycine via alanine-glyoxylate transaminase. Based on isotopomer analysis, pyruvate carboxylase and pyruvate dehydrogenase appeared to be equal points for pyruvate entry into the Krebs cycle. In the 5.5 mM U-13C-glucose plus 2.7 mM 2-13C/15N-glycine emergence treatment used to simulate 12 h of “low tide”, oysters accumulated more 13C-labeled metabolites, including both anaerobic glycolytic and aerobic Krebs cycle intermediates. The aerobic metabolites could be the biochemical result of the gaping behavior of mollusks during emergence. The change in tissue distribution and mass balance of 13C-labeled nutrients (U-13C-glucose and 2-13C/15N-glycine) provides the basis for a new quantitative fluxomic method for elucidating sub-lethal environmental effects in marine organisms called whole body mass balance phenotyping (WoMBaP).
Keywords: 1H & 13C NMR; metabolomic; fluxomic; oyster; mass balance; 2-13C/15N-glycine; U-13C-glucose 1H &; 13C NMR; metabolomic; fluxomic; oyster; mass balance; 2-13C/15N-glycine; U-13C-glucose
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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MDPI and ACS Style

Tikunov, A.P.; Stoskopf, M.K.; Macdonald, J.M. Fluxomics of the Eastern Oyster for Environmental Stress Studies. Metabolites 2014, 4, 53-70.

AMA Style

Tikunov AP, Stoskopf MK, Macdonald JM. Fluxomics of the Eastern Oyster for Environmental Stress Studies. Metabolites. 2014; 4(1):53-70.

Chicago/Turabian Style

Tikunov, Andrey P.; Stoskopf, Michael K.; Macdonald, Jeffrey M. 2014. "Fluxomics of the Eastern Oyster for Environmental Stress Studies." Metabolites 4, no. 1: 53-70.

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