Contents lists available at ScienceDirect Ecotoxicology and Environmental Safety journal homepage: www.elsevier.com/locate/ecoenv HSP70 expression in Biomphalaria glabrata snails exposed to cadmium Rebeca da Silva Cantinha a,b , Sueli Ivone Borrely b , Nancy Oguiura a , Carlos Alberto de Bragança Pereira c , Marcela M. Rigolon a , Eliana Nakano a, ⁎ a Instituto Butantan, Laboratório de Parasitologia, Avenida Vital Brasil, 1500, Butantã, São Paulo, SP CEP 05503-900, Brazil b Instituto de Pesquisas Energéticas e Nucleares, Avenida Professor Lineu Prestes, 2242, Cidade Universitária, São Paulo, SP CEP 05508-000, Brazil c Departamento de Estatística, Instituto de Matemática e Estatística, Universidade de São Paulo, Rua do Matão, 1010, Cidade Universitária, São Paulo, SP CEP 05008- 090, Brazil ARTICLE INFO Keywords: Protein induction Biomarker Bioindicator Mollusk Acquired resistance ABSTRACT In this study, the effects of the heavy metal cadmium on the stress protein HSP70 are investigated in freshwater mollusks Biomphalaria glabrata. Adult snails were exposed for 96 h to CdCl 2 at concentrations ranging from 0.09 to 0.7 mg L -1 (LC 50/96 h =0.34 (0.30–0.37). Time and concentration-dependent increases in the expression of HSP70 were observed at sub-lethal levels in the immunoblotting assay. Further, an increased survival to a lethal heat shock was observed in animals pre-exposed to a nonlethal concentration of cadmium, evidencing the induction of acquired tolerance. The present study demonstrated the inducibility of B. glabrata HSP70 by cadmium, a relevant environmental contaminant, at non-lethal levels, providing evidences that the assessment of HSP70 in B. glabrata can be regarded as a suitable biomarker for ecotoxicological studies. 1. Introduction The heat shock response, firstly described in drosophila upon exposure to elevated temperature (Ritossa, 1962), involves the induc- tion of a set of proteins known as stress proteins or heat shock proteins (HSPs) in response to environmental insults (Lindquist, 1986). Heat shock proteins can be broadly placed into five major families according to their molecular weight, amino acid sequence homologies and functions and are frequently referred to as HSP100, HSP90, HSP70, HSP60 and the small HSP stress-proteins. The HSP70 family proteins differ from other classes of heat shock proteins being one of most highly conserved, with more than 50% of homology between man, drosophila, mouse, yeast and bacteria and the first to be induced under stress conditions. It is one of the most widely studied and well defined classes of HSPs (Lindquist, 1986; Gupta et al., 2010). At cellular level, HSPs are involved in the maintenance of protein homeostasis and their role in protecting cells from stress is strongly suggested by the character of an emergency response, being extremely rapid and very strong (Parsell and Lindquist, 1993). Although the role of HSPs at the organismal level is not well established, some studies suggest the association of aberrant heat shock responses with diseases including cancer, neurodegenerative disorders, ischemia or hypoxia, virus infection, inflammation and wound healing (Kim et al., 2007). Exposure to a wide range of physical and chemical stressors proved to elicit the cellular stress response with increases in HSP70 levels (Sanders, 1993; Bierkens, 2000; Gupta et al., 2010). Despite the non- specific nature of the stress response, heat shock proteins have been postulated as possible biomarkers in ecotoxicology by their role in the recovery of damaged proteins, characterizing an initial response that can be used in protocols to evaluate damage to organisms subjected to environmental aggressors (Sanders, 1993; Bierkens, 2000). In addition, HSP70 reflects a direct link between exposure and cellular damage, and its highly conserved nature among different species supports its use as an early marker of environmental stress (Mukhopadhyay et al., 2003). Studies with organisms from the most diverse phyla proposed the use of HSPs, especially the HSP70, as biomarkers in ecotoxicology (Nadeau et al., 2001; Ireland et al., 2004; Bednarek et al., 2016). In aquatic species, HSP70 has been applied as indicator of alterations and biological damage, either in natural environment or in laboratory (Sanders, 1993; Sanders et al., 1995; Williams et al., 1996; Tedengren et al., 2000; Singer et al., 2005; Radlowska and Pempkowiak, 2002; Piano et al., 2004; Pruski and Dixon, 2007; Ivanina et al., 2009; Cantinha et al., 2013; Wali and Balkhi, 2016). Freshwater snails B. glabrata have been reared in our laboratory for more than 30 years and data from our former studies showed that this is a suitable species for studies on biological effects of chemical con- taminants (Nakano et al., 2003; Estevam et al., 2006; Tallarico et al., 2014). In addition to toxicity analysis, endpoints for detection of effects http://dx.doi.org/10.1016/j.ecoenv.2017.02.026 Received 3 November 2016; Received in revised form 13 February 2017; Accepted 16 February 2017 ⁎ Corresponding author. E-mail addresses: rcantinha@gmail.com (R. da Silva Cantinha), sborrely@ipen.br (S.I. Borrely), nancyoguiura@butantan.gov.br (N. Oguiura), cadebp@gmail.com (C.A. de Bragança Pereira), marcelarigolon@hotmail.com (M.M. Rigolon), eliana.nakano@butantan.gov.br (E. Nakano). Ecotoxicology and Environmental Safety 140 (2017) 18–23 0147-6513/ © 2017 Elsevier Inc. All rights reserved. MARK