title: Growth, photosynthetic and respiratory responses to sub-lethal copper concentrations in Scenedesmus incrassatulus (Chlorophyceae).
abstract: In the present paper we investigated the effects of sub-lethal concentrations of Cu2+ in the growth and metabolism of Scenedesmus incrassatulus. We found that the effect of Cu2+ on growth, photosynthetic pigments (chlorophylls and carotenoids) and metabolism do not follow the same pattern. Photosynthesis was more sensitive than respiration. The analysis of chlorophyll a fluorescence transient shows that the effect of sub-lethal Cu2+ concentration in vivo, causes a reduction of the active PSII reaction centers and the primary charge separation, decreasing the quantum yield of PSII, the electron transport rate and the photosynthetic O2 evolution. The order of sensitivity found was: Growth>photosynthetic pigments content=photosynthetic O2 evolution>photosynthetic electron transport>respiration. The uncoupled relationship between growth and metabolism is discussed.
authors.affiliation: Laboratorio de Biotecnología de Microalgas, Departamento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ave. IPN 2508, San Pedro Zacatenco, C.P. 07360, México DF, Mexico.
authors.forename: Hugo Virgilio
authors.initials: HV
authors.lastname: Perales-Vela
authors.forename: Sergio
authors.initials: S
authors.lastname: González-Moreno
authors.forename: Carmen
authors.initials: C
authors.lastname: Montes-Horcasitas
authors.forename: Rosa Olivia
authors.initials: RO
authors.lastname: Cañizares-Villanueva
mesh_terms: D002338:Carotenoids / Q000096:biosynthesis; D002734:Chlorophyll / Q000096:biosynthesis; D000077194:Chlorophyll A; D003300:Copper / Q000633:toxicity*; D004579:Electron Transport / Q000187:drug effects; D007700:Kinetics; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D044444:Scenedesmus / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D002734:Chlorophyll; D002338:Carotenoids; D003300:Copper; D010100:Oxygen; D000077194:Chlorophyll A