title: Saxitoxin Modulates Immunological Parameters and Gene Transcription in Mytilus chilensis Hemocytes.
abstract: Saxitoxin (STX) is a neurotoxin produced by dinoflagellates in diverse species, such as Alexandrium spp., and it causes paralytic shellfish poisoning (PSP) in humans after the ingestion of contaminated shellfish. Recent studies have suggested that the immune functions of bivalves could be affected by harmful algae and/or by their toxins. Herein, hemocytes are the main effector cells of the immune cellular response. In this study, we evaluated the response of hemocytes from the mussel Mytilus chilensis to STX exposure in a primary culture. Cell cultures were characterized according to size and complexity, while reactive oxygen species (ROS) production was evaluated using a dichlorofluorescein diacetate (DCFH-DA) assay. Finally, phagocytic activity was measured using both flow cytometry and fluorescence microscopy assays. Additionally, gene transcription of candidate genes was evaluated by qPCR assays. The results evidenced that exposures to different concentrations of STX (1-100 nM) for 24 h did not affect cell viability, as determined by an MTT assay. However, when hemocytes were exposed for 4 or 16 h to STX (1-100 nM), there was a modulation of phagocytic activity and ROS production. Moreover, hemocytes exposed to 100 nM of STX for 4 or 16 h showed a significant increase in transcript levels of genes encoding for antioxidant enzymes (SOD, CAT), mitochondrial enzymes (COI, COIII, CYTB, ATP6, ND1) and ion channels (K+, Ca2+). Meanwhile, C-type lectin and toll-like receptor genes revealed a bi-phase transcriptional response after 16 and 24-48 h of exposure to STX. These results suggest that STX can negatively affect the immunocompetence of M. chilensis hemocytes, which were capable of responding to STX exposure in vitro by increasing the mRNA levels of antioxidant enzymes.
authors.affiliation: Laboratory of Cell Culture and Marine Genomics, Marine Biotechnology Unit, Faculty of Natural and Oceanographic Sciences and Program COPAS Sur-Austral, University of Concepción, Concepción 4070386, Chile. aastuya@udec.cl.
authors.forename: Allisson
authors.initials: A
authors.lastname: Astuya
authors.affiliation: Laboratory of Cell Culture and Marine Genomics, Marine Biotechnology Unit, Faculty of Natural and Oceanographic Sciences and Program COPAS Sur-Austral, University of Concepción, Concepción 4070386, Chile. crislericarrera@udec.cl.
authors.forename: Crisleri
authors.initials: C
authors.lastname: Carrera
authors.affiliation: Laboratory of Cell Culture and Marine Genomics, Marine Biotechnology Unit, Faculty of Natural and Oceanographic Sciences and Program COPAS Sur-Austral, University of Concepción, Concepción 4070386, Chile. viulloa@udec.cl.
authors.forename: Viviana
authors.initials: V
authors.lastname: Ulloa
authors.affiliation: Laboratory of Cell Culture and Marine Genomics, Marine Biotechnology Unit, Faculty of Natural and Oceanographic Sciences and Program COPAS Sur-Austral, University of Concepción, Concepción 4070386, Chile. amaballay@udec.cl.
authors.forename: Ambbar
authors.initials: A
authors.lastname: Aballay
authors.affiliation: Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, Concepción 4070386, Chile. gustavonunez@udec.cl.
authors.forename: Gustavo
authors.initials: G
authors.lastname: Núñez-Acuña
authors.affiliation: Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS/UBO/IRD/IFREMER, Institut Universitaire Européen de la Mer, Technopole Brest Iroise, 29280 Plouzané, France. helene.hegaret@univ-brest.fr.
authors.forename: Hélène
authors.initials: H
authors.lastname: Hégaret
authors.affiliation: Laboratory of Biotechnology and Aquatic Genomics, Interdisciplinary Center for Aquaculture Research (INCAR), University of Concepción, Concepción 4070386, Chile. crisgallardo@udec.cl.
authors.forename: Cristian
authors.initials: C
authors.lastname: Gallardo-Escárate
mesh_terms: D000818:Animals; D006434:Hemocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D049878:Mytilus / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D018384:Oxidative Stress; D010587:Phagocytosis; D011042:Poisons / Q000494:pharmacology* / Q000633:toxicity; D012530:Saxitoxin / Q000494:pharmacology* / Q000633:toxicity; D014158:Transcription, Genetic; D059467:Transcriptome
chemical_list: D011042:Poisons; D012530:Saxitoxin
keywords: hemocytes; immune response; paralytic shellfish poisoning; reactive oxygen species (ROS); saxitoxin