کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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5510258 | 1538975 | 2017 | 7 صفحه PDF | دانلود رایگان |
We investigated the aerobic scope of chicken embryos, that is, the margin of increase of oxygen consumption (VÌO2) above its normal value. VÌO2 was measured by an open-flow methodology at embryonic ages E3, E7, E11, E15, E19 and at E20 at the internal (IP) and external pipping (EP) phases, at the normal incubation temperature (Ta = 38 °C), in hypothermia (Ta = 30 °C) and in hyperthermia (Ta = 41 and 44 °C). In the cold, Q10 averaged ~ 2 at all ages, except in IP and EP when lower values (~ 1.5) indicated some degree of thermogenesis. In hyperthermia (38-44 °C) Q10 was between 1 and 1.4. Hyperthermia had no significant effects on VÌO2 whether the results combined all ages or considered individual age groups, except in IP (in which VÌO2 increased 8% with 44 °C) and EP embryos (+ 13%). After opening the air cell, which exposed the embryo to a higher O2 pressure, hyperthermic VÌO2 was significantly higher than in normothermia in E19 (+ 13%), IP (+ 22%) and EP embryos (+ 22%). We conclude that in chicken embryos throughout most of incubation neither heat nor oxygen availability limits the normal (normoxic-normothermic) values of VÌO2. Only close to hatching O2-diffusion represents a limiting factor to the embryo's VÌO2. Hence, embryos differ from postnatal animals for a nearly absent aerobic scope, presumably because their major sources of energy expenditure (growth and tissue maintenance) are constantly maximized.
Journal: Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology - Volume 212, October 2017, Pages 81-87