Biotoxicity of Sodium nitrite, Cadmium chloride and Toxaphene in Hydra, a Cnidarian model

Abstract

This study aimed to investigate the effects of food additive such as sodium nitrite (NaNO2) and the hazard chemical substances such as cadmium chloride (CdCl2) and toxaphene in a Cnidarian model, Hydra magnipapillata. Sodium nitrite has been added as a color former in foods and widely used for ham, sausages and fishcakes. The food additives are included extremely low in foods but their long term effects may not be expected simply. Cadmium and toxaphene are well known hazardous chemicals and their toxicity has been studied in many organisms but rarely in Cnidarians. This is the first approach to examine the chemical toxicity in Hydra magnipapillata and we investigated the effects on the mortality, asexual reproduction and regeneration in the exposure to 3 chemicals. The 24 h LC50 for NaNO2 was determined to 6 mM, for CdCl2 to 2 mg/L, and finally Toxaphene to 24 mg/L. The budding rate which represents asexual reproduction significantly decreased in 120 &#53409; of NaNO2, 480 ;g/L of toxaphene, and 20 ;g/L of CdCl2 after exposed for 11 days (p < 0.05). To examine the effects on body regeneration, hydra heads were excised then the body columns were exposed to those three chemicals. The head regeneration was prohibited at 4 mM in NaNO2 and 10 mg/L in toxaphene, but CdCl2 did not affect the head regeneration up to 1 mg/L. As the results, we found that those 3 chemicals showed the biotoxicity in Hydra as generally found in other animals and in further study we will examine the toxicities at molecular level such as specific gene expression level changes based on these results.