title: Calcium mediates the cellular response of Chlamydomonas reinhardtii to the emerging aquatic pollutant Triclosan.
abstract: The present study was aimed at investigating the role of intracellular free calcium, [Ca2+]c, in the early cellular response of the green alga Chlamydomonas reinhardtii to the emergent pollutant Triclosan (13.8μM; 24h of exposure). There is a growing concern about the persistence and toxicity of this antimicrobial in aquatic environments, where non-target organisms such as C. reinhardtii, a primary producer of ecological relevance, might be severely impacted. A mechanistic study was undertaken which combined flow cytometry protocols, physiological as well as gene expression analysis. As an early response, Triclosan strongly altered [Ca2+]chomeostasis which could be prevented by prechelation with the intracellular calcium chelator BAPTA-AM. Triclosan induced ROS overproduction which ultimately leads to oxidative stress with loss of membrane integrity, membrane depolarization, photosynthesis inhibition and mitochondrial membrane depolarization; within this context, Triclosan also induced an increase in caspase 3/7 activity and altered the expression of metacaspase genes which are indicative of apoptosis. All these adverse outcomes were dependent on [Ca2+]c. Interestingly, an interconnection between [Ca2+]calterations and increased ROS formation by Triclosan was found. Taken altogether these results shed light on the mechanisms behind Triclosan toxicity in the green alga Chlamydomonas reinhardtii and demonstrate the role of [Ca2+]cin mediating the observed toxicity.
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: González-Pleiter
authors.affiliation: Laboratorio de Microbiología, Facultad de Ciencias, Universidad da Coruña, Campus de A Zapateira s/n, 15008 A Coruña, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Rioboo
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Reguera
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Isidro
authors.initials: I
authors.lastname: Abreu
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Leganés
authors.affiliation: Laboratorio de Microbiología, Facultad de Ciencias, Universidad da Coruña, Campus de A Zapateira s/n, 15008 A Coruña, Spain.
authors.forename: Ángeles
authors.initials: Á
authors.lastname: Cid
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain. Electronic address: francisca.pina@uam.es.
authors.forename: Francisca
authors.initials: F
authors.lastname: Fernández-Piñas
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002118:Calcium / Q000494:pharmacology*; D020013:Calcium Signaling / Q000187:drug effects / Q000235:genetics; D020169:Caspases / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016825:Chlamydomonas reinhardtii / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D010788:Photosynthesis / Q000187:drug effects / Q000235:genetics; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013481:Superoxides / Q000378:metabolism; D014260:Triclosan / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D005456:Fluorescent Dyes; D014874:Water Pollutants, Chemical; D013481:Superoxides; D014260:Triclosan; D006861:Hydrogen Peroxide; D020169:Caspases; D002118:Calcium; D000111:Acetylcysteine
keywords: Apoptosis; BAPTA-AM; Chlamydomonas reinhardtii; Intracellular free calcium homeostasis; Oxidative stress; Triclosan