Toxicity Effects of Anionic Surfactants Sodium Dodecyl Sulphate (SDS) to Planarian Dugesia japonica Zuoqing Yuan

Sodium dodecyl Sulphate (SDS) is a kind of anionic surfactant that denatures membrane proteins of cells. It is used in detergents, household cleaning products, and in the mining and oil industries. It can be present in sufficient concentrations to constitute toxicity problems to aquatic organisms in untreated effluents.

Freshwater planarians have the ability to regenerate their whole body from a small piece of the body, so they have been widespread applied in developmental biology and neuroscience research. Furthermore, they have a high sensitivity to toxins with widespread application in toxicological and genotoxicity studies.

In this study we used planarians Dugesia japonica, which belong to the phylum Platyhelminthes, class Turbellaria, order Tricladida, family Dugesiidae, as an animal assay. The purpose of this study was to evaluate aquatic toxicity of SDS by examining the effects of SDS on survival, behavior, regrowth of the head and antioxidant activity in planarians D. japonica.

Mean lethal concentration (LC50)

Daphnia magna has been suggested to be the most sensitive species to surfactants. Data on SDS toxicity obtained from the 48-h planarian toxicity test in our study was 5.8 mg/L. However, data on SDS toxicity obtained from the 48-h Daphnia magna test in the literature was 6.2-9 mg/L. Thus, planarians Dugesia japonica also have highly sensitivity to SDS among aquatic organisms.

Fig. 1 Mortality of D. japonica exposed to SDS after 1-h exposure.

Fig. 2 Effect of SDS in planarian motility.

Fig. 3 Recovery of SDS exposure.

eyespots auricles Fig.4 Regeneration performance of regenerating planarians exposed to different concentrations of SDS.

Our results showed that the appearance of auricles was easier affected by SDS than that of eyespots in the decapitated D. japonica fragments. Therefore, the auricle tissues in regenerating planarians might be a potential biomarker for SDS (and possibly other surfactants) pollution.

Fig.6 Changes in activities of SOD (units/mg protein) in regenerating planarians exposed to different concentrations of SDS.

Fig. 7 Changes in activities of CAT (units/mg protein) in regenerating planarians exposed to different concentrations of SDS.

The enzymatic antioxidant defenses of regenerating planarians were significantly altered by SDS. The increase in antioxidant enzyme activities could primarily be a response to the SDS. We can conclude that planarian D.japonica can be applied as a good bioindicator organism for the evaluation of SDS (and possibly other surfactants) effects upon freshwater invertebrates in a freshwater environment.