title: Effects of microcystin-producing and microcystin-freeMicrocystis aeruginosa on enzyme activity and nutrient content in the rotifer Brachionus calyciflorus.
abstract: Toxic cyanobacterial blooms disrupt freshwater recreation and adversely affect zooplankton. The freshwater cyanobacterium Microcystis aeruginosa produces microcystins, which are compounds toxic to rotifers. This study evaluated the effects of M. aeruginosa on enzyme activity and nutrient content in the rotifer Brachionus calyciflorus Pallas. The rotifers were fed on Chlorella pyrenoidosa, Scenedesmus obliquus, microcystin-producing and microcystin-free M. aeruginosa alone, and mixtures of green algae combined with toxic and nontoxic cyanobacteria, respectively. Activities of amylase, pepsase, trypsin, cellulase, superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were assessed after rotifer exposure to an environmental stressor. Nutrients analyzed were glycogen, protein, and triglyceride (TG). Single cyanobacteria and mixtures combined with toxic M. aeruginosa inhibited SOD activity. CAT and GPx activities significantly increased in rotifers fed with the mixture of Chlorella and toxic cyanobacteria. The activity of digestive enzymes increased compared with the Chlorella group in single and mixed diets. Glycogen and protein decreased in Microcystis mixtures, whereas TG content increased. The grazing rate (G) of the rotifers decreased with grazing time. High G value was observed with green algae in every treatment group. Although the toxins released after grazing on Microcystis affected rotifer enzyme activity and nutrient content, B. calyciflorus changed its physiological performance and grazing intensity with food type in response to eutrophic conditions.
authors.affiliation: Jiangsu Province Key Laboratory for Biodiversity & Biotechnology and Jiangsu Province Key Laboratory for Fisheries Live Food, School of Live Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, People's Republic of China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Jiangsu Province Key Laboratory for Biodiversity & Biotechnology and Jiangsu Province Key Laboratory for Fisheries Live Food, School of Live Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, People's Republic of China.
authors.forename: Yuqi
authors.initials: Y
authors.lastname: Su
authors.affiliation: Jiangsu Province Key Laboratory for Biodiversity & Biotechnology and Jiangsu Province Key Laboratory for Fisheries Live Food, School of Live Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, People's Republic of China.
authors.forename: Kai
authors.initials: K
authors.lastname: Ouyang
authors.affiliation: Jiangsu Province Key Laboratory for Biodiversity & Biotechnology and Jiangsu Province Key Laboratory for Fisheries Live Food, School of Live Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, People's Republic of China.
authors.forename: Xinglan
authors.initials: X
authors.lastname: Chen
authors.affiliation: Jiangsu Province Key Laboratory for Biodiversity & Biotechnology and Jiangsu Province Key Laboratory for Fisheries Live Food, School of Live Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing, 210023, People's Republic of China. yangjx@njnu.edu.cn.
authors.forename: Jiaxin
authors.initials: J
authors.lastname: Yang
mesh_terms: D000818:Animals; D002708:Chlorella / Q000378:metabolism*; D052998:Microcystins / Q000378:metabolism*; D046931:Microcystis / Q000378:metabolism; D012403:Rotifera / Q000187:drug effects
chemical_list: D052998:Microcystins; C078588:microcystin
keywords: Antioxidant enzyme activity; Brachionus calyciflorus; Digestive enzyme activity; Microcystins; Microcystis aeruginosa; Nutrient content