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Effects of hypoxia on oxygen affinity, hemoglobin pattern, and blood volume of early chicken embryos
Insights
Hypoxic chicken embryos adapt to low oxygen by altering hemoglobin and increasing blood oxygen affinity. These changes enhance oxygen transport and survival during development.
Area of Science:
- Embryology
- Physiology
- Biochemistry
Background:
- Hypoxia, or low oxygen levels, presents significant challenges to developing organisms.
- Chicken embryos undergo developmental changes in hemoglobin and blood oxygen transport during incubation.
Purpose of the Study:
- To investigate the effects of hypoxia on chicken embryo development.
- To analyze changes in oxygen affinity, hemoglobin patterns, and blood volume under hypoxic conditions.
Main Methods:
- Chicken embryos were subjected to hypoxia (13.5% O2) between 4 and 9 days of incubation.
- Measurements included hemoglobin pattern, red blood cell appearance, blood oxygen capacity, blood volume, oxygen affinity, and adenosine 5'-triphosphate (ATP) concentration.
Main Results:
- Hypoxic embryos showed an earlier transition to adult hemoglobin due to premature definitive red cell appearance.
- Increased oxygen affinity was observed in hypoxic embryos over 0.1-0.2 g, linked to decreased red cell ATP.
- A heightened Bohr effect in younger hypoxic embryos facilitated better oxygen extraction.
Conclusions:
- Chicken embryos exhibit adaptive changes in blood oxygen transport in response to hypoxia.
- These adaptations, including altered hemoglobin and increased oxygen affinity, help compensate for reduced environmental oxygen.
- The findings support the hypothesis that embryonic oxygen affinity changes are driven by the need to adapt to changing oxygen uptake conditions.
Abstract:
We have investigated the influence of hypoxia (13.5% O2) on the oxygen affinity, hemoglobin pattern, and blood volume of chicken embryos. Data were collected between 4 and 9 days of incubation. It was found that the transition from embryonic to adult hemoglobin starts earlier in hypoxic embryos, due to a premature appearance of definitive red cells in the circulation. Blood oxygen capacity and total blood volume (related to embryonic weight) were not different from the controls. However, hypoxic embryos weighing more than 0.1-0.2 g have a significantly increased oxygen affinity (and decreased red cell adenosine 5'-triphosphate concentration). The higher O2 affinity partly compensates for the adverse effects of the lowered environmental PO2. In hypoxic embryos younger than 6 days, the Bohr effect is drastically increased, which allows a better oxygen extraction. Thus, the chicken embryo seems to be able to develop adaptive changes of blood O2 transport during hypoxia. The results support the view that the particular ontogenetic pattern of O2 affinity changes seen in avian or mammalian embryos arose from the need to adapt to the steadily changing conditions for O2 uptake.