| 2-Methylhopanoids are maximally produced in akinetes of Nostoc punctiforme: geobiological implications. | |
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MedLine Citation:
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PMID: 19811542 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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2-Methylhopanes, molecular fossils of 2-methylbacteriohopanepolyol (2-MeBHP) lipids, have been proposed as biomarkers for cyanobacteria, and by extension, oxygenic photosynthesis. However, the robustness of this interpretation is unclear, as 2-methylhopanoids occur in organisms besides cyanobacteria and their physiological functions are unknown. As a first step toward understanding the role of 2-MeBHP in cyanobacteria, we examined the expression and intercellular localization of hopanoids in the three cell types of Nostoc punctiforme: vegetative cells, akinetes, and heterocysts. Cultures in which N. punctiforme had differentiated into akinetes contained approximately 10-fold higher concentrations of 2-methylhopanoids than did cultures that contained only vegetative cells. In contrast, 2-methylhopanoids were only present at very low concentrations in heterocysts. Hopanoid production initially increased threefold in cells starved of nitrogen but returned to levels consistent with vegetative cells within 2 weeks. Vegetative and akinete cell types were separated into cytoplasmic, thylakoid, and outer membrane fractions; the increase in hopanoid expression observed in akinetes was due to a 34-fold enrichment of hopanoid content in their outer membrane relative to vegetative cells. Akinetes formed in response either to low light or phosphorus limitation, exhibited the same 2-methylhopanoid localization and concentration, demonstrating that 2-methylhopanoids are associated with the akinete cell type per se. Because akinetes are resting cells that are not photosynthetically active, 2-methylhopanoids cannot be functionally linked to oxygenic photosynthesis in N. punctiforme. |
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Authors:
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D M Doughty; R C Hunter; R E Summons; D K Newman |
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. Date: 2009-10-07 |
Journal Detail:
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Title: Geobiology Volume: 7 ISSN: 1472-4669 ISO Abbreviation: Geobiology Publication Date: 2009 Dec |
Date Detail:
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Created Date: 2009-11-17 Completed Date: 2010-01-12 Revised Date: 2010-09-27 |
Medline Journal Info:
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Nlm Unique ID: 101185472 Medline TA: Geobiology Country: England |
Other Details:
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Languages: eng Pagination: 524-32 Citation Subset: IM |
Affiliation:
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Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Cell Membrane
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chemistry Molecular Structure Nostoc / chemistry, growth & development*, metabolism* Triterpenes / metabolism* |
| Grant Support | |
ID/Acronym/Agency:
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//Howard Hughes Medical Institute; //Howard Hughes Medical Institute |
| Chemical | |
Reg. No./Substance:
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0/Triterpenes; 471-62-5/hopane |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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