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Effect of salt on malondialdehyde and antioxidant enzymes in seedling roots of Jerusalem artichoke (Helianthus tuberosus L.)

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Chen Q. , Zhang M. , Shen S.

Acta Physiologiae Plantarum

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2011

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tom 33

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nr 2

EN

Two cultivars of Jerusalem artichoke (Helianthus tuberosus L.) differing in genotype, Red skin (cv. R., salt-tolerant but low-yield) and White skin (cv. W., salt-sensitive but high-yield), were used to investigate malondialdehyde (MDA) content and antioxidant enzyme activity changes in their roots under a hydroponic culture system with 250 mM NaCl. The results showed that MDA contents in roots of the two genotypes increased, but MDA content of cv. R. was higher than that of cv. W. Changes in all antioxidant enzymes in roots of both varieties exhibited a similar trend, namely increased initially and then decreased. However, there were still some differences existing between the two cultivars. In other words, activities of the other two antioxidant enzymes except catalase (CAT) and peroxidase (POD) in roots of cv. R. were less than controls at 48 h, while all others except ascorbate peroxidase (APX) in roots of cv. W. were greater than controls. The peak of superoxide dismutase (SOD) activity of cv. W. was observed to appear earlier than that of cv. R. CAT activity of cv. W. was significantly greater than the value of cv. R. and the latter showed a moderate trend. POD activity of cv. R. obtained the maximum at 6 h, whereas the peak of cv. W. displayed at 24 h. APX activity of cv. R. declined more than that of cv. W. These results suggested that there was a lower efficiency of scavenging reactive oxygen species (ROS) in cv. R. roots. Concomitantly, salt stress caused more severe damage to roots of cv. R. Antioxidant enzymes in roots were inadequate to elucidate salt-tolerance mechanisms of the whole plant.

2

Numerical investigation of the undrained compression and pull-out capacity of suction foudations in clay

100%

Du J. , Du S. , Shen S. , Yin Z.

Polish Maritime Research

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2015

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tom 22

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nr Special Issue S1

EN

This paper presents the results of three-dimensional finite difference analysis of suction foundations in uniform and non-uniform clays under undrained conditions. The Tresca criterion was used to simulate the stress-strain response. The bearing capacity of the foundations was investigated, with the degree of nonhomogeneity (kD/sum) of soil varying from 0 to 5, and the embedment depth being up to four times the foundation diameter. The end bearing capacity factor in compression and the reverse bearing capacity factor in tension were both calculated and were compared with each other under different foundation displacements. Numerical results showed that the ultimate bearing capacity factor can have the same value in cases of both compression and tension. The recommended ultimate bearing capacity factor is determined on the basis of the embedment ratio and displacement magnitude, and the displacement is not more than 30% of the foundation diameter. Finally, two equations are proposed to evaluate both the bearing capacity factor and the effective depth factor

3

Physiological responses of two Jerusalem artichoke cultivars to drought stress induced by polyethylene glycol

100%

Zhang M. , Chen Q. , Shen S.

Acta Physiologiae Plantarum

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2011

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tom 33

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nr 2

EN

Physiological responses of two Jerusalem artichoke (Helianthus tuberosus L.) cultivars with different drought sensitivity to drought stress induced by polyethylene glycol (PEG) 6000 were investigated by characterizing water status, membrane lipid peroxidation, key antioxidant enzymes activity, and proline accumulation. It was observed that the drought-tolerant Jerusalem artichoke cv. Xiuyan maintained a relatively higher water status than the drought-sensitive cv. Yulin upon drought treatments. Meanwhile, lower levels of malondialdehyde (MDA) as well as higher levels of free proline occurred in cv. Xiuyan after 36 h drought treatments. Moreover, the activities of catalase (CAT) and superoxide dismutase (SOD) in cv. Xiuyan were higher than cv. Yulin after drought stress. These results indicated that drought sensitivities actually differ between Jerusalem artichoke cv. Xiuyan and cv. Yulin, and the cv. Xiuyan was more tolerant to drought stress caused by polyethylene glycol.

4

Effects of ZnO, CuO, Au, and TiO2 nanoparticles on Daphnia magna and early life stages of zebrafish danio rerio

75%

Liu J. , Fan D. , Wang L. , Shi L. , Ding J. , Chen Y. , Shen S.

Environment Protection Engineering

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2014

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tom Vol. 40, nr 1

139--149

EN

The effects of four different kinds of nanoparticles (NPs), namely, CuO, ZnO, TiO2, and Au, of the sizes ranging from <20 nm to 50 nm on Daphnia magna, early life stage of zebrafish, and various enzymes have been investigated. The experimental results showed that the NPs inhibited both the body length and hatching rate of zebrafish larvae; the small nanoparticles exhibited more toxicity. In a 21 day chronic toxicity test, metal ions of higher concentrations significantly reduced the number of Daphnia magna offspring. Studies on enzyme activity showed that the NPs reduced the glutathione content and inhibited catalase and superoxide dismutase activities, resulting in shorter body length, lower hatching success, and lower reproduction of zebrafish larvae. Therefore, studies should focus more on the potential toxicity of smaller NPs.

5

Al-induced secretion of organic acid, gene expression and root elongation in soybean roots

63%

Wu D. , Zhao M. , Shen S. , Fu Y. , Sasaki T. , Yamamoto Y. , Wei W. , Shen H.

Acta Physiologiae Plantarum

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2013

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tom 35

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nr 01

EN

Al-activated organic acid transporter genes (ALMT and MATE) and plasma membrane H?-ATPase gene (PHA) are known to contribute to the regulation of organic acid secretion in several crops. However, it remains unclear how these genes interact to modulate organic acid exudation in the same plant species. In this study, Al-induced expression of genes (GmALMT1, GmMATE1 and GmPHA1), secretion of organic acid and root elongation were characterized in soybean roots. Results indicated that treatment with 50 lM Al activated the expression of GmALMT1, GmMATE1 and GmPHA1, and the exudation of citrate and malate significantly in apical 5 mm region of soybean seedlings, but inhibited root elongation by 57.8 %. The highest malate exudation rate and the maximal expression of GmALMT1 and GmPHA1 were observed after 2 h of 50 lM Al treatment, while the corresponding values for citrate exudation rate and GmMATE1 expression occurred at 8 h. The exudation of malate and citrate contributed to but could not recover Al-triggered root elongation. A root-split experiment indicated that Al-activated gene expression, organic acid secretion and root growth inhibition required the direct contact of Al3?. The removal of shoots in soybean seedlings decreased Al-activated gene expression by 26.1–40.5 %, and secretion of organic acid by 14.7–40.2 %. Furthermore, shoot excision aggravated Al-inhibited root elongation, indicating the existence of other Al tolerance mechanism except the exudation of organic acid. These results suggested that Al-activated expression of GmPHA1-, GmMATE1- and GmALMT1-mediated exudation of malate and citrate, and shoots played an important role in Al toxicity resistance in soybean roots.