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Cadmium-Induced Changes in Antioxidant Enzyme Activities in Rice(Oryza sativa L. cv. Dongjin)
Ali, Mohammad Babar,Chun, Hyun Sik,Kim, Byung Ki,Lee, Chin Bum 한국식물학회 2002 Journal of Plant Biology Vol.45 No.3
We studied how the relationship between cadmium (Cd) toxicity and oxidative stress influenced the growth, photo-synthetic efficiency, lipid peroxidation, and activity of ntioxidative enzymes in the roots and leaves of rice (Oryza sativa L Dongjin). Plants were exposed to Cd for 21 d. Both seedling growth and photosynthetic efficiency decreased gradually with increasing cadmium concentrations. Lipid peroxidation increased slowly in both roots and leaves, causing oxidative stress. However, each tissue type responded differently to Cd concentrations with regard to the induction/inhibition of antioxidative enzymes. The activity of superoxide dismutase (SOD) increased in both roots and leaves. Ascorbate peroxidase (APX) activity increased in leaves treated with up to 0.25 μM Cd, then decreased gradually at higher concentrations. In contrast, APX activity in roots increased and remained constant between 0.25 and 25 μM Cd. Enhanced peroxidase (POD) activity was recorded for treatments with up to 25 μM Cd, gradually decreasing at higher concentrations in the leaves but remaining unchanged in the roots. Catalase (CAT) activity increased in the roots, but decreased in the leaves, whereas the activity of glutathione reductase (GR) was enhanced in both roots and leaves, where it remained elevated at higher Cd concentrations. These results suggest that rice seedlings tend to cope with free radicals generated by Cd through coordinated, enhanced activities of the antioxidative enzymes involved in detoxification.
Response of Antioxidant Enzymes in Rice(Oryza sativa L. cv. Dongjin) under Mercury Stress
Ali, Mohammad Babar,Chun, Hyun Sik,Lee, Chin Bum 한국식물학회 2002 Journal of Plant Biology Vol.45 No.3
We studied the effects of different concentrations of mercury (0.0 to 100 μM) on growth and photosynthetic efficiency in rice plants treated for 21 d. In addition, we investigated how this metal affected the malondialdehyde (MDA) content as well as the activity of five antioxidant enzymes - superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), guaiacol peroxidase (POD), and catalase (CAT). Photosynthetic efficiency (F_v/F_m) and seedling growth decreased as the concentration of Hg was increased in the growth media. Plants also responded to Hg-induced oxidative stress by changing the levels of their antioxidative enzymes. Enhanced lipid peroxidation was observed in both leaves and roots that had been exposed to oxidative stress, with leaves showing higher enzymatic activity. Both SOD and APX activities increased in treatments with up to 50 μM Hg, then decreased at higher concentrations. In the leaves, both CAT and POD activities increased gradually, with CAT levels decreasing at higher concentrations. In the roots, however, CAT activity remained unchanged while that of POD increased a bit more than did the control for concentrations of up to 10 μM Hg. At higher Hg levels, both CAT and POD activities decreased. GR activity increased in leaves exposed to no more than 0.25 μM Hg, then decreased gradually. In contrast, its activity was greatly inhibited in the roots. Based on these results, we suggest that when rice plants are exposed to different concentrations of mercury, their antioxidative enzymes become involved in defense mechanisms against the free radicals that are induced by this stress.
Ali, Mohammad Babar,Hahn, Eun Joo,Paek, Kee-Yoeup Elsevier 2006 Enzyme and microbial technology Vol.39 No.5
<P><B>Abstract</B></P><P>The effects of CO<SUB>2</SUB> levels (0.03, 0.5, 1, 2 and 5%) on growth and antioxidant responses in 5l bioreactor (working volume 4l) root suspension cultures of <I>Echinacea angustifolia</I> were studied. CO<SUB>2</SUB> caused reduction in growth, malondialdehyde content (MDA), lipoxygenase (LOX, EC 1.13.11.13) activity and superoxide anion (O<SUB>2</SUB><SUP>−</SUP>) accumulation along with high total phenols accumulation and pH levels. Maximal increases (37%) in total phenols were obtained at 1% CO<SUB>2</SUB> compared to the control. An increase in total glutathione and total ascorbate (ASC+DHA), accompanied with enhanced ascorbate–glutathione cycle enzymes were observed in CO<SUB>2</SUB>-treated roots, which played an important role for the detoxification of harmful substances. CO<SUB>2</SUB> also induced an increase in glutathione peroxidase (GPx, EC 1.11.1.9) and glutathione-<I>S</I>-transferase (GST, EC 2.5.18) activities. After native polyacrylamide gel electrophoresis (PAGE) analysis, three superoxide dismutase (SOD, EC 1.15.1.1) isoenzymes were detected. Increase in SOD and CAT (EC 1.11.16) activities observed at 0.5% CO<SUB>2</SUB>-treated roots and induced SOD activity seemed to be mainly due to Mn-SOD. However, both SOD and CAT activities were inhibited at 2 and 5% CO<SUB>2</SUB> but reached similar to control value. Three APX (EC 1.11.1.11) and three guaiacol peroxidase (G-POD, EC 1.11.1.7) isoenzymes were strongly detected, an increase in APX and G-POD activities suggests increased scavenging of ROS, indicating the tolerance to CO<SUB>2</SUB>. These results indicated that limited oxidative damage as shown by lower MDA level, low LOX activity and low O<SUB>2</SUB><SUP>−</SUP> accumulation may be due to the induced activities of antioxidant enzymes and non-enzymatic antioxidant. It is therefore, suggested that roots cultured in a bioreactor could protect themselves from CO<SUB>2</SUB> by altering the defense systems.</P>
A Survey of Cluster-based Routing Schemes for Wireless Sensor Networks
Gulbadan Sikander,Mohammad Haseeb Zafar,Ahmad Raza,Muhammad Inayatullah Babar,Sahibzada Ali Mahmud,Gul Muhammad Khan 한국산학기술학회 2013 SmartCR Vol.3 No.4
In recent times, wireless sensor networks (WSNs) have become progressively more attractive and have found their way into a wide variety of applications and systems because of their low cost, self-organizing behavior, and sensing ability in harsh environments. A WSN is a collection of nodes organized into a network. Routing is a vital technology in WSNs and can be roughly divided into two categories: flat routing and hierarchical routing. In a flat routing topology, all nodes have identical functionality and carry out the same task in the network. Nodes in a hierarchical topology do different tasks in WSNs and are usually arranged into clusters. In this paper, a survey on cluster-based routing schemes for WSNs has been done and comparisons made on the basis of performance factors such as latency, scalability, and energy awareness. Strengths and limitations of each scheme are presented, and open issues that must be addressed in the design of cluster-based routing algorithms are discussed.
Yaser Hassan Dewir,Yu Rangcai,Fan Yanping,Mohammad Babar Ali,Kee Yoeup Paek 한국원예학회 2005 Horticulture, Environment, and Biotechnology Vol.46 No.5
This study was conducted to investigate the response of carnation (Dianthus caryophyllus cv. Oldrush) suspension cell to high temperature and gamma (γ) rays. Carnation cells were exposed to different doses of γ-radiation (0-6000 rad). Both radiated and non-radiated cells grown at 25℃ were then exposed to the temperature treatments of 35℃ (continuous exposure for 2 weeks), 45℃ (exposure 5 h/day for 2 weeks), and 55℃ (exposure for 1 h). The activities of reactive oxygen species scavenging enzymes (superoxide dismutase, catalase, and peroxidase), cell viability, and proline content were determined. The results showed that γ-radiation treatments protected carnation cells against the progressive oxidative damage by high temperature stress. The continuous exposure to heat stress could be more favorable to obtain tolerant cells. This tolerance has been indicated by increased accumulation of free proline and antioxidative activity, which are considered as a protective physiological response to high temperature stress.