Van Voorhies, W. A.: Broad oxygen tolerance in the nematode Caenorhabditis elegans.

I studied the effects of oxygen tensions ranging from 0 to 90 kPa on the metabolism, movement, and survivorship in the free-living, soil nematode Caenorhabditis elegans. C. elegans requires oxygen to develop and survive. However, it can maintain a normal metabolic rate at oxygen levels of 3.6 kPa and has near normal metabolic levels at oxygen levels as low as 2 kPa. The ability to withstand low ambient oxygen levels appears to be a consequence of the small body size of C. elegans which allows diffusion to readily supply oxygen to cells without requiring any specialized respiratory or metabolic adaptations. Thus, the small size of this organism pre-adapts C. elegans to living in soil environments that commonly become hypoxic. Movement in C. elegans appears to be of relatively minor metabolic cost. Different developmental stages of C. elegans are able to withstand up to 24 hrs of anoxia without major mortality. Longer periods significantly increased mortality, particularly for eggs. Remarkably, long-term exposure to 100% oxygen had no effect on C. elegans metabolic rate and populations were able to survive for a least 50 generations in 100% (90 kPa) oxygen. Such hyperoxic conditions are fatal to most organisms within a short period.