HR: 0800h
AN: B21B-0886    [Abstracts]
TI: Influence of iron deficiency on the growth rate and physiological state of Prorocentrum micans Ehrenberg
AU: * Huan-Xin, W
EM: gswenghx@zju.edu.cn
AF: Institute of Environment & Biogeochemistry, Zhejiang University, Hangzhou, 310027 China
AU: Xiang-Wei, S
AF: Institute of Environment & Biogeochemistry, Zhejiang University, Hangzhou, 310027 China
AU: Jing-Ke, W
EM: wengj@purdue.edu
AF: Department of Biochemistry, Purdue University, West Lafayette, IN 47907-1153 United States
AU: Ya-Chao, Q
AF: Institute of Environment & Biogeochemistry, Zhejiang University, Hangzhou, 310027 China
AB: Previous researches had shown that iron is an important limiting element to marine primary production. However, the mechanism of how iron affects marine algae is not well understood. Prorocentrum micans Ehrenberg is an armoured marine planktonic dinoflagellate, which causes harmful red tide when blooming. In this research, we discussed the mechanism of iron deficiency affecting the growth rate and physiological state of P. micans Ehrenberg, based on the observation of the growth of P. micans Ehrenberg under iron deficiency. The results showed that the growth rate of P. micans Ehrenberg decreased under iron deficiency, as the time to reach the peak of cell numbers was delayed 3-4 days compared to the control group. Meanwhile, the maximal cell number and the concentration of chlorophyll a dropped slightly. Examination of cell morphology by transmission electron microscope showed that the arrangement of P. micans Ehrenberg chloroplast granum was disturbed under iron deficiency. The thylakoids exhibited twisted structure with larger interstices among the thylakoid layers. Chloroplast membrane system folded abnormally and fewer starch particles were synthesized and accumulated compared to the control group. In addition, many cavities appeared in mitochondria, and a few cells developed incomplete nuclear envelop. The energy spectrogram of the algal cells showed that the relative ratio of the contents of the elements in cell also changed as the degree of iron deficiency changed. The iron deficiency-induced morphological changes of P. micans Ehrenberg cell organelles may be due to the misfolding of some core proteins that originally require iron ion as folding center. The structural abnormality of the major cell organelles further led to the functional retardation or loss in photosynthesis, electron transport, and metabolism, which blocks normal growth of P. micans Ehrenberg. Taken together, the research helped to improve our understanding on the limiting effects of iron on marine algae growth and proposed a potential way to control red tides caused by algae blooming.
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting