Effects of Nonylphenol and Nonylphenol Monoethoxylate on Hemocytes of the Giant Freshwater Prawn (Macrobrachium rosenbergii): An in Vitro Study on Viability and Immune Response

Abstract

Nonylphenol polyethoxylates (NPnEOs) constitute an important class of non-ionic surfactants that are widely used in many detergent formulations and plastic products for industrial and domestic use. Several metabolic products of NPnE0s formed by a complex microbial degradation pattern have been demonstrated that are more toxic than the parent compound. The aim of this study was to investigate the effects of nonylphenol (NP) and nonylphenol monoethoxylate (NP1EO) on hemocytes of the giant freshwater prawn (Macrobrachium rosenbergii), including phenoloxidase (PO) activity, respiratory burst and hemocyte viability, by means of in vitro exposure experiments. The results showed that both NP and NP1EO could increase the P0 activity after hemocytes were separately treated at 0.01, 0.05, and 0.1 mM for 5 min; however, a decrease of activity was detected after treatment at 0.05 mM for 20 min. Hemocytes treated with NP or NP1EO showed a reduction in respiratory burst and the reduction effect correlated with increases in either the concentration or the treatment time. At the same time, using the annexin assay to examine the toxicity of both chemicals to hemocytes, it was found that hemocytes exposed to NP or NP1EO for 5 min would primarily die via apoptosis. According to these results, we suggest that both chemicals examined could damage hemocytes and further influence the defense mechanism of prawns. This study reveals an important precaution for prawn cultivation.