title: Copper-induced synthesis of ascorbate, glutathione and phytochelatins in the marine alga Ulva compressa (Chlorophyta).
abstract: In order to analyze the synthesis of antioxidant and heavy metal-chelating compounds in response to copper stress, the marine alga Ulva compressa (Chlorophyta) was exposed to 10 μM copper for 7 days and treated with inhibitors of ASC synthesis, lycorine, and GSH synthesis, buthionine sulfoximine (BSO). The levels of ascorbate, in its reduced (ASC) and oxidized (DHA) forms, glutathione, in its reduced (GSH) and oxidized (GSSG) forms, and phytochelatins (PCs) were determined as well as activities of enzymes involved in ASC synthesis, L-galactose dehydrogenase (GDH) and L-galactono 1,4 lactone dehydrogenase (GLDH), and in GSH synthesis, γ-glutamylcysteine synthase (γ-GCS) and glutathione synthase (GS). The level of ASC rapidly decreased to reach a minimum at day 1 that remained low until day 7, DHA decreased until day 1 but slowly increased up to day 7 and its accumulation was inhibited by lycorine. In addition, GSH level increased to reach a maximal level at day 5 and GSSG increased up to day 7 and their accumulation was inhibited by BSO. Activities of GDH and GLDH increased until day 7 and GLDH was inhibited by lycorine. Moreover, activities of γ-GCS and GS increased until day 7 and γ-GCS was inhibited by BSO. Furthermore, PC2, PC3 and PC4, increased until day 7 and their accumulation was inhibited by BSO. Thus, copper induced the synthesis of ascorbate, glutathione and PCs in U. compressa suggesting that these compounds are involved in copper tolerance. Interestingly, U. compressa is, until now, the only ulvophyte showing ASC, GSH and PCs synthesis in response to copper excess.
authors.affiliation: Departamento de Biología, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40 Correo 33, Santiago, Chile.
authors.forename: Macarena
authors.initials: M
authors.lastname: Mellado
authors.forename: Rodrigo A
authors.initials: RA
authors.lastname: Contreras
authors.forename: Alberto
authors.initials: A
authors.lastname: González
authors.forename: Geraldine
authors.initials: G
authors.lastname: Dennett
authors.forename: Alejandra
authors.initials: A
authors.lastname: Moenne
mesh_terms: D047151:Amaryllidaceae Alkaloids / Q000494:pharmacology; D001205:Ascorbic Acid / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D003300:Copper / Q000494:pharmacology*; D003683:Dehydroascorbic Acid / Q000378:metabolism; D004789:Enzyme Activation; D005691:Galactose Dehydrogenases / Q000378:metabolism; D005978:Glutathione / Q000096:biosynthesis*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000037:antagonists & inhibitors / Q000378:metabolism; D010617:Phenanthridines / Q000494:pharmacology; D054811:Phytochelatins / Q000096:biosynthesis*; D013997:Time Factors; D044445:Ulva / Q000187:drug effects* / Q000378:metabolism
chemical_list: D047151:Amaryllidaceae Alkaloids; D010617:Phenanthridines; D019328:Buthionine Sulfoximine; D003300:Copper; D054811:Phytochelatins; D005691:Galactose Dehydrogenases; C047959:galactose dehydrogenase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C093910:galactonolactone dehydrogenase; D005978:Glutathione; C015330:lycorine; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid