title: Effects of the naturally-occurring contaminant microcystins on the Azolla filiculoides-Anabaena azollae symbiosis.
abstract: Harmful algal blooms (HABs) contaminate aquatic ecosystems and are responsible for animal poisoning worldwide. We conducted a toxicity test with the aquatic fern and the biofertilizer, Azolla filiculoides. The sporophytes were exposed to three concentrations (0.01, 0.1 and 1μgmL(-1)) of a microcystin (MC) cyanobacterial crude extract and purified MC-LR. The growth of A. filiculoides decreased only at 1μgmL(-1) crude extract concentration while with MC-LR it decreased at all the tested concentrations, indicating that the presence of other compounds in the crude extract altered toxicity and stimulated the fern growth at lower concentrations (0.01 and 0.1μgmL(-1)). Both phycoerythrocyanin and allophycocyanin levels decreased in all the concentrations of crude extract and MC-LR. The phycocyanin had a marked increase at 0.1μgmL(-1) crude extract concentration and a marked decrease at 1μgmL(-1) MC-LR concentration. These changes in the phycobiliprotein content indicate a shift in the antenna pigments of the cyanobionts of A. filiculoides. The changes in two oxidative stress enzymes, glutathione reductase for the crude extract assay and glutathione peroxidase for MC-LR assay, points towards the induction of stress defense responses. The low bioconcentration factor in both crude extract and MC-LR treatments can suggest the low uptake of microcystins, and indicates that the aquatic fern can be used as a biofertilizer and as animal feed but is not suitable for MC phytoremediation.
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal. Electronic address: anapereira271268@yahoo.com.
authors.forename: A L
authors.initials: AL
authors.lastname: Pereira
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal. Electronic address: beneditamonteiro@hotmail.com.
authors.forename: B
authors.initials: B
authors.lastname: Monteiro
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal. Electronic address: joana_passo@hotmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Azevedo
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal. Electronic address: amoclclix@gmail.com.
authors.forename: A
authors.initials: A
authors.lastname: Campos
authors.affiliation: Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Rua Dr Roberto Frias, 4200-465 Porto, Portugal; Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319 Porto, Portugal. Electronic address: hosorio@ipatimup.pt.
authors.forename: H
authors.initials: H
authors.lastname: Osório
authors.affiliation: Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal; Department of Biology, Faculty of Sciences of the University of Porto, Rua do Campo Alegre, 4069-007 Porto, Portugal. Electronic address: vvascon@fc.up.pt.
authors.forename: V
authors.initials: V
authors.lastname: Vasconcelos
mesh_terms: D017033:Anabaena / Q000737:chemistry; D000821:Animal Feed; D000975:Antioxidants / Q000378:metabolism; D001673:Biodegradation, Environmental; D004305:Dose-Response Relationship, Drug; D029624:Ferns / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D005308:Fertilizers; D052998:Microcystins / Q000633:toxicity*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000254:growth & development / Q000502:physiology; D013559:Symbiosis; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D005308:Fertilizers; D052998:Microcystins; D010940:Plant Proteins; D014874:Water Pollutants, Chemical
keywords: Anabaena azollae; Antioxidative enzymes; Azolla filiculoides; Growth; Microcystins; Photosynthetic pigments