| The chemokinetic and chemotactic behavior of Rhodobacter sphaeroides: two independent responses. | |
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MedLine Citation:
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PMID: 8282697 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Rhodobacter sphaeroides exhibits two behavioral responses when exposed to some compounds: (i) a chemotactic response that results in accumulation and (ii) a sustained increase in swimming speed. This latter chemokinetic response occurs without any apparent long-term change in the size of the electrochemical proton gradient. The results presented here show that the chemokinetic response is separate from the chemotactic response, although some compounds can induce both responses. Compounds that caused only chemokinesis induced a sustained increase in the rate of flagellar rotation, but chemoeffectors which were also chemotactic caused an additional short-term change in both the stopping frequency and the duration of stops and runs. The response to a change in chemoattractant concentration was a transient increase in the stopping frequency when the concentration was reduced, with adaptation taking between 10 and 60 s. There was also a decrease in the stopping frequency when the concentration was increased, but adaptation took up to 60 min. The nature and duration of both the chemotactic and chemokinetic responses were concentration dependent. Weak organic acids elicited the strongest chemokinetic responses, and although many also caused chemotaxis, there were conditions under which chemokinesis occurred in the absence of chemotaxis. The transportable succinate analog malonate caused chemokinesis but not chemotaxis, as did acetate when added to a mutant able to transport but not grow on acetate. Chemokinesis also occurred after incubation with arsenate, conditions under which chemotaxis was lost, indicating that phosphorylation at some level may have a role in chemotaxis. Aspartate was the only chemoattractant amino acid to cause chemokinesis. Glutamate caused chemotaxis but not chemokinesis. These data suggest that (i) chemotaxis and chemokinesis are separate responses, (ii) metabolism is required for chemotaxis but not chemokinesis, (iii) a reduction in chemoattractant concentration may cause the major chemotactic signal, and (iv) a specific transport pathway(s) may be involved in chemokinetic signalling in R. sphaeroides. |
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Authors:
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H L Packer; J P Armitage |
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Publication Detail:
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Type: Comparative Study; Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Journal of bacteriology Volume: 176 ISSN: 0021-9193 ISO Abbreviation: J. Bacteriol. Publication Date: 1994 Jan |
Date Detail:
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Created Date: 1994-02-14 Completed Date: 1994-02-14 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 2985120R Medline TA: J Bacteriol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 206-12 Citation Subset: IM |
Affiliation:
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Department of Biochemistry, University of Oxford, England. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Arsenates
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pharmacology Carboxylic Acids / pharmacology Cell Adhesion Cell Movement / drug effects, physiology Chemotaxis / drug effects, physiology* Dose-Response Relationship, Drug Image Processing, Computer-Assisted Monosaccharides / pharmacology Rhodobacter sphaeroides / drug effects, physiology* Time Factors |
| Grant Support | |
ID/Acronym/Agency:
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//Wellcome Trust |
| Chemical | |
Reg. No./Substance:
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0/Arsenates; 0/Carboxylic Acids; 0/Monosaccharides; 7631-89-2/sodium arsenate |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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