Our investigation into the reported differences in ethanol sensitivity for swimming behavior led to the unexpected finding that the worms' sensitivity to ethanol depends on the osmolarity of the external medium, and that the worms are able to change their sensitivity to the effects of osmolarity based on experience. Therefore, the constituents of the exogenous medium are critical to note in future alcohol studies using C. elegans. We speculate that the permeability of the worm to exogenous ethanol might change depending on the history of exposure. Dynamic permeability may be adaptive for an animal that must occasionally encounter dangerous chemicals, such as ethanol, while roaming through its natural soil environment. Future study of this phenomenon in C. elegans may give rise to novel strategies to alter excess permeation of ethanol into specific tissues to prevent toxicity.
