Definition of Planarian Mortality in an Acute Toxicity Test: A Case Study on Dugesia japonica Exposed to 1-Octyl-3-methylimidazolium Bromide

In order to define the mortality criteria of planarian objectively,a case study of Dugesia japonica exposed to 1-octyl-3-methylimidazolium bromide(C8mim]Br)was performed followed by a recovery culture.The results showed that defining planarian mortality in light of its body disintegration was appropriate.If the disintegrated tissue of a planarian was more than 1/4 of its body length,it would completely degenerate.However,a planarian would regenerate the lost tissue and return to normal after a few days’recovery culture if the disintegrated part was less than 1/4 of body length.Therefore,we propose to use body disintegration as the endpoint of planarian mortality,i.e.,1/4 body length degenerated is the critical threshold of mortality and survival of planarians when exposed to toxicants.This criterion could be adapted in the standardization of testing protocols and comparability of acute toxicity test or other toxicological research using planarian as the test animal.