title: Sulfur Deprivation Results in Oxidative Perturbation in Chlorella sorokiniana (211/8k).
abstract: Sulfur deficiency in plant cells has not been considered as a potential abiotic factor that can induce oxidative stress. We studied the antioxidant defense system of Chlorella sorokiniana cultured under sulfur (S) deficiency, imposed for a maximum period of 24 h, to evaluate the effect of an S shortage on oxidative stress. S deprivation induced an immediate (30 min) but transient increase in the intracellular H2O2 content, which suggests that S limitation can lead to a temporary redox disturbance. After 24 h, S deficiency in Chlorella cells decreased the glutathione content to <10% of the value measured in cells that were not subjected to S deprivation. Consequently, we assumed that the cellular antioxidative mechanisms could be altered by a decrease in the total glutathione content. The total ascorbate pool increased within 2 h after the initiation of S depletion, and remained high until 6 h; however, ascorbate regeneration was inhibited under limited S conditions, indicated by a significant decrease in the ascorbate/dehydroascorbate (AsA/DHA) ratios. Furthermore, ascorbate peroxidase (APX) and superoxide dismutase (SOD) were activated under S deficiency, but we assumed that these enzymes were involved in maintaining the cellular H2O2 balance for at least 4 h after the initiation of S starvation. We concluded that S deprivation triggers redox changes and induces antioxidant enzyme activities in Chlorella cells. The accumulation of total ascorbate, changes in the reduced glutathione/oxidized glutathione (GSH/GSSG) ratios and an increase in the activity of SOD and APX enzymes indicate that oxidative perturbation occurs during S deprivation.
authors: Dipartimento di Biologia, Università di Napoli Federico II, Via Foria 223, I-80139 Napoli, Italy.
authors: Giovanna
authors: G
authors: Salbitani
authors: Dipartimento di Biologia, Università di Napoli Federico II, Via Foria 223, I-80139 Napoli, Italy.
authors: Vincenza
authors: V
authors: Vona
authors: Dipartimento di Biologia, Università di Napoli Federico II, Via Foria 223, I-80139 Napoli, Italy.
authors: Claudia
authors: C
authors: Bottone
authors: Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Unità di ricerca per la Frutticoltura, Via Torrino 2, 81100 Caserta, Italy.
authors: Milena
authors: M
authors: Petriccione
authors: Dipartimento di Biologia, Università di Napoli Federico II, Via Foria 223, I-80139 Napoli, Italy simona.carfagna@unina.it.
authors: Simona
authors: S
authors: Carfagna
mesh_terms: D020418:Algal Proteins / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D002708:Chlorella / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D042541:Intracellular Space / Q000378:metabolism; D010084:Oxidation-Reduction; D012995:Solubility; D013455:Sulfur / Q000378:metabolism*; D013482:Superoxide Dismutase / Q000378:metabolism; D013997:Time Factors
chemical_list: D020418:Algal Proteins; D000975:Antioxidants; D013455:Sulfur; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; D005978:Glutathione; D001205:Ascorbic Acid
keywords: Ascorbate; Chlorella sorokiniana; Glutathione; Oxidative stress; Reactive oxygen species; Sulfur starvation