Department of Biological Sciences, Brock University, St. Catharines, Ontario L2S 3A1, Canada.
J Insect Physiol. 2011 Apr;57(4):444-51. doi: 10.1016/j.jinsphys.2011.01.005. Epub 2011 Jan 15.
We examined physiological phenotypes of Drosophila melanogaster in hypoxic to hyperoxic atmospheres. We performed measurements on life span or behavioural function in 5, 21, 40, 60, and 80% O(2), and combined this with literature data for 2% and 100% O(2). O(2) incubation resulted in a concentration-dependent reduction of life span in both hypoxia and hyperoxia, though different measures of life span were affected differently. We also examined how behavioural and metabolic functions were affected by exposure to hyperoxia (up to 60% O(2)). Climbing behaviour was measured as a fast (4 s) and slow (55 s) response in a negative geotaxis assay. In normoxia, both measures of climbing response declined exponentially until disappearing completely. Interestingly, survivorship was very high until the loss of climbing ability, after which it dropped rapidly. This pattern appeared accelerated in 40% O(2). However, while flies in 60% O(2) also apparently lost their fast climbing ability immediately prior to the drop in survivorship, they maintained considerable climbing ability over the longer trial. Metabolism, measured by CO(2) release, did not change with age in normoxic flies, but was significantly lower in flies exposed to hyperoxia, particularly as the flies aged. There was, however, a slight increase in water loss rate with age in normoxia, while in hyperoxia, water loss was reduced. Uniquely, the water loss rates of flies in 60% O(2) doubled immediately prior to the end of their life span. Because ageing results in generally irreversible functional declines, we examined if functional declines in hyperoxia (60% O(2)) were also irreversible, or whether some functioning could recover after a return to normoxia. After 7 days of recovery, water loss rates decreased, CO(2) exhalation slightly increased, and climbing ability was partially recovered. Therefore, the effect of O(2) on D. melanogaster function is non-linear, may be reversible, and may include unique phenotypes that arise at some O(2) concentrations, and not others.
我们研究了果蝇在低氧到高氧环境中的生理表型。我们在 5%、21%、40%、60%和 80%O2 下测量了寿命或行为功能，并将其与 2%和 100%O2 的文献数据相结合。O2 孵育导致在低氧和高氧中寿命呈浓度依赖性降低，尽管寿命的不同测量方式受到不同的影响。我们还研究了行为和代谢功能如何受到高氧（高达 60%O2）暴露的影响。在负趋地性测定中，作为快速（4 秒）和慢速（55 秒）反应测量了攀爬行为。在常氧下，两种攀爬反应测量值均呈指数下降，直到完全消失。有趣的是，存活率非常高，直到失去攀爬能力，之后迅速下降。这种模式在 40%O2 中似乎加速了。然而，虽然 60%O2 中的苍蝇在丧失生存能力之前立即明显丧失了快速攀爬能力，但它们在较长的试验中仍保持相当大的攀爬能力。通过 CO2 释放测量的代谢在常氧下的正常苍蝇中不会随年龄而变化，但在高氧下，特别是随着苍蝇衰老，代谢显著降低。然而，在常氧下，水损失率随年龄略有增加，而在高氧下，水损失减少。独特的是，在寿命结束前，60%O2 中的苍蝇的水损失率立即翻了一番。由于衰老导致普遍不可逆转的功能下降，我们检查了高氧（60%O2）中的功能下降是否也是不可逆转的，或者在返回常氧后是否可以恢复一些功能。恢复 7 天后，水损失率降低，CO2 呼气略有增加，攀爬能力部分恢复。因此，O2 对 D. melanogaster 功能的影响是非线性的，可能是可逆的，并且可能包括在某些 O2 浓度下出现而不是在其他浓度下出现的独特表型。
