Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

A Nitrate-Induced frq-Less Oscillator in Neurospora crassa

A Nitrate-Induced frq-Less Oscillator in Neurospora crassa When nitrate is the only nitrogen source, Neurospora crassa’s nitrate reductase (NR) shows endogenous oscillations in its nitrate reductase activity (NRA) on a circadian time scale. TheseNRAoscillations can be observed in darkness or continuous light conditions and also in a frq9 mutant in which no functional FRQ protein is formed. Even in a white-collar-1 knockout mutant, NRA oscillations have been observed, although with a highly reduced amplitude. This indicates that the NRAoscillations are not a simple output rhythm of the whitecollar–driven frq oscillator but may be generated by another oscillator that contains the nit-3 autoregulatory negative feedback loop as a part. In this negative feedback loop, a product in the reaction chain catalyzed by nitrate reductase, probably glutamine, induces repression of the nitrate reductase gene and thus downregulates its own production. This is the first example of an endogenous, nutritionally induced daily rhythm with known molecular components that is observed in the absence of an intact FRQ protein. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Biological Rhythms SAGE

Loading next page...
 
/lp/sage/a-nitrate-induced-frq-less-oscillator-in-neurospora-crassa-FUHuo2qvbe

References (50)

Publisher
SAGE
Copyright
Copyright © by SAGE Publications
ISSN
0748-7304
eISSN
1552-4531
DOI
10.1177/0748730404265532
pmid
15245647
Publisher site
See Article on Publisher Site

Abstract

When nitrate is the only nitrogen source, Neurospora crassa’s nitrate reductase (NR) shows endogenous oscillations in its nitrate reductase activity (NRA) on a circadian time scale. TheseNRAoscillations can be observed in darkness or continuous light conditions and also in a frq9 mutant in which no functional FRQ protein is formed. Even in a white-collar-1 knockout mutant, NRA oscillations have been observed, although with a highly reduced amplitude. This indicates that the NRAoscillations are not a simple output rhythm of the whitecollar–driven frq oscillator but may be generated by another oscillator that contains the nit-3 autoregulatory negative feedback loop as a part. In this negative feedback loop, a product in the reaction chain catalyzed by nitrate reductase, probably glutamine, induces repression of the nitrate reductase gene and thus downregulates its own production. This is the first example of an endogenous, nutritionally induced daily rhythm with known molecular components that is observed in the absence of an intact FRQ protein.

Journal

Journal of Biological RhythmsSAGE

Published: Aug 1, 2004

There are no references for this article.