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Oxidative stress in Scenedesmus sp. during short- and long-term exposure to Cu2+ and Zn2+.
Chemosphere. 2006 Jan; 62(4):538-44.C

Abstract

Algae are exposed to elevated levels of heavy metals in water bodies generally for a long-term, and occasionally for a short-term duration. The present study deals with oxidative stress in Scenedesmus sp., commonly found in nutrient-rich freshwaters, during short- (6h) and long-term (7d) exposure to Cu(2+) and Zn(2+). The cells accumulated almost 2- and 4-times more Cu(2+) and Zn(2+) inside the cells during long-term than during short-term exposure to these metals. But the data on photosynthetic O(2) evolution and cell viability suggest that Scenedesmus sp. experienced lesser metal stress in long-term than in short-term experiment. Although malondialdehyde content was slightly higher in the long-term experiment, the amount produced by one unit intracellular metal was significantly lower than that in the short-term experiment. Superoxide dismutase activity of Scenedesmus sp. was >30% higher during long-term than during short-term exposure to Cu(2+) and Zn(2+). But, catalase and ascorbate peroxidase activities increased only at 2.5 microM Cu(2+) and 25 microM Zn(2+) when oxidative stress was mild, but were inhibited at 10 microM Cu(2+) under intense oxidative stress. Cu(2+) and Zn(2+) reduced glutathione reductase activity and total SH content of Scenedesmus sp. in both the experiments, with greater reduction occurring in the long-term experiment. The depletion of total thiol was positively related with the intracellular level of metals. Thiols might have helped Scenedesmus sp. in overcoming metal-induced oxidative stress, but depletion of thiol pool is known to make cells vulnerable to oxidative stress. The study suggests that antioxidant enzymes play a role only under mild oxidative stress. An increased accumulation of proline seems to be an important strategy for alleviating metal-induced oxidative stress in Scenedesmus sp. The study shows that Scenedesmus sp. could acclimatize during long-term exposure to toxic concentrations of the test metals.

Authors+Show Affiliations

Tripathi BN
Laboratory of Algal Biology, Department of Botany, Banaras Hindu University, Varanasi 221 005, India.
Mehta SK
No affiliation info available
Amar A
No affiliation info available
Gaur JP
No affiliation info available

MeSH

CopperLipid PeroxidationOxidative StressOxidoreductasesOxygenPhotosynthesisProlineScenedesmusTime FactorsWater Pollutants, ChemicalZinc

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16084572

Citation

Tripathi, B N., et al. "Oxidative Stress in Scenedesmus Sp. During Short- and Long-term Exposure to Cu2+ and Zn2+." Chemosphere, vol. 62, no. 4, 2006, pp. 538-44.
Tripathi BN, Mehta SK, Amar A, et al. Oxidative stress in Scenedesmus sp. during short- and long-term exposure to Cu2+ and Zn2+. Chemosphere. 2006;62(4):538-44.
Tripathi, B. N., Mehta, S. K., Amar, A., & Gaur, J. P. (2006). Oxidative stress in Scenedesmus sp. during short- and long-term exposure to Cu2+ and Zn2+. Chemosphere, 62(4), 538-44.
Tripathi BN, et al. Oxidative Stress in Scenedesmus Sp. During Short- and Long-term Exposure to Cu2+ and Zn2+. Chemosphere. 2006;62(4):538-44. PubMed PMID: 16084572.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Oxidative stress in Scenedesmus sp. during short- and long-term exposure to Cu2+ and Zn2+. AU - Tripathi,B N, AU - Mehta,S K, AU - Amar,Anshu, AU - Gaur,J P, Y1 - 2005/08/09/ PY - 2004/10/19/received PY - 2005/06/01/revised PY - 2005/06/17/accepted PY - 2005/8/9/pubmed PY - 2006/3/17/medline PY - 2005/8/9/entrez SP - 538 EP - 44 JF - Chemosphere JO - Chemosphere VL - 62 IS - 4 N2 - Algae are exposed to elevated levels of heavy metals in water bodies generally for a long-term, and occasionally for a short-term duration. The present study deals with oxidative stress in Scenedesmus sp., commonly found in nutrient-rich freshwaters, during short- (6h) and long-term (7d) exposure to Cu(2+) and Zn(2+). The cells accumulated almost 2- and 4-times more Cu(2+) and Zn(2+) inside the cells during long-term than during short-term exposure to these metals. But the data on photosynthetic O(2) evolution and cell viability suggest that Scenedesmus sp. experienced lesser metal stress in long-term than in short-term experiment. Although malondialdehyde content was slightly higher in the long-term experiment, the amount produced by one unit intracellular metal was significantly lower than that in the short-term experiment. Superoxide dismutase activity of Scenedesmus sp. was >30% higher during long-term than during short-term exposure to Cu(2+) and Zn(2+). But, catalase and ascorbate peroxidase activities increased only at 2.5 microM Cu(2+) and 25 microM Zn(2+) when oxidative stress was mild, but were inhibited at 10 microM Cu(2+) under intense oxidative stress. Cu(2+) and Zn(2+) reduced glutathione reductase activity and total SH content of Scenedesmus sp. in both the experiments, with greater reduction occurring in the long-term experiment. The depletion of total thiol was positively related with the intracellular level of metals. Thiols might have helped Scenedesmus sp. in overcoming metal-induced oxidative stress, but depletion of thiol pool is known to make cells vulnerable to oxidative stress. The study suggests that antioxidant enzymes play a role only under mild oxidative stress. An increased accumulation of proline seems to be an important strategy for alleviating metal-induced oxidative stress in Scenedesmus sp. The study shows that Scenedesmus sp. could acclimatize during long-term exposure to toxic concentrations of the test metals. SN - 0045-6535 UR - https://www.unboundmedicine.com/medline/citation/16084572/Oxidative_stress_in_Scenedesmus_sp__during_short__and_long_term_exposure_to_Cu2+_and_Zn2+_ DB - PRIME DP - Unbound Medicine ER -