title: The brown seaweed Sargassum cymosum: changes in metabolism and cellular organization after long-term exposure to cadmium.
abstract: Sargassum cymosum was exposed to cadmium (Cd) to determine any physiological and ultrastructural effects. To accomplish this, S. cymosum samples were cultivated under photosynthetic active radiation (PAR) and Cd (0, 0.1, 0.2, 0.4 and 0.8 mg L-1) during 7 and 14 days in laboratory-controlled conditions (0 mg L-1Cd at both exposure times as control). Seaweeds had high retention capacity (over 90 %) for both exposure times. Growth rates showed significant increases by 14 days, especially for 0.1 and 0.4 mg L-1Cd. Photosynthetic parameters were unaffected by Cd treatments. Chlorophyll contents were present in higher concentrations for all Cd treatments compared to respective control. Carotenoid profile showed significant differences in total composition and proportion of fucoxanthin and β-carotene, and no lutein was detected at 14 days. Phenolic and flavonoid compounds showed major accumulation at 14 days. Transmission electron microscopy (TEM) analyses presented major alterations in Cd-treated samples, when compared with respective control, in particular disorganization of cell wall fibrils. When compared to respective control samples, multivariate analyses showed disparate and complex interactions among metabolites in Cd-exposed seaweeds, giving evidence of physiological defence response. Thus, it can be concluded that Cd is a stressor for S. cymosum, resulting in physiological and structural alterations related to defence mechanisms against oxidative stress and toxicological effects resulting from long-term metal exposure. However, in the present paper, some observed changes also appear to result from acclimation mechanisms under lower concentration of Cd relative to the tolerance of S. cymosum to experimental conditions.
authors.affiliation: Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Giulia B
authors.initials: GB
authors.lastname: Costa
authors.affiliation: Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Carmen
authors.initials: C
authors.lastname: Simioni
authors.affiliation: Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Débora T
authors.initials: DT
authors.lastname: Pereira
authors.affiliation: Plant Morphogenesis and Biochemistry Laboratory, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Fernanda
authors.initials: F
authors.lastname: Ramlov
authors.affiliation: Plant Morphogenesis and Biochemistry Laboratory, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Maraschin
authors.affiliation: Institute of Bioscience, University of São Paulo, CEP, Sao Paulo, SP, 05508-090, Brazil.
authors.forename: Fungyi
authors.initials: F
authors.lastname: Chow
authors.affiliation: Phycology Laboratory, Department of Botany, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Paulo A
authors.initials: PA
authors.lastname: Horta
authors.affiliation: Plant Cell Biology Laboratory, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil.
authors.forename: Zenilda L
authors.initials: ZL
authors.lastname: Bouzon
authors.affiliation: Postgraduate Program in Cell Biology and Development, Department of Cell Biology, Embryology and Genetics, Federal University of Santa Catarina, CP 476, Florianopolis, SC, 88049-900, Brazil. edcash@ccb.ufsc.br.
authors.forename: Éder C
authors.initials: ÉC
authors.lastname: Schmidt
mesh_terms: D000704:Analysis of Variance; D000975:Antioxidants / Q000378:metabolism; D002104:Cadmium / Q000032:analysis / Q000633:toxicity*; D002241:Carbohydrates / Q000032:analysis; D002470:Cell Survival / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D002851:Chromatography, High Pressure Liquid; D005419:Flavonoids / Q000032:analysis; D005453:Fluorescence; D015999:Multivariate Analysis; D010636:Phenols / Q000032:analysis; D010788:Photosynthesis / Q000187:drug effects; D025341:Principal Component Analysis; D044647:Sargassum / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D012623:Seawater / Q000737:chemistry; D012624:Seaweed / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D012995:Solubility
chemical_list: D000975:Antioxidants; D002241:Carbohydrates; D005419:Flavonoids; D010636:Phenols; D002104:Cadmium; D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: Biosorption; Cellular ultrastructure; Long-term acclimation; Sargassum cymosum; Scanning electron microscopy; Toxicology