title: Growth, toxin production, active oxygen species and catalase activity of Microcystis aeruginosa (Cyanophyceae) exposed to temperature stress.
abstract: Microcystis are known for their potential ability to synthesize toxins, mainly microcystins (MCs). In order to evaluate the effects of temperature on chlorophyll a (Chl a), growth, physiological responses and toxin production of a native Microcystis aeruginosa, we exposed the cells to low (23°C) and high (29°C) temperature in addition to a 26°C control treatment. Exponential growth rate was significantly higher at 29°C compared to 23°C and control, reaching 0.43, 0.32 and 0.33day(-)(1) respectively. In addition, there was a delay of the start of exponential growth at 23°C. However, the intracellular concentration of Chl a decreased significantly due to temperature change. A significant increase in intracellular ROS was observed in coincidence with the activation of enzymatic antioxidant catalase (CAT) during the first two days of exposure to 23° and 29°C in comparison to the control experiment, decreasing thereafter to nearly initial values. Five MCs were determined by LC-MS/MS analysis. In the experiments, the highest MC concentration, 205fg [Leu(1)] MC-LR.cell(-1) expressed as MC-LR equivalent was measured in the beginning of the experiment and subsequently declined to 160fg.cell(-1) on day 2 and 70fg.cell(-1) on day 4 in cells exposed to 29°C. The same trend was observed for all other MCs except for the least abundant MC-LR which showed a continuous increase during exposure time. Our results suggest a high ability of M. aeruginosa to perceive ROS and to rapidly initiate antioxidant defenses with a differential response on MC production.
authors.affiliation: Área de Toxicología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina; CONICET, Buenos Aires, Argentina.
authors.forename: Leda
authors.initials: L
authors.lastname: Giannuzzi
authors.affiliation: Alfred Wegener Institute, Bremerhaven, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Krock
authors.affiliation: Área de Toxicología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina; CONICET, Buenos Aires, Argentina.
authors.forename: Melina Celeste Crettaz
authors.initials: MC
authors.lastname: Minaglia
authors.affiliation: Área de Toxicología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina.
authors.forename: Lorena
authors.initials: L
authors.lastname: Rosso
authors.affiliation: Depto. Radiobiología, Comisión Nacional de Energía Atómica, Argentina.
authors.forename: Christian
authors.initials: C
authors.lastname: Houghton
authors.affiliation: Área de Toxicología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina; CONICET, Buenos Aires, Argentina.
authors.forename: Daniela
authors.initials: D
authors.lastname: Sedan
authors.affiliation: CONICET, Buenos Aires, Argentina; IBIMOL-FisicoQuímica, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Malanga
authors.affiliation: Gerencia de Química, Comisión Nacional de Energía Atómica, Argentina.
authors.forename: Mariela
authors.initials: M
authors.lastname: Espinosa
authors.affiliation: Área de Toxicología, Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina; CONICET, Buenos Aires, Argentina.
authors.forename: Darío
authors.initials: D
authors.lastname: Andrinolo
authors.affiliation: Depto. Radiobiología, Comisión Nacional de Energía Atómica, Argentina. Electronic address: mhernando@cnea.gov.ar.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Hernando
mesh_terms: D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D018533:Biomass; D002374:Catalase / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002853:Chromatography, Liquid; D052998:Microcystins / Q000378:metabolism*; D046931:Microcystis / Q000201:enzymology* / Q000254:growth & development; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D013696:Temperature; D013997:Time Factors
chemical_list: D000975:Antioxidants; D001426:Bacterial Proteins; D052998:Microcystins; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D002374:Catalase; D000077194:Chlorophyll A
keywords: Catalase; Chlorophyll; Microcystin variants; ROS