| Photo-oxidative stress impacts the expression of genes encoding iron metabolism components in Chlamydomonas. | |
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MedLine Citation:
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PMID: 19067961 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Chlamydomonas, like other organisms, regulates iron assimilation very tightly through differential expression of iron assimilation components. Nevertheless, in the presence of excess iron, cells do overaccumulate iron but without an evident phenotype. As iron toxicity is attributed to reactive oxygen species, we tested the impact of photon flux density (PFD) on cells with increased iron content. We noted that growth at > 500 micromol m(-2) s(-1) is inhibited as iron content of the medium is increased, suggesting that high light exacerbates the systems of iron toxicity and vice versa. Cells grown in high light selectively down-regulate the abundance of iron assimilation components, ferroxidase and FEA1, and storage protein ferritin1. At the RNA level, the abundance of ferroxidase (FOX1), iron reductase (FRE1), iron assimilatory protein (FEA1) and ferritin (FER1) mRNAs is also decreased. The time course of the response to high light compared to the response to Rose Bengal and H2O2 treatments suggests that both singlet oxygen and H2O2 may be implicated in the high light response. This hypothesis is supported by the recapitulation of some but not all of the high light responses in the carotenoid-deficient, high light-sensitive npq1lor1 strain. We conclude that responses to iron nutrition and PFD are connected, and the determination of an optimum for photosynthetic growth for each is dependent on the other. This work defines a fourth stage of iron nutrition in Chlamydomonas, the iron excess situation, which can be molecularly and physiologically distinguished from the iron-limited, iron-deficient and iron-replete stages, described previously. |
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Authors:
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Joanne C Long; Sabeeha S Merchant |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S. |
Journal Detail:
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Title: Photochemistry and photobiology Volume: 84 ISSN: 0031-8655 ISO Abbreviation: Photochem. Photobiol. Publication Date: 2008 Nov-Dec |
Date Detail:
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Created Date: 2008-12-10 Completed Date: 2009-02-03 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0376425 Medline TA: Photochem Photobiol Country: United States |
Other Details:
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Languages: eng Pagination: 1395-403 Citation Subset: IM |
Affiliation:
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Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Chlamydomonas / genetics, metabolism* Gene Expression Regulation Iron / metabolism* Oxidative Stress* Photochemistry |
| Chemical | |
Reg. No./Substance:
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7439-89-6/Iron |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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