Antioxidative response of Lemna minor

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• 作者：Marija Babić ; S ; ra Radić ; Petra Cvjetko ; Vibor Roje ; Branka Pevalek-Kozlina ; Mirjana Pavlica
• 关键词：Lemna minor L. ; Thallium ; Oxidative stress ; Genotoxicity
• 刊名：Aquatic Botany
• 出版年：2009
• 出版时间：October 2009
• 年：2009
• 卷：91
• 期：3
• 页码：166-172
• 全文大小：499 K

文摘

The physiological effects of thallium(I)-acetate on the duckweed Lemna minor after 1-, 4-, 7- and 14-d exposure were analyzed. High bioaccumulation of Tl (221 mg kg⁻¹ dry wt at 2.0 μM Tl-acetate) caused an inhibition of plant growth. After 14-d exposure, 0.2, 0.5, 1.0 and 2.0 μM Tl-acetate reduced the frond-number growth rate by 21.1 % , 39.4 % , 66 % and 83.1 % , respectively. Tl-acetate also induced a modulation of the antioxidative response by depleting the ascorbate content and affecting the antioxidative enzymes activities. Superoxide dismutase showed a continuous increase of activity (31–67 % ) after Tl-acetate exposure. Other antioxidative enzymes displayed a biphasic response to both the concentration and the exposure period. Exposure up to 7 d decreased the catalase activity (up to 40 % ) in plants treated with higher Tl-acetate concentrations. In contrast, 14-d exposure increased the activity of the enzyme (≥90 % ). Short-term exposure increased ascorbate peroxidase activity (13–41 % ), except in plants exposed to the highest Tl-acetate concentration. However, 14-d exposure decreased the enzyme activity at all concentrations tested (38–60 % ). Although pyrogallol peroxidase activity increased (up to 26 % ) during 4-d exposure, longer exposures to the highest two concentrations decreased the activity of the enzyme (25–48 % ). In general, short-term exposure to Tl-acetate activated the antioxidant capacity, which resulted in recovery of the frond-number growth rates in Tl-treated plants. In spite of the activation of the antioxidative response during short-term exposure, higher Tl-acetate concentrations increased the hydrogen peroxide level (up to 45 % ) and induced marked oxidative damage to lipids, proteins and DNA. Longer exposure induced a decline of the antioxidative response, and plants showed the symptoms of oxidative damage even at lower Tl-acetate concentrations. The genotoxic effect was evaluated by an alkaline version of the cellular and acellular Comet assay, which revealed an indirect genotoxic effect of Tl-acetate, suggesting oxidatively induced damage to DNA.