Aquatic Toxicology 114–115 (2012) 39–48 Contents lists available at SciVerse ScienceDirect Aquatic Toxicology jou rn al h om epa ge: www.elsevier.com/locate/aquatox Effects of a toxic cyanobacterial bloom (Planktothrix agardhii) on fish: Insights from histopathological and quantitative proteomic assessments following the oral exposure of medaka fish (Oryzias latipes) Benjamin Marie a , Hélène Huet a,b , Arul Marie a,c , Chakib Djediat a,d , Simone Puiseux-Dao a , Arnaud Catherine a , Isabelle Trinchet a , Marc Edery a,∗ a UMR 7245 CNRS Molécules de communication et adaptation des microorganismes, équipe Cyanobactéries, Cyanotoxines et Environnement, Muséum National d’Histoire Naturelle, 12 rue Buffon, F-75231 Paris Cedex 05, France b Laboratoire d’Anatomie Pathologique, Ecole Nationale Vétérinaire d’Alfort, 7 Avenue du Général de Gaulle, F-94704 Maisons-Alfort Cedex, France c Plateforme de spectrométrie de masse et de protéomique, Muséum National d’Histoire Naturelle, 43 rue Buffon, F-75231 Paris Cedex 05, France d Plateforme de microscopie électronique, Muséum National d’Histoire Naturelle, 12 rue Buffon, F-75231 Paris Cedex 05, France a r t i c l e i n f o Article history: Received 24 October 2011 Received in revised form 7 February 2012 Accepted 11 February 2012 Keywords: Cyanotoxins Medaka fish Microcystins Liver Vitellogenin a b s t r a c t Cyanobacterial toxic blooms often occur in freshwater lakes and constitute a potential health risk to human populations, as well as to fish and other aquatic organisms. Microcystin-LR (the cyanotoxin most commonly detected in the freshwater environment) is a potent hepatotoxin, deregulating the kinase pathway by inhibiting phosphatases 1 and 2A. Although toxicological effects have been clearly linked to the in vitro exposure of fish to purified microcystins, cyanotoxins are produced by the cyanobacteria together with numerous other potentially toxic molecules, and their overall and specific implications for the health of fish have still not been clearly established and remain puzzlingly difficult to assess. The medaka fish (Oryzias latipes) was chosen as an in vitro model for studying the effects of a cyanobacte- rial bloom on liver protein contents using a gel free quantitative approach, iTRAQ, in addition to pathology examinations on histological preparations. Fish were gavaged with 5 L cyanobacterial extracts (Plank- tothrix agardhii) from a natural bloom (La Grande Paroisse, France) containing 2.5 g equiv. MC-LR. 2 h after exposure, the fish were sacrificed and livers were collected for analysis. Histological observations indicate that hepatocytes present glycogen storage loss, and cellular damages, together with immuno- logical localization of MCs. Using a proteomic approach, 304 proteins were identified in the fish livers, 147 of them with a high degree of identification confidence. Fifteen of these proteins were statistically significantly different from those of controls (gavaged with water only). Overall, these protein regulation discrepancies clearly indicate that oxidative stress and lipid regulation had occurred in the livers of the exposed medaka fish. In contrast to previous pure microcystin-LR gavage experiments, marked induction of vitellogenin 1 protein was observed for the first time with a cyanobacterial extract. This finding was confirmed by ELISA quantification of vitellogenin liver content, suggesting that the Planktothrix bloom extract had induced the occurrence of an endocrine-disrupting effect. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Toxin-producing harmful algal blooms occur throughout the world and constitute a major cause of concern for both public health and environmental ecology. To date, at least 46 cyanobac- terial species have been shown to produce toxins (Chorus, 2005; ∗ Corresponding author at: UMR 7245 CNRS-USM 0505 Molécules de communi- cation et adaptation des micro-organismes, Muséum National d’Histoire Naturelle, 12 rue Buffon, F-75231 Paris Cedex 05, France. Tel.: +33 140793126; fax: +33 140793594. E-mail addresses: medery@mnhn.fr, bmarie@mnhn.fr (M. Edery). Zurawell et al., 2005). The microcystin-producing cyanobacterium Planktothrix is one of the most widespread and important toxin- producing cyanobacteria genera in temperate climate lakes (Ernst et al., 2001). Indeed, Planktothrix species are predominant in sev- eral European lakes, ranging from natural mesotrophic alpine lakes (Planktothrix rubescens; Jacquet et al., 2005) to the eutrophic water of artificial lakes (Planktothrix agardhii; Catherine et al., 2008). Concerns about the toxicological potential of freshwater cyanobacteria have mainly focused on the microcystins (MCs), and more specifically on the MC-LR, which is the most fre- quently detected MC variant in the environment (at concentrations frequently exceeding the World Health Organization advisory 0166-445X/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.aquatox.2012.02.008