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Rhythmic and sustained oscillations in metabolism and gene expression of Cyanothece sp ATCC 51142 under constant light

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Title Rhythmic and sustained oscillations in metabolism and gene expression of Cyanothece sp ATCC 51142 under constant light
 
Creator GAUDANA, SB
KRISHNAKUMAR, S
ALAGESAN, S
DIGMURTI, MG
VISWANATHAN, GA
CHETTY, M
WANGIKAR, PP
 
Subject diazotrophic cyanobacteria
diurnal rhythm
kaiC
nit RT-PCR
SP STRAIN ATCC-51142
UNICELLULAR DIAZOTROPHIC CYANOBACTERIUM
CIRCADIAN CLOCK
PCC 7942
TRANSCRIPTIONAL REGULATION
SYNECHOCOCCUS-ELONGATUS
MIXOTROPHIC CONDITIONS
CULTURE
PHASE
DARK
 
Description Cyanobacteria, a group of photosynthetic prokaryotes, oscillate between day and nighttime metabolisms with concomitant oscillations in gene expression in response to light/dark cycles (LD).The oscillations in gene expression have been shown to sustain in constant light (LL) with a free running period of 24 h in a model cyanobacterium Synechococcus elongatus PCC 7942. However, equivalent oscillations in metabolism are not reported under LL in this non-nitrogen fixing cyanobacterium. Here we focus on Cyanothece sp. ATCC 51142, a unicellular, nitrogen-fixing cyanobacterium known to temporally separate the processes of oxygenic photosynthesis and oxygen-sensitive nitrogen fixation. In a recent report, metabolism of Cyanothece 51142 has been shown to oscillate between photosynthetic and respiratory phases under LL with free running periods that are temperature dependent but significantly shorter than the circadian period. Further, the oscillations shift to circadian pattern at moderate cell densities that are concomitant with slower growth rates. Here we take this understanding forward and demonstrate that the ultradian rhythm under LL sustains at much higher cell densities when grown under turbulent regimes that simulate flashing light effect. Our results suggest that the ultradian rhythm in metabolism may be needed to support higher carbon and nitrogen requirements of rapidly growing cells under LL. With a comprehensive Real time PCR based gene expression analysis we account for key regulatory interactions and demonstrate the interplay between clock genes and the genes of key metabolic pathways. Further, we observe that several genes that peak at dusk in Synechococcus peak at dawn in Cyanothece and vice versa. The circadian rhythm of this organism appears to be more robust with peaking of genes in anticipation of the ensuing photosynthetic and respiratory metabolic phases.
 
Publisher FRONTIERS RESEARCH FOUNDATION
 
Date 2014-10-16T13:48:09Z
2014-10-16T13:48:09Z
2013
 
Type Article
 
Identifier FRONTIERS IN MICROBIOLOGY, 4
http://dx.doi.org/10.3389/fmicb.2013.00374
http://dspace.library.iitb.ac.in/jspui/handle/100/15705
 
Language en