title: Stress-responsive expression of a glutathione S-transferase (delta) gene in waterflea Daphnia magna challenged by microcystin-producing and microcystin-free Microcystis aeruginosa.
abstract: Harmful cyanobacterial blooms resulting from eutrophication and global warming have emerged as a worldwide environmental concern. Some zooplankton populations, including Daphnia, have been shown to adapt locally to microcystin-producing Microcystis. Previous in vitro experiments indicate that glutathione-S-transferase (GST) may act as the first step of detoxification in Daphnia by conjugating microcystins (MCs) with glutathione. The GST family is categorized into many classes, and different classes present distinct responses to MC detoxification. To date, however, the molecular mechanism of single class GST participation in buffering the toxic effects of MCs in Daphnia remains poorly known. In this study, a full-length delta-GST cDNA of Daphnia magna (Dm-dGST) was isolated and characterized through bioinformatics. Differential gene expression studies revealed that short-term exposure to microcystin-producing (MP) Microcystis aeruginosa increased Dm-dGST transcript levels. By contrast, long-term exposure to MP or microcystin-free (MF) M. aeruginosa decreased Dm-dGST transcript levels. Together with changes in three other antioxidation biomarkers (catalase, CuZn- and Mn-superoxide dismutase), it is concluded that Dm-dGST can potentially biotransform MCs to reduce their toxicity. The present study highlights the importance of Dm-dGST in response to MC toxicity and may thus facilitate future research on the molecular mechanisms of MC tolerance in zooplankton under an increasing eutrophic world.
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Lyu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Gu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Bangping
authors.initials: B
authors.lastname: Li
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Yichun
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Changcan
authors.initials: C
authors.lastname: Wu
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China.
authors.forename: Haoyong
authors.initials: H
authors.lastname: Guan
authors.affiliation: Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, Nanjing 210023, China. Electronic address: yangzhou@njnu.edu.cn.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Yang
mesh_terms: D000818:Animals; D003621:Daphnia / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D005982:Glutathione Transferase / Q000235:genetics*; D052998:Microcystins / Q000494:pharmacology; D046931:Microcystis / Q000737:chemistry / Q000502:physiology*; D013312:Stress, Physiological / Q000187:drug effects / Q000235:genetics
chemical_list: D052998:Microcystins; D005982:Glutathione Transferase
keywords: Cyanobacteria; Detoxification; Microcystin; Molecular interaction; Zooplankton