Antioxidant properties of the mucus secreted by Laeonereis acuta (Polychaeta, Nereididae): A defense against environmental pro-oxidants? ☆ Tarsila B. Moraes a , Josencler L. Ribas Ferreira a , Carlos E. da Rosa a,b , Juliana Z. Sandrini a,b , Ana P. Votto a,b , Gilma S. Trindade a,b , Laura A. Geracitano a,b , Paulo C. Abreu c , José M. Monserrat a,b, ⁎ a Departamento de Ciências Fisiológicas, Fundação Universidade Federal do Rio Grande (FURG), Cx. P. 474, CEP 96.201-900, Rio Grande, RS, Brasil b Programa de Pós-Graduação em Ciências Fisiológicas, Fisiologia Animal Comparada (FURG), Brasil c Departamento de Oceanografia (FURG), Brasil Received 2 September 2005; received in revised form 27 October 2005; accepted 28 October 2005 Available online 15 December 2005 Abstract Polychaeta species like Laeonereis acuta (Nereididae) usually secrete great amounts of mucus that wrap the animal inside. Taking into account that fungi action in the sediment and UV radiation acting on dissolved organic matter in the water produces reactive oxygen species (ROS) like hydrogen peroxide (H 2 O 2 ), it was considered that the mucus secretion could represent an antioxidant defense against environmental ROS. Antioxidant enzymes (catalase—CAT; superoxide dismutase—SOD; glutathione peroxidase—GPx and glutathione-S-transferase—GST) and total antioxidant capacity (TOSC) were determined in worms and mucus secretion. Higher (p b 0.05) CAT, GPx and TOSC values were registered in mucus samples respect worms, SOD activity was similar (p N 0.05) in both kind of samples, and absence of GST activity was observed in mucus samples, suggesting absence of catalyzed phase II reactions. In assays conducted with hepatoma cell lines exposed to H 2 O 2 , it was verified that: (1) mucus co-exposure significantly (p b 0.05) lowered DNA damage induced by H 2 O 2 ; (2) ROS production was significantly (p b 0.05) reduced when cells were exposed simultaneously with mucus samples and H 2 O 2 respect H 2 O 2 alone. It can be concluded that the mucus production contributes substantially to the antioxidant defense system of the worm against environmental ROS through the interception or degradation of H 2 O 2 , peroxyl and hydroxyl radicals. © 2005 Elsevier Inc. All rights reserved. Keywords: Antioxidant defenses; DNA damage; Mucus secretion; Polychaeta; Reactive oxygen species 1. Introduction The aquatic environment is a complex mixture that produces directly or indirectly several reactive oxygen species (ROS) like hydroxyl radical (HO . ) and hydrogen peroxide (H 2 O 2 ) through fungal action (Schlegel, 1992) in the sediment and/or UV radiation in presence of organic matter (Herut et al., 1998; Yocis et al., 2000; Gerringa et al., 2004). It also has been reported that harmful red tide dinoflagellate species like Cochlodinium polykrikoides possess oxidases that allow them to produce superoxide anion (O 2 ˙- ), a feature that has been hypothesized as one of the key factors for fish mortality during algal blooms (Kim et al., 2000, 2002). Other environmental factors like low water temperature have been considered as direct or indirect modulators of ROS pro- duction, since cold seawater presents higher oxygen solubility that could augment oxidative stress in polar organisms. The review of Abele and Puntarulo (2004) remarked the fact that some polar invertebrate species present higher levels of anti- oxidants, and that they are more vulnerable than temperate Comparative Biochemistry and Physiology, Part C 142 (2006) 293 – 300 www.elsevier.com/locate/cbpc ☆ This paper is part of a special issue of CBP dedicated to “The Face of Latin American Comparative Biochemistry and Physiology” organized by Marcelo Hermes-Lima (Brazil) and co-edited by Carlos Navas (Brazil), Tania Zenteno- Savín (Mexico) and the editors of CBP. This issue is in honour of Cicero Lima and the late Peter W. Hochachka, teacher, friend and devoted supporter of Latin American science. ⁎ Corresponding author. Departamento de Ciências Fisiológicas, Fundação Universidade Federal do Rio Grande (FURG), Cx. P. 474, CEP 96.201-900, Rio Grande, RS, Brasil. Tel.: +55 53 32336856. E-mail address: jose@octopus.furg.br (J.M. Monserrat). 1532-0456/$ - see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.cbpc.2005.10.017