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Gluconeogenesis and carbon utilization in embryos from small and large chicken eggs
Author(s) -
Sunny Nishanth E,
Adamany Jessica,
Bequette Brian J
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.21.5.a344
Subject(s) - gluconeogenesis , glycogen , alanine , biology , embryo , medicine , carbohydrate , biochemistry , glycerol , amino acid , chemistry , endocrinology , metabolism , fishery
In chick embryos, limited carbohydrate in‐ovo necessitates high rates of gluconeogenesis from amino acids and/or triglyceride‐glycerol for glycogen synthesis and other metabolic functions. The aim was to quantify gluconeogenesis and glucose carbon recycling during the latter stages of development in small versus large eggs. [U‐ 13 C]Glucose (15 mg in 75 μL water) was injected into the amniotic fluid of small (54 to 58 g) and large (66 to 70 g) eggs for three consecutive days prior to tissue and blood collection on d 12, 14, 16 and 18 embryonic (5 eggs/age group). Blood was analyzed by GC‐MS for 13 C‐mass isotopomer distribution in glucose, alanine, aspartate and glutamate. On d 16 and 18, embryo weights of small eggs were less than large eggs (17.8 and 20.6 g vs. 23.4 and 27.8 g; P<0.05). Gluconeogenesis (0.97 to 1.38 g/d) and glucose carbon recycling (30%) did not differ between small and large embryos; however, there was an increase (P < 0.01) in these fluxes from d 12 onwards. There was a significant contribution of glucose carbon to alanine flux (5 to 65%; P< 0.01), but only a small portion of aspartate (0.2 to 10%) and no glutamate derived from glucose. The latter indicates limited entry of glucose carbon into the Krebs cycle. In summary, small egg‐embryos maintained similar rates of gluconeogenesis compared to large egg‐embryos, despite their small embryonic size.