Article

Gas exchange and hatchability of chicken eggs incubated at simulated high altitude.

Journal of Applied Physiology (Impact Factor: 3.43). 03/1985; 58(2):416-8.
Source: PubMed

ABSTRACT Chicken eggs laid at sea level were incubated at sea level (control conditions), at a simulated altitude of 5.5 km without any further measures (natural conditions), and at a simulated altitude of 5.7 km at optimal incubator gas composition (optimal conditions). Under optimal conditions the incubator relative humidity was 70% throughout incubation, the gas mixture supplied to the incubator contained 45% O2-55% N2, and the ventilation rate was reduced to 6% of control in order to maintain the normal air-space gas tensions and to compensate for the increased eggshell conductance at altitude. The embryos that developed under control conditions showed a normal CO2 production with 94% hatchability of fertile eggs. Under natural conditions at altitude all embryos died within a few days. Optimal conditions resulted in an almost normal gas exchange and in an improvement of hatchability from 0 to 81% of fertile eggs.

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    • "Specific processes that take place during embryonic lung development and structures in animals that live at high altitudes are the basis for highly efficient pulmonary ventilation, which leads to altitude adaptation [2], [3]. For plain chickens at low altitudes, inadequate oxygen exchange results in hypoxia syndrome and is lethal [4]–[6]. Therefore, determining the particular altitude adaptation characteristics of high-altitude chickens is important. "
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    ABSTRACT: The lungs undergo changes that are adaptive for high elevation in certain animal species. In chickens, animals bred at high elevations (e.g., Tibet chickens) are better able to hatch and survive under high-altitude conditions. In addition, lowland chicken breeds undergo physiological effects and suffer greater mortality when they are exposed to hypoxic conditions during embryonic development. Although these physiological effects have been noted, the mechanisms that are responsible for hypoxia-induced changes in lung development and function are not known. Here we have examined the role of a particular microRNA (miRNA) in the regulation of lung development under hypoxic conditions. When chicks were incubated in low oxygen (hypoxia), miR-15a was significantly increased in embryonic lung tissue. The expression level of miR-15a in hypoxic Tibet chicken embryos increased and remained relatively high at embryonic day (E)16-20, whereas in normal chickens, expression increased and peaked at E19-20, at which time the cross-current gas exchange system (CCGS) is developing. Bcl-2 was a translationally repressed target of miR-15a in these chickens. miR-16, a cluster and family member of miR-15a, was detected but did not participate in the posttranscriptional regulation of bcl-2. Around E19, the hypoxia-induced decrease in Bcl-2 protein resulted in apoptosis in the mesenchyme around the migrating tubes, which led to an expansion and migration of the tubes that would become the air capillary network and the CCGS. Thus, interfering with miR-15a expression in lung tissue may be a novel therapeutic strategy for hypoxia insults and altitude adaptation.
    PLoS ONE 06/2014; 9(6):e98868. DOI:10.1371/journal.pone.0098868 · 3.23 Impact Factor
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    • "However, cardiac output drops in hypoxic embryos (Piiper et al 1980) and this response may offset the benefits of the onset of adult haemoglobin synthesis and improved blood 0 2 affinity. It is unknown how these characteristics vary from those of wild birds incubated at high altitude, Chicken eggs can be incubated successfully at a simulated altitude of 5·7 km in incubator consisting of 70% relative humidity, 45% O 2 , and 55% N 2 (Visschedijk 1985). These conditions offset the high rates of water loss at that altitude and prevent hypoxia in the embryos. "
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