NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Ecological physiology of Synechococcus sp. strain SH-94-5, a naturally occurring cyanobacterium deficient in nitrate assimilationSynechococcus sp. strain SH-94-5 is a nitrate assimilation-deficient cyanobacterium which was isolated from an ammonium-replete hot spring in central Oregon. While this clone could grow on ammonium and some forms of organic nitrogen as sole nitrogen sources, it could not grow on either nitrate or nitrite, even under conditions favoring passive diffusion. It was determined that this clone does not express functional nitrate reductase or nitrite reductase and that the lack of activity of either enzyme is not due to inactivation of the cyanobacterial nitrogen control protein NtcA. A few other naturally occurring cyanobacterial strains are also nitrate assimilation deficient, and phylogenetic analyses indicated that the ability to utilize nitrate has been independently lost at least four times during the evolutionary history of the cyanobacteria. This phenotype is associated with the presence of environmental ammonium, a negative regulator of nitrate assimilation gene expression, which may indicate that natural selection to maintain functional copies of nitrate assimilation genes has been relaxed in these habitats. These results suggest how the evolutionary fates of conditionally expressed genes might differ between environments and thereby effect ecological divergence and biogeographical structure in the microbial world.
Document ID
20040112389
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Miller, S. R.
(University of Oregon Eugene, Oregon 97403, United States)
Castenholz, R. W.
Date Acquired
August 21, 2013
Publication Date
July 1, 2001
Publication Information
Publication: Applied and environmental microbiology
Volume: 67
Issue: 7
ISSN: 0099-2240
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other

Available Downloads

There are no available downloads for this record.
No Preview Available