Behavioral and electrophysiologic responses of Drosophila melanogaster to prolonged periods of anoxia

Sensitivity to anoxia varies tremendously among phyla and species. Most mammals are exquisitely sensitive to low concentrations of inspired oxygen, while some fish, turtles and crustacea are very resistant. To determine the basis of anoxia tolerance, it would be useful to utilize a model system which can yield mechanistic answers. We studied the fruit fly, Drosophila melanogaster, to determine its anoxia resistance since this organism has been previously studied using a variety of approaches and has proven to be very useful in a number of areas of biology. Flies were exposed to anoxia for periods of 5-240 min, and, after 1-2 min in anoxia, Drosophila lost coordination, fell down, and became motionless. However, they tolerated a complete nitrogen atmosphere for up to 4 h following which they recovered. In addition, a nonlinear relation existed between time spent in anoxia and time to recovery. Extracellular recordings from flight muscles in response to giant fiber stimulation revealed complete recovery of muscle-evoked response, a response that was totally absent during anoxia. Mean O2 consumption per gram of tissue was substantially reduced in low O2 concentrations (20% of control). We conclude from these studies that: (1) Drosophila melanogaster is very resistant to anoxia and can be useful in the study of mechanisms of anoxia tolerance; and (2) the profound decline in metabolic rate during periods of low environmental O2 levels contributes to the survival of Drosophila.