title: Copper affects biochemical and physiological responses of Selenastrum gracile (Reinsch).
abstract: Copper is an essential metal for several physiological and metabolic processes, but a narrow range regulate its effect in phytoplankton cells. It can affect the production of biomolecules and be toxic at concentrations slightly above those required, e.g. decreasing photosynthesis and increasing respiration. The aims of this study were to analyse the changes in growth and chlorophyll a synthesis, and in biochemistry (total carbohydrates, proteins, lipids and fatty acids) of the freshwater microalga Selenastrum gracile after exposure to copper. Exponentially growing cells were exposed to 5 concentrations of free copper ions (Cu2+) ranging from 0.7 (control) to 13 × 10-8M for up to 120 h. Free Cu2+ion concentrations were calculated through the chemical equilibrium model MINEQL+. We observed that copper was responsible for a decrease in cell density and an increase in total protein and lipid production, but no effect on total carbohydrates was detected. The increase in phospholipids and sterols and a decrease in saturated fatty acids under copper exposure suggest a change in conformation of the cell membrane, by decreasing its fluidity. We suggest this serves the cell as a system to avoid the internalization of metal, thereby acting as a detoxifying mechanism.
authors.affiliation: Departamento de Hidrobiologia, Centro de Ciências Biológicas e da Saúde (CCBS), Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luís, Km 235, São Carlos, SP, 13565-905, Brazil. swertsbio@gmail.com.
authors.forename: Giseli S
authors.identifier: http://orcid.org/0000-0002-2251-3494
authors.initials: GS
authors.lastname: Rocha
authors.affiliation: Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Parrish
authors.affiliation: Departamento de Botânica, Centro de Ciências Biológicas e da Saúde (CCBS), Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luís, Km 235, São Carlos, SP, 13565-905, Brazil.
authors.forename: Ana T
authors.initials: AT
authors.lastname: Lombardi
authors.affiliation: Departamento de Hidrobiologia, Centro de Ciências Biológicas e da Saúde (CCBS), Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luís, Km 235, São Carlos, SP, 13565-905, Brazil.
authors.forename: Maria
authors.initials: M
authors.lastname: da G G Melão
mesh_terms: D000460:Chlorophyta / Q000502:physiology*; D003300:Copper / Q000633:toxicity*; D005227:Fatty Acids; D010743:Phospholipids; D010788:Photosynthesis / Q000187:drug effects; D010839:Phytoplankton / Q000502:physiology*; D018675:Toxicity Tests; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D005227:Fatty Acids; D010743:Phospholipids; D014874:Water Pollutants, Chemical; D003300:Copper
keywords: Chlorophyceae; Fatty acids; Freshwater; Lipids; Metal