Department of Animal and Avian Sciences, University of Maryland, College Park 20742, USA.
J Anim Sci. 2010 Mar;88(3):912-21. doi: 10.2527/jas.2009-2479. Epub 2009 Dec 4.
We hypothesized that, as the supply of preformed glucose diminishes during development, the embryo would transition to a greater rate of gluconeogenesis (GNG) and that GNG would be greater in embryos from small vs. typical size eggs. Gluconeogenesis by embryos from small (51.1 +/- 3.46 g) and typical size (65 +/- 4.35 g) broiler breeder eggs was measured by dosing [(13)C(6)]glucose (15 mgxegg(-1)) into the chorio-allantoic fluid for 3 consecutive days to achieve isotopic steady-state before blood collection on embryonic day (e) 12, e14, e16, and e18 (4 to 5 eggsxsize(-1)xd(-1)). The (13)C-Mass isotopomer enrichment of blood glucose was determined by gas chromatography-mass spectrometry. On e14, e16, and e18, but not on e12, embryos from small eggs weighed less (P < 0.05) than typical size eggs. For both sizes of eggs, blood glucose concentration, glucose entry rate (g.d(-1)), and Cori cycling and glucose (13)C-recycling (% of entry rate) increased (P < 0.05) with development. On e12 and e14, rates of glucose entry and Cori cycle flux were greater (P < 0.05) for embryos from small eggs. When standardized to BW (g.100 g of BW(-1)xd(-1)), glucose entry and Cori and non-Cori cycle fluxes were greater for embryos from small eggs. From e12 through e18, blood concentrations of gluconeogenic AA (threonine, glutamine, arginine, proline, isoleucine, and valine) were 25 to 48% less (P < 0.01) in embryos from small eggs. In conclusion, embryos from small eggs exhibit greater rates of GNG earlier in development compared with typical size eggs and, perhaps as a consequence, their reduced embryonic growth may result from diverting greater supplies of AA toward GNG.
我们假设，随着胚胎发育过程中预先形成的葡萄糖供应减少，胚胎将过渡到更高的糖异生（GNG）速率，并且来自小尺寸与典型尺寸卵的胚胎的 GNG 将会更高。通过向绒毛尿囊液中剂量注射[13C（6）]葡萄糖（15 mgxegg（-1）），从小（51.1 +/- 3.46 g）和典型尺寸（65 +/- 4.35 g）肉鸡种蛋中获得胚胎的糖异生，以在采血前实现同位素稳态在胚胎日（e）12、e14、e16 和 e18（4 至 5 eggsxsize（-1）xd（-1））。通过气相色谱-质谱法确定血液葡萄糖的[13C-Mass 同位素丰度。在 e14、e16 和 e18 日，但不在 e12 日，来自小蛋的胚胎体重较轻（P < 0.05）。对于两种大小的卵，血液葡萄糖浓度、葡萄糖进入率（g.d（-1））、Cori 循环和葡萄糖（13C）再循环（进入率的%）均随发育而增加（P < 0.05）。在 e12 和 e14 日，来自小蛋的胚胎的葡萄糖进入率和 Cori 循环通量更高（P < 0.05）。当标准化到 BW（g.100 g 的 BW（-1）xd（-1））时，来自小蛋的胚胎的葡萄糖进入和 Cori 和非 Cori 循环通量更高。从 e12 到 e18 日，来自小蛋的胚胎的血液中糖异生 AA（苏氨酸、谷氨酰胺、精氨酸、脯氨酸、异亮氨酸和缬氨酸）的浓度低 25-48%（P < 0.01）。总之，与典型尺寸卵相比，来自小蛋的胚胎在发育早期表现出更高的 GNG 速率，并且，也许是由于这个原因，它们的胚胎生长减少可能是由于将更多的 AA 供应转向 GNG。
