Document Detail

The formation of Zn-Chl a in Chlorella heterotrophically grown in the dark with an excessive amount of Zn2+.
MedLine Citation:
PMID:  15753102     Owner:  NLM     Status:  MEDLINE    
Chlorella, when heterotrophically cultivated in the dark, is able to grow with Zn2+ at 10-40 mM, which is 10 times the concentration lethal to autotrophically grown cells. However, the lag phase is prolonged with increasing concentrations of Zn2+; for example, in this study, 1 d of the control lag phase was prolonged to about 16 d with Zn2+ at 16.7 mM (x2,000 of the control). Once the cells started to grow, the log phase was finished within 4-6 d regardless of Zn concentration, which was almost the same as that of the control. The photosysystem I reaction center chlorophyll, P700, and the far-red fluorescence were detected only after the late log phase of the growth curve, suggesting that chlorophyll-protein complexes can be organized after cell division has ceased. Interestingly, at more than 16.7 mM of Zn2+, Zn-chlorophyll a was accumulated and finally accounted for about 25% of the total chlorophyll a in the late stationary phase. We found that the Zn-chlorophyll a was present in the thylakoid membranes and not in the soluble fractions of the cells. The rather low fluorescence yield at around 680 nm in the stationary phase suggests that Zn-chlorophyll a can transfer its excitation energy to other chlorophylls. Before accumulation of Zn-chlorophyll a, a marked amount of pheophytin a was temporally accumulated, suggesting that Zn-chlorophyll a could be chemically synthesized via pheophytin a.
Isamu Ikegami; Aki Nemoto; Kohki Sakashita
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-03-07
Journal Detail:
Title:  Plant & cell physiology     Volume:  46     ISSN:  0032-0781     ISO Abbreviation:  Plant Cell Physiol.     Publication Date:  2005 May 
Date Detail:
Created Date:  2005-05-26     Completed Date:  2005-09-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9430925     Medline TA:  Plant Cell Physiol     Country:  Japan    
Other Details:
Languages:  eng     Pagination:  729-35     Citation Subset:  IM    
Faculty of Pharmaceutical Sciences, Teikyo University, Sagamiko, Kanagawa, 199-0195 Japan.
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MeSH Terms
Cell Division / drug effects,  physiology
Chlorella / drug effects*,  growth & development,  metabolism*
Chlorophyll / biosynthesis*,  chemistry
Dose-Response Relationship, Drug
Pheophytins / metabolism
Photosynthetic Reaction Center Complex Proteins / drug effects*,  metabolism
Photosystem I Protein Complex / drug effects,  metabolism
Thylakoids / drug effects,  metabolism
Zinc / metabolism,  pharmacology*
Reg. No./Substance:
0/Pheophytins; 0/Photosynthetic Reaction Center Complex Proteins; 0/Photosystem I Protein Complex; 1406-65-1/Chlorophyll; 479-61-8/chlorophyll a; 603-17-8/pheophytin a; 7440-66-6/Zinc

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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