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The Scientific World Journal
Volume 2012 (2012), Article ID 982957, 15 pages
http://dx.doi.org/10.1100/2012/982957
Research Article

Zinc Affects Differently Growth, Photosynthesis, Antioxidant Enzyme Activities and Phytochelatin Synthase Expression of Four Marine Diatoms

1Mer, Molécules, Santé, EA 2160, LUNAM Université, Faculté des Sciences et Techniques, Université du Maine, Avenue Olivier Messiaen, 72085 Le Mans cedex 9, France
2Laboratory of Plant Physiology, Department of Biology, University of Education of Ho Chi Minh City, 5th District, 280 An Duong Vuong, Ho Chi Minh City, Vietnam
3Plant Physiology Department, Faculty of Biology, University of Natural Sciences, 227 Nguyen Van Cu, 5th District, Ho Chi Minh City, Vietnam

Received 28 October 2011; Accepted 10 January 2012

Academic Editor: Mahir D. Mamedov

Copyright © 2012 Thi Le Nhung Nguyen-Deroche et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Zinc-supplementation (20 μM) effects on growth, photosynthesis, antioxidant enzyme activities (superoxide dismutase, ascorbate peroxidase, catalase), and the expression of phytochelatin synthase gene were investigated in four marine diatoms (Amphora acutiuscula, Nitzschia palea, Amphora coffeaeformis and Entomoneis paludosa). Zn-supplementation reduced the maximum cell density. A linear relationship was found between the evolution of gross photosynthesis and total chlorophyll content. The Zn treatment decreased the electron transport rate except in A. coffeaeformis and in E. paludosa at high irradiance. A linear relationship was found between the efficiency of light to evolve oxygen and the size of the light-harvesting antenna. The external carbonic anhydrase activity was stimulated in Zn-supplemented E. paludosa but was not correlated with an increase of photosynthesis. The total activity of the antioxidant enzymes did not display any clear increase except in ascorbate peroxidase activity in N. palea. The phytochelatin synthase gene was identified in the four diatoms, but its expression was only revealed in N. palea, without a clear difference between control and Zn-supplemented cells. Among the four species, A. paludosa was the most sensitive and A. coffeaeformis, the most tolerant. A. acutiuscula seemed to be under metal starvation, whereas, to survive, only N. palea developed several stress responses.